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.

Reevaluating Disease-Free Survival as an Endpoint vs Overall Survival in Stage III Adjuvant Colon Cancer Trials

BACKGROUND

Disease-free survival (DFS) with a 3-year median follow-up (3-year DFS) was validated as a surrogate for overall survival (OS) with a 5-year median follow-up (5-year OS) in adjuvant chemotherapy colon cancer (CC) trials. Recent data show further improvements in OS and survival after recurrence in patients who received adjuvant FOLFOX. Hence, reevaluation of the association between DFS and OS and determination of the optimal follow-up duration of OS to aid its utility in future adjuvant trials are needed.

METHODS

Individual patient data from 9 randomized studies conducted between 1998 and 2009 were included; 3 trials tested biologics. Trial-level surrogacy examining the correlation of treatment effect estimates of 3-year DFS with 5 to 6.5-year OS was evaluated using both linear regression (RWLS2) and Copula bivariate (RCopula2) models and reported with 95% confidence intervals (CIs). For R2, a value closer to 1 indicates a stronger correlation.

RESULTS

Data from a total of 18 396 patients were analyzed (median age = 59 years; 54.0% male), with 54.1% having low-risk tumors (T1-3 and N1), 31.6% KRAS mutated, 12.3% BRAF mutated, and 12.4% microsatellite instability high or deficient mismatch repair tumors. Trial-level correlation between 3-year DFS and 5-year OS remained strong (RWLS2 = 0.82, 95% CI = 0.67 to 0.98; RCopula2 = 0.92, 95% CI = 0.83 to 1.00) and increased as the median follow-up of OS extended. Analyses limited to trials that tested biologics showed consistent results.

CONCLUSIONS

Three-year DFS remains a validated surrogate endpoint for 5-year OS in adjuvant CC trials. The correlation was likely strengthened with 6 years of follow-up for OS.

Trastuzumab for early-stage, HER2-positive breast cancer: a meta-analysis of 13 864 women in seven randomised trials

BACKGROUND

Trastuzumab targets the extracellular domain of the HER2 protein. Adding trastuzumab to chemotherapy for patients with early-stage, HER2-positive breast cancer reduces the risk of recurrence and death, but is associated with cardiac toxicity. We investigated the long-term benefits and risks of adjuvant trastuzumab on breast cancer recurrence and cause-specific mortality.

METHODS

We did a collaborative meta-analysis of individual patient data from randomised trials assessing chemotherapy plus trastuzumab versus the same chemotherapy alone. Randomised trials that enrolled women with node-negative or node-positive, operable breast cancer were included. We collected individual patient-level data on baseline characteristics, dates and sites of first distant breast cancer recurrence and any previous local recurrence or second primary cancer, and the date and underlying cause of death. Primary outcomes were breast cancer recurrence, breast cancer mortality, death without recurrence, and all-cause mortality. Standard intention-to-treat log-rank analyses, stratified by age, nodal status, oestrogen receptor (ER) status, and trial yielded first-event rate ratios (RRs).

FINDINGS

Seven randomised trials met the inclusion criteria, and included 13 864 patients enrolled between February, 2000, and December, 2005. Mean scheduled treatment duration was 14·4 months and median follow-up was 10·7 years (IQR 9·5 to 11·9). The risks of breast cancer recurrence (RR 0·66, 95% CI 0·62 to 0·71; p<0·0001) and death from breast cancer (0·67, 0·61 to 0·73; p<0·0001) were lower with trastuzumab plus chemotherapy than with chemotherapy alone. Absolute 10-year recurrence risk was reduced by 9·0% (95% CI 7·4 to 10·7; p<0·0001) and 10-year breast cancer mortality was reduced by 6·4% (4·9 to 7·8; p<0·0001), with a 6·5% reduction (5·0 to 8·0; p<0·0001) in all-cause mortality, and no increase in death without recurrence (0·4%, -0·3 to 1·1; p=0·35). The proportional reduction in recurrence was largest in years 0-1 after randomisation (0·53, 99% CI 0·46 to 0·61), with benefits persisting through years 2-4 (0·73, 0·62 to 0·85) and 5-9 (0·80, 0·64 to 1·01), and little follow-up beyond year 10. Proportional recurrence reductions were similar irrespective of recorded patient and tumour characteristics, including ER status. The more high risk the tumour, the larger the absolute reductions in 5-year recurrence (eg, 5·7% [95% CI 3·1 to 8·3], 6·8% [4·7 to 9·0], and 10·7% [7·7 to 13·6] in N0, N1-3, and N4+ disease).

INTERPRETATION

Adding trastuzumab to chemotherapy for early-stage, HER2-positive breast cancer reduces recurrence of, and mortality from, breast cancer by a third, with worthwhile proportional reductions irrespective of recorded patient and tumour characteristics.

FUNDING

Cancer Research UK, UK Medical Research Council.

Use of Total Neoadjuvant Therapy for Locally Advanced Rectal Cancer: Initial Results From the Pembrolizumab Arm of a Phase 2 Randomized Clinical Trial

Importance

Total neoadjuvant therapy (TNT) is often used to downstage locally advanced rectal cancer (LARC) and decrease locoregional relapse; however, more than one-third of patients develop recurrent metastatic disease. As such, novel combinations are needed.

Objective

To assess whether the addition of pembrolizumab during and after neoadjuvant chemoradiotherapy can lead to an improvement in the neoadjuvant rectal (NAR) score compared with treatment with FOLFOX (5-fluorouracil, leucovorin, and oxaliplatin) and chemoradiotherapy alone.

Design, Setting, and Participants

In this open-label, phase 2, randomized clinical trial (NRG-GI002), patients in academic and private practice settings were enrolled. Patients with stage II/III LARC with distal location (cT3-4 ≤ 5 cm from anal verge, any N), with bulky disease (any cT4 or tumor within 3 mm of mesorectal fascia), at high risk for metastatic disease (cN2), and/or who were not candidates for sphincter-sparing surgery (SSS) were stratified based on clinical tumor and nodal stages. Trial accrual opened on August 1, 2018, and ended on May 31, 2019. This intent-to-treat analysis is based on data as of August 2020.

Interventions

Patients were randomized (1:1) to neoadjuvant FOLFOX for 4 months and then underwent chemoradiotherapy (capecitabine with 50.4 Gy) with or without intravenous pembrolizumab administered at a dosage of 200 mg every 3 weeks for up to 6 doses before surgery.

