Machine Learning Predicts Oxaliplatin Benefit in Early Colon Cancer

PURPOSE

A combination of fluorouracil, leucovorin, and oxaliplatin (FOLFOX) is the standard for adjuvant therapy of resected early-stage colon cancer (CC). Oxaliplatin leads to lasting and disabling neurotoxicity. Reserving the regimen for patients who benefit from oxaliplatin would maximize efficacy and minimize unnecessary adverse side effects.

METHODS

We trained a new machine learning model, referred to as the colon oxaliplatin signature (COLOXIS) model, for predicting response to oxaliplatin-containing regimens. We examined whether COLOXIS was predictive of oxaliplatin benefits in the CC adjuvant setting among 1,065 patients treated with 5-fluorouracil plus leucovorin (FULV; n = 421) or FULV + oxaliplatin (FOLFOX; n = 644) from NSABP C-07 and C-08 phase III trials. The COLOXIS model dichotomizes patients into COLOXIS+ (oxaliplatin responder) and COLOXIS- (nonresponder) groups. Eight-year recurrence-free survival was used to evaluate oxaliplatin benefits within each of the groups, and the predictive value of the COLOXIS model was assessed using the P value associated with the interaction term (int P) between the model prediction and the treatment effect.

RESULTS

Among 1,065 patients, 526 were predicted as COLOXIS+ and 539 as COLOXIS-. The COLOXIS+ prediction was associated with prognosis for FULV-treated patients (hazard ratio [HR], 1.52 [95% CI, 1.07 to 2.15]; P = .017). The model was predictive of oxaliplatin benefits: COLOXIS+ patients benefited from oxaliplatin (HR, 0.65 [95% CI, 0.48 to 0.89]; P = .0065; int P = .03), but COLOXIS- patients did not (COLOXIS- HR, 1.08 [95% CI, 0.77 to 1.52]; P = .65).

CONCLUSION

The COLOXIS model is predictive of oxaliplatin benefits in the CC adjuvant setting. The results provide evidence supporting a change in CC adjuvant therapy: reserve oxaliplatin only for COLOXIS+ patients, but further investigation is warranted.

Breast Cancer Index and Prediction of Extended Aromatase Inhibitor Therapy Benefit in Hormone Receptor-Positive Breast Cancer from the NRG Oncology/NSABP B-42 Trial

PURPOSE

BCI (H/I) has been shown to predict extended endocrine therapy (EET) benefit. We examined BCI (H/I) for EET benefit prediction in NSABP B-42, which evaluated extended letrozole therapy (ELT) in patients with hormone receptor-positive breast cancer after 5 years of ET.

EXPERIMENTAL DESIGN

A stratified Cox model was used to analyze RFI as the primary endpoint, with DR, BCFI, and DFS as secondary endpoints. Because of a nonproportional effect of ELT on DR, time-dependent analyses were performed.

RESULTS

The translational cohort included 2,178 patients (45% BCI (H/I)-High, 55% BCI (H/I)-Low). ELT showed an absolute 10-year RFI benefit of 1.6% (P = 0.10), resulting in an underpowered primary analysis (50% power). ELT benefit and BCI (H/I) did not show a significant interaction for RFI (BCI (H/I)-Low: 10 years absolute benefit 1.1% [HR, 0.70; 95% confidence interval (CI), 0.43-1.12; P = 0.13]; BCI (H/I)-High: 2.4% [HR, 0.83; 95% CI, 0.55-1.26; P = 0.38]; Pinteraction = 0.56). Time-dependent DR analysis showed that after 4 years, BCI (H/I)-High patients had significant ELT benefit (HR = 0.29; 95% CI, 0.12-0.69; P < 0.01), whereas BCI (H/I)-Low patients were less likely to benefit (HR, 0.68; 95% CI, 0.33-1.39; P = 0.29; Pinteraction = 0.14). Prediction of ELT benefit by BCI (H/I) was more apparent in the HER2- subset after 4 years (ELT-by-BCI (H/I) Pinteraction = 0.04).

CONCLUSIONS

BCI (H/I)-High versus BCI (H/I)-Low did not show a statistically significant difference in ELT benefit for the primary endpoint (RFI). However, in time-dependent DR analysis, BCI (H/I)-High patients experienced statistically significant benefit from ELT after 4 years, whereas (H/I)-Low patients did not. Because BCI (H/I) has been validated as a predictive marker of EET benefit in other trials, additional follow-up may enable further characterization of BCI's predictive ability.

NSABP FB-10: a phase Ib/II trial evaluating ado-trastuzumab emtansine (T-DM1) with neratinib in women with metastatic HER2-positive breast cancer

BACKGROUND

We previously reported our phase Ib trial, testing the safety, tolerability, and efficacy of T-DM1 + neratinib in HER2-positive metastatic breast cancer patients. Patients with ERBB2 amplification in ctDNA had deeper and more durable responses. This study extends these observations with in-depth analysis of molecular markers and mechanisms of resistance in additional patients.

METHODS

Forty-nine HER2-positive patients (determined locally) who progressed on-treatment with trastuzumab + pertuzumab were enrolled in this phase Ib/II study. Mutations and HER2 amplifications were assessed in ctDNA before (C1D1) and on-treatment (C2D1) with the Guardant360 assay. Archived tissue (TP0) and study entry biopsies (TP1) were assayed for whole transcriptome, HER2 copy number, and mutations, with Ampli-Seq, and centrally for HER2 with CLIA assays. Patient responses were assessed with RECIST v1.1, and Molecular Response with the Guardant360 Response algorithm.

RESULTS

The ORR in phase II was 7/22 (32%), which included all patients who had at least one dose of study therapy. In phase I, the ORR was 12/19 (63%), which included only patients who were considered evaluable, having received their first scan at 6 weeks. Central confirmation of HER2-positivity was found in 83% (30/36) of the TP0 samples. HER2-amplified ctDNA was found at C1D1 in 48% (20/42) of samples. Patients with ctHER2-amp versus non-amplified HER2 ctDNA determined in C1D1 ctDNA had a longer median progression-free survival (PFS): 480 days versus 60 days (P = 0.015). Molecular Response scores were significantly associated with both PFS (HR 0.28, 0.09-0.90, P = 0.033) and best response (P = 0.037). All five of the patients with ctHER2-amp at C1D1 who had undetectable ctDNA after study therapy had an objective response. Patients whose ctHER2-amp decreased on-treatment had better outcomes than patients whose ctHER2-amp remained unchanged. HER2 RNA levels show a correlation to HER2 CLIA IHC status and were significantly higher in patients with clinically documented responses compared to patients with progressive disease (P = 0.03).

CONCLUSIONS

The following biomarkers were associated with better outcomes for patients treated with T-DM1 + neratinib: (1) ctHER2-amp (C1D1) or in TP1; (2) Molecular Response scores; (3) loss of detectable ctDNA; (4) RNA levels of HER2; and (5) on-treatment loss of detectable ctHER2-amp. HER2 transcriptional and IHC/FISH status identify HER2-low cases (IHC 1+ or IHC 2+ and FISH negative) in these heavily anti-HER2 treated patients. Due to the small number of patients and samples in this study, the associations we have shown are for hypothesis generation only and remain to be validated in future studies. Clinical Trials registration NCT02236000.

Long-Term Follow-Up of the Anthracyclines in Early Breast Cancer Trials (USOR 06-090, NSABP B-46-I/USOR 07132, and NSABP B-49 [NRG Oncology])

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.The primary joint efficacy analysis of the Anthracyclines in Early Breast Cancer (ABC) trials reported in 2017 failed to demonstrate nonanthracycline adjuvant therapy was noninferior to anthracycline-based regimens in high-risk, early breast cancer. Full analyses of the studies had proceeded when the prespecified futility boundary was crossed at a planned futility analysis for the ability to demonstrate noninferiority of a nonanthracycline regimen with continued follow-up. These results were presented with 3.3 years of median follow-up. This manuscript reports results of the final analyses of the study efficacy end points conducted with 6.9 years of median follow-up. Long-term analysis of invasive disease-free survival (IDFS), the primary end point of the ABC trials, remains consistent with the original results, as noninferiority of the nonanthracycline regimens could not be declared on the basis of the original criteria. The secondary end point of recurrence-free interval, which excluded deaths not due to breast cancer as events, favored anthracycline-based regimens, and tests for heterogeneity were significant for hormone receptor status (P = .02) favoring anthracycline regimens for the hormone receptor-negative cohorts. There was no difference in overall survival, and review of the type of IDFS events in the groups suggested reductions in cancer recurrences achieved with anthracycline regimens were offset by late leukemias and deaths unrelated to breast cancer.

Radiotherapy to regional nodes in early breast cancer: an individual patient data meta-analysis of 14 324 women in 16 trials

BACKGROUND

Radiotherapy has become much better targeted since the 1980s, improving both safety and efficacy. In breast cancer, radiotherapy to regional lymph nodes aims to reduce risks of recurrence and death. Its effects have been studied in randomised trials, some before the 1980s and some after. We aimed to assess the effects of regional node radiotherapy in these two eras.

METHODS

In this meta-analysis of individual patient data, we sought data from all randomised trials of regional lymph node radiotherapy versus no regional lymph node radiotherapy in women with early breast cancer (including one study that irradiated lymph nodes only if the cancer was right-sided). Trials were identified through the EBCTCG's regular systematic searches of databases including MEDLINE, Embase, the Cochrane Library, and meeting abstracts. Trials were eligible if they began before Jan 1, 2009. The only systematic difference between treatment groups was in regional node radiotherapy (to the internal mammary chain, supraclavicular fossa, or axilla, or any combinations of these). Primary outcomes were recurrence at any site, breast cancer mortality, non-breast-cancer mortality, and all-cause mortality. Data were supplied by trialists and standardised into a format suitable for analysis. A summary of the formatted data was returned to trialists for verification. Log-rank analyses yielded first-event rate ratios (RRs) and confidence intervals.

FINDINGS

We found 17 eligible trials, 16 of which had available data (for 14 324 participants), and one of which (henceforth excluded), had unavailable data (for 165 participants). In the eight newer trials (12 167 patients), which started during 1989-2008, regional node radiotherapy significantly reduced recurrence (rate ratio 0·88, 95% CI 0·81-0·95; p=0·0008). The main effect was on distant recurrence as few regional node recurrences were reported. Radiotherapy significantly reduced breast cancer mortality (RR 0·87, 95% CI 0·80-0·94; p=0·0010), with no significant effect on non-breast-cancer mortality (0·97, 0·84-1·11; p=0·63), leading to significantly reduced all-cause mortality (0·90, 0·84-0·96; p=0·0022). In an illustrative calculation, estimated absolute reductions in 15-year breast cancer mortality were 1·6% for women with no positive axillary nodes, 2·7% for those with one to three positive axillary nodes, and 4·5% for those with four or more positive axillary nodes. In the eight older trials (2157 patients), which started during 1961-78, regional node radiotherapy had little effect on breast cancer mortality (RR 1·04, 95% CI 0·91-1·20; p=0·55), but significantly increased non-breast-cancer mortality (1·42, 1·18-1·71; p=0·00023), with risk mainly after year 20, and all-cause mortality (1·17, 1·04-1·31; p=0·0067).

INTERPRETATION

Regional node radiotherapy significantly reduced breast cancer mortality and all-cause mortality in trials done after the 1980s, but not in older trials. These contrasting findings could reflect radiotherapy improvements since the 1980s.

FUNDING

Cancer Research UK, Medical Research Council.

Ten-year update: NRG Oncology/National Surgical Adjuvant Breast and Bowel Project B-42 randomized trial: extended letrozole therapy in early-stage breast cancer

BACKGROUND

The National Surgical Adjuvant Breast and Bowel Project B-42 trial evaluated extended letrozole therapy (ELT) in postmenopausal breast cancer patients who were disease free after 5 years of aromatase inhibitor (AI)-based therapy. Seven-year results demonstrated a nonstatistically significant trend in disease-free survival (DFS) in favor of ELT. We present 10-year outcome results.

METHODS

In this double-blind, phase III trial, patients with stage I-IIIA hormone receptor-positive breast cancer, disease free after 5 years of an AI or tamoxifen followed by an AI, were randomly assigned to 5 years of letrozole or placebo. Primary endpoint was DFS, defined as time from random assignment to breast cancer recurrence, second primary malignancy, or death. All statistical tests are 2-sided.

RESULTS

Between September 2006 and January 2010, 3966 patients were randomly assigned (letrozole: 1983; placebo: 1983). Median follow-up time for 3923 patients included in efficacy analyses was 10.3 years. There was statistically significant improvement in DFS in favor of letrozole compared with placebo (hazard ratio [HR] = 0.85, 95% confidence interval [CI] = 0.74 to 0.96; P  = .01; 10-year DFS: placebo = 72.6%, letrozole = 75.9%, absolute difference = 3.3%). There was no difference in the effect of letrozole on overall survival (HR = 0.97, 95% CI = 0.82 to 1.15; P  = .74). Letrozole statistically significantly reduced breast cancer-free interval events (HR = 0.75, 95% CI = 0.62 to 0.91; P = .003; absolute difference in cumulative incidence = 2.7%) and distant recurrences (HR = 0.72, 95% CI = 0.55 to 0.92; P = .01; absolute difference = 1.8%). The rates of osteoporotic fractures and arterial thrombotic events did not differ between treatment groups.

CONCLUSIONS

The beneficial effect of ELT on DFS persisted at 10 years. Letrozole also improved breast cancer-free interval and distant recurrences without improving overall survival. Careful assessment of potential risks and benefits is necessary for selecting appropriate candidates for ELT.

Gene Expression and Benefit of Chemotherapy in Women With Node-Negative, Estrogen Receptor-Positive Breast Cancer

PURPOSE

The 21-gene recurrence score (RS) assay quantifies the likelihood of distant recurrence in women with estrogen receptor-positive, lymph node-negative breast cancer treated with adjuvant tamoxifen. The relationship between the RS and chemotherapy benefit is not known.

METHODS

The RS was measured in tumors from the tamoxifen-treated and tamoxifen plus chemotherapy-treated patients in the National Surgical Adjuvant Breast and Bowel Project (NSABP) B20 trial. Cox proportional hazards models were utilized to test for interaction between chemotherapy treatment and the RS.

RESULTS

A total of 651 patients were assessable (227 randomly assigned to tamoxifen and 424 randomly assigned to tamoxifen plus chemotherapy). The test for interaction between chemotherapy treatment and RS was statistically significant (P = .038). Patients with high-RS (≥ 31) tumors (ie, high risk of recurrence) had a large benefit from chemotherapy (relative risk, 0.26; 95% CI, 0.13 to 0.53; absolute decrease in 10-year distant recurrence rate: mean, 27.6%; SE, 8.0%). Patients with low-RS (< 18) tumors derived minimal, if any, benefit from chemotherapy treatment (relative risk, 1.31; 95% CI, 0.46 to 3.78; absolute decrease in distant recurrence rate at 10 years: mean, -1.1%; SE, 2.2%). Patients with intermediate-RS tumors did not appear to have a large benefit, but the uncertainty in the estimate can not exclude a clinically important benefit.

CONCLUSION

The RS assay not only quantifies the likelihood of breast cancer recurrence in women with node-negative, estrogen receptor-positive breast cancer, but also predicts the magnitude of chemotherapy benefit.

Re-Evaluation of Pathologic Complete Response as a Surrogate for Event-Free and Overall Survival in Human Epidermal Growth Factor Receptor 2-Positive, Early Breast Cancer Treated With Neoadjuvant Therapy Including Anti-Human Epidermal Growth Factor Receptor 2 Therapy

PURPOSE

Pathologic complete response (pCR) has prognostic importance and is frequently used as a primary end point, but doubts remain about its validity as a surrogate for event-free survival (EFS) and overall survival (OS) in human epidermal growth factor receptor 2 (HER2)-positive, early breast cancer.

