First-in-Human Evaluation of Site-Specifically Labeled 89Zr-Pertuzumab in Patients with HER2-Positive Breast Cancer

Radioimmunoconjugates targeting human epidermal growth factor receptor 2 (HER2) have shown potential to noninvasively visualize HER2-positive tumors. However, the stochastic approach that has been traditionally used to radiolabel these antibodies yields poorly defined and heterogeneous products with suboptimal in vivo performance. Here, we describe a first-in-human PET study on patients with HER2-positive breast cancer evaluating the safety, biodistribution, and dosimetry of 89Zr-site-specific (ss)-pertuzumab PET, a site-specifically labeled radioimmunoconjugate designed to circumvent the limitations of random stochastic lysine labeling. Methods: Six patients with HER2-positive metastatic breast cancer were enrolled in a prospective clinical trial. Pertuzumab was site-specifically modified with desferrioxamine (DFO) via a novel chemoenzymatic strategy and subsequently labeled with 89Zr. Patients were administered 74 MBq of 89Zr-ss-pertuzumab in 20 mg of total antibody intravenously and underwent PET/CT at 1 d, 3-4 d, and 5-8 d after injection. PET imaging, whole-body probe counts, and blood draws were performed to assess the pharmacokinetics, biodistribution, and dosimetry. Results: 89Zr-ss-pertuzumab PET/CT was used to assess HER2 status and heterogeneity to guide biopsy and decide the next line of treatment at progression. The radioimmunoconjugate was able to detect known sites of malignancy, suggesting that these tumor lesions were HER2-positive. The optimal imaging time point was 5-8 d after administration, and no toxicities were observed. Dosimetry estimates from OLINDA showed that the organs receiving the highest doses (mean ± SD) were kidney (1.8 ± 0.5 mGy/MBq), liver (1.7 ± 0.3 mGy/MBq), and heart wall (1.2 ± 0.1 mGy/MBq). The average effective dose for 89Zr-ss-pertuzumab was 0.54 ± 0.03 mSv/MBq, which was comparable to both stochastically lysine-labeled 89Zr-DFO-pertuzumab and 89Zr-DFO-trastuzumab. One patient underwent PET/CT with both 89Zr-ss-pertuzumab and 89Zr-DFO-pertuzumab 1 mo apart, with 89Zr-ss-pertuzumab demonstrating improved lesion detection and higher tracer avidity. Conclusion: This study demonstrated the safety, dosimetry, and potential clinical applications of 89Zr-ss-pertuzumab PET/CT. 89Zr-ss-pertuzumab may detect more lesions than 89Zr-DFO-pertuzumab. Potential clinical applications include real-time evaluation of HER2 status to guide biopsy and assist in treatment decisions.

Germline Testing in Patients With Breast Cancer: ASCO-Society of Surgical Oncology Guideline

PURPOSE

To develop recommendations for germline mutation testing for patients with breast cancer.

METHODS

An ASCO-Society of Surgical Oncology (SSO) panel convened to develop recommendations based on a systematic review and formal consensus process.

RESULTS

Forty-seven articles met eligibility criteria for the germline mutation testing recommendations; 18 for the genetic counseling recommendations.

RECOMMENDATIONS

BRCA1/2 mutation testing should be offered to all newly diagnosed patients with breast cancer ≤65 years and select patients >65 years based on personal history, family history, ancestry, or eligibility for poly(ADP-ribose) polymerase (PARP) inhibitor therapy. All patients with recurrent breast cancer who are candidates for PARP inhibitor therapy should be offered BRCA1/2 testing, regardless of family history. BRCA1/2 testing should be offered to women who develop a second primary cancer in the ipsilateral or contralateral breast. For patients with prior history of breast cancer and without active disease, testing should be offered to patients diagnosed ≤65 years and selectively in patients diagnosed after 65 years, if it will inform personal and family risk. Testing for high-penetrance cancer susceptibility genes beyond BRCA1/2 should be offered to those with supportive family histories; testing for moderate-penetrance genes may be offered if necessary to inform personal and family cancer risk. Patients should be provided enough pretest information for informed consent; those with pathogenic variants should receive individualized post-test counseling. Variants of uncertain significance should not impact management, and patients with such variants should be followed for reclassification. Referral to providers experienced in clinical cancer genetics may help facilitate patient selection and interpretation of expanded testing, and provide counseling of individuals without pathogenic germline variants but with significant family history.Additional information is available at www.asco.org/breast-cancer-guidelines.

Standard-of-care systemic therapy with or without stereotactic body radiotherapy in patients with oligoprogressive breast cancer or non-small-cell lung cancer (Consolidative Use of Radiotherapy to Block [CURB] oligoprogression): an open-label, randomised, controlled, phase 2 study

BACKGROUND

Most patients with metastatic cancer eventually develop resistance to systemic therapy, with some having limited disease progression (ie, oligoprogression). We aimed to assess whether stereotactic body radiotherapy (SBRT) targeting oligoprogressive sites could improve patient outcomes.

METHODS

We did a phase 2, open-label, randomised controlled trial of SBRT in patients with oligoprogressive metastatic breast cancer or non-small-cell lung cancer (NSCLC) after having received at least first-line systemic therapy, with oligoprogression defined as five or less progressive lesions on PET-CT or CT. Patients aged 18 years or older were enrolled from a tertiary cancer centre in New York, NY, USA, and six affiliated regional centres in the states of New York and New Jersey, with a 1:1 randomisation between standard of care (standard-of-care group) and SBRT plus standard of care (SBRT group). Randomisation was done with a computer-based algorithm with stratification by number of progressive sites of metastasis, receptor or driver genetic alteration status, primary site, and type of systemic therapy previously received. Patients and investigators were not masked to treatment allocation. The primary endpoint was progression-free survival, measured up to 12 months. We did a prespecified subgroup analysis of the primary endpoint by disease site. All analyses were done in the intention-to-treat population. The study is registered with ClinicalTrials.gov, NCT03808662, and is complete.

FINDINGS

From Jan 1, 2019, to July 31, 2021, 106 patients were randomly assigned to standard of care (n=51; 23 patients with breast cancer and 28 patients with NSCLC) or SBRT plus standard of care (n=55; 24 patients with breast cancer and 31 patients with NSCLC). 16 (34%) of 47 patients with breast cancer had triple-negative disease, and 51 (86%) of 59 patients with NSCLC had no actionable driver mutation. The study was closed to accrual before reaching the targeted sample size, after the primary efficacy endpoint was met during a preplanned interim analysis. The median follow-up was 11·6 months for patients in the standard-of-care group and 12·1 months for patients in the SBRT group. The median progression-free survival was 3·2 months (95% CI 2·0-4·5) for patients in the standard-of-care group versus 7·2 months (4·5-10·0) for patients in the SBRT group (hazard ratio [HR] 0·53, 95% CI 0·35-0·81; p=0·0035). The median progression-free survival was higher for patients with NSCLC in the SBRT group than for those with NSCLC in the standard-of-care group (10·0 months [7·2-not reached] vs 2·2 months [95% CI 2·0-4·5]; HR 0·41, 95% CI 0·22-0·75; p=0·0039), but no difference was found for patients with breast cancer (4·4 months [2·5-8·7] vs 4·2 months [1·8-5·5]; 0·78, 0·43-1·43; p=0·43). Grade 2 or worse adverse events occurred in 21 (41%) patients in the standard-of-care group and 34 (62%) patients in the SBRT group. Nine (16%) patients in the SBRT group had grade 2 or worse toxicities related to SBRT, including gastrointestinal reflux disease, pain exacerbation, radiation pneumonitis, brachial plexopathy, and low blood counts.

INTERPRETATION

The trial showed that progression-free survival was increased in the SBRT plus standard-of-care group compared with standard of care only. Oligoprogression in patients with metastatic NSCLC could be effectively treated with SBRT plus standard of care, leading to more than a four-times increase in progression-free survival compared with standard of care only. By contrast, no benefit was observed in patients with oligoprogressive breast cancer. Further studies to validate these findings and understand the differential benefits are warranted.

FUNDING

National Cancer Institute.

Cost-Effectiveness of Adjuvant Olaparib for Patients With Breast Cancer and Germline BRCA1/2 Mutations

Importance

The OlympiA trial found that 1 year of adjuvant olaparib therapy can improve distant disease-free survival and overall survival from early-stage breast cancer in patients with a germline BRCA1/2 mutation. However, olaparib, an oral poly-adenosine diphosphate ribose polymerase inhibitor, is estimated to cost approximately $14 000 per month in the US.

Objective

To estimate the incremental cost-effectiveness of adjuvant olaparib compared with no olaparib in eligible patients.

Design, Setting, and Participants

In an economic evaluation from a health care system perspective, the cost-effectiveness of adjuvant olaparib was analyzed using a Markov state-transition model. The model simulated costs and lifetime health outcomes of 42-year-old women with high-risk early-stage breast cancer and a known BRCA1/2 mutation who completed definitive primary therapy and neoadjuvant or adjuvant systemic therapy. The study was conducted from August 2021 to July 2023. The effectiveness of olaparib was based on the findings of the OlympiA randomized clinical trial, and other model parameters were identified from the literature. The model was calibrated to the 1-, 2-, 3-, and 4-year distant disease-free and overall survival observed in the OlympiA trial, and olaparib was assumed to reduce the risk of distant recurrence only in the first 4 years.

Exposure

One year of adjuvant olaparib or no adjuvant olaparib.

Main Outcome and Measure

Incremental cost-effectiveness ratio (ICER) in 2021 US dollars per quality-adjusted life-year (QALY) gained. All outcomes were discounted by 3% annually.

Results

In the base case, adjuvant olaparib was associated with a 1.25-year increase in life expectancy and a 1.20-QALY increase at an incremental cost of $133 133 compared with no olaparib. The resulting ICER was approximately $111 000 per QALY gained. At a willingness-to-pay threshold of $150 000 per QALY, olaparib was cost-effective at its 2021 price and in more than 92% of simulations in probabilistic sensitivity analysis. The results were sensitive to assumptions about the effectiveness of olaparib and quality of life for patients with no disease recurrence.

Conclusions and Relevance

In this study, from a US health care system perspective, adjuvant olaparib was a cost-effective option for patients with high-risk, early-stage breast cancer and a germline BRCA1/2 mutation.