Main Outcomes and Measures

The primary end point was the NAR score. Secondary end points included pathologic complete response (pCR) rate, SSS, disease-free survival, and overall survival. This report focuses on end points available after definitive surgery (NAR score, pCR, SSS, clinical complete response rate, margin involvement, and safety).

Results

A total of 185 patients (126 [68.1%] male; mean [SD] age, 55.7 [11.1] years) were randomized to the control arm (CA) (n = 95) or the pembrolizumab arm (PA) (n = 90). Of these patients, 137 were evaluable for NAR score (68 CA patients and 69 PA patients). The mean (SD) NAR score was 11.53 (12.43) for the PA patients (95% CI, 8.54-14.51) vs 14.08 (13.82) for the CA patients (95% CI, 10.74-17.43) (P = .26). The pCR rate was 31.9% in the PA vs 29.4% in the CA (P = .75). The clinical complete response rate was 13.9% in the PA vs 13.6% in the CA (P = .95). The percentage of patients who underwent SSS was 59.4% in the PA vs 71.0% in the CA (P = .15). Grade 3 to 4 adverse events were slightly increased in the PA (48.2%) vs the CA (37.3%) during chemoradiotherapy. Two deaths occurred during FOLFOX: sepsis (CA) and pneumonia (PA). No differences in radiotherapy fractions, FOLFOX, or capecitabine doses were found.

Conclusions and Relevance

Pembrolizumab added to chemoradiotherapy as part of total neoadjuvant therapy was suggested to be safe; however, the NAR score difference does not support further study.

Trial Registration

ClinicalTrials.gov Identifier: NCT02921256.

Comparison of Radiation With or Without Concurrent Trastuzumab for HER2-Positive Ductal Carcinoma In Situ Resected by Lumpectomy: A Phase III Clinical Trial

PURPOSE

Preclinical studies report that trastuzumab (T) can boost radiotherapy (RT) effectiveness. The primary aim of the B-43 trial was to assess the efficacy of RT alone vs concurrent RT plus T in preventing recurrence of ipsilateral breast cancer (IBTR) in women with ductal carcinoma in situ (DCIS).

PATIENTS AND METHODS

Eligibility: Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1, DCIS resected by lumpectomy, known estrogen receptor (ER) and/or progesterone receptor (PgR), and human epidermal growth factor receptor 2 (HER2) status by centralized testing. Whole-breast RT was given concurrently with T. Stratification was by menopausal status, adjuvant endocrine therapy plan, and nuclear grade. Definitive intent-to-treat primary analysis was to be conducted when either 163 IBTR events occurred or all accrued patients were on study ≥ 5 years.

RESULTS

There were 2,014 participants who were randomly assigned. Median follow-up time as of December 31, 2019, was 79.2 months. At primary definitive analysis, 114 IBTR events occurred: RT arm, 63 and RT plus T arm, 51 (hazard ratio [HR], 0.81; 95% CI, 0.56 to 1.17; P value = .26). There were 34 who were invasive: RT arm, 18 and RT plus T arm, 20 (HR, 1.11; 95% CI, 0.59 to 2.10; P value = .71). Seventy-six were DCIS: RT arm, 45 and RT plus T arm, 31 (HR, 0.68; 95% CI, 0.43 to 1.08; P value = .11). Annual IBTR event rates were: RT arm, 0.99%/y and RT plus T arm, 0.79%/y. The study did not reach the 163 protocol-specified events, so the definitive analysis was triggered by all patients having been on study for ≥ 5 years.

CONCLUSION

Addition of T to RT did not achieve the objective of 36% reduction in IBTR rate but did achieve a modest but statistically nonsignificant reduction of 19%. Nonetheless, this trial had negative results. Further exploration of RT plus T is needed in HER2-positive DCIS before its routine delivery in patients with DCIS resected by lumpectomy.

Abstract 532: Association of pCR and the 8-gene signature: NRG Oncology/NSABP B-41

Background: Lapatinib (L), a HER2 signaling, tyrosine kinase inhibitor, demonstrated numerically higher pCR in NSABP B-41 when added to paclitaxel (AC→P) and trastuzumab (T) following doxorubicin + cyclophosphamide (62% v 52.5%). We previously validated an 8-gene signature that predicted the degree of T benefit in NSABP B-31 and NCCTG9831. The purpose of this study is to determine the association of pCR with the 8- gene T-benefit groups, enabling the possibility of stratifying patients (pts) who do or do not receive benefit from L.

Methods: Normalized B-41 nCounter® Breast Cancer 360 gene expression data was used to define the three T-benefit groups: large-, moderate-, and no-. The 8-gene signature was modified to use only 7 genes because one of the 8 genes was not included in the nCounter code set. The ability of the 7-gene signature to predict T benefit was equivalent to the 8-gene signature when tested in B-31. Comparisons within each treatment arm were made with Fisher's exact test.

Results: The pCR rates were significantly different among the three groups in the AC→P+T arm: Large: 24/28 (86%); Moderate: 13/32 (41%); and No: 1/9 (11%); p&lt;0.001, but were not significantly different in the other two arms; a trend for significance was seen in the AC→P+T+L arm (Table 1). We also tested if L would improve pCR when added to AC→P+T in any of the 7-gene benefit groups compared to T. There was a non-significant, numerical increase in pCR in the no-benefit group in the AC→P+T+L arm (44%) v the AC→P+T arm (11%) (p=0.29).

Conclusions: The significant association of the modified 8-gene benefit groups with pCR in the AC→P+T arm suggests this signature could identify pts who may benefit from dual HER2-targeted neoadjuvant therapy. This could be tested in a meta-analysis including other neoadjuvant trials.