METHODS

We obtained individual-patient data from randomized trials of neoadjuvant anti-HER2 therapy that enrolled at least 100 patients, had data for pCR, EFS, and OS, and a median follow-up of at least 3 years. We quantified the patient-level association between pCR (defined as ypT0/Tis ypN0) and both EFS and OS using odds ratios (ORs, with ORs >1.00 indicating a benefit from achieving a pCR). We quantified the trial-level association between treatment effects on pCR and on EFS and OS using R2 (with values above 0.75 considered as indicating strong associations).

RESULTS

Eleven of 15 eligible trials had data for analysis (3,980 patients, with a median follow-up of 62 months). Considering all trials, we found strong patient-level associations, with ORs of 2.64 (95% CI, 2.20 to 3.07) for EFS and 3.15 (95% CI, 2.38 to 3.91) for OS; however, trial-level associations were weak, with an unadjusted R2 of 0.23 (95% CI, 0 to 0.66) for EFS and 0.02 (95% CI, 0 to 0.17) for OS. We found qualitatively similar results when grouping trials according to different clinical questions, when analyzing only patients with hormone receptor-negative disease, and when using a more stringent definition of pCR (ypT0 ypN0).

CONCLUSION

Although pCR may be useful for patient management, it cannot be considered as a surrogate for EFS or OS in neoadjuvant trials of HER2-positive, operable breast cancer.

Replication of genetic associations of chemotherapy-related cardiotoxicity in the adjuvant NSABP B-31 clinical trial

Background

The cardiotoxic effects of doxorubicin, trastuzumab, and other anticancer agents are well known, but molecular genetic testing is lacking for the early identification of patients at risk for therapy-related cardiac toxicity.

Methods

Using the Agena Bioscience MassARRAY system, we genotyped TRPC6 rs77679196, BRINP1 rs62568637, LDB2 rs55756123, RAB22A rs707557, intergenic rs4305714, LINC01060 rs7698718, and CBR3 rs1056892 (V244M) (previously associated with either doxorubicin or trastuzumab-related cardiotoxicity in the NCCTG N9831 trial of anthracycline-based chemotherapy ± trastuzumab) in 993 patients with HER2+ early breast cancer from the NSABP B-31 trial of adjuvant anthracycline-based chemotherapy ± trastuzumab. Association analyses were performed with outcomes of congestive heart failure (N = 29) and maximum decline in left ventricular ejection fraction (LVEF) using logistic and linear regression models, respectively, under an additive model with age, baseline LVEF, and previous use of hypertensive medications as covariates.

Results

Associations of maximum decline in LVEF in the NCCTG N9831 patients did not replicate in the NSABP B-31 patients. However, TRPC6 rs77679196 and CBR3 rs1056892 were significantly associated with congestive heart failure, p < 0.05, with stronger associations observed in patients treated with chemotherapy only (no trastuzumab) or in the combined analysis of all patients relative to those patients treated with chemotherapy + trastuzumab.

Conclusions

TRPC6 rs77679196 and CBR3 rs1056892 (V244M) are associated with doxorubicin-induced cardiac events in both NCCTG N9831 and NSABP B-31. Other variants previously associated with trastuzumab-related decline in LVEF failed to replicate between these studies.

Pathologic Complete Response and Individual Patient Prognosis After Neoadjuvant Chemotherapy Plus Anti-Human Epidermal Growth Factor Receptor 2 Therapy of Human Epidermal Growth Factor Receptor 2-Positive Early Breast Cancer

PURPOSE

The achievement of pathologic complete response (pCR) is strongly prognostic for event-free survival (EFS) and overall survival (OS) in patients with early breast cancer (EBC), and adapting postneoadjuvant therapy improves long-term outcomes for patients with HER2-positive disease not achieving pCR. We sought to investigate prognostic factors for EFS and OS among patients with and without pCR after neoadjuvant systemic treatment consisting of chemotherapy plus anti-HER2 therapy.

MATERIALS AND METHODS

We used individual data from 3,710 patients randomly assigned in 11 neoadjuvant trials for HER2-positive EBC with ≥100 patients enrolled, available data for pCR, EFS, and OS, and follow-up ≥3 years. We assessed baseline clinical tumor size (cT) and clinical nodal status (cN) as prognostic factors using stratified (by trial and treatment) Cox models separately for hormone receptor-positive versus hormone receptor-negative disease, and for patients who had pCR (pCR+; ypT0/is, ypN0) versus patients who did not achieve a pCR (pCR-).

RESULTS

The median follow-up overall was 61.2 months. In pCR+ patients, cT and cN were significant independent prognostic factors for EFS, whereas only cT was a significant predictor for OS. In pCR- patients, cT, cN, and hormone receptor status were significant independent predictors for both EFS and OS. Regardless of hormone receptor status, cT, and cN, the 5-year EFS/OS rates were higher in pCR+ patients than in pCR- patients. In most subsets with regards to hormone receptor and pCR status, cT and cN were independent prognostic factors for both EFS and OS, including pCR+ patients.

CONCLUSION

These results confirm that patients achieving pCR have far better survival outcomes than patients who do not. The traditional poor prognostic features, namely tumor size and nodal status, remain important even after a pCR.

Biomarker Data from the Phase III KATHERINE Study of Adjuvant T-DM1 versus Trastuzumab for Residual Invasive Disease after Neoadjuvant Therapy for HER2-Positive Breast Cancer

PURPOSE

In KATHERINE, adjuvant T-DM1 reduced risk of disease recurrence or death by 50% compared with trastuzumab in patients with residual invasive breast cancer after neoadjuvant therapy (NAT) comprised of HER2-targeted therapy and chemotherapy. This analysis aimed to identify biomarkers of response and differences in biomarker expression before and after NAT.

EXPERIMENTAL DESIGN

Exploratory analyses investigated the relationship between invasive disease-free survival (IDFS) and HER2 protein expression/gene amplification, PIK3CA hotspot mutations, and gene expression of HER2, PD-L1, CD8, predefined immune signatures, and Prediction Analysis of Microarray 50 intrinsic molecular subtypes, classified by Absolute Intrinsic Molecular Subtyping. HER2 expression on paired pre- and post-NAT samples was examined.

RESULTS

T-DM1 appeared to improve IDFS versus trastuzumab across most biomarker subgroups, except the HER2 focal expression subgroup. High versus low HER2 gene expression in residual disease was associated with worse outcomes with trastuzumab [HR, 2.02; 95% confidence interval (CI), 1.32-3.11], but IDFS with T-DM1 was independent of HER2 expression level (HR, 1.01; 95% CI, 0.56-1.83). Low PD-L1 gene expression in residual disease was associated with worse outcomes with trastuzumab (HR, 0.66; 95% CI, 0.44-1.00), but not T-DM1 (HR, 1.05; 95% CI, 0.59-1.87). PIK3CA mutations were not prognostic. Increased variability in HER2 expression was observed in post-NAT versus paired pre-NAT samples.

CONCLUSIONS

T-DM1 appears to overcome HER2 resistance. T-DM1 benefit does not appear dependent on immune activation, but these results do not rule out an influence of the tumor immune microenvironment on the degree of response.

Population, Clinical, and Scientific Impact of National Cancer Institute's National Clinical Trials Network Treatment Studies

PURPOSE

In the United States, the National Cancer Institute National Cancer Clinical Trials Network (NCTN) groups have conducted publicly funded oncology research for 50 years. The combined impact of all adult network group trials has never been systematically examined.

METHODS

We identified randomized, phase III trials from the adult NCTN groups, reported from 1980 onward, with statistically significant findings for ≥ 1 clinical, time-dependent outcomes. In the subset of trials in which the experimental arm improved overall survival, gains in population life-years were estimated by deriving trial-specific hazard functions and hazard ratios to estimate the experimental treatment benefit and then mapping this trial-level benefit onto the US cancer population using registry and life-table data. Scientific impact was based on citation data from Google Scholar. Federal investment costs per life-year gained were estimated. The results were derived through December 31, 2020.

RESULTS

One hundred sixty-two trials comprised of 108,334 patients were analyzed, representing 29.8% (162/544) of trials conducted. The most common cancers included breast (34), gynecologic (28), and lung (14). The trials were cited 165,336 times (mean, 62.2 citations/trial/year); 87.7% of trials were cited in cancer care guidelines in favor of the recommended treatment. These studies were estimated to have generated 14.2 million (95% CI, 11.5 to 16.5 million) additional life-years to patients with cancer, with projected gains of 24.1 million (95% CI, 19.7 to 28.2 million) life-years by 2030. The federal investment cost per life-year gained through 2020 was $326 in US dollars.

CONCLUSION

NCTN randomized trials have been widely cited and are routinely included in clinical guidelines. Moreover, their conduct has predicted substantial improvements in overall survival in the United States for patients with oncologic disease, suggesting they have contributed meaningfully to this nation's health. These findings demonstrate the critical role of government-sponsored research in extending the lives of patients with cancer.

Effect of preoperative chemotherapy on the outcome of women with operable breast cancer

PURPOSE

To determine, in women with primary operable breast cancer, if preoperative doxorubicin (Adriamycin) and cyclophosphamide (Cytoxan; AC) therapy yields a better outcome than postoperative AC therapy, if a relationship exists between outcome and tumor response to preoperative chemotherapy, and if such therapy results in the performance of more lumpectomies.

PATIENTS AND METHODS

Women (1,523) enrolled onto National Surgical Adjuvant Breast and Bowel Project (NSABP) B-18 were randomly assigned to preoperative or postoperative AC therapy. Clinical tumor response to preoperative therapy was graded as complete (cCR), partial (cPR), or no response (cNR). Tumors with a cCR were further categorized as either pathologic complete response (pCR) or invasive cells (pINV). Disease-free survival (DFS), distant disease-free survival (DDFS), and survival were estimated through 5 years and compared between treatment groups. In the preoperative arm, proportional-hazards models were used to investigate the relationship between outcome and tumor response.

RESULTS

There was no significant difference in DFS, DDFS, or survival (P = .99, .70, and .83, respectively) among patients in either group. More patients treated preoperatively than postoperatively underwent lumpectomy and radiation therapy (67.8% v 59.8%, respectively). Rates of ipsilateral breast tumor recurrence (IBTR) after lumpectomy were similar in both groups (7.9% and 5.8%, respectively; P = .23). Outcome was better in women whose tumors showed a pCR than in those with a pINV, cPR, or cNR (relapse-free survival [RFS] rates, 85.7%, 76.9%, 68.1%, and 63.9%, respectively; P < .0001), even when baseline prognostic variables were controlled. When prognostic models were compared for each treatment group, the preoperative model, which included breast tumor response as a variable, discriminated outcome among patients to about the same degree as the postoperative model.

CONCLUSION

Preoperative chemotherapy is as effective as postoperative chemotherapy, permits more lumpectomies, is appropriate for the treatment of certain patients with stages I and II disease, and can be used to study breast cancer biology. Tumor response to preoperative chemotherapy correlates with outcome and could be a surrogate for evaluating the effect of chemotherapy on micrometastases; however, knowledge of such a response provided little prognostic information beyond that which resulted from postoperative therapy.

Mixed invasive ductal lobular carcinoma is clinically and pathologically more similar to invasive lobular than ductal carcinoma

BACKGROUND

Mixed invasive ductal lobular carcinoma (mDLC) remains a poorly understood subtype of breast cancer composed of coexisting ductal and lobular components.

METHODS

We sought to describe clinicopathologic characteristics and determine whether mDLC is clinically more similar to invasive ductal carcinoma (IDC) or invasive lobular carcinoma (ILC), using data from patients seen at the University of Pittsburgh Medical Center.

RESULTS

We observed a higher concordance in clinicopathologic characteristics between mDLC and ILC, compared to IDC. There is a trend for higher rates of successful breast-conserving surgery after neoadjuvant chemotherapy in patients with mDLC compared to patients with ILC, in which it is known to be lower than in those with IDC. Metastatic patterns of mDLC demonstrate a propensity to develop in sites characteristic of both IDC and ILC. A meta-analysis evaluating mDLC showed shared features with both ILC and IDC with significantly more ER-positive and fewer high grades in mDLC compared to IDC, although mDLCs were significantly smaller and included fewer late-stage tumours compared to ILC.

CONCLUSIONS

These findings support clinicopathologic characteristics of mDLC driven by individual ductal vs lobular components and given the dominance of lobular pathology, mDLC features are often more similar to ILC than IDC. This study exemplifies the complexity of mixed disease.

Long-term outcomes of dual vs single HER2-directed neoadjuvant therapy in NSABP B-41

BACKGROUND

The primary aim of this randomized neoadjuvant trial in operable, HER2-positive breast cancer, was to determine the efficacy on pathologic complete response (pCR) of substituting lapatinib (L) for trastuzumab (T) or adding L to T, in combination with weekly paclitaxel (WP) following AC. Results on pCR were previously reported. Here, we report data on planned secondary endpoints, recurrence-free interval (RFI) post-surgery, and overall survival (OS).

METHODS

All patients received standard AC q3 weeks × 4 cycles followed by WP (80 mg/m²) on days 1, 8, and 15, q28 days × 4 cycles. Concurrently with WP, patients received either T (4 mg/kg load, then 2 mg/kg) weekly until surgery, L (1250 mg) daily until surgery, or weekly T plus L (750 mg) daily until surgery. Following surgery, all patients received T to complete 52 weeks of HER2-targeted therapy. 522 of 529 randomized patients had follow-up. Median follow-up was 5.1 years.

RESULTS

RFI at 4.5 years was 87.2%, 79.4% (p = 0.34; HR = 1.37; 95% CI 0.80, 2.34), and 89.4% (p = 0.37; HR = 0.70; 0.37, 1.32) for arms T, L, and TL, respectively. The corresponding five-year OS was 94.8%, 89.1% (p = 0.34; HR = 1.46; 0.68, 3.11), and 95.8% (p = 0.25; HR = 0.58; 0.22, 1.51), respectively. Patients with pCR had a much better prognosis, especially in the ER-negative cohort: RFI (HR = 0.23, p < 0.001) and OS (HR = 0.28, p < 0.001).

CONCLUSIONS

Although pCR, RFI, and OS were numerically better with the dual combination and less with L, the differences were not statistically significant. However, achievement of pCR again correlated with improved outcomes, especially remarkable in the ER-negative subset.

CLINICAL TRIALS REGISTRATION

NCT00486668.