Impact of reactive changes on multigene testing: histopathologic analysis of low-grade breast cancers with high-risk 21-gene recurrence scores

PURPOSE

The 21-gene recurrence score (RS) assay predicts the recurrence risk and magnitude of chemotherapy benefit in patients with invasive breast cancer (BC). This study examined low-grade tumors yielding a high-risk RS and their outcomes.Kindly check the edit made in the article titleOk  METHODS: We compared patients with grade 1 BC and a high-risk RS to those with low-risk RS. Histologic sections were reviewed and features reported to elevate the RS were noted, mainly biopsy cavity and reactive stromal changes (BXC).

RESULTS

A total of 54 patients had high-risk RS (median RS of 28, range 26-36). On review, BXC were seen in all cases. Thirty BCs in this group also had low to negative PR. Treatment regimens included: chemoendocrine therapy (63%), endocrine therapy alone (31%) and no adjuvant therapy (6%). There were no additional breast cancer events over a median follow-up of 54.0 months (range 6.2 to 145.3). A total of 108 patients had low-risk RS (median RS of 7, range 0-9). BXC were seen in 47% of cases and none were PR negative. One patient had a recurrence at 64.8 months while the rest had no additional events over a median of 68.1 months (2.4 to 100).

CONCLUSION

We provide further evidence that reactive stromal changes and/or low-PR scores enhance the elevation of the RS. A high-RS result in low grade, PR-positive BC may not reflect actual risk and any suspected discrepancies should be discussed with the management teams. Multigene testing results should be interpreted after correlation with pathologic findings to optimize patient care.

Mutational Status is Associated with a Higher Rate of Pathologic Complete Response After Neoadjuvant Chemotherapy in Hormone Receptor-Positive Breast Cancer

BACKGROUND

Pathologic complete response (pCR) to neoadjuvant chemotherapy (NAC) occurs in up to 20% of hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) breast cancers. Whether this differs among BRCA mutation carriers is uncertain. This study compared pCR between BRCA1/2 mutation carriers and matched sporadic control subjects.

METHODS

From November 2013 to January 2022, this study identified 522 consecutive women with clinical stage I to III HR+/HER2- breast cancer treated with NAC and surgery. The study matched BRCA1/2 mutation carriers 1:2 to non-carriers in terms of age, clinical tumor (cT) and nodal (cN) stage, and differentiation. Two-sample non-parametric tests compared baseline characteristics. Multivariable logistic regression assessed pCR (i.e., ypT0/ispN0) by BRCA1/2 mutational status.

RESULTS

Of the 522 women (median age, 50 years), 59 had BRCA1/2 mutations, 78% of which were clinically node positive. Anthracycline-based NAC was administered to 97%. More BRCA1/2 mutation carriers were younger, had cT1 tumors, and had poorly differentiated disease. After matching, 58 BRCA1/2 mutation carriers were similar to 116 non-carriers in terms of age (p = 0.6), cT (p = 0.9), cN stage (p = 0.7), and tumor differentiation (p > 0.9). Among the mutation carriers, the pCR rate was 15.5% for BRCA1/2, 38% (8/21) for BRCA1, and 2.7% (1/37) for BRCA2 versus 7.8% (9/116) for the non-carriers (p < 0.001). After NAC, 5 (41.7%) of the 12 BRCA1 mutation carriers converted to pN0 versus 10 (37%) of the 27 BRCA2 mutation carriers and 19 (20.9%) of the 91 non-carriers (p = 0.3). In the multivariable analysis, BRCA1 mutation status was associated with higher odds of pCR than non-carrier status (odds ratio [OR] 6.31; 95% confidence interval [CI] 1.95-20.5; p = 0.002), whereas BRCA2 mutation status was not (OR 0.45; 95% CI 0.02-2.67; p = 0.5).

CONCLUSIONS

This study showed that BRCA1 mutation carriers with HR+/HER2- breast cancers have a higher rate of pCR than sporadic cancers and may derive greater benefit from chemotherapy. The use of NAC to downstage these patients should be considered.

Development of a novel measure of advanced cancer patients' perceived utility of secondary germline findings from tumor genomic profiling

Objective

Tumor genomic profiling (TGP) can inform advanced cancer patients' treatment decisions, and also reveal secondary germline findings-information about inherited risks for cancer and other disorders. We sought to develop a measure of patient perceptions of the clinical and personal utility of secondary germline findings.

Methods

We developed a draft survey based on literature and patient interview data (n=40). We evaluated and refined the survey through cognitive interviews with advanced cancer patients who received secondary germline findings from TGP (n=10). The survey was psychometrically validated with data from two independent samples of advanced cancer patients undergoing TGP (total n=349).

Results

Cognitive interviews offered opportunities for survey refinement and confirmation of its comprehensible nature. Exploratory and confirmatory factor analysis of the survey identified 16 items across three subscales with strong internal consistency (Cronbach's alpha ≥0.79): perceived utility for others, perceived utility for self and health, and confidence in secondary findings.

Conclusion

We developed a novel valid scale with promise for measuring advanced cancer patients' perceptions of the utility of secondary germline findings.

Innovation

We offer a new patient-derived measure of perceived utility of and confidence in secondary germline findings with potential applications for precision oncology research and clinical communication.

Association of Moderate-Risk Breast Cancer Genes with Contralateral Prophylactic Mastectomy and Bilateral Disease

BACKGROUND

The impact of ATM, CHEK2, and PALB2, the three most prevalent moderate-risk breast cancer genes, on surgical decision making is not well known.

METHODS

Our retrospective study included patients with resectable non-metastatic breast cancer who underwent multigene panel testing between July 2014 and January 2020 with at least one genetic alteration (pathogenic or variant of uncertain significance [VUS] in ATM [n = 49], CHEK [n = 57], or PALB2 [n = 27]). Our objectives were to determine the rate of contralateral prophylactic mastectomy (CPM) and the rate of bilateral breast cancer. Univariable analyses (UVA) and multivariable analyses (MVA) were performed to identify factors associated with CPM and bilateral breast cancer.

RESULTS

The rate of CPM was 39% (n = 49/127), with 54% (n = 25/46) of patients with a pathogenic mutation and 30% (n = 24/81) of patients with a VUS choosing CPM. On MVA, premenopausal status (odds ratio [OR] 3.46) and a pathogenic alteration (OR 3.01) were associated with increased use of CPM. Bilateral disease was noted in 16% (n = 22/138). Patients with pathogenic mutations had a 22% (n = 11/51) incidence of bilateral breast cancer, while patients with VUS had a 13% (n = 11/87) incidence, although this was not statistically significant on UVA or MVA. On MVA, premenopausal status was associated with a decreased risk of bilateral disease (OR 0.33, p = 0.022). During follow-up, a breast cancer event occurred in 16% (n = 22/138).

CONCLUSIONS

Our study identified a high rate of CPM among those with ATM, CHEK2, and PALB2 alterations, including VUS. Further studies are needed to clarify reasons for CPM among patients with moderate-risk alterations.

Genomic analysis of advanced breast cancer tumors from talazoparib-treated gBRCA1/2mut carriers in the ABRAZO study

These analyses explore the impact of homologous recombination repair gene mutations, including BRCA1/2 mutations and homologous recombination deficiency (HRD), on the efficacy of the poly(ADP-ribose) polymerase (PARP) inhibitor talazoparib in the open-label, two-cohort, Phase 2 ABRAZO trial in germline BRCA1/2-mutation carriers. In the evaluable intent-to-treat population (N = 60), 58 (97%) patients harbor ≥1 BRCA1/2 mutation(s) in tumor sequencing, with 95% (53/56) concordance between germline and tumor mutations, and 85% (40/47) of evaluable patients have BRCA locus loss of heterozygosity indicating HRD. The most prevalent non-BRCA tumor mutations are TP53 in patients with BRCA1 mutations and PIK3CA in patients with BRCA2 mutations. BRCA1- or BRCA2-mutated tumors show comparable clinical benefit within cohorts. While low patient numbers preclude correlations between HRD and efficacy, germline BRCA1/2 mutation detection from tumor-only sequencing shows high sensitivity and non-BRCA genetic/genomic events do not appear to influence talazoparib sensitivity in the ABRAZO trial.ClinicalTrials.gov identifier: NCT02034916.

Risk of Radiation-Associated Secondary Malignancies among Patients with Breast Cancer Harboring TP53 Germline Variants

PURPOSE/OBJECTIVE(S)

Radiation-associated malignancies are rare and poorly understood. TP53 encodes a multifunctional protein that maintains genome integrity and is the most common somatically mutated gene in cancer. Germline pathogenic variants of TP53 predispose carriers to several cancers comprising the Li-Fraumeni syndrome. It is hypothesized that carriers are also at increased risk of radiotherapy (RT)-associated secondary malignancies; however, reports are mixed. We evaluated the risk of secondary malignancies after breast RT among patients with Li-Fraumeni syndrome.

MATERIALS/METHODS

This multi-institutional cohort study included carriers of TP53 germline variants who underwent surgical treatment for breast cancer between 1980 and 2020. Patients were stratified based on germline TP53 classification (pathogenic variants [PV] vs variants of uncertain significance [VUS]). The primary outcome of interest was the cumulative incidence risk of developing an in-field secondary cancer after radiotherapy for primary breast carcinoma.

RESULTS

Ninety-one patients (57 PV and 34 VUS) were evaluated with a median age of 36 years (interquartile range [IQR] 31, 42) and a median follow up of 7.9 years (IQR 4.7, 14.4). Among those with PV who received RT (n = 22), 4 secondary non-breast cancers developed in the radiation field (15-year cumulative incidence 19% [95% CI: 4-43%]), whereas, among those with PV who did not receive RT (n = 35), 0 secondary non-breast cancers were observed in the treated breast (15-year cumulative incidence 0%; p = 0.043). We observed 3 radiation-associated sarcomas among patients with PV who received RT (15-year risk 12% [95% CI 2-33%]) compared with 0 among those who did not receive RT (p = 0.08). No RT-associated sarcomas were observed among 18 patients with TP53 VUS who received RT. RT was not associated with overall survival, despite higher T and N breast cancer stage among those receiving RT (p = 0.33). As expected, patients with PV were more likely than those with VUS to develop any secondary cancer following breast cancer treatment (15-year risk: 54% [95% CI: 33-72%] vs. 14% [95% CI: 3-36%]).