Support: Lombardi CCC; BCRF; GSK; P30CA051008; Genentech; NSABP

Table 1.pCR rates in trastuzumab benefit groups in NSABP B-41pCR rates in Breast and NodesTreatmentNo BenefitIntermediateLarge BenefitEntire Cohortp valueAC→P+T1/9 (11.1%)13/32(40.6%)24/28 (85.7%)38/69 (55.1%)&lt;0.001AC→P+L2/7 (28.6%)11/26 (42.3%)14/31 (45.2%)27/64 (42.2%)0.82AC→P+T+L4/9 (44.4%)11/25 (44.0%)20/27 (74.1%)35/61 (57.4%)0.051

Citation Format: Nan Song, Xiaoqing E. Tan, Ying Wang, Rim S. Kim, Hanna Bandos, Gong Tang, Eleftherios Mamounas, Charles E. Geyer, Priya Rastogi, Samuel A. Jacobs, Ashok Srinivasan, Peter C. Lucas, Soonmyung Paik, Norman Wolmark, Sandra M. Swain, Katherine L. Pogue-Geile. Association of pCR and the 8-gene signature: NRG Oncology/NSABP B-41 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 532.

Adjuvant Olaparib for Patients with BRCA1- or BRCA2-Mutated Breast Cancer

BACKGROUND

Poly(adenosine diphosphate-ribose) polymerase inhibitors target cancers with defects in homologous recombination repair by synthetic lethality. New therapies are needed to reduce recurrence in patients with BRCA1 or BRCA2 germline mutation-associated early breast cancer.

METHODS

We conducted a phase 3, double-blind, randomized trial involving patients with human epidermal growth factor receptor 2 (HER2)-negative early breast cancer with BRCA1 or BRCA2 germline pathogenic or likely pathogenic variants and high-risk clinicopathological factors who had received local treatment and neoadjuvant or adjuvant chemotherapy. Patients were randomly assigned (in a 1:1 ratio) to 1 year of oral olaparib or placebo. The primary end point was invasive disease-free survival.

RESULTS

A total of 1836 patients underwent randomization. At a prespecified event-driven interim analysis with a median follow-up of 2.5 years, the 3-year invasive disease-free survival was 85.9% in the olaparib group and 77.1% in the placebo group (difference, 8.8 percentage points; 95% confidence interval [CI], 4.5 to 13.0; hazard ratio for invasive disease or death, 0.58; 99.5% CI, 0.41 to 0.82; P<0.001). The 3-year distant disease-free survival was 87.5% in the olaparib group and 80.4% in the placebo group (difference, 7.1 percentage points; 95% CI, 3.0 to 11.1; hazard ratio for distant disease or death, 0.57; 99.5% CI, 0.39 to 0.83; P<0.001). Olaparib was associated with fewer deaths than placebo (59 and 86, respectively) (hazard ratio, 0.68; 99% CI, 0.44 to 1.05; P = 0.02); however, the between-group difference was not significant at an interim-analysis boundary of a P value of less than 0.01. Safety data were consistent with known side effects of olaparib, with no excess serious adverse events or adverse events of special interest.

CONCLUSIONS

Among patients with high-risk, HER2-negative early breast cancer and germline BRCA1 or BRCA2 pathogenic or likely pathogenic variants, adjuvant olaparib after completion of local treatment and neoadjuvant or adjuvant chemotherapy was associated with significantly longer survival free of invasive or distant disease than was placebo. Olaparib had limited effects on global patient-reported quality of life. (Funded by the National Cancer Institute and AstraZeneca; OlympiA ClinicalTrials.gov number, NCT02032823.).

MAF Amplification and Adjuvant Clodronate Outcomes in Early-Stage Breast Cancer in NSABP B-34 and Potential Impact on Clinical Practice

Background

The Adjuvant Zoledronic Acid (ZA) study in early breast cancer (AZURE) showed correlation between a nonamplified MAF gene in the primary tumor and benefit from adjuvant ZA. Adverse ZA outcomes occurred in MAF-amplified patients. NSABP B-34 is a validation study.

Methods

A retrospective analysis of MAF gene status in NSABP B-34 was performed. Eligible patients were randomly assigned to standard adjuvant systemic treatment plus 3 years oral clodronate (1600 mg/daily) or placebo. Tumors were tested for MAF gene amplification and analyzed for their relationship to clodronate for disease-free survival (DFS) and overall survival (OS) in MAF nonamplified patients. All statistical tests were 2-sided .

Results

MAF status was assessed in 2533 available primary tumor samples from 3311 patients. Of these, 37 withdrew consent; in 77 samples, no tumor was found; 536 assays did not meet quality standards, leaving 1883 (77.8%) evaluable for MAF assay by fluorescence in situ hybridization (947 from placebo and 936 from clodronate arms). At 5 years, in MAF nonamplified patients receiving clodronate, DFS improved by 30% (hazard ratio = 0.70, 95% confidence interval = 0.51 to 0.94; P = .02). OS improved at 5 years (hazard ratio = 0.59, 95% confidence interval = 0.37 to 0.93; P = .02) remaining statistically significant for clodronate throughout study follow-up. Conversely, adjuvant clodronate in women with MAF-amplified tumors was not associated with benefit but rather possible harm in some subgroups. Association between MAF status and menopausal status was not seen.

Conclusions

Nonamplified MAF showed statistically significant benefits (DFS and OS) with oral clodronate, supporting validation of the AZURE study.

Breast Cancer Index (BCI) and prediction of benefit from extended aromatase inhibitor (AI) therapy (tx) in HR+ breast cancer: NRG oncology/NSABP B-42