Abstract P1-04-10: Association of stromal tumor infiltrating lymphocytes (sTILs) in pretreatment biopsies in different molecular subtypes of HER2+/ER+ breast cancer: Assessment of NRG Oncology/NSABP B-52

Background: The primary aim of the NRG Oncology/NSABP B-52 clinical trial was to test if estrogen deprivation (ED) administered concomitantly with neoadjuvant docetaxel, carboplatin, trastuzumab, and pertuzumab (TCHP), would improve the pCR rate in patients with HER2+/ER+ early breast cancer. A numerical increase in the pCR rate was observed with ED (46.1% v 40.9%), but the difference was not statistically significant. The purposes of this study were to assess the association of sTILs in pretreatment biopsies with pCR in the total population and within the molecular subtypes of breast cancer and to assess changes in sTILs between pre- and on-treatment biopsies. The secondary endpoints of recurrence-free interval (RFI) and overall survival (OS) are currently being analyzed and will be presented along with association of these endpoints with sTILs in pretreatment biopsies in the total cohort and within molecular subtypes. Methods: Scoring of sTILs on routine H&E slides from pre-treatment biopsies with sufficient tumor from 249 of the 315 patients (79%) entered in B-52 were performed by one of two pathologists (SKM, RSM). Both pathologists scored sTILs on a subset of 64 patients to document concordance. Wilcoxon two-sided test, box and whisker plots, and forest plots were used to assess associations with pCR. Molecular subtypes were determined utilizing RNA-seq data and AIMS subtyping method. On-treatment biopsies were available in 46 patients and were scored and compared to paired baseline samples. Results: Good concordance between pathologists was established with an inter-pathologist difference of ˂20% difference between scores in 92% of cases. sTILs in pre-treatment samples were associated with pCR across both arms of the trial (p=0.0074) and in the TCHP+ED arm (p=0.033), but not in the TCHP arm (p=0.093). The distribution of intrinsic subtypes was 34% luminal B, 29% luminal A, 28% HER2E, 5.8% normal, and 2.7% basal, with no significant differences between the arms. Presence of sTILs showed a trend for association with pCR in HER2E pre-treatment samples (p=0.054) but not in non-HER2E (p=0.75). Similarly, sTILs were associated with pCR in non-luminal tumors (p=0.055) but not in luminal tumors (p=0.44). Stratification by treatment arm and menopausal status suggested sTILs are associated with pCR in premenopausal women treated with TCHP (OR: 1.04, 95% CI=1.00-1.09). Interestingly, decreases in the sTIL scores with treatment were associated with pCR in the TCHP+ED arm (p=0.01) but not in the TCHP arm. Analysis of RFI and OS on B-52 is ongoing and will be presented along with associations of sTILs with intrinsic subtypes for RFI and OS. Conclusions: Although a positive correlation between sTILs and pCR was observed, the clinical utility appears limited because of the extensive overlap in the TIL scores between pCR and non-pCR tumors. Significance for a positive association of sTILs with pCR was detected in HER2E but not in luminal tumors. This may be due to the molecular differences of the subtypes, or the make-up of the TILs, or both. The association of a decrease in sTILs with TCHP+ED treatment needs further investigation. The small number of samples is a limitation of the study; however, the B-52 protocol specified that the collection of the B-52 samples was for the purpose of exploratory analysis. Our results highlight the molecular heterogeneity of the HER+/ER+ patient population and suggests that different treatment strategies may be required in future treatment regimens for this patient population. Support: NSABP Foundation; BCRF; 3U10CA180868-03S2, -180822; UG1CA189867; Genentech.

Citation Format: Katherine L. Pogue-Geile, Sai K. Maley, Rim S. Kim, Ying Wang, Roberto Salgado, Corey Lipchik, Huichen Feng, Reena S. Cecchini, Samuel A. Jacobs, Ashok Srinivasan, Eleftherios (Terry) Mamounas, Charles E. Geyer Jr, Priya Rastogi, C. Kent Osborne, Soonmyung Paik, Norman Wolmark, Peter C. Lucas, Mothaffar Rimawi. Association of stromal tumor infiltrating lymphocytes (sTILs) in pretreatment biopsies in different molecular subtypes of HER2+/ER+ breast cancer: Assessment of NRG Oncology/NSABP B-52 [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-04-10.

Abstract OT1-12-01: A phase III trial evaluating De-escalation of Breast Radiation (DEBRA) following breast-conserving surgery (BCS) of stage 1, HR+, HER2-, RS ≤18 breast cancer: NRG-BR007

BACKGROUND: Approximately 50% of newly diagnosed breast cancers are stage 1, with the majority being ER/PR-positive, HER2-negative. Genomic assays such as Oncotype DX® have identified pts with reduced distant metastasis and without benefit from chemotherapy, freeing patients from excess toxicity. Also, these genomic assays are prognostic of local-regional recurrence (LRR). The de-escalation of therapy is of interest to pts, providers, and payers. Low risk, as identified by Oncotype and Mammaprint®, is associated with low LRR after BCS and breast radiotherapy (RT). METHODS: We hypothesize that BCS alone is non-inferior to BCS plus RT for ipsilateral breast recurrence (IBR) and breast preservation in women intending appropriate endocrine therapy (ET) for stage 1 (ER and/or PR positive, HER2-negative, with an Oncotype DX Recurrence Score [RS] of ≤18) breast cancer. Stratification is by age (&lt; 60; ≥60), tumor size (≤1 cm; &gt;1-2cm), and RS (&lt; 11; 11-18). Pts are randomized post-BCS to Arm 1 with breast RT using standard methods (hypo- or conventional-fractionated whole breast RT with or without boost, APBI) plus 5 years of ET (tamoxifen or AI) or Arm 2 with 5 years of ET (tamoxifen or AI) alone. The specific regimen of ET in both arms is at the treating physician’s discretion. Eligible pts are stage 1: pT1 (2 cm), pN0, age ≥50 to &lt; 70 years, s/p BCS with negative margins (no ink on tumor), s/p axillary nodal staging (SNB or ALND), ER and/or PR positive (ASCO/CAP), HER2-negative (ASCO/CAP), and have an Oncotype DX RS of ≤18 (diagnostic core biopsy or resected specimen). Primary endpoint is IBR. Secondary endpoints are breast conservation rate, invasive in-breast recurrence, recurrence-free interval, distant disease-free survival, overall survival, patient-reported breast pain, patient-reported worry about recurrence, and adherence to ET. We assume a clinically acceptable difference in IBR of 4% at 10 years to judge omission of RT as non-inferior (10-year event-free survival for RT group is 95.6% versus 91.6% for the omission-of-RT group). The study is designed to be able to detect non-inferiority with 80% power and a one-sided α=0.025, and assuming that there would be a ramp-up in accrual in the first two years of the study (leveling off in Years 3-5), 1,670 (835 per arm) patients are required to be randomized. Conservative loss to follow-up is 1% per year. Some of the T1a pts screened will have Oncotype DX scores &gt;18, making them ineligible for the study. In the accrual process, pts will be required to register (1,714 patients) to ensure that our final randomized cohort is 1,670 pts. Accrual as of 6-30-2022 is 169 screened and 147 randomized. Contact information: Protocol: CTSU member website: https://www.ctsu.org. NRG Oncology Pgh Clinical Coordinating Dpt: 1-800-477-7227 or ccdPGH@NRGOncology.org. Support: U10CA180868, -180822, UG1CA189867. NCT04852887.

Citation Format: Julia White, Reena S. Cecchini, Eleanor E. Harris, Eleftherios (Terry) Mamounas, Daniel Stover, Patricia A. Ganz, Reshma Jagsi, Carmen Bergom, Valérie Théberge, Mahmoud B. El-Tamer, Richard Zellars, Dean A. Shumway, Guang-Pei Chen, Stewart J. Anderson, Thomas B. Julian, Norman Wolmark, Wendy Rea. A phase III trial evaluating De-escalation of Breast Radiation (DEBRA) following breast-conserving surgery (BCS) of stage 1, HR+, HER2-, RS ≤18 breast cancer: NRG-BR007 [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT1-12-01.

Abstract OT2-16-05: Safety Analyses of NRG BR004: A Randomized, Double-blind, Phase III Trial of Taxane/Trastuzumab/Pertuzumab with Atezolizumab or Placebo in First-line HER2-Positive Metastatic Breast Cancer (MBC)

Background: The CLEOPATRA trial established trastuzumab, pertuzumab and a taxane (THP) as a standard of care for first line metastatic, HER2-positve breast cancer with median progression-free survival (PFS) of 18.7 months and median OS of 57 months. NRG BR004 was a phase III, placebo-controlled trial designed to determine whether the addition of the PD-L1 inhibitor, atezolizumab, to THP would improve progression-free survival (PFS), relative to THP/placebo in patients with newly documented HER2-positive measurable metastatic breast cancer.

Methods: BR004 was designed to detect an improvement in the primary endpoint of PFS in patients with measurable disease from 16.5 to 22.5 months with addition of atezolizumab (HR 0.733). A sample size of 600 would provide 80% power with a type I error rate of 0.05 to detect such an improvement when 326 PFS events had been reported. Monthly accrual was projected at 30 patients per month with completion of accrual in 24 months. In addition to routine monitoring of safety data by the IDMC every 6 months, a formal analysis of the toxicity data was to be performed 16 weeks after the 100th patient had been randomized with review by the IDMC.

Results: First patient was randomized on May 1, 2019, and after 37 months 190 patients had been randomized. Several amendments were not successful in addressing the low accrual rate. The IDMC began regular monitoring of safety and accrual data in July 2020 and reviewed the formal safety analysis in February 2022. As of the February 2022 IDMC meeting, four Grade 5 adverse events (AEs) had been reported (2 occurring in 2020 and 2 in 2021), one of which occurred in a patient with evolving liver failure due to rapid disease progression at the start of therapy. The recommendation was to continue without modification, but notice was given the Grade 5 AEs had occurred on the same treatment arm without unblinding. When additional Grade 5 AEs occurred on 3/4/2022 and 4/27/2022 both on the same study arm with none reported on the other arm, accrual was held until the IDMC could review updated safety data, narratives of the Grade 5 AEs and the overall context of the trial. There was no evidence of clinically important imbalances between Grade 3 and Grade 4 AEs between the arms., Based on an uncertain but material safety signal, the ongoing accrual challenges, and determination that the clinical question being addressed was no longer sufficiently compelling, the IDMC recommended that the trial should be permanently closed to further enrollment. Summary safety data from 187 treated patients are provided in the Table. A decision was made to discontinue atezolizumab/placebo in patients receiving the investigational component of the trial therapy and unblind investigators and patients. The study will continue to collect information on PFS events, deaths and late immune AEs through April of 2024 when PFS and OS will be analyzed.

Conclusions: The imbalance in Grade 5 AEs which occurred on BR004 coupled with continued poor accrual and the changing landscape in HER2+ MBC resulted in early closure of enrollment and unblinding of patients. Follow-up continues to assess PFS, OS and monitor for delayed immune AEs.

Support: U10CA180868, -189867, -180822; U24CA196067; and Genentech.

NRG-GI004/SWOG-S1610: Colorectal Cancer Metastatic dMMR Immuno-Therapy (COMMIT) study—A randomized phase III study of atezolizumab (atezo) monotherapy versus mFOLFOX6/bevacizumab/atezo in the first-line treatment of patients (pts) with deficient DNA mismatch repair (dMMR) or microsatellite instability high (MSI-H) metastatic colorectal cancer (mCRC)

TPS258

Background: Despite the superiority in progression-free survival (PFS) of inhibition of programmed cell death-1 (PD-1) pathway in dMMR/MSI-H as compared to chemotherapy with either anti-vascular endothelial growth factor receptor (VEGFr) or anti-epithelial growth factor receptor (EGFr) antibodies in mCRC, more pts had progressive disease as the best response in the anti-PD1 monotherapy arm (29.4% v 12.3%) with mean PFS of 13.7 mos, with ~45% of pts in the immunotherapy arm progressed at 12 mos (KEYNOTE 177). We hypothesize that dMMR/MSI-H mCRC pts may be more effectively treated with the combination of PD-1 pathway blockade and mFOLFOX6/bevacizumab (bev) rather than with anti-PD-1 therapy (atezo) alone. Preclinical work demonstrated synergistic effects between anti-PD-1/anti-VEGF and between oxaliplatin/anti-PD-1 in murine CRC models and phase II data, which showed activity of anti-PD-1/anti-VEGF in chemotherapy refractory colon cancer. A recent randomized trial subgroup analysis of 8 pts with dMMR metastatic colon cancer treated with FOLFOXIRI+bev+atezo, with the first patient having progression ~16 mos (AtezoTRIBE). Additionally, in other solid tumor malignancies, anti-PD1 plus anti-VEGFr (i.e., HCC and RCC) as well as anti-PD1 plus chemotherapy (i.e., gastric and esophageal cancers) combinations are standard first-line treatments. Methods: The redesigned COMMIT study was reactivated on 1/29/2021 as a two-arm prospective phase III open-label trial randomizing (1:1) mCRC dMMR/MSI-H to atezo monotherapy v mFOLFOX6/bev+atezo combination. Assuming our control arm, atezo monotherapy (48% PFS at 24 mos as assessed by site investigator), we have 80% power to detect a hazard ratio of 0.6 (equivalent to 64.4% PFS at 24 mos) with alpha 0.025 one-sided. Stratification factors include BRAFV600E status, metastatic site, and prior adjuvant CRC therapy. Secondary endpoints include OS, objective response rate, safety profile, disease control rate, and duration of response. Health-related quality of life is an exploratory objective. Archived tumor tissue and blood samples will be collected for correlative studies. Key inclusion criteria are: mCRC without prior chemotherapy for advanced disease; dMMR tumor determined by local CLIA-certified IHC assay (MLH1/MSH2/MSH6/PMS2) or MSI-H by local CLIA-certified PCR or NGS panel; and measurable disease per RECIST. Enrollment actively continues to the target accrual of 211 patients randomized between the two immunotherapy arms. Clinical trial: NCT02997228. Support: U10CA180868, -180822, -180888, UG1CA189867, U24CA196067; Genentech, Inc. Clinical trial information: NCT05080673 .

Phase II/III study of circulating tumor DNA as a predictive biomarker in adjuvant chemotherapy in patients with stage II colon cancer: NRG-GI005 (COBRA)

TPS259

Background: Detection of circulating tumor DNA (ctDNA) shed into the bloodstream represents a highly specific and sensitive approach for identifying microscopic or residual tumor cells after surgical resection. For patients (pts) with colon cancer (CC), the detection of ctDNA is associated with persistent disease after resection and outperforms traditional clinical and pathological features in prognosticating risk for recurrence. However, for pts with stage II CC, there are currently no validated biomarkers predicting benefit in identifying pts whose residual disease cancer be cleared by adjuvant chemotherapy. We hypothesize that for pts whose stage II colon cancer has been resected and who have no traditional high-risk features, a positive ctDNA status may identify those who will benefit from adjuvant chemotherapy. Methods: In this prospective phase II/III clinical trial, pts (N=1,408) with resected stage II CC without traditional high-risk features and whom the evaluating oncologist deems suitable for active surveillance (i.e., not needing adjuvant chemotherapy) will be randomized 1:1 into 2 arms: standard-of-care/observation (Arm A), or prospective testing for ctDNA (Arm B). Postoperative blood will be analyzed for ctDNA with the Guardant Reveal assay, covering CC-relevant mutations and CC-specific methylation profiling. Pts in Arm B with ctDNA detected will be treated with 6 months of adjuvant (FOLFOX) chemotherapy. For all pts in Arm A, ctDNA status will be analyzed retrospectively at the time of endpoint analysis. The primary endpoints are clearance of ctDNA with adjuvant chemotherapy (phase II) and recurrence-free survival (RFS) for “ctDNA-detected” pts treated with or without adjuvant chemotherapy (phase III). Secondary endpoints will include time-to-event outcomes (OS, RFS, TTR) by ctDNA marker status and treatment, prevalence of detectable ctDNA in stage II CC, and rates of compliance with assigned intervention. Archived normal and matched tumor and blood samples will be collected for exploratory correlative research. Enrollment continues across North America to the 540-patient phase II endpoint. Support: U10CA180868, -180822; UG1CA189867; GuardantHealth. Clinical trial information: NCT04068103 .