CONCLUSION

Carriers of pathogenic variants of TP53 are at elevated risk of developing secondary malignancies after breast cancer treatment. This population is at particular risk of developing in-field secondary cancers following RT. This iatrogenic risk must be weighed against the anticipated therapeutic benefit of tumor control. Shared decision making is crucial in the radiotherapeutic management of breast cancer patients harboring the Li-Fraumeni syndrome.

Germline Pathogenic Variants and Genetic Counseling by Ancestry in Patients With Epithelial Ovarian Cancer

PURPOSE

To evaluate rates of germline pathogenic/likely pathogenic variants (PVs) and genetic counseling by ancestry in patients with epithelial ovarian cancer (EOC).

METHODS

Patients with pathologically confirmed EOC who underwent clinical tumor-normal sequencing from January 1, 2015, to December 31, 2020, inclusive of germline analysis of ≥76 genes were included. Patients with newly identified PVs were referred for Clinical Genetics Service (CGS) counseling. Ancestry groups were defined using self-reported race/ethnicity and Ashkenazi Jewish (AJ) heritage. Genetic ancestry was inferred computationally using validated algorithms. Logistic regression models were built.

RESULTS

Of 1,266 patients, self-reported ancestry (AJ, 17%; Asian, 10%; Black/African American, 5.4%; Hispanic, 6.2%; non-Hispanic White, 57%; other, 0.16%; unknown, 4.0%) correlated with genetic ancestry (AJ ancestry, 18%; admixed, 10%; African, 4%; East Asian [EAS], 6%; European, 56%; Native American, 0.2%; South Asian [SAS], 4%; unknown, 2%). Germline PVs were observed in 313 (25%) patients, including 195 (15%) with PVs in EOC-associated genes. Those with PVs were younger at diagnosis (59 v 62 years; P < .001) and more likely to have high-grade serous ovarian cancer (83% v 72%; P = .009). PV prevalence varied between ancestry groups (P < .001), with highest rates in the AJ (39.9%) and Asian (26.5%) groups and similar rates (>10%) across other ancestry groups. Use of genetic ancestry demonstrated similar findings and further characterized high rates of PV in EAS/SAS groups. Younger age, high-grade serous histology, and self-reported AJ or Asian ancestry were associated with PV in an EOC-associated gene. Rates of CGS counseling for newly identified PVs were high (80%) across ancestry groups.

CONCLUSION

Rates of PV, particularly in EOC-associated genes, were high regardless of ancestry, with similar rates of counseling between groups, emphasizing the importance of universal genetic testing in all patients with EOC.

Comprehensive analysis of germline drivers in endometrial cancer

BACKGROUND

We sought to determine the prevalence of germline pathogenic variants (gPVs) in unselected patients with endometrial cancer (EC), define biallelic gPVs within tumors, and describe their associations with clinicopathologic features.

METHODS

Germline assessment of at least 76 cancer predisposition genes was performed in patients with EC undergoing clinical tumor-normal Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets (MSK-IMPACT) sequencing from January 1, 2015, to June 30, 2021. In patients with gPVs, biallelic alterations in ECs were identified through analysis of loss of heterozygosity and somatic PVs. Clinicopathologic variables were compared using nonparametric tests.

RESULTS

Of 1625 patients with EC, 216 (13%) had gPVs, and 15 patients had 2 gPVs. There were 231 gPVs in 35 genes (75 [32%] high penetrance; 39 [17%] moderate penetrance; and 117 [51%] low, recessive, or uncertain penetrance). Compared with those without gPVs, patients with gPVs were younger (P = .002), more often White (P = .009), and less obese (P = .025) and had differences in distribution of tumor histology (P = .017) and molecular subtype (P < .001). Among 231 gPVs, 74 (32%) exhibited biallelic inactivation within tumors. For high-penetrance gPVs, 63% (47 of 75) of ECs had biallelic alterations, primarily affecting mismatch repair (MMR) and homologous recombination related genes, including BRCA1,BRCA2, RAD51D, and PALB2. Biallelic inactivation varied across molecular subtypes with highest rates in microsatellite instability-high (MSI-H) or copy-number (CN)-high subtypes (3 of 12 [25%] POLE, 30 of 77 [39%] MSI-H, 27 of 60 [45%] CN-high, 9 of 57 [16%] CN-low; P < .001).

CONCLUSIONS

Of unselected patients with EC, 13% had gPVs, with 63% of gPVs in high-penetrance genes (MMR and homologous recombination) exhibiting biallelic inactivation, potentially driving cancer development. This supports germline assessment in EC given implications for treatment and cancer prevention.

OlympiAD extended follow-up for overall survival and safety: Olaparib versus chemotherapy treatment of physician's choice in patients with a germline BRCA mutation and HER2-negative metastatic breast cancer

BACKGROUND

In the Phase III OlympiAD study, olaparib significantly prolonged progression-free survival versus chemotherapy treatment of physician's choice (TPC) in patients with germline BRCA-mutated (gBRCAm), human epidermal growth factor receptor 2-negative metastatic breast cancer (mBC). In the final pre-specified analysis (64% maturity), median overall survival (OS) was 19.3 months for olaparib and 17.1 months for TPC (P = 0.513). Post-hoc extended follow-up, 25.7 months longer than previously reported for OS, is reported.

PATIENTS AND METHODS

Patients with gBRCAm, human epidermal growth factor receptor 2-negative mBC, who had received ≤2 lines of chemotherapy for metastatic disease, were randomised 2:1 to olaparib (300 mg bid) or TPC. During extended follow-up, OS was analysed every 6 months using the stratified log-rank test (overall population) and Cox proportional hazards model (pre-specified subgroups).

RESULTS

In the overall population (302 patients; 76.8% maturity), median OS was 19.3 months for olaparib and 17.1 months for TPC (hazard ratio 0.89, 95% confidence interval 0.67-1.18); median follow-up was 18.9 and 15.5 months, respectively. Three-year survival was 27.9% for olaparib versus 21.2% for TPC. With olaparib, 8.8% of patients received study treatment for ≥3 years versus none with TPC. In first-line mBC, median OS was longer for olaparib than TPC (22.6 versus 14.7 months; hazard ratio 0.55, 95% confidence interval 0.33-0.95) and 3-year survival was 40.8% for olaparib versus 12.8% for TPC. No new serious adverse events related to olaparib were observed.

CONCLUSIONS

OS was consistent with previous analyses from OlympiAD. These findings support the possibility of meaningful long-term survival benefit with olaparib, particularly in first-line mBC.

Clinical Impact of a Rapid Genetic Testing Model for Advanced Prostate Cancer Patients

PURPOSE

Genetic testing may alter clinical management for individuals with metastatic prostate cancer by identifying additional therapies. Traditional counseling models are unlikely to enable time-sensitive therapeutic decision-making. This study aimed to determine the feasibility and clinical impact of an alternative hereditary genetic testing model.

MATERIALS AND METHODS

As part of a multicenter, single-arm prospective trial, individuals with advanced prostate cancer were referred by their oncologist for testing of 14 genes associated with hereditary prostate cancer. Pretest education (brochure and video) was provided in the oncology clinic. Questionnaires assessing participant satisfaction with both pretest education and decision to undergo genetic testing were collected. A genetic counselor contacted participants by phone to obtain family history and discuss results. Medical records were queried to determine whether a change in clinical management was discussed.

RESULTS

Of 501 participants consented to germline analysis, 51 (10.2%) had at least 1 pathogenic/likely pathogenic variant. Change in treatment was discussed with 22/48 (45.8%) of eligible participants who tested positive. Feasibility of this model was assessed by participant satisfaction and turnaround time. Average±SD satisfaction with the pretest education (15.5±2.2, 4-20 scale) and with the decision to undergo genetic testing (17.1±2.9, 4-20 scale) were both high. Results were returned 20 days (median) after sample collection.

CONCLUSIONS

Oncologist-initiated germline genetic testing in collaboration with a genetic counselor is a feasible approach to testing advanced prostate cancer patients with impactful clinical actionability. The testing model and educational material serve as resources to clinicians treating prostate cancer patients.

Summary of the experiences, knowledge, medical management, and family communication of monoallelic MUTYH carriers

Germline genetic testing for inherited cancer risk is increasingly being performed with multigene panel testing with MUTYH often included on colorectal cancer- and polyposis-focused panels, as well as on broader pan-cancer panels. With up to 1%-2% of the general population being monoallelic MUTYH carriers, pathogenic/likely pathogenic (P/LP) variants in MUTYH are one of the most common findings on multigene cancer panels. However, little is known about patient experience and understanding of monoallelic MUTYH P/LP variants, nor whether such findings influence medical management recommendations and familial communication, which this study aims to better understand. Monoallelic P/LP MUTYH carriers were recruited from the Prospective Registry of Multiplex Testing (PROMPT) and completed a cross-sectional self-report survey on sociodemographic characteristics, medical and family history, experiences with MUTYH genetic testing, genetics and MUTYH knowledge, perceived cancer risk, and familial communication. Of 115 eligible PROMPT participants, 49 (43%) completed the survey who were primarily female (94%), white (96%), had a history of cancer (61%), and a median age of 51.4 years. Most participants (61%) reported satisfaction with how their healthcare provider managed their genetic test result and care, and 65% of survey participants reported their provider recommended colonoscopy based on their genetic test results. Participants' responses also reflected variable levels of knowledge regarding cancer risks and screening recommendations for MUTYH carriers. The majority (98%) of participants shared their genetic test results with at least some of their relatives; however, only 13% of eligible relatives reportedly underwent cascade testing. Taken together, this study provides needed insight into the overall experiences of monoallelic MUTYH carriers and highlights numerous areas for improvement in clinician education, communication, and management of these individuals.