501

Background: The BCI HOXB13/IL17BR ratio (BCI-H/I) has been shown to predict endocrine tx (ET) and extended ET (EET) benefit. We examined the effect of BCI-H/I for EET benefit prediction in NSABP B-42, evaluating extended letrozole tx (ELT) in HR+ breast cancer patients (pts) who completed 5 yrs of ET. Methods: All pts with available primary tumor tissue were eligible. Primary endpoint was recurrence-free interval (RFI). Secondary endpoints were distant recurrence (DR), breast cancer-free interval (BCFI), and disease-free survival (DFS). Stratified Cox proportional hazards model was used. Due to a non-proportional effect of ELT on DR, time-dependent secondary analyses (≤4y, >4y) were performed. Likelihood ratio test evaluated treatment by BCI-H/I interaction. Results: In 2,179 pts analyzed (60% N0; 62% AI only; 80% HER2-), 45% were BCI-H/I-High and 55% BCI-H/I-Low. ELT showed an absolute 10y benefit of 1.6% for RFI (HR=0.77, 95% CI 0.57-1.05, p=0.10) (BCI-H/I-Low: 1.1% [HR=0.69, 0.43-1.11, p=0.13]; BCI-H/I-High: 2.4% [HR=0.83, 0.55-1.26, p=0.38]; interaction p=0.55). There was no statistically significant ELT by BCI-H/I interaction for BCFI (BCI-H/I-Low: HR=0.53, 0.36-0.78, p=0.001; BCI-H/I-High: HR=0.85, 0.60-1.21, p=0.36; interaction p=0.07) or for DFS (BCI-H/I-Low: HR=0.75, 0.58-0.95, p=0.017; BCI-H/I-High: HR=0.81, 0.64-1.04, p=0.09; interaction p=0.62). Before 4y, there was no statistically significant ELT benefit on DR in either BCI-H/I group. After 4y, BCI-H/I-High pts had statistically significant ELT benefit on DR (HR: 0.29, 0.12-0.69, p=0.003), while BCI-H/I-Low pts were less likely to benefit (HR: 0.68, 0.33-1.39, p=0.28) (interaction p=0.14). Conclusions: BCI-H/I prediction of ELT benefit on RFI was not confirmed. In time-dependent DR analyses, BCI-H/I-High pts had statistically significant benefit from ELT after 4y, while BCI-H/I-Low pts did not. Observed ELT benefit on BCFI in BCI-H/I-Low pts was primarily driven by second primary breast cancers. Additional follow-up is needed to further characterize BCI-H/I predictive ability in this study. Support: U10CA180868, -180822, U24CA196067; Novartis; Biotheranostics. Clinical trial information: NCT00382070. [Table: see text]

Examination of the tumor immune microenvironment (TIME) with multispectral immunofluorescence (m-IF): Association of markers with prognosis and bevacizumab (bev) benefit in NRG Oncology/NSABP C-08

3516

Background: The purpose of this study was to quantify different molecules of TIME including T cells, macrophages, and immune checkpoint proteins (ICPs), and determine their association with clinical outcomes and treatment benefit in pts enrolled in C-08, which tested the efficacy of adding bev to 5-fluoruracil+leucovorin+oxaliplatin. Our pre-specified, NCTN-CCSC approved primary objective hypothesized that pts with more CD8 cells would have a better prognosis and receive benefit from bev. Methods: Tissue microarrays were used to assess TIME of 1,509 C-08 pts using m-IF and the Vectra Pathology System. Three m-IF panels were used to quantitatively assess T cells (CD3, CD8, CD45RO, FOXP3), macrophages (CD68, CD163), and ICPs (PD-1, PD-L1, CTLA4, TIM3, LAG3, OX40) in stromal and tumor (panCK) regions. The primary objective was to determine the association between overall survival (OS) and high (top 3rd) v low CD8 expression in both stromal and tumor regions. All markers were tested for associations with OS and recurrence-free interval (RFI) and with bev prediction using Cox models and median cut points. Results: Based on our pre-specified analysis, pts with high CD8 cells had better OS, HR=0.66 (95%CI: 0.49-0.88), p=0.005 but pts with high CD8 cells did not receive bev benefit. All T cells and double stained CD8/PD-1 were associated with better RFI. CD3, CD8, CD68, PD-1, PD-L1, and LAG3 cells were associated with better OS. PD-1 and CD8/PD-1 were associated with RFI in pts with deficient mismatch repair (dMMR) and proficient (p)MMR but TIM3, CD3/CD45RO and CD163 were only associated with RFI in dMMR. Association of CD8 cells with bev benefit (RFI) was seen in dMMR pts, HR 0.27 (95% CI: 0.1-0.73), p=.01 and OS, HR=0.27, (95% CI: 0.12-0.64), p=0.0028 but there was no significant interaction. Single staining CD8, PD-1, and double staining CD8/PD-1 cells were associated with bev benefit in dMMR pts but with bev harm in pMMR pts. However, pts with tumors having >1% of PD-1 and PD-L1 cells (n=197 including 76 dMMR, 100 pMMR, and 21 unknown), received significant bev benefit (int p=.0056). Conclusions: CD8 cells were associated with better OS but were not associated with bev benefit. All T cells and PD-1, PD-L1, and LAG3 cells, were associated with better prognosis in the entire cohort but when pts were stratified for MMR status differences in their association with prognosis and bev benefit emerged. PD-1, CD8, and CD8/PD-1 cells were associated with bev harm in pMMR but bev benefit in dMMR. A significant interaction for the association of high % PD-1 and PD-L1 with bev benefit regardless of MMR status may be a chance finding. However, VEGF has immunosuppressive effects and bev may block these effects in tumors with high PD-L1 and PD-1, regardless of MMR status. NCT: 00096278 PA DOH, U10CA-180868, -180822, -196067, Genentech, Sanofi; NSABP. Clinical trial information: 00096278.

NRG Oncology/NSABP B-47 menstrual history study: impact of adjuvant chemotherapy with and without trastuzumab

The NRG Oncology/NSABP B-47 menstrual history (MH) study examined trastuzumab effects on menstrual status and associated circulating reproductive hormones. MH was evaluated by questions related to hysterectomy, oophorectomy, and reported menstrual changes. Pre/perimenopausal women were assessed at entry, 3, 6, 12, 18, 24, 30, and 36 months. Consenting women had estradiol and FSH measurement at entry, 3, 6, 12, 18, and 24 months. Logistic regression determined predictors of amenorrhea and hormone levels at 12, 24, and 36 months. Between 2/8/2011 and 2/10/2015, 3270 women with node-positive/high-risk node-negative HER2-low breast cancer were enrolled. There were 1,458 women enrolled in the MH study; 1231 consented to baseline blood samples. Trastuzumab did not contribute to a higher amenorrhea rate. Amenorrhea predictors were consistent with earlier studies; however, to our knowledge, this is the largest prospective study to include serial reproductive hormone measurements to 24 months and clinical amenorrhea reports to 36 months. These data can help to counsel patients regarding premature menopause risk.