NSABP C-14: CORRECT-MRD II—Second colorectal cancer clinical validation study to predict recurrence using a circulating tumor DNA assay to detect minimal residual disease

TPS284

Background: Detectable ctDNA after resection of early-stage solid tumors has been associated with very high risk of recurrence, suggesting ctDNA is evidence of minimal residual disease (MRD). Several studies are ongoing to investigate the role of ctDNA in the optimal management of pts with colorectal cancer using different assay technologies. Methods: This is a prospective, observational, multicenter study in the United States and Canada of 750 patients who have undergone complete surgical resection for stage II or III colorectal cancer, who have FFPE tissue available from the primary resection sufficient for a novel bespoke MRD assay and are willing to provide serial whole blood specimens for ctDNA analysis. Participants are asked to provide study specimens after definitive surgical resection, pre-recurrence follow-up, and clinical recurrence (if applicable). Recently amended eligibility criteria include inclusion of rectal cancer patients who have completed neo-adjuvant therapy and surgical resection, as well as enrollment of all stage II and III patients regardless of microsatellite stability status. The Oncotype Colon Recurrence Score will be assessed on all patients from their surgical specimen if criteria are met for this testing. ctDNA will be analyzed with an NGS-based tumor-informed MRD assay that identifies somatic genomic alterations from DNA derived from the patient’s tumor tissue, subtracts germline variants, and detects a selected subset of tumor-specific (bespoke) ctDNA in their blood. All primary tumor specimens will undergo full exome and transcriptome sequencing using the Oncomap ExTra assay. If there is evidence of disease recurrence, the metastatic tissue will also undergo Oncomap ExTra testing, which will be shared with participants. The primary objective is to validate the association of post-definitive therapy and pre-recurrence follow-up ctDNA positivity with recurrence-free interval (RFI). Further objectives are to assess the: sensitivity and specificity of ctDNA positivity for subsequent clinical recurrence; contribution of post-surgery baseline, post-adjuvant therapy, and pre-recurrence follow-up ctDNA results on RFI; time from positive ctDNA to clinical recurrence in participants who had a positive ctDNA result; and compare the Oncotype Colon Recurrence Score estimate of 3-year recurrence risk with the observed 3-year recurrence rate. The primary analysis will use a Cox proportional hazards regression applied to the RFI with ctDNA result (positive or negative) measured at post-surgical baseline (or end of adjuvant therapy if used) and serially after that as a single, time-dependent covariate. Protocol#: NSABP C-14 / ES 16-002. Support: NSABP Foundation, ExactSciences Clinical trial information: 05210283 .

Long-term results from NRG-GI002: A phase II clinical trial platform using total neoadjuvant therapy (TNT) in locally advanced rectal cancer (LARC)

7

Background: This NCTN multi-arm randomized phase II modular clinical trial platform utilizes TNT with parallel experimental arms (EAs) in LARC. EAs are not intended for direct comparison, but rather to concurrently randomized control arm (CA) patients. Primary endpoint (EP) and available secondary EPs (from EA1 using veliparib [V], PARPi; and EA2 using pembrolizumab [P], anti-PD-1) have been previously reported. We present long-term outcomes of all pts enrolled (NCT02921256). Methods: Stage II/III pts with MSS LARC (with any ONE of the following: distal location [cT3-4 ≤5cm from anal verge, any N]; bulky [any cT4 or tumor within 3mm of mesorectal fascia]; high risk for metastatic disease [cN2]; or not a sphincter-sparing surgery [SSS] candidate) were randomized to CA (neoadjuvant FOLFOX [x 4mo] → chemoRT [capecitabine with 50.4Gy] → surgery 8-12 wks later). EA1 added V (400mg PO BID) and EA2 added P (200mg IV Q3 wks x 6 doses) each concurrent with chemoRT. Primary EP: 4-point reduction in Neoadjuvant Rectal Cancer (NAR) score with a one-sided α=0.10, 80% power. NAR compared by linear model controlling for clinical T4 at entry (Y/N). Secondary EPs: OS, DFS. p-values are two-sided. Results: From 10/2016-2/2018, 178 pts were randomized (88 CA, 90 EA1). From 8/2018-5/2019, 185 pts were randomized (95 CA, 90 EA2). Baseline characteristics were previously reported. Median follow-up is 3.50 yrs for the 1st comparison. Median follow-up is 3.15 yrs for the 2nd comparison. Updated primary and long-term secondary outcomes are in the table. Conclusions: With longer follow-up, addition of V to TNT provided no significant differences in the NAR score or 3yr outcomes. The addition of P to TNT was associated with a statistically significant improvement in 3yr OS, but not DFS. Correlative molecular analyses are ongoing. Support: U10CA180868, -180822; UG1-189867; U24-196067; AbbVie; Merck. Clinical trial information: NCT02921256 . [Table: see text]

NRG GI008: Colon adjuvant chemotherapy based on evaluation of residual disease (CIRCULATE-US)

TPS260

Background: Currently, there are no biomarkers validated prospectively in randomized studies for resected colon cancer (CC) to determine need for adjuvant chemotherapy (AC). However, circulating tumor DNA (ctDNA) represents a highly specific and sensitive approach (especially with serial monitoring) for identifying minimal/molecular residual disease (MRD) post-surgery in CC patients (pts), and may outperform traditional clinical and pathological features in prognosticating risk for recurrence. CC pts who do not have detectable ctDNA (ctDNA-) are at a much lower risk of recurrence and may be spared the toxicities associated with AC. Furthermore, for CC pts with detectable ctDNA (ctDNA+) who are at a very high risk of recurrence, the optimal AC regimen has not been established. We hypothesize that for pts whose CC has been resected, ctDNA status may be used to risk-stratify for making decisions about AC. Methods: In this prospective phase II/III trial, up to 1,912 pts with resected stage III A, B (all pts) and stage II, IIIC (ctDNA+ only) CC will be enrolled. Based on the post-operative ctDNA status using personalized and tumor-informed assay (Signatera™, bespoke assay), those who are ctDNA- (Cohort A) will be randomized to immediate AC with fluoropyrimidine (FP) + oxaliplatin (Ox) for 3-6 mos per established guidelines vs . serial ctDNA monitoring. Patients who are ctDNA+ post-operatively or with serial monitoring (Cohort B) will be randomized to FP+Ox vs . more intensive AC with addition of irinotecan (I) for 6 mos. The primary endpoints for Cohort A are time to ctDNA+ status (phase II) and disease-free survival (DFS) (phase III) in the immediate vs . delayed AC arms. The primary endpoint for Cohort B is DFS in the FP+Ox vs FP+Ox+I arms for both phase II and phase III portions of the trial. Secondary endpoints include prevalence of detectable ctDNA post-operatively, time-to-event outcomes (overall survival and time to recurrence) by ctDNA status, and the assessment of compliance to adjuvant therapy. Biospecimens including archival tumor tissue, as well as post-operative plus serial matched/normal blood samples, will be collected for exploratory correlative research. Active enrollment across the NCTN started in June, 2022. Support: U10-CA-180868, -180822; UG1CA-189867; Natera, Inc. Clinical trial information: NCT05174169 .

NRG-BR007: A phase III trial evaluating de-escalation of breast radiation (DEBRA) following breast-conserving surgery (BCS) of stage 1, hormone receptor+, HER2-, RS ≤18 breast cancer

TPS613

Background: Approximately 50% of newly diagnosed breast cancers are stage 1, with the majority being ER/PR-positive, HER2-negative. Genomic assays such as the Oncotype DX® have identified patients (pts) with reduced risk of distant metastasis and without benefit from chemotherapy added to endocrine therapy, freeing them from excess toxicity. Genomic assays are also recognized as prognostic for in-breast recurrence (IBR) after BCS and could similarly allow de-escalation of adjuvant radiotherapy (RT). Reducing overtreatment is of interest to pts, providers, and payers. Methods: We hypothesize that BCS alone is non-inferior to BCS plus RT for in-breast recurrence and breast preservation in women intending endocrine therapy (ET) for stage 1 breast cancer (ER &/or PR positive, HER2-negative with an Oncotype DX Recurrence Score [RS] of ≤18). Stratification is by age (<60; ≥60), tumor size (≤1 cm; >1-2cm), & (RS <11, RS 11-18). Pts are randomized post-BCS to Arm 1 with breast RT using standard methods (hypo- or conventional-fractionated whole breast RT with/without boost, APBI) with ≥5 yrs of ET (tamoxifen or AI) or Arm 2 with ≥5 yrs of ET (tamoxifen or AI) alone. The specific regimen of ET in both arms is at the treating physician’s discretion. Eligible pts are stage 1: pT1 (2 cm), pN0, age ≥50 to <70 yrs, s/p BCS with negative margins (no ink on tumor), s/p axillary nodal staging (SNB or ALND), ER &/or PR positive (ASCO/CAP), HER2-negative (ASCO/CAP), and Oncotype DX RS of ≤18 (diagnostic core biopsy or resected specimen). Primary endpoint is in-breast recurrence. Secondary endpoints are breast conservation rate, invasive in-breast recurrence, relapse-free interval, distant disease-free survival, overall survival, patient-reported breast pain, patient-reported worry about recurrence, and adherence to ET. We assume a clinically acceptable difference in of 4% at 10 yrs to judge omission of RT as non-inferior (10-yr event-free survival for RT group is 95.6% vs 91.6% for the omission of RT group). The study is powered to detect a non-inferiority with 80% power and a one-sided α=0.025, assuming that there would be a ramp-up in accrual in the first two years (leveling off in Yrs 3-5); 1,670 (835 per arm) pts are required to be randomized. Conservative loss to follow-up is 1% per yr. Some of the T1a pts screened may have Oncotype DX scores >18, making them ineligible for the study. In the accrual process, pts will be required to register (1,714 pts) to ensure that our final randomized cohort is 1,670 pts. Current accrual (2-2-2022) is 52 screened and 45 randomized. Support: U10CA180868, -180822, NCT04852887. Clinical trial information: NCT04852887.

NSABP FC-11: A phase II study of neratinib (N) plus trastuzumab (T) or N plus cetuximab (C) in patients (pts) with "quadruple wild-type" metastatic colorectal cancer (mCRC) based on HER2 status

3564

Background: Patients (pts) with KRAS wild-type (WT) mCRC treated with single agent anti-EGFR therapy (tx) have improved OS compared to BSC but only a 10-15% response rate. Prior EGFR tx may upregulate HER amplification. For pts with quadruple WT mCRC (KRAS, NRAS, BRAF, PIC3KA), data suggest that dual targeting of the MAPK pathway, specifically EGFR and HER2, may be more effective. The purpose of this study was to evaluate the activity of dual MAPK pathway inhibition based on HER2 status: amplified (amp), non-amplified (non-amp), or mutated (mt). Methods: This 2-arm phase II trial enrolled pts with quad WT mCRC with ECOG PS 0-2, adequate organ function, prior oxaliplatin- and irinotecan-based regimens, and known HER2 status. Arm 1: HER2 amp (confirmed as >2.14 copy number by Guardant 360) and prior anti-EGFR tx or HER2 mt (with qualifying mt) with or without prior anti-EGFR tx; Arm 2: HER2 non-amp or HER2 amp without prior anti-EGFR tx. Tx included T 4 mg/kg IV loading dose → 2 mg/kg/wk and N 240 mg po daily (Arm 1) or C 400 mg/m2 IV loading dose → 250 mg/m2/wk and N 240 mg po daily (Arm 2). Imaging was performed every 8 wks with response per RECIST 1.1. Primary end point (EP) of each arm was 6 mo PFS (PFS6). Secondary EPs: Response rate (ORR), clinical benefit rate (CBR), toxicity and exploratory assessments of N pharmacokinetics, genetic and molecular analyses, and evaluation of multiple drug combinations in PDX/PDXO models. We tested H0: PFS6 <0.13 v HA: PFS6 >0.47 (α=0.05; power=0.90 to reject HA). Treating 15 pts in each arm, if ≥5 pts are alive and progression free (PFS6 0.33), the arm is worth further testing. Results: From Jul 2018 - Mar 2021, 25 pts enrolled from 9 different centers. Arm 1 closed due to poor accrual (n=4). Those pts have been excluded from further analysis. Arm 2 enrolled 21 pts. with 15 evaluable for response by imaging. Early discontinuation occurred in 6 of 21 pts: 2 withdrew consent, 3 due to toxicity, and 1 physician withdrawal. Of the 15 evaluable pts, there were 6 PR, 5 of 13 HER2 non-amp, 1 of 2 HER2 amp, (duration 120-171 days; mean 140) and 5 SD (duration 59-231 days; mean 124). The ORR (CR/PR) in all pts who received at least one dose of tx is 33% (6/20). 8 of 15 evaluable pts (53%) were progression free at cycle 6. Common grade 3+ AEs (>5%) included diarrhea (24%), rash (8%), and abdominal pain/distension (8%), without any grade 5 AEs. Conclusions: The combination of C+N was reasonably well tolerated with expected toxicities of diarrhea and rash. The ORR, CBR, and PFS compare favorably to pts previously relapsed following oxaliplatin and irinotecan and treated with single-agent anti-EGFR tx. Upon entry, biopsies for PDX implantation had an engraftment success rate of ̃80%. We anticipate using these grafts to establish PDXO models for molecular analyses and further drug testing. Support: NSABP Foundation, Puma Biotechnology. Clinical trial information: NCT03457896.

Colon adjuvant chemotherapy based on evaluation of residual disease (CIRCULATE-US): NRG-GI008

TPS3643

Background: Currently, there are no biomarkers validated prospectively in randomized studies for resected colon cancer (CC) to determine need for adjuvant chemotherapy (AC). However, circulating tumor DNA (ctDNA) represents a highly specific and sensitive approach (especially with serial monitoring) for identifying minimal/molecular residual disease (MRD) post-surgery in CC patients (pts), and may outperform traditional clinical and pathological features in prognosticating risk for recurrence. CC pts who do not have detectable ctDNA (ctDNA-) are at a much lower risk of recurrence and may be spared the toxicities associated with AC. Furthermore, for CC pts with detectable ctDNA (ctDNA+) who are at a very high risk of recurrence, the optimal AC regimen has not been established. We hypothesize that for pts whose CC has been resected, ctDNA status may be used to risk stratify for making decisions about AC. Methods: In this prospective phase II/III trial, up to 1,912 pts with resected stage III A, B (all pts) and stage II, IIIC (ctDNA+ only) CC will be enrolled. Based on the post-operative ctDNA status using personalized and tumor informed assay (SignateraTM, bespoke assay), those who are ctDNA- (Cohort A) will be randomized to immediate AC with fluoropyrimidine (FP) + oxaliplatin (Ox) for 3-6 mos per established guidelines vs . serial ctDNA monitoring. Patients who are ctDNA+ post-operatively or with serial monitoring (Cohort B) will be randomized to FP+Ox vs . more intensive AC with addition of irinotecan (I) for 6 mos. The primary endpoints for Cohort A are time to ctDNA+ status (phase II) and disease-free survival (DFS) in phase III in the immediate vs . delayed AC arms. The primary endpoint for Cohort B is DFS in the FP+Ox vs FP+Ox+I arms for both phase II and phase III portions of the trial. Secondary endpoints include prevalence of detectable ctDNA post-operatively, time-to-event outcomes (overall survival and time to recurrence) by ctDNA status, and the assessment of compliance to adjuvant therapy. Biospecimens including archival tumor tissue, post-operative and serial matched/normal blood samples will be collected for exploratory correlative research. Active enrollment across the NCTN started in early 2022. Support: U10-CA-180868, -180822; UG1CA-189867; Clinical trial information: NCT05174169.