Abstract P4-01-09: Characterization of breast cancer brain metastases overall and progression-free survival and timing of cyclin-dependent kinase 4/6 inhibitor use: Retrospective single institution experience

Background Approximately 15% of patients (pts) with hormone receptor (HR)+ human epidermal growth factor receptor 2 (HER2)- breast cancer will develop brain metastases (BM) (Kuksis et al, NeuroOnc 2021). Cyclin dependent kinase 4/6 inhibitors (CDK4/6i) with an endocrine therapy partner are recommended 1st line treatments in HR+HER2- metastatic breast cancer (MBC). Preclinical models show that CDK4/6i can cross the blood brain barrier (BBB). In vitro assays have shown that abemaciclib crosses the BBB more effectively than palbociclib or ribociclib (George et al, Front Oncol 2021). The efficacy of CDK4/6i in patients with breast cancer BM is not well described. Methods We examined prior treatment data for 368 pts with HR+HER2- BM who received a CDK4/6i between 2015 to 2021. The primary endpoint was overall survival (OS) from the time of starting CDK4/6i after BM development. CNS progression free survival (PFS) was assessed in pts who received CDK4/6i after BM development. We examined the relationship between OS, type and timing of CDK4/6i in multivariate analyses. Statistical analyses were conducted using R 4.1.2 software. Results Of the total cohort of 368 pts, 23% (n=86) had de novo MBC and 77% (n=282) had relapsed MBC. At initial presentation of MBC 79% (n=290) of pts had no BM, 19% (n=71) had BM and extracranial disease and 2% (n=7) had BM only. 56% (n=205) received a CDK4/6i before BM development, 37% (n=136) received a CDK4/6i after BM development and 7% (n=27) received a CDK 4/6i both before and after BM development. The most common CDK4/6i used first was palbociclib (85%, n=312) followed by abemaciclib (13%, n=47) and ribociclib (2%, n=9). At the time of data cutoff 277 pts were dead, 55 were alive and 36 were lost to follow up. The median follow-up of surviving pts from BM development was 32 months. 163 pts received a CDK4/6i post BM: palbociclib (66%, n=108), abemaciclib (31%, n=51) and ribociclib (3%, n=4). Of these 163 pts 83% (n=136) received a CDK4/6i as their 1st or 2nd systemic treatment post BM. In the cohort of 163 pts who received a CDK4/6i post BM, 9% did not receive local BM therapy, 40% had whole brain radiotherapy (WBRT), 34% had stereotactic surgery (SRS) alone and 17% had surgery +/- SRS. The median CNS PFS for pts who received a CDK4/6i after BM was 21 months with palbociclib and 14 months with abemaciclib (p value 0.11). Too few pts received ribociclib for analysis. CNS PFS was 21 months for pts receiving a CDK4/6i only after BM development and 10 months for those who received CDK4/6i both before and after BM diagnosis (p = 0.01). Pts who died prior to CNS progression were censored. Median OS from the time of starting CDK4/6i after BM development for pts receiving a CDK4/6i only after BM development was 25 months versus 12 months for those who received it both before and after BM development (p = 0.03). There was no statistically significant difference in OS when adjusting for the type of local BM treatment received, time from initial MBC diagnosis to BM, or the Breast Graded Prognostic Assessment (GPA) score (Sperduto et al, IJROBP 2020). Conclusions This observation suggests that there is a greater OS benefit from the time of starting CDK4/6i after BM development in pts who receive CDK4/6i solely after BM development compared to pts who received a CDK4/6i both before and after BM development. This is not unexpected given the known OS benefit associated with early use of these agents. Our unique observation of longer CNS PFS for patients who did not receive CDK4/6i prior to BM but who received it afterward suggests that CDK4/6i exposure prior to BM development may lead to development of resistance mechanisms that reduces CNS efficacy upon rechallenging with CDK4/6i after BM development. There was no statistically significant difference in post-BM CNS PFS by type of CDK4/6i received. This motivates investigation of biomarkers for patient selection and our ongoing work in collecting a matched comparison cohort of HR+HER2- pts with BM who never received CDK4/6i.

Citation Format: Sonya Chew Minmin, Yuan Chen, Daniel Kelly, Mark E. Robson, Andrew D Seidman. Characterization of breast cancer brain metastases overall and progression-free survival and timing of cyclin-dependent kinase 4/6 inhibitor use: Retrospective single institution experience [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 P4-01-09.

Abstract P4-02-14: Gain of HER2 Amplification in Patients with HR+/HER2- and Triple Negative Early Breast Cancer Treated with Neoadjuvant Chemotherapy

Background: Neoadjuvant chemotherapy (NAC) is standard of care for the majority of patients with clinical stage II-III triple negative breast cancer (TNBC) and is considered in high-risk patients with hormone receptor positive (HR+)/human epidermal growth factor receptor 2 (HER2) negative (-) tumors, with expected pathological complete response (pCR) rates of 40-60% and 10-12%, respectively. In HER2- patients with residual disease (RD) after NAC, there is limited data on rates of gain of HER2 amplification. The biological and clinical significance of this phenomenon is unknown and determining the best adjuvant therapy for these patients remains a challenge. We sought to determine the rate of HER2 gain in a cohort of consecutive patients with HER2- breast cancer (BC) treated with NAC.

Methods: From 01/2021 to 12/2021, we identified patients with HER2- breast cancer treated with NAC followed by surgery at our institution. Patients who received neoadjuvant endocrine therapy were excluded. The rates of pCR (ypT0/is ypN0) and HER2 status pre- and post-NAC were assessed. Estrogen receptor (ER), progesterone receptor (PR) and HER2 status on surgery specimens were internally determined for all patients using ASCO/CAP 2020 guidelines. ER-low was defined as ER expression by immunohistochemistry (IHC) 1-10%.

Results: We included 256 patients, 130 (51%) HR+/HER2- [13/130(10%) ER-low] and 126 (49%) TNBC. Median age was 48 years (range 25-82) and the majority presented with clinical T2 (57%) and N1 (59%). Of 130 patients with HR+/HER2-tumors, 120 (92%) received dose-dense (dd) doxorubicin/cyclophosphamide-paclitaxel (AC-T). Of 126 TNBC patients, 46 (37%) received ddAC followed by carboplatin in combination with paclitaxel +/- pembrolizumab. Centralized HER2 status assessment on the core biopsy was performed in 22% of samples. Overall, pCR was achieved in 40% of TNBC and 11% of HR+/HER2-. Among the 192 patients with RD, the rate of HER2 gain was 8/192 (4%), including 3% (2/76) of TNBC and 5% (6/116) of HR+/HER2- patients. 7 of the 8 patients (88%) converted from IHC 1+ or 2+ fluorescence in situ hybridization (FISH) not amplified on core biopsy to IHC 2+ FISH amplified on the surgical specimen. In only 1 case, the HER2 status converted from IHC2+ FISH not amplified to IHC3+. 3/8 patients had multifocal disease. All 6 patients with HR+/HER2- BC and HER2 gain had high (&gt;90%) ER expression (Table 1). All but one patient with HER2 gain received adjuvant anti-HER2 therapy. After a median follow-up of 10 months, no recurrence events occurred in this group.12 of the remaining 184 patients experienced a recurrence [11 distant recurrences (8 and 3, in the TNBC and HR+/HER2- groups, respectively), and there was 1 local event (localized chest wall recurrence) in the HR+/HER2- group].

Conclusions: At a single center, we found that in patients with HER2- BC treated with NAC, HER2 gain in patients with RD was uncommon and occurred more frequently in those with HR+ tumors. Analysis of a larger cohort is ongoing to corroborate these results. It is remains to be determined if this phenomenon represents a true HER2 status conversion or tumor heterogeneity.

Table 1: Clinico-pathological characteristics of patients with HER2 gain on residual disease

Citation Format: Emanuela Ferraro, Sonya Chew Minmin, Anton Safonov, Andrea V. Barrio, Shanu Modi, Andrew D Seidman, Hanna Y Wen, Edi Brogi, Mark E. Robson, Chau T Dang. Gain of HER2 Amplification in Patients with HR+/HER2- and Triple Negative Early Breast Cancer Treated with Neoadjuvant Chemotherapy [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 P4-02-14.

Abstract P4-02-01: Efficacy of HER2 ADCs against HER2 inhibitor resistance alterations in the PI3K and MAPK pathways in HER2-positive breast cancer

Background: HER2 positive (HER2+) breast cancers harboring downstream MAPK or PI3K pathway alterations manifest persistent downstream signaling on anti-HER2 inhibitors with metastatic patients having worse outcomes on first line trastuzumab and pertuzumab (HP) therapy. However, HER2 antibody-drug conjugates (ADCs) are not as dependent upon potent signal transduction inhibition to exert their antitumor effects. To further investigate, we sought to determine whether MAPK and/or PI3K alterations affect the biologic or clinical outcomes of patients and models receiving HER2 ADCs. Methods: We performed prospective genomic sequencing using MSK-IMPACT on patients with advanced HER2+ breast cancer who received trastuzumab emtansine (T-DM1) in the metastatic setting between March 2013 and July 2021. We collected detailed information on clinical outcomes and correlates through our institutional IRB-approved retrieval process. HER2/ER/PR status at the time of metastatic recurrence were defined as per ASCO/CAP guidelines. Cox proportional hazard models were used to determine the association between MAPK and PI3K pathways alterations and progression-free survival (PFS) on T-DM1. Common mutations associated with outcomes were modeled in HER2+ breast cancer cell lines using short hairpin RNAs and CRISPR/Cas9, and the sensitivity to HER2 ADC was evaluated via cell proliferation and xenograft assays. Results: We identified 185 HER2+ breast cancer patients treated with T-DM1 at any line (median: 5) whose primary (N=65) or metastatic (N=120) tumor samples were sequenced. Median age was 55 (range: 20-87). The majority of the patients received T-DM1 in 2nd or 3rd line (52%) and received prior trastuzumab or HER2 TKI in metastatic setting (96%). 74/185 (40%) had de novo metastatic breast cancer and 119/185 (64%) had ER/PR+/HER2+ disease. Pathogenic activating alterations involving the MAPK pathway were observed in 14% of patients with the most frequent alterations being ERBB2 activating mutations (42%) and NF1 loss (34%). PI3K pathway alterations were identified in 42% of the patients, the majority being activating mutations of PIK3CA (87%). MAPK alterations were significantly enriched in the metastatic tumors compared to the treatment-naïve primaries (20% vs 3%, p=0.001), while PI3K alterations were not (44% vs 40%, p=0.6). To reduce the possible confounding resistance mechanisms induced by prior treatment, we restricted the survival analyses to patients who received T-DM1 up to 3rd line of therapy (N=100). On multivariable analysis adjusted for ER/PR status (positive vs negative), stage at the presentation of metastatic disease (de novo metastatic vs recurrence), treatment line and type of sequenced sample (primary vs metastatic), patients with MAPK (N=14) and PI3K (N= 38) alterations had similar PFS compared to wild type (HR 1.20, 95%CI 0.62-2.30, p=0.6 and HR 1.23, 95%CI 0.77-1.95, p=0.4, respectively). Similar results were found in the combined analysis including alterations in either pathway (N=48, HR 1.28, 95%CI 0.81-2.04, p=0.3). To verify the antiproliferative effect of HER2 ADCs on breast cancer cells with MAPK pathway activation, we depleted NF1 in a panel of HER2+ breast cancer cell lines. Consistently, MAPK-altered cell lines were sensitive to FDA-approved HER2 ADCs including trastuzumab deruxtecan (T-DXd). Conclusions: In contrast to H/P therapy, T-DM1 therapy was equally effective in tumors with downstream PI3K or MAPK alterations and wild type tumors. Expanded analysis on a larger cohort, including a subgroup of patients treated with novel HER2 ADCs such as T-DXd will be presented. The characterization of PI3K and MAPK pathways status in metastatic HER2+ breast cancer may inform prioritization of treatment options.