Utility of the 70-gene MammaPrint assay for prediction of benefit from extended letrozole therapy (ELT) in the NRG Oncology/NSABP B-42 trial

502

Background: The 70-gene MammaPrint (MP) assay predicts risk of distant recurrence (DR) in hormone-receptor positive early-stage breast cancer and classifies cancers as Low Risk or High Risk. NSABP B-42 evaluated ELT in patients (pts) who had completed 5 yrs of adjuvant endocrine therapy (tx). The primary objective was to determine the utility of MP to identify pts enrolled in NSABP B-42 who are likely to benefit from ELT. Methods: A total of 1,866 pts from B-42 had available MP results. Primary endpoint is DR. Secondary endpoints are disease-free survival (DFS) and breast cancer-free interval (BCFI). For the primary analysis, pts were classified as High Risk (MP-H) (MP score ≤0.000) or Low Risk (MP-L) (MP score > 0.000). Exploratory analyses were performed for MP-L subcategories: MP Ultralow Risk (MP-UL) (MP score > 0.355) and MP-L but not MP-UL (MP-LNUL) (MP score > 0.000, ≤0.355). Likelihood ratio test based on stratified Cox proportional hazards (PH) model was used for treatment by risk group interaction. Stratified log-rank test was used to compare treatment groups. Hazard ratios and 95% CI were computed based on the stratified Cox PH model. Results: Among 1,866 pts, 706 (38%) were MP-H and 1,160 (62%) were MP-L. Of the MP-L, 252 (22%) were MP-UL. There were no significant differences in the distribution of patient and tumor characteristics between the MP group and the rest of the B-42 cohort, except for HER2 status. ELT effect was more pronounced in the MP cohort than in the overall B-42 population. For DR, there was statistically significant ELT benefit in MP-L (HR = 0.43, 95% CI 0.25-0.74, p = 0.002), but not MP-H (HR = 0.65, 0.34-1.24, p = 0.19) (interaction p = 0.38). For DFS, there was statistically significant ELT benefit in MP-L, but not MP-H (interaction p = 0.015). Similar findings were observed for BCFI (interaction p = 0.006). Within subcategories of MP-L, there was statistically significant ELT benefit in MP-LNUL, but not in MP-UL for all three endpoints, however the power in MP-UL was limited due to low number of pts (Table). Clinical trial information: 00382070. Conclusions: Statistically significant ELT benefit was observed for MP-L, but not MP-H. The treatment by risk group interaction was not statistically significant for DR, but it was for DFS and BCFI. The benefit appears to be stronger in MP-LNUL than in MP-UL. NCT: 00382070. Support: U10CA180868, -180822, U24CA196067; Novartis; Agendia.[Table: see text]

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)

TPS3622

Background: There are currently no validated predictive biomarkers for stage II resected colon cancer (CC) after adjuvant chemotherapy. However, circulating tumor DNA (ctDNA) that is 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 as a prognostic factor to assess 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 no 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 GuardantHealth LUNAR panel, 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. The trial is actively accruing towards the phase II endpoint in North America. NCT#: 04068103. Support: U10-CA-180868, -180822; UG1CA-189867; GuardantHealth. Clinical trial information: NCT04068103.

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

TPS3618

Background: The superiority of inhibition of programmed cell death-1 (PD-1) pathway in dMMR/MSI-H over chemotherapy with either anti-vascular endothelial growth factor receptor (VEGFr) or anti- epithelial growth factor receptor (EGFr) antibodies in mCRC has been demonstrated in a phase III trial (N Engl J Med 2020; 383:2207). However, more patients had progressive disease as the best response in the anti-PD1 monotherapy arm (29.4% vs. 12.3%) with mean progression-free survival (PFS) of 13.7 months. Preclinical models have demonstrated synergistic interactions between FOLFOX, anti-VEGF, and anti-PD-1. We hypothesize that the dMMR/MSI-H mCRC patients may be more effectively treated by the combination of PD-1 pathway blockade and mFOLFOX6/bevacizumab (bev) rather than with anti-PD-L1 therapy (atezo) alone. Methods: Initially a three-arm study, the mFOLFOX6/bev arm was closed to new enrollment on 6-4-20 due to emerging data; the redesigned COMMIT trial was reactivated on 1/29/2021 as a prospective phase III open-label trial that randomizes (1:1) mCRC dMMR/MSI-H pts (N=211) to either atezo monotherapy or mFOLFOX6/bev+atezo combination. Stratification factors include BRAFV600E status, metastatic site, and prior adjuvant CRC therapy. Primary endpoint is PFS as assessed by site investigator. Secondary endpoints include overall survival (OS), objective response rate (RECIST v1.1), 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. Clinical trial: NCT02997228. Support: U10CA180868, -180822, -180888, -180819, UG1CA189867, U24CA196067; Genentech, Inc. Clinical trial information: NCT02997228.

Adjuvant T-DM1 versus trastuzumab in patients with residual invasive disease after neoadjuvant therapy for HER2-positive breast cancer: subgroup analyses from KATHERINE

BACKGROUND

In the KATHERINE study (NCT01772472), patients with residual invasive early breast cancer (EBC) after neoadjuvant chemotherapy (NACT) plus human epidermal growth factor receptor 2 (HER2)-targeted therapy had a 50% reduction in risk of recurrence or death with adjuvant trastuzumab emtansine (T-DM1) versus trastuzumab. Here, we present additional exploratory safety and efficacy analyses.

PATIENTS AND METHODS

KATHERINE enrolled HER2-positive EBC patients with residual invasive disease in the breast/axilla at surgery after NACT containing a taxane (± anthracycline, ± platinum) and trastuzumab (± pertuzumab). Patients were randomized to adjuvant T-DM1 (n = 743) or trastuzumab (n = 743) for 14 cycles. The primary endpoint was invasive disease-free survival (IDFS).

RESULTS

The incidence of peripheral neuropathy (PN) was similar regardless of neoadjuvant taxane type. Irrespective of treatment arm, baseline PN was associated with longer PN duration (median, 105-109 days longer) and lower resolution rate (∼65% versus ∼82%). Prior platinum therapy was associated with more grade 3-4 thrombocytopenia in the T-DM1 arm (13.5% versus 3.8%), but there was no grade ≥3 hemorrhage in these patients. Risk of recurrence or death was decreased with T-DM1 versus trastuzumab in patients who received anthracycline-based NACT [hazard ratio (HR) = 0.51; 95% confidence interval (CI): 0.38-0.67], non-anthracycline-based NACT (HR = 0.43; 95% CI: 0.22-0.82), presented with cT1, cN0 tumors (0 versus 6 IDFS events), or had particularly high-risk tumors (HRs ranged from 0.43 to 0.72). The central nervous system (CNS) was more often the site of first recurrence in the T-DM1 arm (5.9% versus 4.3%), but T-DM1 was not associated with a difference in overall risk of CNS recurrence.