NSAB C-14: CORRECT-MRD II—Second colorectal cancer clinical validation study to predict recurrence using a circulating tumor DNA assay to detect minimal residual disease

TPS3632

Background: Patients (pts) with stage II and III colon cancer (CC) have unique post-operative decisions regarding adjuvant chemotherapy (ACT). There is a subset of stage II pts with defined clinicopathologic features associated with poor prognosis who may benefit from ACT, although more discriminating and objective predictors of benefit are needed. In addition, there may be a subset of Stage III CC pts who could tolerate a de-escalation of ACT or who may require intensification of ACT to improve clinical outcome. Detectable ctDNA after resection of early-stage solid tumors has been associated with very high risk of recurrence, suggesting ctDNA is evidence of minimal residual disease (MRD). Several studies are ongoing to investigate the role of ctDNA in the optimal management of pts with CC using different assay technologies. Methods: This is a prospective, observational, multicenter study in the United States and Canada of 750 pts who have undergone complete surgical resection for stage II or III CC, have FFPE tissue available from the primary resection sufficient for a novel bespoke MRD assay, and are willing to provide serial whole blood specimens for ctDNA analysis. Subjects are asked to provide study specimens at baseline, pre-recurrence follow-up, and clinical recurrence (if applicable) study visits. ctDNA will be analyzed with an NGS-based MRD assay that identifies somatic genetic alterations from DNA derived from the pt’s tumor tissue, subtracts germline variants, and detects a subset of these tumor-specific (bespoke) ctDNA in the pt’s blood. The primary objective is to validate the association of post-definitive therapy and pre-recurrence follow-up ctDNA positivity with recurrence-free interval (RFI). Further objectives are to assess the: sensitivity and specificity of ctDNA positivity for subsequent clinical recurrence; contribution of post-surgery baseline, post-adjuvant therapy, and pre-recurrence follow-up ctDNA results on RFI; time from positive ctDNA to clinical recurrence in subjects who had a positive ctDNA result; and compare the Oncotype Colon Recurrence Score estimate of 3 yr recurrence risk with the observed 3 yr recurrence rate. The primary analysis will use a Cox proportional hazards regression applied to the RFI with ctDNA result (positive or negative) measured at post-surgical baseline (or end of ACT if ACT was used) and serially after that as a single, time-dependent covariate. Protocol: 16-002/NSABP C-14. Support: NSABP Foundation. Clinical trial information: 05210283.

Testing of a machine learning (ML) model for ability to predict oxaliplatin and bevacizumab (bev) benefit in NRG Oncology/NSABP C-07 and C-08

3607

Background: Through mining The Cancer Genome Atlas (TCGA) data and a large set of transcriptomes of CRC in GEO, we constructed 15 metagenes reflecting the transcriptomic impact of major driver genes of CRC. Independent of any clinical information, we used metagenes as features to further develop an ML model, then tested it using gene expression (GE) data from C-07 and C-08. Methods: We carried out a prospectively designed and double-blind study to evaluate the clinical utility of the ML model in the adjuvant setting. Samples were classified as Sig+ or Sig-. Association of signatures with recurrence free interval were tested using log-rank test, and significance was set at P<0.05. Cox regression models were used to estimate hazard ratios in univariate and multivariate models and for significance testing in multivariate models. Clinical variables included in multivariate models were nodal status, age, sex, and T stage. Results: We tested the ML model for its ability to predict oxaliplatin benefit in all C-07 pts with available GE data (n=846). Sig+ pts received significant benefit from oxaliplatin (HR=0.68, 95% CI=0.48-0.95, p=0.025) but Sig- did not (Sig- HR=1.05, 95% CI=0.72-1.53, p=0.79), however, the int p value showed only a trend for significance (int p=0.091). Sig+ remained significant for oxaliplatin benefit in multivariate analysis (HR=0.67, 95% CI=0.48-0.95, p=0.024). When we combined all C-07 pts (C-07 FULV-trtd n=298, FLOX n=304) with C-08 FOLFOX-treated pts (n=226) the Sig+ was significantly associated with oxaliplatin benefit (HR=0.65, 95% CI=0.48-0.89, p=0.0065) with a significant int p=0.03. We also tested the signature for association with bev benefit in C-08 (n=438), using a different cut off. Sig+ showed only a trend for an association with bev benefit (HR=0.63, 95% CI=0.35-1.12, p=0.11). To increase the power to detect bev benefit, we also tested the signature for association with bev benefit in all C-08 patients and C-07 pts treated with FLOX. The Sig+ group received significant benefit from bev (HR=0.58, 95% CI=0.36-0.94, p=0.025) but the Sig- group did not (HR=1.02, 95% CI=0.64-1.63, p=0.94), however, the int p was not significant (p=0.101). The model also showed an association with prognosis within the FULV treatment arm in C-07 (HR=1.51, 95% CI=1.07-2.14, p=0.018) and the FOLFOX+bev arm in C-08 (HR=0.55, 95% CI=0.30-1.01, p=0.049). Conclusions: Although our study is not optimally powered, our analyses indicate that the ML model was predictive for oxaliplatin benefit in stage II and III CC and may be useful for detecting bev benefit. Importantly, the Sig- population is candidate for omitting oxaliplatin (de-escalation) in adjuvant setting but will require further validation. Support: PA DOH, U10CA-180868, -180822, -196067, Genentech, Sanofi; NSABP. Clinical trial information: 00096278, 00004931.

NSABP FC-12: A single-arm, phase II study to evaluate treatment with gevokizumab in patients with stage II/III colon cancer who remain ctDNA+ after curative surgery and adjuvant chemotherapy

TPS3642

Background: Detection of circulating tumor DNA (ctDNA) in patients (pts) following surgery is indicative of presence of minimal/molecular residual disease (MRD) and confers a near-certain risk of disease recurrence. Therapeutic strategies to treat MRD following standard curative therapies are needed because the risk of recurrence is high and therapeutic intervention may provide clinical benefit to patients. Gevokizumab is a recombinant humanized monoclonal antibody targeting interleukin-1β (IL-1β), which is involved in all phases of the malignant process (tumorigenesis, invasion, metastasis, angiogenesis, progression, and the modulation of anti-tumor immunity). Gevokizumab has been validated in pre-clinical colon cancer (CC) models and safety established in the advanced-stage clinical setting. In this trial in progress, we aim to test the efficacy of gevokizumab in pts with early-stage CC with MRD (ctDNA-positivity) following definitive treatment. Methods: NSABP FC-12 is a single-arm, multi-centered phase II study that will include pts with stage II/III CC who test MRD+ within 6 wks following completion of curative surgery and ≥3 mos of adjuvant chemotherapy. MRD will be assessed using a personalized and tumor-informed ctDNA assay (Signatera bespoke assay). Gevokizumab will be given at a flat dose of 120 mg IV every 28 days for 13 cycles. The primary endpoint is relapse-free survival (RFS) following initiation of study therapy through one year of follow-up. Secondary endpoints are rate of ctDNA clearance at 8 wks from start of study therapy, as well as safety, toxicity, pharmacokinetics, and immunogenicity of gevokizumab. Exploratory and correlative endpoints will include outcomes associated with ctDNA clearance kinetics, tumor mutations, tumor mutational burden, circulating methylated DNA, tumor immune microenvironment profile, peripheral blood immune profile, and stool microbiome analyses. The enrollment period will be ̃12 mos. Pts will be followed for 18 mos following enrollment with ctDNA analysis at prespecified timepoints until imaging is positive for recurrence of disease or death. CT scans will be at 6-mo intervals. RFS will be determined in pts who clear ctDNA at 8 wks compared to those who do not. A single-stage design to test the null hypothesis that the 12-mo RFS is P≥0.20 versus the alternative (HA) that P≥0.35 has a sample size of 31 (alpha=0.151; power 0.811). If ≥9 of 31 pts (29%) are alive and recurrence-free at 12 mos, then gevokizumab will be considered promising for further study. Enrollment continues towards the primary endpoint. Clinical trial information: 05178576.

Using T stage to predict outcomes of adjuvant oxaliplatin (OX)-based chemotherapy (CT) in stage III colon cancer (CC): An ACCENT pooled analysis

3606

Background: Standard adjuvant CT for stage III CC are FOLFOX and CAPOX. Recently, IDEA study separated stage III patients (pts) into low risk (T1 to 3, N1) and high risk (T4 or N2). We recently confirmed benefit of OX in both risk groups. However, we observed a difference in the two high-risk subgroups, with benefit in N2 but not in T4 (Margalit O et al; Clin Colorectal Cancer 2021). This prompted us to compare outcomes (OS/TTR) between treatment with OX vs. without OX within sub-stage III CC groups defined by T and N. Methods: We pooled 4941 stage III CC pts from the three studies evaluating 6 months of CT with fluoropyrimidine (FP) ± OX: MOSAIC, C-07 and XELOXA. Baseline characteristics were compared using χ2 and t-test. OS was compared between OX and no OX in T and N subgroups. Kaplan-Meier analyses, adjusted and unadjusted Cox models stratified by study were used. Sub-groups classification was done according to OX benefit and verified by interaction test (Int) considered as significant with a P<0.1. We considered for recommendation of using OX-based adjuvant CT, 1) significant benefit in OS, 2) significant Int between substage and adjuvant therapy, and 3) the three individual trials showing similar results (benefit or non-benefit of OX). Results: In stage III population, T3 pts were 74.9%, T1-2 12.4%, T4 13.1%, while N stage was N1 64.7% and N2 35.3%. Population was well balanced according to treatment allocation in most subgroups. A significant benefit of OX was only observed in T3N1 and T3N2 (OS HR 0.76). Whatever N stage, there was no significant benefit of OX in the T1-2 and T4 subgroups. The effect of OX+FP vs FP alone in OS of the three studies differed between T3 and T1-2 subgroups (P = 0.047). Interaction was borderline between T3 and T4 subgroups (P = 0.10) but there was no interaction between T1-2 and T4 subgroups (P = 0.429). A benefit of OX in TTR remained in the T4 population. Discrepancy between advantage in time to relapse (TTR) and no advantage in OS was not explained by survival post relapse. Conclusions: Our analysis suggested that pts with T1-2N1-2 and T4N1-2 disease had no OS benefit of addition of OX to FP. The good survival achieved with FP alone in T1-2N1-2 pts (5-yr OS 89%) question the addition of OX. In the T4 population our results suggested that benefit of OX was limited and that further studies should assess this issue or at least stratify pts on T stage in the future adjuvant trials in CC. [Table: see text]

Colorectal cancer metastatic dMMR immuno-therapy (COMMIT) study: A randomized phase III study of atezolizumab (atezo) monotherapy versus mFOLFOX6/bevacizumab/atezo in the first-line treatment of patients (pts) with deficient DNA mismatch repair (dMMR) or microsatellite instability high (MSI-H) metastatic colorectal cancer (mCRC)—NRG-GI004/SWOG-S1610

TPS3647

Background: Despite the superiority in progression-free survival (PFS) of inhibition of programmed cell death-1 (PD-1) pathway in dMMR/MSI-H as compared to chemotherapy with either anti-vascular endothelial growth factor receptor (VEGFr) or anti-epithelial growth factor receptor (EGFr) antibodies in mCRC, more pts had progressive disease as the best response in the anti-PD1 monotherapy arm (29.4% v 12.3%) with mean PFS of 13.7 mos, with ̃45% of pts in the IO arm progressed at 12 mos ( N Engl J Med 2020; 383:2207). We hypothesize that the dMMR/MSI-H mCRC pts may be more effectively treated with the combination of PD-1 pathway blockade and mFOLFOX6/bevacizumab (bev) rather than with anti-PD-1 therapy (atezo) alone. Preclinical work demonstrated synergistic effects between anti-PD-1/anti-VEGF and between oxaliplatin/anti-PD-1 in murine CRC models and phase II data, which showed activity of anti-PD-1/anti-VEGF in chemotherapy refractory colon cancer. A recent randomized trial subgroup analyses of 8 pts with dMMR metastatic colon cancer treated with FOLFOXIRI+bev+atezo, with the first patient having progression ̃16 mos ( ESMO 2021, Abstt LBA20). Additionally, in other solid tumor malignancies, anti-PD1 plus anti-VEGFr (i.e., HCC and RCC) as well as anti-PD1 plus chemotherapy (i.e., gastric and esophageal cancers) combinations are standard first-line treatments. Methods: The redesigned COMMIT study was reactivated on 1/29/2021 as a two-arm prospective phase III open-label trial randomizing (1:1) mCRC dMMR/MSI-H to atezo monotherapy v mFOLFOX6/bev+atezo combination. Assuming our control arm, atezo monotherapy (48% PFS at 24 mos as assessed by site investigator), we have 80% power to detect a hazard ratio of 0.6 (equivalent to 64.4% PFS at 24 mos) with alpha 0.025 one-sided. Stratification factors include BRAFV600E status, metastatic site, and prior adjuvant CRC therapy. Secondary endpoints include OS, objective response rate, safety profile, disease control rate, and duration of response. Health-related quality of life is an exploratory objective. Archived tumor tissue and blood samples will be collected for correlative studies. Key inclusion criteria are: mCRC without prior chemotherapy for advanced disease; dMMR tumor determined by local CLIA-certified IHC assay (MLH1/MSH2/MSH6/PMS2) or MSI-H by local CLIA-certified PCR or NGS panel; and measurable disease per RECIST. Enrollment actively continues to the target accrual of 211 patients randomized between the two immunotherapy arms. Support: U10CA180868, -180822, -180888, UG1CA189867, U24CA196067. Clinical trial information: NCT02997228.

NSABP FC-10: A phase Ib study of pembrolizumab (pembro) in combination with pemetrexed (pem) and oxaliplatin (oxali) in patients with chemo-refractory metastatic colorectal cancer (mCRC)

3569

Background: Most pts with mCRC have microsatellite stable (MSS) disease (95%) which is unresponsive to checkpoint inhibition. Chemotherapy activity is mediated through both cytotoxicity as well as immunological effects including reduced T-regulatory cell activity, enhanced tumor antigen presentation, and induced PD-L1 tumor cell expression. Chemotherapy with checkpoint inhibitors can potentially activate T cells and alter the microenvironment to improve outcomes. Our purpose was to evaluate pembro plus pem in a safety run-in (cohort 1) and the same with dose-escalated oxali (cohort 2). Methods: Eligible pts with MSS mCRC had ECOG PS of 0-1, measurable metastatic disease, adequate organ function, and prior treatment with fluoropyrimidine-, oxali-, and irinotecan-based therapies (plus an anti-EGFR agent, if apropos). Cohort 1 treatment was pem 500 mg/m2 IV plus pembro 200 mg IV every 3 wks. Cohort 2 treatment was the same, plus oxali at an escalating dose of 85-120 mg/m2 utilizing a 3+3 design with expansion of 6 additional pts at the RP2D. Imaging was performed every 3 cycles; response was determined by RECIST 1.1. Primary endpoint (EP) of each cohort: safety and best ORR with cohort 2 also to establish the RP2D. Secondary EPs: Clinical benefit rate (CBR), PFS, OS at 1 year, and exploratory assessments of circulating immunologic profiles and molecular predictors of response. Descriptive statistics were planned as a signal-seeking study. Results: From Jul 2019-Apr 2021, 34 pts enrolled from 4 different centers. In cohort 1 (n=15), one pt was taken off study due to LFT elevation and orchitis attributed to pembro with reduced lymphadenopathy upon withdrawal. There was 1 PR (duration 686 days) and 4 SDs (61, 66, 124, 128 days) among 11 evaluable for response. There were no unexpected nor grade 5 toxicities. In cohort 2 (n=19), 2 pts achieved a PR (127 and 185 days), with SDs in 5 (59, 63, 69, 115, 437), among 13 evaluable for response. At oxali dose of 85 mg/m2, 1/6 pts had DLT (grade 4 neutropenia ≥7 days); another 1/6 pts had DLT at 120 mg/m2 (grade 3 AST/ALT). The RP2D was 120 mg/m2. Common grade 3/4 AEs included: neutropenia (24%), anemia (9%), fatigue (9%), abdominal pain (6%), nausea (6%), and ALT/AST (6%). There was no febrile neutropenia nor any grade 5 events. Combined cohort rates of PR/CBR were 3/24 (12.5%) and 12/24 (50%), respectively. Conclusions: In this study of heavily pretreated pts with MSS mCRC, combining pembro plus pem or pem+oxali was well tolerated. Overall CBR was 50%, with objective responses (PRs) in 3/24 (12.5%) evaluable pts. This compares favorably with KEYNOTE 016, in which pembro in MSS mCRC pts had 0/18 objective responses and CBR=11% (2/18). Further studies testing these agents in earlier lines of treatment with robust correlative analyses is supported. Support: NSABP Foundation; Merck; Lilly. Clinical trial information: NCT03626922.