Citation Format: Emanuela Ferraro, Anton Safonov, Yuan Chen, Charlie White, Antonio Marra, Mehnaj Ahmed, Barbara Acevedo, Chau T Dang, Shanu Modi, David B. Solit, Larry Norton, Mark E. Robson, Jorge Reis-Filho, Sarat Chandarlapaty, Pedram Razavi. Efficacy of HER2 ADCs against HER2 inhibitor resistance alterations in the PI3K and MAPK pathways in HER2-positive breast cancer [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 P4-02-01.

Abstract P4-02-18: Impact of clonal hematopoiesis on disease progression following CDK4/6 inhibitor therapy

Background Clonal Hematopoiesis (CH) is a well-established risk factor for adverse clinical outcomes including all-cause mortality, cardiovascular disease, and progression to hematologic malignancies. The presence of CH has been shown to adversely impact overall survival in non-hematologic cancers, however whether CH modulates response to specific therapies in breast cancer is not known. Here we investigate the impact of CH mutations on disease progression in patients with metastatic estrogen receptor (ER) positive breast cancer undergoing treatment with first line CDK4/6 inhibitors and endocrine therapy (CDK4/6i+ET). Methods We analyzed data from a well annotated cohort of patients with ER+ breast cancer who received endocrine therapy and CDK4/6 inhibitors. All patients underwent prospective tumor and matched WBC sequencing utilizing the MSK-IMPACT assay. CH variants were detected in blood samples utilizing the well-validated variant detection and filtration pipeline of MSK-IMPACT. CH mutations were defined as putative drivers (CH-PD) or non-putative drivers (CH) as previously described. To ensure the presence of CH at the time of therapy initiation, only patients who had CH sampling performed from 6 months before through 4 months after initiation of CDK4/6i+ET were included. We compared progression free survival (PFS) in patients with and without CH, as well as by CH-PD status and DNMT3A CH mutations. We investigated clinical covariates including type of endocrine therapy, receipt of prior neoadjuvant or adjuvant chemotherapy, and age at start of CDK4/6i+ET. Results The final cohort was comprised of 378 patients, of whom 135 (35.7%) had CH. The median time between sample collection and CDK4/6i+ET initiation was 0 (IQR -0.79 to 0.47 months). Patients with CH were older at time of therapy initiation (median 63.0 versus 54.7 years, p &lt; 0.001). There were no significant differences between groups in terms of endocrine therapy (aromatase inhibitor or fulvestrant), prior chemotherapy, and time from CH sample collection to CDK4/6i+ET start. Univariate Cox-proportional hazard analysis did not reveal a difference between progression free survival and overall CH (HR 0.96, 95% CI 0.75 – 1.23, p = 0.76), CH-PD (HR 1.05, 0.77 – 1.43, p = 0.77), or DNMT3A mutations (HR 1.12, 0.80 – 1.60, p = 0.52) compared to patients without CH. Interestingly, age less than 60 years was found to be associated with PFS outcome (univariate HR 1.57, 1.22 – 2.01, p = 0.0004). Multivariate analysis adjusted for endocrine therapy partner and age at CDK4/6i+ET therapy did not reveal an association between outcome and overall CH (HR 1.07, 0.83 – 1.39, p = 0.59). In patients younger than age 60, presence of overall CH did not confer a significant PFS difference (HR 0.90, 0.63 – 1.29, p = 0.57). In the subset of patients older than 60 (n = 168) presence of CH conferred numerically, but not statistically, significant shorter PFS (HR 1.41 [0.96 – 2.09], p = 0.08). In this population, CH-PD conferred a shorter PFS (HR 1.75, 1.12 – 2.72, p = 0.02). Conclusion We found that CH, CH-PD and DNMT3A CH mutations did not affect PFS among metastatic ER+ breast cancer patients treated with first line CDK4/6 inhibitors. Younger age was associated with increased risk of progression, warranting further investigation. In the subset of patients with age older than 60, CH-PD conferred a shorter PFS. Further data, incorporating records of dose reductions, will be presented at the meeting.

Citation Format: Jacqueline Tao, Pablo Sanchez Vela, Anton Safonov, Emanuela Ferraro, Sebastia Franch Exposito, Kamal Menghrajani, Ryan Ptashkin, Elizabeth Comen, Lior Z. Braunstein, Mark E. Robson, Sarat Chandarlapaty, Jorge Reis-Filho, Michael Berger, Ahmet Zehir, Larry Norton, Ross Levine, Pedram Razavi. Impact of clonal hematopoiesis on disease progression following CDK4/6 inhibitor therapy [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 P4-02-18.

Abstract P5-08-07: Dietary patterns among women with early-stage breast cancer from the Healthy Living Program

Background: Diet is a modifiable risk factor for breast cancer risk and mortality. Current guidelines recommend a diet that provides a diverse array of nutrients, comprised predominantly of fruits/vegetables and whole grains, with limited added sugar. The Healthy Living Program (HLP) is a clinical program at Memorial Sloan Kettering Cancer Center for patients with early-stage breast cancer that offers longitudinal, personalized lifestyle management starting at the time of diagnosis. Here, we report dietary patterns among the HLP cohort and association with baseline body mass index (BMI). Methods: We included all patients enrolled in the HLP from September 2020-February 2022. At the time of enrollment, participants complete a survey containing the National Cancer Institute (NCI) Dietary Screener Questionnaire (DSQ), which consists of consumption frequency questions for 26 food items over the past month. Total daily intake equivalents are calculated for foods from every diet factor group according to standard NCI DSQ scoring as follows: 1) Total daily cup equivalents of fruits/vegetables, which includes fruit, fruit juice, salad, potatoes, beans, other vegetables, tomato sauce, salsa, and pizza; 2) Total daily ounce equivalents of whole grains, which includes cereal, whole grain bread, whole grain rice, and popcorn; 3) Total teaspoon (tsp) equivalents of added sugars from candy, doughnuts, cookies/cake/pie, cereal, ice cream, and sugar-sweetened beverages including soda, fruit drinks, and sugar/honey in coffee/tea. Adherence to recommended daily intake of fruits/vegetables, whole grains, and added sugars was assessed as per the 2020-2025 Dietary Guidelines, the American Institute for Cancer Research, and the World Health Organization guidelines. Patient and tumor characteristics were abstracted from medical records. Results: Among the 399 patients included, the median age at diagnosis was 58 and median baseline BMI was 26.1 kg/m2. 45 patients had carcinoma in situ (11.3%), 296 had stage I disease (74.2%), 51 had stage II disease (12.8%), and 7 had stage III disease (1.8%). 316 had hormone-receptor positive disease (89.3%), 24 had HER2-positive disease (6.8%), and 26 had triple-negative disease (7.3%). 106 participants (27%) met the guideline recommendation of ≥4-5 cup equivalents of fruits/vegetables daily and 3 participants (0.8%) met the guideline recommendation of ≥3 ounces equivalents of whole grains daily. All patients in the cohort met the guideline recommendation of &lt; 6 tsp equivalents of added sugars daily. Only 2 patients (0.5%) met guidelines for all three diet factors. Baseline BMI was significantly higher among patients who did not meet the recommended fruit/vegetable intake than among those who did (26.9 kg/m2 vs. 24.5 kg/m2, p=0.016). There were no significant differences in BMI between those who did and did not adhere to the other diet factor guidelines and no significant association between tumor stage or histology and dietary guideline adherence. Conclusion: Most patients with early-stage breast cancer did not meet the recommended daily intake of fruits/vegetables or whole grains. Participants who did not meet the fruit and vegetable intake guideline had significantly higher BMI at diagnosis. These findings indicate that lifestyle assessment near the time of breast cancer diagnosis identifies patients that could benefit from personalized dietary interventions to optimize prognostic factors such as BMI.

Citation Format: Bethina Liu, Sherry Shen, Erica Salehi, Yuan Chen, Nicolas Toumbacaris, Johnny Allsop, Cara Anselmo, Stacie Corcoran, Bridget Kelly, Rocco Magnoli, Andrea Smith, Melissa Emerzian, Julia Brockway-Marchello, Doreen Bacotti, Mark E. Robson, Neil M. Iyengar. Dietary patterns among women with early-stage breast cancer from the Healthy Living Program [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 P5-08-07.