CONCLUSIONS

T-DM1 provides clinical benefit across patient subgroups, including small tumors and particularly high-risk tumors and does not increase the overall risk of CNS recurrence. NACT type had a minimal impact on safety.

Association of Immunophenotype With Pathologic Complete Response to Neoadjuvant Chemotherapy for Triple-Negative Breast Cancer: A Secondary Analysis of the BrighTNess Phase 3 Randomized Clinical Trial

Importance

Adding carboplatin to standard neoadjuvant chemotherapy (NAC) in triple-negative breast cancer (TNBC) likely benefits a subset of patients; however, determinants of benefit are poorly understood.

Objective

To define the association of molecular subtype, tumor proliferation, and immunophenotype with benefit of carboplatin added to NAC for patients with stages II to III TNBC.

Design, Setting, and Participants

This was a prespecified secondary analysis of a phase 3, double-blind, randomized clinical trial (BrighTNess) that enrolled 634 women across 145 centers in 15 countries. Women with clinical stages II to III TNBC who had undergone pretreatment biopsy were eligible to participate. Whole transcriptome RNA sequencing was performed on the biopsy specimens. The prespecified end point was association of pathologic complete response (pCR) with gene expression-based molecular subtype, with secondary end points investigating established signatures (proliferation, immune) and exploratory analyses of immunophenotype. Data were collected from April 2014 to March 2016. The study analyses were performed from January 2018 to March 2019.

Interventions

Neoadjuvant chemotherapy with paclitaxel followed by doxorubicin and cyclophosphamide, or this same regimen with carboplatin or carboplatin plus veliparib.

Main Outcomes and Measures

Association of gene expression-based molecular subtype (PAM50 and TNBC subtypes) with pCR.

Results

Of the 634 women (median age, 51 [range, 22-78] years) enrolled in BrighTNess, 482 (76%) patients had evaluable RNA sequencing data, with similar baseline characteristics relative to the overall intention-to-treat population. Pathologic complete response was significantly more frequent in PAM50 basal-like vs nonbasal-like cancers overall (202 of 386 [52.3%] vs 34 of 96 [35.4%]; P = .003). Carboplatin benefit was not significantly different in basal-like vs nonbasal-like subgroups (P = .80 for interaction). In multivariable analysis, proliferation (hazard ratio, 0.36; 95% CI, 0.21-0.61; P < .001) and immune (hazard ratio, 0.62; 95% CI, 0.49-0.79; P < .001) signatures were independently associated with pCR. Tumors above the median for proliferation and immune signatures had the highest pCR rate (84 of 125; 67%), while those below the median for both signatures had the lowest pCR rate (42 of 125; 34%). Exploratory gene expression immune analyses suggested that tumors with higher inferred CD8+ T-cell infiltration may receive greater benefit with addition of carboplatin.

Conclusions and Relevance

In this secondary analysis of a randomized clinical trial, triple-negative breast cancer subtyping revealed high pCR rates in basal-like and immunomodulatory subsets. Analysis of biological processes related to basal-like and immunomodulatory phenotypes identified tumor cell proliferation and immune scores as independent factors associated with achieving pCR; the benefit of carboplatin on pCR was seen across all molecular subtypes. Further validation of immunophenotype with existing biomarkers may help to escalate or de-escalate therapy for patients with TNBC.

Trial Registration

ClinicalTrials.gov Identifier: NCT02032277.

Benefit of Oxaliplatin in Stage III Colon Cancer According to IDEA Risk Groups: Findings from the ACCENT Database of 4934 Patients

BACKGROUND

The International Duration Evaluation of Adjuvant Chemotherapy (IDEA) pooled analysis compared 3 to 6 months of adjuvant chemotherapy for stage III colon cancer. Patients were classified into low risk and high risk, suggesting low-risk patients may be offered only 3 months of treatment. In this study, we aimed to assess the benefit of oxaliplatin in the adjuvant setting per IDEA risk groups, using data from 3 large adjuvant phase III studies, namely Multicenter International Study of Oxaliplatin/Fluorouracil/ Leucovorin in the Adjuvant Treatment of Colon Cancer (MOSAIC), C-07, and XELOXA.

METHODS

Using the MOSAIC, C-07, and XELOXA previously published studies, we identified 2810 low-risk and 2124 high-risk patients with stage III colon cancer. We used Cox regression model to evaluate the magnitude of survival differences between IDEA risk groups, according to oxaliplatin use. Based on design similarity and equivalent follow-up data, MOSAIC and C-07 were pooled, whereas XELOXA was analyzed separately. Subgroup analyses were also performed for T4 and/or N2 patients.

RESULTS

Individuals with IDEA low and high risk derived overall survival benefit from the addition of oxaliplatin to adjuvant chemotherapy, with adjusted hazard ratios of 0.79 (0.66-0.95) and 0.84 (0.71-0.99), respectively. Among individuals with IDEA high risk, those with T4 disease did not gain overall survival benefit from addition of oxaliplatin with hazard ratio of 0.95 (0.71-1.27). Similar results were demonstrated using data from the XELOXA study.

CONCLUSION

IDEA risk classification per se does not predict benefit from addition of oxaliplatin to adjuvant chemotherapy in stage III colon cancer. T4 disease may predict lack of benefit from oxaliplatin addition.