Aromatase inhibitors versus tamoxifen in premenopausal women with oestrogen receptor-positive early-stage breast cancer treated with ovarian suppression: a patient-level meta-analysis of 7030 women from four randomised trials

BACKGROUND

For women with early-stage oestrogen receptor (ER)-positive breast cancer, adjuvant tamoxifen reduces 15-year breast cancer mortality by a third. Aromatase inhibitors are more effective than tamoxifen in postmenopausal women but are ineffective in premenopausal women when used without ovarian suppression. We aimed to investigate whether premenopausal women treated with ovarian suppression benefit from aromatase inhibitors.

METHODS

We did a meta-analysis of individual patient data from randomised trials comparing aromatase inhibitors (anastrozole, exemestane, or letrozole) versus tamoxifen for 3 or 5 years in premenopausal women with ER-positive breast cancer receiving ovarian suppression (goserelin or triptorelin) or ablation. We collected data on baseline characteristics, dates and sites of any breast cancer recurrence or second primary cancer, and dates and causes of death. Primary outcomes were breast cancer recurrence (distant, locoregional, or contralateral), breast cancer mortality, death without recurrence, and all-cause mortality. As distant recurrence invariably results in death from breast cancer several years after the occurrence, whereas locoregional recurrence and new contralateral breast cancer are not usually fatal, the distant recurrence analysis is shown separately. Standard intention-to-treat log-rank analyses estimated first-event rate ratios (RR) and their confidence intervals (CIs).

FINDINGS

We obtained data from all four identified trials (ABCSG XII, SOFT, TEXT, and HOBOE trials), which included 7030 women with ER-positive tumours enrolled between June 17, 1999, and Aug 4, 2015. Median follow-up was 8·0 years (IQR 6·1-9·3). The rate of breast cancer recurrence was lower for women allocated to an aromatase inhibitor than for women assigned to tamoxifen (RR 0·79, 95% CI 0·69-0·90, p=0·0005). The main benefit was seen in years 0-4 (RR 0·68, 99% CI 0·55-0·85; p<0·0001), the period when treatments differed, with a 3·2% (95% CI 1·8-4·5) absolute reduction in 5-year recurrence risk (6·9% vs 10·1%). There was no further benefit, or loss of benefit, in years 5-9 (RR 0·98, 99% CI 0·73-1·33, p=0·89) or beyond year 10. Distant recurrence was reduced with aromatase inhibitor (RR 0·83, 95% CI 0·71-0·97; p=0·018). No significant differences were observed between treatments for breast cancer mortality (RR 1·01, 95% CI 0·82-1·24; p=0·94), death without recurrence (1·30, 0·75-2·25; p=0·34), or all-cause mortality (1·04, 0·86-1·27; p=0·68). There were more bone fractures with aromatase inhibitor than with tamoxifen (227 [6·4%] of 3528 women allocated to an aromatase inhibitor vs 180 [5·1%] of 3502 women allocated to tamoxifen; RR 1·27 [95% CI 1·04-1·54]; p=0·017). Non-breast cancer deaths (30 [0·9%] vs 24 [0·7%]; 1·30 [0·75-2·25]; p=0·36) and endometrial cancer (seven [0·2%] vs 15 [0·3%]; 0·52 [0·22-1·23]; p=0·14) were rare.

INTERPRETATION

Using an aromatase inhibitor rather than tamoxifen in premenopausal women receiving ovarian suppression reduces the risk of breast cancer recurrence. Longer follow-up is needed to assess any impact on breast cancer mortality.

FUNDING

Cancer Research UK, UK Medical Research Council.

Abstract P3-17-03: Raising the level of cancer care around the world: The feasibility and perceived benefit of a virtual breast tumor board

Introduction: It is well established that multidisciplinary tumor boards improve the decision-making process for cancer patients. Tumor boards have been shown to improve the accuracy of diagnosis and staging, optimize patient outcomes, increase adherence to guidelines, and educate our peers and trainees. However, over 80% of patients in the United States receive their cancer care in the community setting, where access to multi-disciplinary tumor boards may not be readily available. This may particularly impact underserved populations who often lack the resources to travel to an academic center for second opinions or treatment. The problem is worse in low-resource countries. Virtual expert tumor boards could provide an effective solution. Methods: Preeminent breast oncology faculty from around the Unites States were assembled into virtual tumor board panels via an online platform to discuss challenging cases submitted by community providers and trainees. These tumor boards consisted of a moderator, a breast radiologist, a breast medical oncologist, a breast surgeon, and a breast radiation oncologist. The purpose of this ongoing endeavor is to educate community oncologists on how to best manage challenging cases. Following tumor board discussions, written recommendations were shared with submitting providers within 48 hours and recordings of the discussions were also later provided. After submitting providers watched the recording of their case discussion, we conducted a survey to determine their perceived benefit of the expert panel discussion. Results: From Sept 2020 to June 2021, ten breast cancer panels were virtually convened with 17 expert faculty panelists. During that time, 21 providers submitted 94 cases from the U.S. and around the world to be discussed by the expert panel. Thirty-three percent of the providers who submitted a case to be discussed have subsequently submitted an additional case to a later panel. Surveys were sent to all submitting providers and responses were recorded from 16/21 submitters (76.2%).

Conclusion: With more than three out of four submitters responding, we learned that not only is it feasible to convene virtual expert breast tumor boards to discuss challenging cases, but the vast majority of respondents learned new information, changed management of their patients, and wanted to submit additional cases. This effort could raise the level of breast cancer care around the world. Ongoing assessment of educational and patient care impacts will be necessary.

QuestionNumber answered (n)Number who answered yes (%)Number who answered no (%)Did you learn something new from the PrecisCa discussion of your case scenario?1614 (87.5)2 (12.5)Will anything you learned from the PrecisCa discussion of your case scenario change the management of this or future patients?1615 (93.8)1 (6.2)Are you likely to submit a future challenging case scenario to PrecisCa?1616 (100)0 (0)

Citation Format: Naomi Dempsey, Lauren Chiec, Mikala Lodder, Erin Shonkwiler, Kayla Haines, Reshma Mahtani, William Gradishar, Thomas Buchholz, Anne O'Dea, Norman Wolmark, Sara Hurvitz, Joyce O'Shaughnessy, Maxine Jochelson, Reni Butler, Eleftherios Mamounas, Frank Vicini, Mark Pegram, Chirag Shah, Tari King, Ruth O'Regan, Monica Morrow, Mohammad Jahanzeb. Raising the level of cancer care around the world: The feasibility and perceived benefit of a virtual breast tumor board [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-17-03.

Abstract P3-18-04: Evaluating -escalation of reast adiation () following lumpectomy for breast conservative treatment of stage 1, hr+, HER2-, RS ≤18 breast cancer: NRG-BR007 a phase III trial

Roughly 50% of newly diagnosed breast cancer is stage 1, the majority being ER/PR positive, HER2- negative. Genomic assays such as Oncotype DX® have identified patients with reduced distant metastasis and lack of chemotherapy benefit, allowing patients to avoid excess toxicity. These genomic assays have been shown to be prognostic for local-regional recurrence (LRR). The de-escalation of therapy is of interest to patients, providers, and payers. Low risk, as identified by both the use of Oncotype and Mammaprint® is associated with low LRR after lumpectomy and breast radiotherapy. TRIAL DESIGN: In the DEBRA trial, we hypothesized that breast-conserving surgery (BCS) alone is non-inferior to BCS plus radiotherapy for in-breast cancer control and breast preservation in women intending appropriate endocrine therapy for stage 1 (ER and/or PR-positive, HER2-negative, and Oncotype DX Recurrence Score [RS] low) breast cancer. Stratification is by age (&lt;60; ≥60), tumor size (≤1 cm; &gt;1-2 cm), and RS &lt;11, RS 11-18. Patients are randomized to either breast radiotherapy (RT) plus endocrine therapy (arm 1) or to observation and endocrine therapy (arm 2). Arm 1 therapy is post-lumpectomy breast RT using standard methods (hypo- or conventional-fractionated whole breast irradiation with or without boost, accelerated partial breast irradiation) and at least 5 years of endocrine therapy (tamoxifen or aromatase inhibitor). In arm 2, at least 5 years of endocrine therapy (tamoxifen or aromatase inhibitor) will be given. The specific regimen of endocrine therapy in both arms is at the treating physician’s discretion. ELIGIBLITY: Patients who are stage 1: pT1 (2 cm), pN0, age ≥50 to &lt;70 years, status post (s/p) lumpectomy with negative margins (no ink on tumor ), s/p axillary nodal staging (SNB or AND), ER and/or PR positive by ASCO/CAP, HER2-negative by ASCO/CAP, and Oncotype DX RS of ≤18 on diagnostic core biopsy or resected specimen. ENDPOINTS: Primary: In-breast recurrence (IBR). Secondary: Breast conservation rate, invasive in-breast recurrence (IIBR), relapse free interval (RFI), distant disease-free survival (DDFS), overall survival (OS), patient-reported breast pain, patient-reported worry about recurrence, and adherence to endocrine therapy. STATISTICS: We assume a clinically acceptable difference in IBR of 4% at 10 years to judge omission of RT as non-inferior (10-year event-free survival for RT group is 95.6% versus 91.6% for the omission of RT group). To be able to detect non-inferiority with 80% power and a one sided α=0.025, and assuming that there would be a ramp-up in accrual in the first two years of the study (leveling off in Years 3-5), 1,670 (835 per arm) patients are required to be randomized. This conservatively assumes loss to follow-up will be 1% per year. Some of the T1a patients accrued to this study will have oncotype DX scores &gt;18, making them ineligible for the study. An extra step in the accrual process will require us to register 1,714 patients to ensure our final randomized cohort is 1,670 patients. Accrual: Screen 1,714 to randomize 1,670 into the study. Contact information: Protocol: CTSU member website: https://www.ctsu.org. NRG Oncology Pgh Clinical Coordinating Dpt: 1-800-477-7227 or ccd@nsabp.org. Support: U10CA180868, U10CA180822. NCT04852887.

Citation Format: Julia White, Stewart J Anderson, Eleanor ER Harris, Eleftherios P Mamounas, Daniel G Stover, Patricia A Ganz, Reshma Jagsi, Reena S Cecchini, Carmen Bergom, Valerie Theberge, Mahmoud El-Tamer, Rich C Zellars, Dean A Shumway, Guang-Pei Chen, Thomas B Julian, Norman Wolmark. Evaluating de-escalation of breast radiation (DEBRA) following lumpectomy for breast conservative treatment of stage 1, hr+, HER2-, RS ≤18 breast cancer: NRG-BR007 a phase III trial [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-18-04.

Abstract P1-07-04: Potential role of the antibody-dependent cellular phagocytosis (ADCP) in tumors achieving pCR in NRG Oncology/NSABP B-52

Background: The NRG Oncology/NSABP B-52 neoadjuvant clinical trial was conducted to test if the addition of estrogen deprivation (ED) would improve the pCR rate in HER2+/ER+ breast cancer patients (pts) treated with docetaxel, carboplatin, trastuzumab, and pertuzumab (TCHP). A numerical increase in pCR rate was observed with ED (46.1% v 40.9%), but the difference was not statistically significant. We have previously quantitated T cells (CD8, FOXP3), macrophages (CD68), and immune checkpoint proteins (PD-1, PD-L1) with multiplex immunofluorescence in B-52 and shown that CD68 and FOXP3 cells were associated with pCR but not CD8 cells. Our purpose was to determine the associations of FCGR genotypes and immune cells with pCR. Methods: A single baseline, pre-treatment FFFPE tissue section per case (N=181) was used to perform a 7-plex multiplex immunofluorescence procedure using opal fluorophores for staining. The Vectra Pathology System and inForm analysis software (Akoya Biosciences) was used for imaging and quantitation of CD8, CD68, FOXP3, PD-1, and PD-L1 cells in both the tumoral and stromal regions. Stromal data is reported here. Favorable- and unfavorable- FcGγR genotypes for FCGR2A-131H/R and FCGR3A-158V/F alleles were determined via the Sequenom MassARRAY iPLEX platform. Rates of pCR with pts with 1 or 2 favorable alleles was compared to pts who were homozygous for the unfavorable allele. Within each genotype, Wilcoxon rank sum test was used to test the association of markers with pCR and within each treatment. Results: No significant association of FCGR2A and 3A alleles with pCR was detected in the entire B-52 cohort, however, among pts with favorable FCGR genotypes (FCGR2A-131-HH, or H/R, FCGR3A-158- VV, or VF HR) the median value of the % CD68 cells was significantly higher in tumors that achieved pCR v those that did not (p=0.0004, p=0.0006), respectively. In pts who were homozygous for the FCGR2A or FCGR3A unfavorable alleles, there was no significant difference in the median values of the % of CD68 cells between pCR and no-pCR tumors. Further stratification of tumors by treatment showed that pts with an FCGR2A or FCGR3A favorable genotype and whose tumors achieved pCR had a higher median value of CD68 only in the TCHP + ED arm (p=0.0007, p=0.0003), respectively and not in the TCHP arm (p=0.059; p=0.21). Higher levels of PD-L1 were associated with pCR in pts with FCGR3A- favorable genotypes, but higher levels of FOXP3 were associated with pCR regardless of genotype. In contrast to the other cell types, higher PD-1 or CD8 cells showed no association with genotypes. Conclusions: This is an exploratory study examining the potential role of ADCP in HER2+/ER+ breast cancer and supports the notion that ADCP may be one mechanism that promotes the elimination of tumor cells in a subset of pts in the neoadjuvant setting. Tumors that achieve pCR have higher % of CD68 cells, in pts with favorable FCGR2A and 3A genotypes than pts who do not. However, in pts with unfavorable FCGR3A or FCGR2A genotypes there was no difference in the median CD68 levels in pCR v no-pCR tumors. When tumors were further stratified by CD68 levels, FCGR3A genotypes, and treatment, the association of pCR in tumors with high CD68 and FCGR3A favorable genotypes was seen only in the TCHP+ED arm. This may indicate that ED may improve pCR rates in some tumors with more macrophages and favorable genotypes. Macrophages are known to have estrogen receptors, and estrogen has been shown to promote the alternative activation of macrophages, potentially dampening down the immune response. Thus, one could speculate that ED may block the estrogen-induced alternative activation of macrophages, allowing the classically activated macrophages to phagocytize tumor cells. Support: BCRF, U10CA180868 & Admin Sup, U24CA196067, Genentech, NSABP Foun.

Citation Format: Katherine L Pogue-Geile, Ying Wang, Huichen Feng, Corey Lipchick, Patrick Gavin, Rim S Kim, Reena S Cecchini, Samuel A Jacobs, Ashok Srinivasan, Sandra M Swain, Eleftherios Mamounas, Charles E Geyer, Jr, Priya Rastogi, Peter C Lucas, C. Kent Osborne, Soonmyung Paik, Norman Wolmark, Mothaffar F Rimawi. Potential role of the antibody-dependent cellular phagocytosis (ADCP) in tumors achieving pCR in NRG Oncology/NSABP B-52 [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-07-04.