Abstract OT2-01-11: ctDNA-guided Adaptive Therapy Escalation in ER+ MBC: A Phase 1b Study with Letrozole, Palbociclib and Onapristone ER

ctDNA-guided Adaptive Therapy Escalation in ER+ MBC: A Phase 1b Study with Letrozole, Palbociclib and Onapristone ER Background: Extended release onapristone (onapristone ER) is a progesterone receptor (PR) antagonist that inhibits hormone-mediated PR activation and stabilizes PR association with corepressors, resulting in an antineoplastic effect when applied alone or in combination with antiestrogen therapy to breast cancer cells in vitro. Recent preclinical studies further suggest that onapristone adds to inhibition of cell proliferation when combined with CDK4/6 inhibitors and fulvestrant. Elevations in ctDNA can precede overt disease progression by a matter of months in metastatic breast cancer and may represent an opportunity for proactive therapeutic intervention. Trial Design: This is an investigator initiated open-label, single institution phase 1b study of onapristone ER added as escalation therapy in patients with ER+, PR+, HER2 negative MBC, who have detectable ctDNA after six months of treatment with letrozole and palbociclib in the first line. The study is supported by Context Therapeutics and involves two stages. Stage 1 is a dose escalation/de-escalation phase of 18 patients maximum, in which the safety and recommended phase 2 dose (RP2D) will be established for onapristone ER when used in combination with letrozole and palbociclib. In stage 2, the dose expansion phase, the RP2D of onapristone will be combined with letrozole and palbociclib in 10 patients to further explore the tolerability of the regimen. ctDNA will be collected serially while patients are on this triplet therapy. Eligibility Criteria: This study is enrolling patients with radiologically measurable or evaluable metastatic or unresectable ER+/PR+/HER2-negative MBC in whom a tumor-derived somatic mutation can be detected in ctDNA at a variant allele fraction of 0.5% or greater after 6 months (+/- 4 weeks) of treatment with first line letrozole and palbociclib without progression, using our in house CLIA certified MSK-ACCESS assay. Adequate organ function and functional status for enrollment are stipulated in the protocol. Specific Aims: The primary objective of this study is to define the safety, tolerability, and recommended phase 2 dose of onapristone ER used in combination with letrozole and palbociclib. Secondary objectives include to investigate ctDNA response rate of the triplet therapy regimen, to gather early data regarding the 6-month clinical benefit rate, overall response rate, and progression free survival of this triplet escalation therapy regimen in high risk ctDNA+ patients, and to evaluate the pharmacokinetics of Onapristone ER when used in combination with letrozole and Palbociclib. Exploratory objective include to describe ctDNA dynamics during antiprogestin therapy escalation in ER+ MBC, as well as the molecular features present in responders vs. non-responders using ctDNA and pre-treatment tissue. Target Accrual: The total planned cohort for the phase I dose escalation is a maximum of 18 patients across 3 dose levels, and the total planned cohort for the dose expansion is 10 patients, with an anticipated maximum total of 28 patients. We will allot for 5 additional patients to account for inevaluability during the dose escalation and expansion portions of the trial. The trial is currently open to enrollment at MSKCC. Contact Information: Dragoj@mskcc.org; Jhaverik@mskcc.org

Citation Format: Joshua Drago, Elaine Walsh, Mithat Gonen, Michael Berger, Mark E. Robson, Sarat Chandarlapaty, Pedram Razavi, Komal Jhaveri. ctDNA-guided Adaptive Therapy Escalation in ER+ MBC: A Phase 1b Study with Letrozole, Palbociclib and Onapristone ER [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 OT2-01-11.

Routine clinical parameters and laboratory testing predict therapy-related myeloid neoplasms after treatment for breast cancer

We aim to identify predictors of therapy-related myeloid neoplasms (t-MN) in patients with breast cancer (BC) and cytopenias to determine the timing of bone marrow biopsy (BMBx). Patients with BC and cytopenias who were referred for BMBx between 2002-2018 were identified using the Memorial Sloan Kettering Cancer Center institutional database. Characteristics associated with the risk of t-MN were evaluated by multivariable logistic regression and included in a predictive model. The average area under the receiver operating characteristic curve (AUC) was estimated by 5-fold cross-validation. Of the 206 BC patients who underwent BMBx included in our study, 107 had t-MN. By multivariable analysis, white blood cell count 4-11 K/mcL, absolute neutrophil count (ANC) ≥1.5 K/mcL, hemoglobin ≥12.2 g/dL, red cell distribution width 11.5-14.5%, the presence of bone metastasis and a time from BC diagnosis to BMBx <15 months significantly decreased the likelihood of t-MN. The average AUC was 0.88. We stratified our cohort by bone metastasis and by findings on peripheral smear. In both the subset without bone metastasis (n=159) and in the cohort with no blasts or dysplastic cells on peripheral smear (n=96) our variables had similar effects on the risk of t-MN. Among the 47 patients with bone metastasis, an ANC ≥1.5 K/mcL was the only variable associated with a decreased risk of t-MN. Our findings show that in patients with BC and unexplained cytopenias, clinical and laboratory parameters can predict t-MN and assist clinicians in determining the timing of a BMBx.

Gene-based Confirmatory Germline Testing Following Tumor-only Sequencing of Prostate Cancer

BACKGROUND

Tumor-only genomic profiling is an important tool in therapeutic management of men with prostate cancer. Since clinically actionable germline variants may be reflected in tumor profiling, it is critical to identify which variants have a higher risk of being germline in origin to better counsel patients and prioritize genetic testing.

OBJECTIVE

To determine when variants found on tumor-only sequencing of prostate cancers should prompt confirmatory germline testing.

DESIGN, SETTING, AND PARTICIPANTS

Men with prostate cancer who underwent both tumor and germline sequencing at Memorial Sloan Kettering Cancer Center from January 1, 2015 to January 31, 2020 were evaluated.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Tumor and germline profiles were analyzed for pathogenic and likely pathogenic ("pathogenic") variants in 60 moderate- or high-penetrance genes associated with cancer predisposition. The germline probability (germline/germline + somatic) of a variant was calculated for each gene. Clinical and pathologic factors were analyzed as potential modifiers of germline probability.

RESULTS AND LIMITATIONS

Of the 1883 patients identified, 1084 (58%) had a somatic or germline pathogenic variant in one of 60 cancer susceptibility genes, and of them, 240 (22%) had at least one germline variant. Overall, the most frequent variants were in TP53, PTEN, APC, BRCA2, RB1, ATM, and CHEK2. Variants in TP53, PTEN, or RB1 were identified in 746 (40%) patients and were exclusively somatic. Variants with the highest germline probabilities were in PALB2 (69%), MITF (62%), HOXB13 (60%), CHEK2 (55%), BRCA1 (55%), and BRCA2 (47%), and the overall germline probability of a variant in any DNA damage repair gene was 40%. Limitations were that most of the men included in the cohort had metastatic disease, and different thresholds for pathogenicity exist for somatic and germline variants.

CONCLUSIONS

Of patients with pathogenic variants found on prostate tumor sequencing, 22% had clinically actionable germline variants, for which the germline probabilities varied widely by gene. Our results provide an evidenced-based clinical framework to prioritize referral to genetic counseling following tumor-only sequencing.

PATIENT SUMMARY

Patients with advanced prostate cancer are recommended to have germline genetic testing. Genetic sequencing of a patient's prostate tumor may also identify certain gene variants that are inherited. We found that patients who had variants in certain genes, such as ones that function in DNA damage repair, identified in their prostate tumor sequencing, had a high risk for having an inherited cancer syndrome.

Deep Interactive Learning-based ovarian cancer segmentation of H&E-stained whole slide images to study morphological patterns of BRCA mutation

Deep learning has been widely used to analyze digitized hematoxylin and eosin (H&E)-stained histopathology whole slide images. Automated cancer segmentation using deep learning can be used to diagnose malignancy and to find novel morphological patterns to predict molecular subtypes. To train pixel-wise cancer segmentation models, manual annotation from pathologists is generally a bottleneck due to its time-consuming nature. In this paper, we propose Deep Interactive Learning with a pretrained segmentation model from a different cancer type to reduce manual annotation time. Instead of annotating all pixels from cancer and non-cancer regions on giga-pixel whole slide images, an iterative process of annotating mislabeled regions from a segmentation model and training/finetuning the model with the additional annotation can reduce the time. Especially, employing a pretrained segmentation model can further reduce the time than starting annotation from scratch. We trained an accurate ovarian cancer segmentation model with a pretrained breast segmentation model by 3.5 hours of manual annotation which achieved intersection-over-union of 0.74, recall of 0.86, and precision of 0.84. With automatically extracted high-grade serous ovarian cancer patches, we attempted to train an additional classification deep learning model to predict BRCA mutation. The segmentation model and code have been released at https://github.com/MSKCC-Computational-Pathology/DMMN-ovary.

Disparities in cancer genetics care by race/ethnicity among pan-cancer patients with pathogenic germline variants

BACKGROUND

Germline risk assessment is increasing as part of cancer care; however, disparities in subsequent genetic counseling are unknown.

METHODS

Pan-cancer patients were prospectively consented to tumor-normal sequencing via custom next generation sequencing panel (Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets) inclusive of germline analysis of ≥76 genes from January 2015 through December 2019 (97.5% research nonbillable) with protocol for genetics referral. Rates of pathogenic/likely pathogenic germline variants (PVs) and downstream counseling were compared across ancestry groups (mutually exclusive groups based on self-reported race/ethnicity and Ashkenazi Jewish [AJ] heritage) using nonparametric tests and multivariable logistic regression models.

RESULTS

Among 15,775 patients (59.6%, non-Hispanic [NH]-White; 15.7%, AJ; 20.5%, non-White [6.9%, Asian; 6.8%, Black/African American (AA); 6.7%, Hispanic; 0.1%, Other], and 4.2%, unknown), 2663 (17%) had a PV. Non-White patients had a lower PV rate (n = 433, 13.4%) compared to NH-Whites (n = 1451, 15.4%) and AJ patients (n = 683, 27.6%), p < .01, with differences in mostly moderate and low/recessive/uncertain penetrance variants. Among 2239 patients with new PV, 1652 (73.8%) completed recommended genetic counseling. Non-White patients had lower rates of genetic counseling (67.7%) than NH-White (73.7%) and AJ patients (78.8%), p < .01, with lower rates occurring in Black/AA (63%) compared to NH-White patients, even after adjustment for confounders (odds ratio, 0.60; 95% confidence interval, 0.37-0.97; p = .036). Non-White, particularly Black/AA and Asian, probands had a trend toward lower rates and numbers of at-risk family members being seen for counseling/genetic testing.

CONCLUSIONS

Despite minimizing barriers to genetic testing, non-White patients were less likely to receive recommended cancer genetics follow-up, with potential implications for oncologic care, cancer risk reduction, and at-risk family members.

LAY SUMMARY

Genetic testing is becoming an important part of cancer care, and we wanted to see if genetics care was different between individuals of different backgrounds. We studied 15,775 diverse patients with cancer who had genetic testing using a test called MSK-IMPACT that was covered by research funding. Clinically important genetic findings were high in all groups. However, Black patients were less likely to get recommended counseling compared to White patients. Even after removing many roadblocks, non-White and especially Black patients were less likely to get recommended genetics care, which may affect their cancer treatments and families.

Inherited Germline Cancer Susceptibility Gene Variants in Individuals with Non-Muscle-Invasive Bladder Cancer

PURPOSE

Identification of inherited germline variants can guide personalized cancer screening, prevention, and treatment. Pathogenic and likely pathogenic (P/LP) germline variants in cancer predisposition genes are frequent among patients with locally advanced or metastatic urothelial carcinoma, but their prevalence and significance in patients with non-muscle-invasive bladder cancer (NMIBC), the most common form of urothelial carcinoma, is understudied.