Abstract PS7-15: Mixed invasive ductal lobular carcinomas (mDLC) are clinically more similar to invasive lobular carcinoma (ILC) than to invasive ductal carcinoma (IDC)

Clinicopathologic differences between histological subtypes of invasive breast cancer are increasingly being appreciated. Mixed invasive ductal lobular carcinomas (mDLC) are thought to be composed of both ductal and lobular components, and we sought to determine whether mDLC clinically align more closely with invasive ductal (IDC) or invasive lobular (ILC) carcinoma subtypes or if they display intermediate or unique features dissimilar to either type. Key clinical and histologic parameters were compared between cohorts of patients with mDLC (N = 410), IDC (N = 12,979), and ILC (N = 1,569) identified from cancer registry data of a single large healthcare system.Patients with mDLC were older (59 years (49 - 68)) than those with IDC (57 years (48 - 67), p = 0.014)) and younger than those with ILC (61 years (51 - 70), p = 0.006). Tumor size in mDLC was larger (19mm (12 - 27)) than IDC (16mm (10 - 25), p &lt; 0.001) and smaller than ILC (20mm (12 - 35), p = 0.036). Similar to ILC, mDLC were more likely than IDC to be ER+ (92% vs 78% in IDC, p &lt; 0.001), and less likely to be HER2+ (8% vs 15% in IDC, p = 0.04). mDLC were also similar to ILC with regards to higher likelihood of diagnosis at higher stage (p &lt; 0.001), yet with lower grade (p &lt; 0.001), at diagnosis as compared to IDC. Heatmap visualization, as well as dimension reduction by multidimentional scaling (MDS), demonstrates significant overlap of the mDLC and ILC cohorts. Furthermore, an elastic net regression model based on clinicopathologic parameters predicts mDLC to align more closely with ILC than IDC. For patients for whom oncotype Dx scores were available, there was a trend for enrichment of low risk RS scores with rare high-risk RS tumors in mDLC, similar to ILC. With regards to response to neoadjuvant chemotherapy, a subset of the aforementioned cohorts who had received neoadjuvant chemotherapy, mDLC (N = 17), IDC (N = 180), and ILC (N = 57), were compared. Among patients in whom breast conserving surgery (BCS) was attempted, patients with IDC were more likely to have a successful BCS than those with ILC, with less margin positivity thereby avoiding re-excision and/or completion mastectomy (70% vs 32%, respectively; p = 0.003). Successful BCS was achieved with mDLC 56% of the time, although compared to IDC and ILC statistical significance was not reached. In a limited cohort receiving neoadjuvant endocrine therapy (mDLC (N = 7), IDC (N = 37), and ILC (N = 21)) no differences with regard to rates of successful BCS were identified. Pathologic complete response rates (pCR) were additionally evaluated, although small study numbers precluded our ability to perform statistical analysis.Collectively, the aforementioned findings support a higher concordance between mDLC and ILC as compared to IDC. It is feasible that the lobular component of mDLC tumors is predominant, leading to the observed histopathologic similarities noted between mDC and ILC cohorts. We are planning meta-analyses including data from other institutions, and molecular studies to further understand complexities of mDLC.The authors acknowledge grant support from ASCO Conquer Cancer (to NW and AN).

Citation Format: Azadeh Nasrazadani, Yujia Li, Yusi Fang, Osama Shah, Jennifer M Atkinson, Joanna S Lee, Priscilla F McAuliffe, Adrian V Lee, George Tseng, Peter Lucas, Steffi Oesterreich, Norman Wolmark. Mixed invasive ductal lobular carcinomas (mDLC) are clinically more similar to invasive lobular carcinoma (ILC) than to invasive ductal carcinoma (IDC) [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS7-15.

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)

TPS158

Background: Despite activity of programmed cell death-1 (PD-1) pathway inhibition in dMMR/MSI-H mCRC, approximately one-third of patients demonstrate progressive disease as best response to anti-PD1 monotherapy. Preclinical models have demonstrated synergistic interactions between FOLFOX, anti-VEGF, and anti-PD-1. We hypothesize that the dMMR/MSI-H mCRC subset may be more effectively targeted by the combination of PD-1 pathway blockade and mFOLFOX6/bevacizumab (bev) rather than with anti-PD-1 therapy (atezo) alone. Methods: Initially a three-arm study, the mFOLFOX6/bev arm was closed to new enrollment on 6-4-20 due to emerging data; the redesigned COMMIT is a prospective phase III open-label trial that will randomize (1:1) mCRC dMMR/MSI-H pts (N=211) to either atezo monotherapy or mFOLFOX6/bev+atezo combination. Stratification factors include BRAFV600E status, metastatic site, and prior adjuvant CRC therapy. Primary endpoint is progression-free survival (PFS) as assessed by site investigator. 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. Support: U10CA180868, -180822, -180888, -180819, UG1CA189867, U24CA196067; Genentech, Inc. Clinical trial information: NCT02997228.

NRG-GI002: A phase II clinical trial platform using total neoadjuvant therapy (TNT) in locally advanced rectal cancer (LARC)—Pembrolizumab experimental arm (EA) primary results

8

Background: This NCTN multi-arm randomized phase II modular clinical trial platform utilizes TNT with parallel EAs in LARC. EAs are not intended for direct comparison, but rather to test a variety of sensitizers or hypotheses in a consistent and homogenous high-risk pt population with correlative biomarkers. Here we report the primary and available secondary endpoints (EPs). Methods: Stage II/III LARC pts (with ONE or more 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 neoadjuvant FOLFOX x 4mo → chemoRT (capecitabine with 50.4Gy +/- pembrolizumab 200mg IV Q3 wks x 6 doses) → surgery 8-12 wks following last dose of radiotherapy. Primary EP: Improvement in Neoadjuvant Rectal Cancer (NAR) score for EA v control potentially representing a 3-4% absolute OS improvement. Secondary EPs: Comparisons of OS, DFS, toxicity, pCR, cCR, therapy completion, negative surgical margins, sphincter sparing surgery (SSS), and exploratory assessments of molecular and radiographic predictors of response and distant failure. Binary EPs compared by Fisher’s exact test. Reported p-values are two-sided. Results: From 8/2018-5/2019, 185 pts were randomized to control (n=95) or pembrolizumab (n= 90). Baseline characteristics were relatively well balanced. 137 pts were evaluable for NAR (68 control, 69 pembrolizumab). Mean NAR was 14.08 for control (95% CI: 10.7-17.4) v 11.53 for pembrolizumab (CI: 8.5-14.6) (p=0.26). pCR=29.4% v 31.9% (p=0.75); cCR=13.6% v 13.9% (p=0.95); and SSS=71.0% v 59.4% (p=0.15). The side effects on Arm 3 were consistent with both CRT and pembrolizumab safety profile. Grade 3/4 AEs were slightly increased on the pembrolizumab arm during and after CRT (48.2 v 37.3%). There were 2 deaths during FOLFOX, one on the control arm due to sepsis; the other on the EA due to pneumonia. There were no statistically significant differences in RT (fractions, dose, boost fractions, or boost dose), FOLFOX or capecitabine doses. Conclusions: Pembrolizumab added to chemoRT as part of TNT was safe and without unexpected short-term toxicities but failed to improve the NAR score. The secondary endpoints including PFS and OS have not been reached. Correlative analysis for both T-cell and myeloid cell populations in the tissue and blood in addition to comprehensive cytokine analysis is ongoing. NCT02921256. Support: U10CA180868, -180822; UG1-189867; U24-196067. Clinical trial information: NCT02921256.