Abstract PD15-05: Assessment of estrogen receptor (ESR1) mRNA expression for prediction of extended aromatase inhibitor benefit in HR-positive breast cancer using NRG Oncology/NSABP B-42

Background: In NSABP B-14, the quantitative levels of ESR1 mRNA, assessed using the standardized 21-gene assay and qRT-PCR platform predicted tamoxifen benefit (interaction p-value &lt;0.001). NSABP B-42 evaluated the effect of extended letrozole in postmenopausal women with hormone receptor-positive breast cancer who have completed 5 years of hormonal therapy with either an aromatase inhibitor or tamoxifen followed by an aromatase inhibitor. We proposed to determine if ESR1 mRNA, reported as the quantitative ER single gene score, is predictive of the magnitude of benefit from extended adjuvant endocrine therapy with letrozole in patients enrolled in NSABP B-42. Methods: This prospectively planned retrospective study used a stratified cohort sample drawn from the 2,589 B-42 patients with available tumor tissue blocks and appropriate consent. All 133 patients who experienced distant recurrence and 48 patients who experienced local/regional but not distant recurrence were included along with a stratified random sample of 547/2,408 patients without recurrence. The primary endpoint was distant recurrence. The primary analysis tested for the interaction between the continuous ER single gene score and the effect of extended letrozole treatment using a weighted Cox proportional hazards regression model. A secondary analysis considered the ER single gene score categorized using the prespecified cutoff of ≤9.1 versus &gt;9.1. Recurrence-free interval was a secondary endpoint. Results: The results of the assay were available for 587 patients. The median ER score was 10.2 (IQR 9.3-11.0). There were 131 patients (23.2% weighted) with ER ≤9.1 and 456 (76.8% weighted) with ER &gt;9.1. No significant interaction of the effect of extended letrozole treatment was found for either the ER single gene score (interaction hazard ratio letrozole vs. placebo with an IQR change in ER score 1.10, 95% CI 0.66 - 1.82, p=.72) or the categories ER ≤9.1 (treatment HR=0.40, 95% CI 0.15-1.06) or ER &gt;9.1 (treatment HR=0.70, 95% CI 0.43-1.12) (interaction p=.32). There was also no apparent prognostic effect of the ER single gene score for distant recurrence with placebo treatment after 5 years of endocrine therapy (p=.12). Results were similar in analyses of any recurrence, analyses adjusting for the proliferation axis from the 21-gene assay, and subgroup analyses by nodal and HER2-status. Conclusions: The B-42 study provided no evidence that ESR1 mRNA as measured by the ER single gene score can inform decisions regarding extended letrozole therapy after 5 years of adjuvant endocrine therapy. Confidence intervals were relatively wide but rule out a strong predictive effect of the ER single gene score in the expected direction. Support: U10CA180868, -180822, U24CA196067; Novartis; Exact Sciences

Citation Format: Eleftherios Mamounas, Hanna Bandos, Priya Rastogi, Michael R Crager, Carolyn Mies, Peter C Lucas, Charles E Geyer, Jr, Louis Fehrenbacher, Mark L Graham, Stephen KL Chia, Adam M Brufsky, Janice M Walshe, Gamini S Soori, Shaker R Dakhil, Soonmyung Paik, Sandra M Swain, Frederick L Baehner, Steven Shak, Norman Wolmark. Assessment of estrogen receptor (ESR1) mRNA expression for prediction of extended aromatase inhibitor benefit in HR-positive breast cancer using NRG Oncology/NSABP B-42 [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr PD15-05.

Abstract GS1-07: Adjuvant palbociclib in HR+/HER2- early breast cancer: Final results from 5,760 patients in the randomized phase III PALLAS trial

Background Advances in the multidisciplinary care of hormone-receptor positive (HR+) early breast cancer (eBC) have markedly improved clinical outcomes: however, disease recurrence may still occur, particularly in patients (pts) with moderate or high-risk cancers at the time of diagnosis. The use of CDK4/6 inhibitors (CDK4/6i) combined with endocrine therapy (ET) is a standard of care for advanced breast cancer, supporting the rationale to study CDK4/6i in the eBC setting. Here we present the final protocol-planned analyses of the global phase III PALLAS trial investigating whether the addition of the CDK4/6i palbociclib (P) to adjuvant ET improves outcomes over ET alone for HR+/HER2- eBC. Methods PALLAS (PALbociclib CoLlaborative Adjuvant Study, NCT02513394) is a randomized phase III open-label trial in which pts with stage II-III HR+/HER2- eBC were randomized to receive either 2 years of P with adjuvant ET (P+ET) or ET alone. The primary endpoint is invasive disease-free survival (iDFS); secondary endpoints include distant recurrence-free survival (DRFS), locoregional recurrence-free survival (LRRFS), overall survival (OS), and safety. Mandatory biospecimen collection has supported the creation of an expansive translational science program, and long-term follow-up is planned. Revised sample size calculations required recruitment of 5600 pts in order to detect a 25% iDFS improvement in patients receiving P+ET with 85% power; this final protocol-planned analysis was planned after 469 iDFS events. Results From September 1, 2015 to November 30, 2018, 5,761 pts (median age 52 years, range 22-90) were randomized in 406 centers in 21 countries worldwide. 1,014 (17.6%) had stage IIA disease (capped) and 4,728 (82.1%) stages IIB/III. 4,754 (82.5%) had received prior (neo)adjuvant chemotherapy. After a protocol-planned 2nd interim analysis in May 2020 crossed the futility threshold, 349 P+ET pts still on active treatment stopped P and were transferred to follow-up. At the time of final analysis cutoff date (November 20, 2020), after a median follow-up of 31 months and 516 events recorded, iDFS was similar between the two arms, with 3-year iDFS of 89.3% (95% CI: 87.8-90.6%) for Palbo+ET, and 89.4% (88.0-90.7%) for ET alone (hazard ratio 0.96, 95% CI: 0.81-1.14). There was no statistically significant difference in secondary outcome endpoints. Subgroup analyses revealed no significant interactions between treatment effect and other factors (including risk category). The safety profile of P was as expected, with grade 3 or 4 neutropenia the most common side effect (safety population: 1759/2841 [61.9%] vs 11/2902 [0.4%]). Overall 42% of pts. discontinued P prior to the planned 2-year duration, 28.2% of Palbo+ET pts discontinued therapy due to adverse events, without an observed impact on survival outcomes. Conclusions Now with the full number of events, this analysis of the PALLAS trial shows that the addition of 2 years of P to ongoing adjuvant ET did not improve survival endpoints for pts with stage II-III HR+/HER2- eBC. Whether P is beneficial in the adjuvant setting for certain sub-groups of pts will be further evaluated with longer-term follow-up and by the ongoing translational science program. Support: ABCSG; AFT; Pfizer; ClinicalTrials.gov Identifier: NCT02513394; https://www.abcsg.org; https://acknowledgments.alliancefound.org

Citation Format: Michael Gnant, Amylou C Dueck, Sophie Frantal, Miguel Martin, Hal Burstein, Richard Greil, Peter Fox, Antonio C Wolff, Arlene Chan, Eric Winer, Christian Singer, Kathy Miller, Marco Colleoni, Michelle Naughton, Gabor Rubovszky, Judith Bliss, Ingrid A Mayer, Guenther G Steger, Zbigniew Nowecki, Olwen Hahn, Norman Wolmark, Hope Rugo, Georg Pfeiler, Hannes Fohler, Otto Metzger, Céline Schurmans, Kathy P Theall, Dongrui R Lu, Kathleen Tenner, Christian Fesl, Angela DeMichele*, Erica L Mayer, *shared last authorship. Adjuvant palbociclib in HR+/HER2- early breast cancer: Final results from 5,760 patients in the randomized phase III PALLAS trial [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr GS1-07.

Association of multiplex-immunofluorescence (m-IF) and gene expression signature with prognosis and bevacizumab (bev) treatment outcomes in NRG oncology/NSABP C-08: Implications for combining immune checkpoint blockade (ICB) and bev

140

Background: NRG Oncology/NSABP C-08 tested the efficacy of adding bev to mFOLFOX in patients (pts) with stage II or III colon cancer. In an unplanned analysis we showed that MMR status was predictive of bev benefit with dMMR pts receiving statistically significant bev benefit. More recently, we showed that immune cells and immune checkpoint proteins have differential effects on prognosis and bev benefit in C-08 (ASC0 2021). As part of a preplanned secondary objective of an NCTN-CCSC approved protocol, we tested the association of VEGFR, VEGFA, and CD31, with clinical outcomes and treatment benefit in dMMR and pMMR pts enrolled in C-08. To determine what subset of pts within C-08 received bev benefit, we tested the 10-gene IFNɣ signature (Ayers et al 2017), which has been shown to associate with response to ICB in other studies. Methods: VEGFR, VEGFA, and CD31 were quantitated in tumors from C-08 pts (N=1,485) using m-IF and the Vectra Pathology System and inForm software. Gene expression data of C-08 (n=387) via DASLR microarrays was used to test the IFNɣ signature for association with bev benefit in dMMR and pMMR pts. All markers were tested for associations with prognosis and bev benefit in dMMR and pMMR pts using recurrence-free interval, median cut points, and Cox models. Results: VEGFR, VEGFA, and CD31 were not prognostic in the total C-08 cohort nor in dMMR or pMMR subsets. However, high VEGFR was associated with bev benefit in dMMR pts p=0.0012, HR=0.08 [95% CI; 0.025-0.224], n=117) but not in pts with pMMR (n=555) (int p=0.03). Pts whose tumors showed higher expression of the IFNɣ signature had a better prognosis than did pts with a low signature. Importantly, in the entire C-08 cohort with available DASL data, pts with low IFNɣ signatures received bev benefit (p=0.034, HR=0.59 [95% CI: 0.36-0.97], n=211). When low IFNɣ tumors were further split by MMR status both dMMR and pMMR pts showed a trend to receive bev benefit, however, numbers of pts were too small to make firm conclusions (dMMR no bev vs. bev p=0.02, n=11; pMMR no bev vs. bev, p=0.051, n=167). Conclusions: High VEGFR is associated with bev benefit in dMMR pts. In agreement with other studies, we observe that the IFNɣ signature is associated with a good prognosis in C-08, however, unique to this study is the observation that IFNɣ low is associated with bev benefit in the entire C-08 cohort. The association of high IFNɣ signature with ICB response seen in several other studies, plus our observation that low IFNɣ is associated with bev benefit in C-08, suggests that bev and ICB are most efficacious on different subsets of pts. Current clinical trial, GI-004, is testing the efficacy of the bev + atezolizumab combination. Examination of these markers may be informative. Support: PA DOH, U10CA-180868, -180822, -196067, Genentech, Sanofi; NSABP Clinical trial information: 00096278.

Behavioral and health outcomes from the NRG Oncology/NSABP B-36 trial comparing two different adjuvant therapy regimens for early-stage node-negative breast cancer

BACKGROUND

The NSABP B-36 compared four cycles of doxorubicin and cyclophosphamide (AC) with six cycles of 5-fluorouracil, epirubicin, and cyclophosphamide (FEC-100) in node-negative early-stage breast cancer. A sub-study within B-36, focusing on symptoms, quality of life (QOL), menstrual history (MH), and cardiac function (CF) was conducted.

PATIENTS AND METHODS

Patients completed the QOL questionnaire at baseline, during treatment, and every 6 months through 36 months. FACT-B Trial Outcome Index (TOI), symptom severity, and SF-36 Vitality and Physical Functioning (PF) scales scores were compared between the two groups using a mixed model for repeated measures analysis. MH was collected at baseline and subsequently assessed if menstrual bleeding occurred within 12 months prior to randomization. Post-chemotherapy amenorrhea outcome was examined at 18 months and was defined as lack of menses in the preceding year. Logistic regression was used to test for association of amenorrhea and treatment. CF assessment was done at baseline and 12 months. Correlation analysis was used to address associations between changes in baseline and 12-month PF and concurrent CF changes measured by LVEF.

RESULTS

FEC-100 patients had statistically significantly lower TOI scores during chemotherapy (P = 0.02) and at 6 months (P < 0.001); lower Vitality score at 6 months (P < 0.01), and lower PF score during the first year than AC patients. There were no statistically significant QOL score differences between the two groups beyond 12 months. No significant differences in symptom severity between the two groups were observed. Rates of amenorrhea were significantly different between FEC-100 and AC (67.4% vs. 59.1%, P < 0.001). There was no association between changes in LVEF and PF (P = 0.38).

CONCLUSIONS

Statistically significant QOL differences between the two groups favored AC; however, the magnitude was small and unlikely to be clinically meaningful. There was a clinical and statistically significant difference in risk for amenorrhea, favoring AC.

TRIAL REGISTRY

NCT00087178; Date of registration: 07/08/2004.

Patient-specific meta-analysis of 12-gene colon cancer recurrence score validation studies for recurrence risk assessment after surgery with or without 5FU and oxaliplatin

BACKGROUND

Individualized estimates of the risk of recurrence in colon cancer patients are needed that reflect current medical practice and available treatment options.

METHODS

Three validation studies of the 12-gene colon recurrence score assay were used with pre-specified patient-specific meta-analysis (PSMA) methods to integrate the 12-gene Oncotype DX Colon Recurrence Score result (RS) with the clinical and pathology risk factors stage, T-stage, mis-match repair (MMR) status, and number of nodes examined to calculate individualized recurrence risk estimates. Baseline risk estimation used the most recent studies, so the risk estimates reflect current medical practice. The effect of fluorouracil (5FU) was estimated with a meta-analysis of two studies. The effect of oxaliplatin was estimated using one of the RS assay validation studies, in which patients were randomized to 5FU with or without oxaliplatin.

RESULTS

The RS result and each of the clinical-pathologic factors provided independent prognostic information for recurrence. Among stage II, T3, MMR-proficient patients with ≥12 nodes examined (the most common scenario), patients with RS ≤30 (approximately 48%) have estimated 5-year recurrence risk ≤10% with surgery alone. Among stage IIIA/B, T3, MMR-deficient patients with ≥12 nodes examined, patients with RS ≤19 (approximately 14%) have an estimated 5-year recurrence risk ≤10% with surgery alone. Among stage IIIA/B, T3, MMR-proficient patients with ≥12 nodes examined, those with RS ≤14 (approximately 6%) have estimated 5-year recurrence risk ≤10% with 5FU alone.

DISCUSSION

The PSMA integrates the 12-gene colon RS result with clinical and pathology factors to provide individualized recurrence risk estimates that reflect current medical practice. The risk estimates are in a range that may help inform treatment decisions for a substantial number of stage II and stage III patients.

Phase II/III study of circulating tumor DNA as a predictive biomarker in adjuvant chemotherapy in patients with stage II colon cancer: NRG-GI005 (COBRA)

TPS233

Background: There are currently no validated predictive biomarkers for stage II resected colon cancer (CC) after adjuvant chemotherapy. However, circulating tumor DNA (ctDNA) shed into the bloodstream represents a highly specific and sensitive approach for identifying microscopic or residual tumor cells. For patients (pts) with CC, the detection of ctDNA is associated with persistent disease after resection and may outperform traditional clinical and pathological features in prognosticating risk for recurrence. We hypothesize that for pts whose stage II colon cancer has been resected and who have no traditional high-risk features, a positive ctDNA status may identify those who will benefit from adjuvant chemotherapy. Methods: In this prospective phase II/III clinical trial, pts (N = 1,408) with resected stage II CC without traditional high-risk features and whom the evaluating oncologist deems suitable for active surveillance (i.e., not needing adjuvant chemotherapy) will be randomized 1:1 into 2 arms: standard-of-care/observation (Arm A), or prospective testing for ctDNA (Arm B). Postoperative blood will be analyzed for ctDNA with the Guardant Reveal assay, covering CC-relevant mutations and CC-specific methylation profiling. Pts in Arm B with ctDNA detected will be treated with 6 months of adjuvant (FOLFOX) chemotherapy. For all pts in Arm A, ctDNA status will be analyzed retrospectively at the time of endpoint analysis. The primary endpoints are clearance of ctDNA with adjuvant chemotherapy (phase II) and recurrence-free survival (RFS) for “ctDNA-detected” pts treated with or without adjuvant chemotherapy (phase III). Secondary endpoints will include time-to-event outcomes (OS, RFS, TTR) by ctDNA marker status and treatment, prevalence of detectable ctDNA in stage II CC, and rates of compliance with assigned intervention. Archived normal and matched tumor and blood samples will be collected for exploratory correlative research. Enrollment continues across North America to the 540-patient phase II endpoint. Support: U10-CA-180868, -180822; UG1CA-189867; GuardantHealth. Clinical trial information: NCT04068103.