EXPERIMENTAL DESIGN

Germline analysis was conducted on paired tumor/normal sequencing results from two distinct cohorts of patients initially diagnosed with NMIBC. Associations between clinicopathologic features and clinical outcomes with the presence of P/LP germline variants in ≥76 hereditary cancer predisposition genes were analyzed.

RESULTS

A similar frequency of P/LP germline variants were seen in our two NMIBC cohorts [12% (12/99) vs. 8.7% (10/115), P = 0.4]. In the combined analysis, P/LP germline variants were found only in patients with high-grade NMIBC (22/163), but none of the 46 patients with low-grade NMIBC (13.5% vs. 0%, P = 0.005). Fifteen (9.2%) patients with high-grade NMIBC had P/LP variants in DNA damage response genes, most within the nucleotide excision repair (ERCC2/3) and homologous recombination repair (BRCA1, NBN, RAD50) pathways. Contrary to prior reports in patients with NMIBC not receiving Bacillus Calmette-Guerin (BCG), P/LP germline variants were not associated with worse recurrence-free or progression-free survival in patients treated with BCG or with risk of developing upper tract urothelial carcinoma.

CONCLUSIONS

Our results support offering germline counseling and testing for all patients with high-grade bladder cancer, regardless of initial tumor stage. Therapeutic strategies that target impaired DNA repair may benefit patients with high-grade NMIBC.

Associations between circulating proteins and risk of breast cancer by intrinsic subtypes: a Mendelian randomisation analysis

BACKGROUND

The aetiologic role of circulating proteins in the development of breast cancer subtypes is not clear. We aimed to examine the potential causal effects of circulating proteins on the risk of breast cancer by intrinsic-like subtypes within the Mendelian randomisation (MR) framework.

METHODS

MR was performed using summary statistics from two sources: the INTERVAL protein quantitative trait loci (pQTL) Study (1890 circulating proteins and 3301 healthy individuals) and the Breast Cancer Association Consortium (BCAC; 106,278 invasive cases and 91,477 controls). The inverse-variance (IVW)-weighted method was used as the main analysis to evaluate the associations between genetically predicted proteins and the risk of five different intrinsic-like breast cancer subtypes and the weighted median MR method, the Egger regression, the MR-PRESSO, and the MRLocus method were performed as secondary analysis.

RESULTS

We identified 98 unique proteins significantly associated with the risk of one or more subtypes (Benjamini-Hochberg false discovery rate < 0.05). Among them, 51 were potentially specific to luminal A-like subtype, 14 to luminal B/Her2-negative-like, 11 to triple negative, 3 to luminal B-like, and 2 to Her2-enriched-like breast cancer (n_total = 81). Associations for three proteins (ICAM1, PLA2R1 and TXNDC12) showed evident heterogeneity across the subtypes. For example, higher levels of genetically predicted ICAM1 (per unit of increase) were associated with an increased risk of luminal B/HER2-negative-like cancer (OR = 1.06, 95% CI = 1.03-1.08, BH-FDR = 2.43 × 10^-4) while inversely associated with triple-negative breast cancer with borderline significance (OR = 0.97, 95% CI = 0.95-0.99, BH-FDR = 0.065, P_{heterogeneity} < 0.005).

CONCLUSIONS

Our study found potential causal associations with the risk of subtypes of breast cancer for 98 proteins. Associations of ICAM1, PLA2R1 and TXNDC12 varied substantially across the subtypes. The identified proteins may partly explain the heterogeneity in the aetiology of distinct subtypes of breast cancer and facilitate the personalised risk assessment of the malignancy.

Germline Pathogenic Variants Impact Clinicopathology of Advanced Lung Cancer

BACKGROUND

The genetic factors that modulate risk for developing lung cancer have not been fully defined. Here, we sought to determine the prevalence and clinical significance of germline pathogenic/likely pathogenic variants (PV) in patients with advanced lung cancer.

METHODS

We studied clinical and tumor characteristics of germline PV in 5,118 patients who underwent prospective genomic profiling using paired tumor-normal tissue samples in 468 cancer genes.

RESULTS

Germline PV in high/moderate-penetrance genes were observed in 222 (4.3%) patients; of these, 193 patients had PV in DNA damage repair (DDR) pathway genes including BRCA2 (n = 54), CHEK2 (n = 30), and ATM (n = 26) that showed high rate of biallelic inactivation in tumors. BRCA2 heterozygotes with lung adenocarcinoma were more likely to be never smokers and had improved survival compared with noncarriers. Fourteen patients with germline PV in lung cancer predisposing genes (TP53, EGFR, BAP1, and MEN1) were diagnosed at younger age compared with noncarriers, and of tumor suppressors, 75% demonstrated biallelic inactivation in tumors. A significantly higher proportion of germline PV in high/moderate-penetrance genes were detected in high-risk patients who had either a family history of any cancer, multiple primary tumors, or early age at diagnosis compared with unselected patients (10.5% vs. 4.1%; P = 1.7e-04).

CONCLUSIONS

These data underscore the biological and clinical importance of germline mutations in highly penetrant DDR genes as a risk factor for lung cancer.

IMPACT

The family members of lung cancer patients harboring PV in cancer predisposing genes should be referred for genetic counseling and may benefit from proactive surveillance.

A breast cancer (BC) risk model incorporating Tyrer-Cuzick version 8 (TCv8) and a polygenic risk score (PRS) for diverse ancestries

557

Background: BC risk assessment is important for guiding personalized screening and risk-reducing interventions. TCv8 is used to estimate BC risk based on age, breast density, family cancer history and other clinical factors. Accuracy may be improved by combining TCv8 with a PRS. We developed and validated a PRS for diverse ancestries based on 149 common genetic variants (PRS-149) comprised of 56 ancestry-informative and 93 BC-associated variants. Here, we describe a BC risk model that combines PRS-149 with TCv8. Methods: Subjects had multigene panel testing for hereditary cancer and were negative for pathogenic variants in known BC susceptibility genes. A combined risk score (CRS), incorporating PRS-149 and TCv8, was developed based on 189,230 women, including 43,444 (23%) with a history of BC. Breast Imaging Reporting and Data System (BI-RADS) breast density measurements were available for 12,363 women. We used multivariable logistic regression to test breast density and PRS-149 for association with risk of BC. An independent test cohort of 6,030 BC-unaffected women with BI-RADS assessment was used to evaluate the effect of PRS-149 on risk stratification. Relative contributions of family history, breast density, other clinical factors in TCv8 and PRS-149 were examined by adding terms sequentially to an ANOVA model. We compared differences in classification of women as high (20%) or low/moderate (20%) remaining lifetime risk according to TCv8 versus CRS. Results: In the development cohort, increased breast density was significantly associated with higher risk of BC (p=3.0x10-6) with an effect size consistent with TCv8. PRS-149 improved BC risk prediction over age, breast density and family history (OR per unit standard deviation: 1.41, 95% CI: 1.37 – 1.46; p: 1.8x10-105). PRS-149 was weakly but significantly correlated with both family history (r=0.09) and breast density (r=0.01). After adjusting for multiple testing, no other factors were correlated with PRS-149. In the independent test cohort, PRS-149 explained 27% of CRS variability after accounting for family history, breast density and other clinical factors. Adding PRS-149 to TCv8 significantly altered risk estimates, with 16.3% (983/6,030) of patients classified differently by CRS versus TCv8. By TCv8 alone, 38.0% (2,289/6,030) of patients were classified as high-risk. Among patients who were high-risk by TCv8, 25.2% (576/2,289) were downgraded by CRS. Conclusions: This is the first BC risk model that includes breast density, family history, and a PRS based on genetically determined ancestry that is validated for diverse populations. Addition of PRS-149 improved risk prediction and substantially modified risk stratification compared to TCv8 alone. Implementation of CRS may therefore lead to improved identification of women who are likely to benefit from increased surveillance and preventive medications.

Allelic dosage of RB1 drives CDK4/6 inhibitor treatment resistance in metastatic breast cancer

1010

Background: We recently reported inferior outcomes to CDK4/6 inhibitors and endocrine therapy (CDK4/6i-ET) associated with germline BRCA2 (g BRCA2) in a cohort of estrogen receptor (ER) positive breast cancers. Co-occurrence of gBRCA2 with loss of heterozygosity (LOH) of neighboring RB1 was found to portend particularly poor outcomes. Here, we sought to define the effects of pre-treatment RB1 allelic copy number status on outcomes of CDK4/6i-ET and the likelihood of developing RB1 loss-of-function (LOF) mutations on CDK4/6i through the analysis of an expanded cohort of metastatic ER+ breast cancer patients. Methods: Patients who underwent sequencing on MSK-IMPACT from April 2014 to May 2021 were included. For every sample preceding CDK4/6i-ET, we performed FACETS to infer RB1 allele specific copy number, ploidy, tumor purity and fraction genome altered (FGA). Patients were categorized based on RB1 allelic status: HetLoss (total of one allelic copy), copy neutral LOH (CNLOH), other allelic imbalance including all other aneuploidy states, and diploid. Progression free survival (PFS) was assessed using univariate and multivariate Cox proportional hazard models adjusted for ET partner and FGA. Firth penalized logistic regression was used to study association of pre-treatment RB1 status with acquired RB1 LOF variants in paired post-CDK4/6i samples. Results: Of 2,630 potentially eligible patients, 279 patients had genomic sequencing performed prior to 1st line CDK4/6i-ET. Of these, 75 (26.8%) exhibited RB1 HetLoss, 39 (14.0%) had CNLOH of RB1, 111 (39.7%) exhibited diploid RB1 state, while 54 (19.4%) had other patterns of RB1 allelic imbalance. All non-diploid RB1 states were associated with significantly shortened PFS relative to diploid (univariate HetLoss HR: 2.05, 95% CI: 1.42, 2.97; CNLOH HR: 2.08, 95% CI: 1.32, 3.25; other imbalance HR: 1.70, 95% CI: 1.11, 2.58). Only HetLoss remained significant when adjusted for FGA (HR 1.61, 95% CI: 1.09, 2.38, p = 0.017). RB1 LOF was rare in pre-CDK4/6i tumors (< 1%); excluding these cases did not change our results. Of the 176 patients with paired pre- and post-CDK4/6i samples, only RB1 HetLoss in pre-CDK4/6i sample was significantly associated with development of RB1 LOF mutations in post-CDK4/6i sample (18.4%) as compared to diploid (4.2%, OR 4.25, 95% CI 1.02, 17.7, p = 0.047). These results indicate that tumors with one functional copy of RB1 are more likely to acquire RB1 LOF on CDK4/6i to achieve biallelic RB1 loss as a mechanism of CDK4/6i resistance. Conclusions: We demonstrate that LOH and allelic imbalance of RB1 are associated with shorter PFS on CDK4/6-ET. We postulate this may occur partly as a result of more frequent acquired RB1 LOF mutations under selective pressure of CDK4/6i. These data supports the implementation of more refined allele-specific copy number methods and identifies a high-risk population for escalated monitoring and treatment approaches.