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)

TPS148

Background: There are currently no validated predictive biomarkers for stage II resected colon cancer (CC) after adjuvant chemotherapy. However, circulating tumor DNA (ctDNA) that is 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 as a prognostic factor to assess 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 no 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 GuardantHealth LUNAR panel, 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. The trial is actively accruing towards the phase II endpoint across all US and Canadian cooperative groups. Support:U10-CA-180868, -180822; UG1CA-189867; GuardantHealth. Clinical trial information: NCT04068103.

Microsatellite Instability in Patients With Stage III Colon Cancer Receiving Fluoropyrimidine With or Without Oxaliplatin: An ACCENT Pooled Analysis of 12 Adjuvant Trials

PURPOSE

In patients with stage III colon cancer (CC) whose tumors demonstrate microsatellite instability (MSI), the efficacy of adjuvant fluoropyrimidine (FP) with or without oxaliplatin has not been clearly demonstrated and the prognostic value of MSI remains uncertain.

MATERIALS AND METHODS

Individual patient data from the ACCENT database were used to evaluate the effect of FP with or without oxaliplatin on disease-free survival (DFS) and overall survival (OS) among patients with MSI stage III CC and the prognostic value of MSI in patients treated with FP plus oxaliplatin, by stratified Cox models adjusted for demographic and clinicopathological factors.

RESULTS

MSI status was available for 5,457 patients (609 MSI, 11.2%; 4848 microsatellite stable [MSS], 88.8%) from 12 randomized clinical trials (RCTs). Oxaliplatin significantly improved OS of MSI patients from the two RCTs testing FP with or without oxaliplatin (n = 185; adjusted hazard ratio [aHR] = 0.52, 95% CI, 0.28 to 0.93). Among the 4,250 patients treated with FP plus oxaliplatin (461 MSI and 3789 MSS), MSI was associated with better OS in the N1 group compared with MSS (aHR = 0.66; 95% CI, 0.46 to 0.95) but similar survival in the N2 population (aHR = 1.13; 95% CI, 0.86 to 1.48; P interaction = .029). The main independent prognosticators of MSI patients treated with FP plus oxaliplatin were T stage (aHR = 2.09; 95% CI, 1.29 to 3.38) and N stage (aHR = 3.57; 95% CI, 2.32 to 5.48). Similar results were observed for DFS in all analyses.

CONCLUSION

Adding oxaliplatin to FP improves OS and DFS in patients with MSI stage III CC. Compared with MSS, MSI patients experienced better outcomes in the N1 group but similar survival in the N2 group.

Validation of the NSABP/NRG Oncology 8-Gene Trastuzumab-benefit Signature in Alliance/NCCTG N9831

Our objective was to validate the NSABP 8-gene trastuzumab-benefit signature, developed and initially validated in NRG Oncology/NSABP B-31 in Alliance/NCCTG N9831. The B-31 and N9831 trials demonstrated the benefit of adding trastuzumab to chemotherapy in the adjuvant setting for HER2+ breast cancer patients. NSABP investigators utilized gene expression profiles of N9831 patients (N = 892) to blindly assign patients to large-, moderate-, or no-trastuzumab benefit groups and then NCCTG investigators assessed the degree of trastuzumab benefit using Cox models adjusted for age, nodes, estrogen receptor/progesterone receptor status, tumor size, and grade. Hazard ratios and 2-sided P values for recurrence-free survival of the predicted large- (n = 387), moderate- (n = 401), and no-benefit (n = 104) groups, based on the 8-gene signature were 0.47 (95% CI = 0.31 to 0.73, P < .001), 0.60 (95% CI = 0.39 to 0.92, P = .02), and 1.54 (95% CI = 0.59 to 4.02, P = .38), respectively (P_interaction  = .02), providing validation of the 8-gene signature in an independent study.

Neratinib-Plus-Cetuximab in Quadruple-WT (KRAS, NRAS, BRAF, PIK3CA) Metastatic Colorectal Cancer Resistant to Cetuximab or Panitumumab: NSABP FC-7, A Phase Ib Study

PURPOSE

In metastatic colorectal cancer (mCRC), HER2 (ERBB2) gene amplification is implicated in anti-EGFR therapy resistance. We sought to determine the recommended phase II dose (RP2D) and efficacy of neratinib, a pan-ERBB kinase inhibitor, combined with cetuximab, in patients with progressive disease (PD) on anti-EGFR treatment.

PATIENTS AND METHODS

Twenty-one patients with quadruple-wild-type, refractory mCRC enrolled in this 3+3 phase Ib study. Standard dosage cetuximab was administered with neratinib at 120 mg, 160 mg, 200 mg, and 240 mg/day orally in 28-day cycles. Samples were collected for molecular and pharmacokinetic studies.

RESULTS

Sixteen patients were evaluable for dose-limiting toxicity (DLT). 240 mg was determined to be the RP2D wherein a single DLT occurred (1/7 patients). Treatment-related DLTs were not seen at lower doses. Best response was stable disease (SD) in 7 of 16 (44%) patients. HER2 amplification (chromogenic in situ IHC) was detected in 2 of 21 (9.5%) treatment-naïve tumors and 4 of 16 (25%) biopsies upon trial enrollment (post-anti-EGFR treatment and progression). Compared with matched enrollment biopsies, 6 of 8 (75%) blood samples showed concordance for HER2 CNV in circulating cell-free DNA. Five SD patients had HER2 amplification in either treatment-naïve or enrollment biopsies. Examination of gene-expression, total protein, and protein phosphorylation levels showed relative upregulation of ≥2 members of the HER-family receptors or ligands upon enrollment versus matched treatment-naïve samples.

CONCLUSIONS

The RP2D of neratinib in this combination was 240 mg/day, which was well tolerated with low incidence of G3 AEs. There were no objective responses; SD was seen at all neratinib doses. HER2 amplification, detectable in both tissue and blood, was more frequent post-anti-EGFR therapy.