Phase II study of durvalumab following neoadjuvant chemoRT in operable rectal cancer: NSABP FR-2

99

Background: Although immunotherapy shows no benefit in microsatellite stable (MSS) colorectal cancer, preclinical models suggest that radiotherapy (RT) can enhance neoantigen presentation, modulate the microenvironment, and improve the likelihood of anti-tumor activity with checkpoint inhibitor use. Using a “window-of-opportunity” study design, this prospective phase II trial will determine the safety and activity of this approach with the anti-PD-L1 agent durvalumab (MEDI4736). Methods: Stage II/III patients (pts) with MSS rectal cancer undergoing standard NCCN guideline-compliant neoadjuvant chemoradiotherapy (CRT) followed by definitive surgery were eligible. Treatment included durvalumab (750mg IV infusion once every 2 wks) for 4 total doses beginning within 3-7 days after CRT completion followed by surgery within 8-12 wks of the final CRT dose. Primary end point (EP): Improvement in modified neoadjuvant rectal cancer (mNAR) score (goal 10.6) compared to historical controls (15.6) targeting a 20% DFS RR reduction and 3-4% absolute OS improvement. Secondary EPs: toxicity, pCR, cCR, therapy completion, negative surgical margins, sphincter preservation, and exploratory assessments of tumor-infiltrating lymphocytes, tumor Immunoscore, circulating immunologic profiles, and molecular predictors of response. We test H0: mNAR ≥15.6 vs HA: mNAR <15.6 at alpha 0.10 one-sided with statistical significance defined as p<0.1. Results: From May 2018 to October 2020, 45 pts were enrolled with 40 pts evaluable for mNAR. Mean mNAR was 12.03 (80% CI: 9.29-14.97) (p=0.06 one-sided). pCR=22.2%; cCR=31.1%; R0 resection=81.0%, and sphincter preservation=71.4%. Side effects were consistent with both CRT and durvalumab safety profile. Most common grade 3 AEs included diarrhea, lymphopenia, and back pain. There was one grade 4 AE (elevated amylase/lipase) and no grade 5 AEs. Remaining secondary and correlative immunologic end points are still being assessed. Conclusions: Durvalumab immediately following CRT prior to surgery for definitive management of rectal cancer was safe and without unexpected short-term toxicities. The primary end point of mean mNAR score was significantly less than our historical control, warranting further investigation. Correlative analyses for immunologic markers of response including PD-(L)1 expression and Immunoscore are ongoing. NCT 03102047. Support: AstraZeneca-Medimmune, NSABP Foundation. Clinical trial information: NCT03102047.

NRG-GI008: Colon adjuvant chemotherapy based on evaluation of residual disease (CIRCULATE-US)

TPS212

Background: Currently, there are no biomarkers validated prospectively in randomized studies for resected colon cancer (CC) to determine need for adjuvant chemotherapy (AC). However, circulating tumor DNA (ctDNA) shed into the bloodstream represents a highly specific and sensitive approach (especially with serial monitoring) for identifying microscopic or residual tumor cells in CC patients (pts) and may outperform traditional clinical and pathological features in prognosticating risk for recurrence. CC pts who do not have detectable ctDNA (ctDNA-) are at a much lower risk of recurrence and may not need AC. Furthermore, for CC pts with detectable ctDNA (ctDNA+) who are at a very high risk of recurrence, the optimal AC regimen has not been established. We hypothesize that for pts whose colon cancer has been resected, ctDNA status may be used to risk stratify for making decisions about AC. Methods: In this prospective phase II/III trial, up to 1,912 pts with resected stage III A, B (all pts) and stage II, IIIC (ctDNA+ only) CC will be enrolled. Based on the post-operative ctDNA status using Natera’s Signatera assay, those who are ctDNA- (Cohort A) will be randomized to immediate AC with fluoropyrimidine (FP) + oxaliplatin (Ox) for 3-6 mos per established guidelines vs serial ctDNA monitoring. Patients who are ctDNA+ post-operatively or with serial monitoring (Cohort B) will be randomized to FP + Ox vs more intensive AC with addition of irinotecan (I) for 6 mos. The primary objectives for Cohort A are time to ctDNA+ status (phase II) and disease-free survival (DFS) in phase III in the immediate vs delayed AC arms. The primary objective for Cohort B is DFS in the FP + Ox vs FP + Ox + I arms for both phase II and phase III portions of the trial. Secondary objectives include prevalence of detectable ctDNA post-operatively, time-to event outcomes (overall survival & time to recurrence) by ctDNA status, and the assessment of compliance to adjuvant therapy. Biospecimens including archival tumor tissue, post-operative and serial matched/ normal blood samples will be collected for exploratory correlative research. Study will activate in early 2022 across the NCTN. NCT#: Pending. Support: U10-CA-180868, -180822; UG1CA-189867; Natera.

NRG-GI004/SWOG-S1610: Colorectal cancer metastatic dMMR immuno-therapy (COMMIT) study—A randomized phase III study of atezolizumab (atezo) monotherapy versus mFOLFOX6/bevacizumab/atezo in the first-line treatment of patients (pts) with deficient DNA mismatch repair (dMMR) or microsatellite instability high (MSI-H) metastatic colorectal cancer (mCRC)

TPS232

Background: Despite the superiority in progression-free survival (PFS) of inhibition of programmed cell death-1 (PD-1) pathway in dMMR/MSI-H as compared to chemotherapy with either anti-vascular endothelial growth factor receptor (VEGFr) or anti-epithelial growth factor receptor (EGFr) antibodies in mCRC, more pts had progressive disease as the best response in the anti-PD1 monotherapy arm (29.4% vs. 12.3%) with mean PFS of 13.7 months ( N Engl J Med 2020; 383:2207). We hypothesize that the dMMR/MSI-H mCRC pts may be more effectively treated by the combination of PD-1 pathway blockade and mFOLFOX6/bevacizumab (bev) rather than with anti-PD-1 therapy (atezo) alone. Preclinical work demonstrated synergistic effects between anti-PD-1/anti-VEGF and between oxaliplatin/anti-PD-1 in murine CRC models and phase II data showed activity of anti-PD-1/anti-VEGF in chemotherapy refractory colon cancer. Additionally, in other solid tumor malignancies, anti-PD1 plus anti-VEGFr (i.e., HCC and RCC) as well as anti-PD1 plus chemotherapy (i.e., gastric and esophageal cancers) combinations are standard first-line treatments. Methods: The redesigned COMMIT study was reactivated on 1/29/2021 as a two-arm prospective phase III open-label trial randomizing (1:1) mCRC dMMR/MSI-H (211 pts) to atezo monotherapy versus mFOLFOX6/bev+atezo combination. Assuming our control arm, atezo monotherapy, 48% PFS at 24 months, as assessed by site investigator, we have 80% power to detect a hazard ratio of 0.6 (equivalent to 64.4% PFS at 24 months) with alpha 0.025 one-sided. Stratification factors include BRAFV600E status, metastatic site, and prior adjuvant CRC therapy. Secondary endpoints include OS, objective response rate, safety profile, disease control rate, duration of response, and centrally-reviewed PFS. Health-related quality of life is an exploratory objective. Archived tumor tissue and blood samples will be collected for correlative studies. Key inclusion criteria are: mCRC without prior chemotherapy for advanced disease; dMMR tumor determined by local CLIA-certified IHC assay (MLH1/MSH2/MSH6/PMS2) or MSI-H by local CLIA-certified PCR or NGS panel; and measurable disease per RECIST. Enrollment actively continues to the target accrual of 211 patients randomized between the two immunotherapy arms. Support: U10CA180868, -180822, -180888, UG1CA189867, U24CA196067; Genentech, Inc. Clinical trial information: NCT02997228.

Long-term efficacy and safety of addition of carboplatin with or without veliparib to standard neoadjuvant chemotherapy in triple-negative breast cancer: 4-year follow-up data from BrighTNess, a randomized phase 3 trial

BACKGROUND

Primary analyses of the phase 3 BrighTNess trial showed addition of carboplatin with/without veliparib to neoadjuvant chemotherapy significantly improved pathological complete response (pCR) rates with manageable acute toxicity in patients with triple-negative breast cancer (TNBC). Here, we report 4.5-year follow-up data from the trial.

DESIGN

Women with untreated stage II-III TNBC were randomized (2:1:1) to paclitaxel (weekly for 12 doses) plus either: (a) carboplatin (every 3 weeks for four cycles) plus veliparib (twice daily); (b) carboplatin plus veliparib placebo; or (c) carboplatin placebo plus veliparib placebo. All patients then received doxorubicin and cyclophosphamide (AC) every 2‒3 weeks for four cycles. The primary endpoint was pCR. Secondary endpoints included event-free survival (EFS), overall survival (OS), and safety. Since the co-primary endpoint of increased pCR with carboplatin plus veliparib with paclitaxel versus carboplatin with paclitaxel was not met, secondary analyses are descriptive.

RESULTS

Of 634 patients, 316 were randomized to carboplatin plus veliparib with paclitaxel, 160 to carboplatin with paclitaxel, and 158 to paclitaxel. With median follow-up of 4.5 years, the hazard ratio [HR] for EFS for carboplatin plus veliparib with paclitaxel versus paclitaxel was 0.63 (95% confidence interval [CI] 0.43‒0.92, P=0.02), but 1.12 (95% CI 0.72‒1.72, P=0.62) for carboplatin plus veliparib with paclitaxel versus carboplatin with paclitaxel. In post hoc analysis, HR for EFS was 0.57 (95% CI 0.36‒0.91, P=0.02) for carboplatin with paclitaxel versus paclitaxel. OS did not differ significantly between treatment arms, nor did rates of myelodysplastic syndromes, acute myeloid leukemia, or other secondary malignancies.

CONCLUSION

Improvement in pCR with addition of carboplatin was associated with long-term EFS benefit with a manageable safety profile, and without increasing the risk of second malignancies, while adding veliparib did not impact EFS. These findings support the addition of carboplatin to weekly paclitaxel followed by AC neoadjuvant chemotherapy for early stage TNBC.

Adjuvant Palbociclib for Early Breast Cancer: The PALLAS Trial Results (ABCSG-42/AFT-05/BIG-14-03)

PURPOSE

Palbociclib is a cyclin-dependent kinase 4 and 6 inhibitor approved for advanced breast cancer. In the adjuvant setting, the potential value of adding palbociclib to endocrine therapy for hormone receptor-positive breast cancer has not been confirmed.

PATIENTS AND METHODS

In the prospective, randomized, phase III PALLAS trial, patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative early breast cancer were randomly assigned to receive 2 years of palbociclib (125 mg orally once daily, days 1-21 of a 28-day cycle) with adjuvant endocrine therapy or adjuvant endocrine therapy alone (for at least 5 years). The primary end point of the study was invasive disease-free survival (iDFS); secondary end points were invasive breast cancer-free survival, distant recurrence-free survival, locoregional cancer-free survival, and overall survival.

RESULTS

Among 5,796 patients enrolled at 406 centers in 21 countries worldwide over 3 years, 5,761 were included in the intention-to-treat population. At the final protocol-defined analysis, at a median follow-up of 31 months, iDFS events occurred in 253 of 2,884 (8.8%) patients who received palbociclib plus endocrine therapy and in 263 of 2,877 (9.1%) patients who received endocrine therapy alone, with similar results between the two treatment groups (iDFS at 4 years: 84.2% v 84.5%; hazard ratio, 0.96; CI, 0.81 to 1.14; P = .65). No significant differences were observed for secondary time-to-event end points, and subgroup analyses did not show any differences by subgroup. There were no new safety signals for palbociclib in this trial.

CONCLUSION

At this final analysis of the PALLAS trial, the addition of adjuvant palbociclib to standard endocrine therapy did not improve outcomes over endocrine therapy alone in patients with early hormone receptor-positive breast cancer.

Clinicopathological and Molecular Characteristics of Early-Onset Stage III Colon Adenocarcinoma: An Analysis of the ACCENT Database

BACKGROUND

Colon cancer (CC) incidence in young adults (age 20-49 years), termed early-onset CC (EO-CC), is increasing.

METHODS

Individual patient data on 35 713 subjects with stage III colon cancer from 25 randomized studies in the Adjuvant Colon Cancer ENdpoint database were pooled. The distributions of demographics, clinicopathological features, biomarker status, and outcome data were summarized by age group. Overall survival, disease-free survival, time to recurrence, and survival after recurrence were assessed by Kaplan-Meier curves and Cox models stratified by treatment arms within studies, adjusting for sex, race, body mass index, performance status, disease stage, grade, risk group, number of lymph nodes examined, disease sidedness, and molecular markers. All statistical tests were 2-sided.

RESULTS

Using a 5% difference between age groups as the clinically meaningful cutoff, patients with stage III EO-CC had similar sex, race, performance status, risk group, tumor sidedness, and T stage compared with patients with late-onset CC (age 50 years and older). EO-CC patients were less likely to be overweight (30.2% vs 36.2%) and more commonly had 12 or more lymph nodes resected (69.5% vs 58.7%). EO-CC tumors were more frequently mismatch repair deficient (16.4% vs 11.5%) and less likely to have BRAFV600E (5.6% vs 14.0%), suggesting a higher rate of Lynch syndrome in EO-CC. Patients with EO-CC had statistically significantly better overall survival (hazard ratio [HR] = 0.81, 95% confidence interval [CI] = 0.74 to 0.89; P < .001), disease-free survival (HR = 0.91, 95% CI = 0.84 to 0.98; P = .01), and survival after recurrence (HR = 0.88, 95% CI = 0.80 to 0.97; P = .008) in the analysis without molecular markers; however, age at onset of CC lost its prognostic value when outcome was adjusted for molecular markers.

CONCLUSION

Tumor biology was found to be a more important prognostic factor than age of onset among stage III colon cancer patients in the Adjuvant Colon Cancer ENdpoint database.

Matched cohort study of germline BRCA mutation carriers with triple negative breast cancer in brightness

In the BrighTNess trial, carboplatin added to neoadjuvant chemotherapy (NAC) was associated with increased pathologic complete response (pCR) rates in patients with stage II/III triple-negative breast cancer (TNBC). In this matched cohort study, cases with a germline BRCA1/2 mutation (gBRCA; n = 75) were matched 1:2 with non-gBRCA controls (n = 150) by treatment arm, lymph node status, and age to evaluate pCR rates and association of benefit from platinum/PARP inhibitors with validated RNA expression-based immune, proliferation, and genomic instability scores among gBRCA with the addition of carboplatin ± veliparib to NAC. Among the well-matched cohorts, odds of pCR were not higher in gBRCA cancers who received standard NAC with carboplatin (OR 0.24, 95% CI [0.04-1.24], p = 0.09) or with carboplatin/veliparib (OR 0.44, 95% CI [0.10-1.84], p = 0.26) compared to non-gBRCA cancers. Higher PAM50 proliferation, GeparSixto immune, and CIN70 genomic instability scores were each associated with higher pCR rate in the overall cohort, but not specifically in gBRCA cases. In this study, gBRCA carriers did not have higher odds of pCR than non-gBRCA controls when carboplatin ± veliparib was added to NAC, and showed no significant differences in molecular, immune, chromosomal instability, or proliferation gene expression metrics.