Interim analysis of a single-center, single-arm, prospective phase 2 study to evaluate the efficacy and safety of benralizumab for alpelisib rash in metastatic PIK3CA-mutant, hormone receptor–positive breast cancer

12100

Background: Rash associated with increased peripheral eosinophils develops in approximately 50% of metastatic breast cancer patients receiving alpelisib. Antihistamines and corticosteroids have limited benefit. Refractory rash may lead to decreased dose intensity and affect clinical outcome. Benralizumab is an anti-IL-5Rα chimeric monoclonal antibody that depletes peripheral eosinophils and has demonstrated benefit in eosinophilic asthma and hypereosinophilic syndrome. We investigate the efficacy and safety of benralizumab for the treatment of alpelisib rash. Methods: We performed a single-center, single-arm, prospective phase 2 study to evaluate the efficacy and safety of benralizumab in cancer patients who developed CTCAE grade 2/3 skin events resulting from immunotherapy or targeted therapies with absolute blood eosinophil counts of ≥300/mcl. While remaining on culprit drugs, patients were treated with benralizumab 30mg once every 4 weeks for the first 3 doses followed by once every 8 weeks for 3 additional doses (approved dosing for eosinophilic asthma). Primary endpoint was clinical response measured as reduction in CTCAE grade 2/3 skin event to grade ≤1 by week 4. Secondary endpoints were patient quality of life (QoL) measured by skindex16, safety data, need for supportive oral corticosteroids, and changes in cytokines and eosinophil biomarkers. This interim analysis focuses on patients with PIK3CA-mutant metastatic breast cancer receiving alpelisib. Results: Between September 16th 2020 and January 1st 2022, we enrolled 10 metastatic breast cancer patients with grade 2/3 rash attributed to alpelisib (5 pts with G3). All patients had a reduction of rash to grade ≤1 (n = 10, p < 0.0001), and a decrease in peripheral absolute eosinophils (mean 500/mcl to 0, p < 0.0001). Of these, 6 patients had been on prophylactic oral antihistamines and 2 had oral steroid coadministration. QoL significantly improved (Skindex16 mean score 58 to 16, p = 0.0001) and eosinophils in skin histology decreased per HPF (mean 6.25 to 0.25, n = 8, p = 0.2) by week 4. An increase in IL-5 > 600% and reduction IL-6 and TNF-α > 50% were reported by week 4 and 8. Grade 1/2 mucositis in 4 patients were reported as adverse events. Conclusions: Our findings suggest that benralizumab is safe and effective for the treatment of grade 2/3 rash with eosinophilia related to alpelisib in patients with breast cancer. A reduction in rash severity was evidenced in all patients, along with improved QoL. Larger controlled studies are in development to evaluate the efficacy of benralizumab for the prevention of alpelisib rash. Clinical trial information: NCT04552288.

Cost effectiveness of adjuvant olaparib for BRCA-mutated, early-stage breast cancer

6593

Background: An interim analysis of the OlympiA trial found that olaparib given in the adjuvant setting can improve distant disease-free and overall survival for patients with early-stage, BRCA-mutated breast cancer; however, the cost-effectiveness of adjuvant olaparib is unknown. This study aimed to evaluate the cost-effectiveness of adjuvant olaparib in patients with early-stage, BRCA-mutated breast cancer. Methods: We used a decision-analytic model to compare outcomes of treatment with and without one year of oral olaparib after completion of systemic therapy in 42-year-old women with BRCA-mutated, early-stage breast cancer. Olaparib’s effectiveness was based on the OlympiA trial, and other model parameters were identified from the literature. We calibrated the model to reflect the 1-, 2-, and 3-year distant disease-free survival (DDFS) and overall survival (OS) observed in the OlympiA trial, and we assumed that olaparib reduced the risk of distant recurrence only in the first 3 years. Olaparib was estimated to cost $14,523 per month. Average lifetime costs were estimated from a health care system perspective in 2021 $ US, and incremental cost-effectiveness ratios (ICER) were estimated as $ per quality-adjusted life-year (QALY) gained. Costs, life-years, and QALYs were discounted by 3% annually. Results: Simulating the OlympiA trial, DDFS for the olaparib arm was 94.3% at 12 months, 90.0% at 24 months, and 87.5% at 36 months, compared to placebo with DDFS of 90.2%, 83.9%, and 80.4% respectively. Similarly, OS for the olaparib arm was 98.1%, 94.8%, and 92.0% compared to 96.9%, 92.3%, and 88.3% with placebo at 12, 24, and 36 months respectively. In the base case, adjuvant olaparib was associated with a 1.21-year increase in life expectancy and a 1.15-QALY increase at an incremental cost of $131,167 compared to placebo. The resulting ICER was about $114,500/QALY gained. At a willingness-to-pay threshold of USD$150,000/QALY, olaparib was cost effective at its current price. Results were sensitive to assumptions about the effectiveness of olaparib and its impact on quality of life. Conclusions: Adjuvant olaparib is cost-effective for women with early-stage, BRCA-mutated breast cancer at the current price of olaparib in the U.S. and at a willingness-to-pay threshold of $150,000. As such, clinicians and payers should consider adjuvant olaparib as a cost-effective option for this patient population. [Table: see text]

Delays in care following a COVID diagnosis

e18675

Background: We sought to describe factors associated with treatment delay among cancer patients with COVID-19. Methods: We conducted a retrospective analysis of de-identified data from the ASCO COVID-19 Cancer Data Registry, a longitudinal cohort study launched in April 2020 with 60 community and academic practices. We evaluated all patients who were documented as having therapy (anticancer drug therapy, surgery or radiation therapy) scheduled at the time of entry into the registry due to a positive SARS-CoV-2 test result. Treatment delay were defined based on length of delay: on schedule or within 14 days, and delay > 14 days or discontinued entirely. The latter is defined as “delay in care”. We used univariate and multivariate logistic analyses to address these questions. Results: At the time of data analysis, 3028 patients were included in the registry, of which 2103 had scheduled drug therapy, 125 had scheduled surgery, and 202 had scheduled radiation. 46% of patients had a drug delay or discontinuation of care. A multivariable logistic regression found that delays were higher among Black patients relative to white patients (OR 1.73, 95%CI 1.27, 2.35), and Hispanic or Latino patients compared to non-Hispanic or Latino patients (OR 1.95, 95%CI 1.36, 2.80). Compared with patients with 0-1 comorbidities, having 2 or more comorbidities was associated with delay in treatment (OR 1.26, 95%CI 1.01, 1.56). Having metastatic disease, rather than local or regional disease (OR 1.61, 95%CI 1.28, 2.04), and having any COVID-19 complications compared to none (OR 1.49, 95%CI 1.22, 1.83) were associated with delay. Relative to the initial outbreak of the pandemic from March-June 2020, having a COVID-19 diagnosis later in the pandemic was associated with lower likelihood of delay (OR 0.45, 95%CI 0.26, 0.74). 47% (95/202) of patients had a radiation delay or discontinuation of care. Factors associated with radiation delay included having 2 or more comorbidities (OR 2.78, 95%CI 1.22, 6.53). 71% (89/125) of patients had a surgical delay or discontinuation care. Factors associated with surgical delay included female sex (OR 6.05, 95%CI 1.34, 34.6), being in the South compared with being in the Midwest (OR 9.00, 95%CI 1.97, 49.0). Counter-intuitively, having 2 or more comorbidities was associated with a lower likelihood of delay (OR 0.27, 95%CI 0.09, 0.90). Being diagnosed with COVID-19 in July-Sept 2020 was associated with lower likelihood of delay (OR 0.07, 95%CI 0.01, 0.49). Conclusions: Previous data has shown persistent disparities in COVID-19-related outcomes in subgroups of disadvantaged and minority patients and populations. Data from our study shows that another disparity borne of treatment delays for chronic disease in the setting of a positive SARS-CoV2 test may also contribute to overall poor outcomes in these vulnerable populations.

A phase 1b/2 study of the BET inhibitor ZEN-3694 in combination with talazoparib for treatment of patients with TNBC without gBRCA1/2 mutations

1023

Background: Metastatic triple negative breast cancer (mTNBC) is an aggressive and heterogeneous cancer with limited therapeutic options. PARP inhibitors (PARPi), approved to treat patients with HER2- breast cancer with a germline BRCA1/2 (gBRCA1/2) mutation, have not shown efficacy in homologous recombination repair (HRR) proficient tumors. In pre-clinical models, the BET inhibitor (BETi) ZEN-3694 sensitizes wild-type (WT) BRCA1/2 tumors to PARPi through downregulation of HRR gene expression, providing a rationale for combination therapy. We previously reported results from the Ph 1b portion of the trial evaluating the combination of ZEN-3694 plus talazoparib, in TNBC patients without gBRCA1/2 mutations; here we present results from the completed Ph 1b/2 study. Methods: A Ph 1b dose finding portion (n = 15) was followed by a single arm Ph 2 Simon 2-stage portion (n = 17+20 (37)). The primary endpoint of the Ph 1b portion of the study was safety and recommended Ph 2 dose (RP2D). The secondary endpoints were pharmacokinetics (PK), pharmacodynamics (PD), and clinical benefit rate (CBR = confirmed objective response rate (ORR) + stable disease > 16 weeks). Ph 2 measured CBR as the primary endpoint, ORR and duration of response (DOR) as key secondary endpoints. Eligibility criteria for Ph 1b included TNBC (ER/PR < 10%, HER2-), WT gBRCA1/2, and > 1 prior cytotoxic regimen for mTNBC, and in the Ph2 portion ER/PR < 1% and < 2 prior cytotoxic regimens for mTNBC. Patients were dosed daily in continuous 28 day cycles until disease progression or unacceptable toxicity. Adverse events, PK, and PD in whole blood and tissue biopsies were assessed. Response endpoints were assessed per RECIST 1.1 every 2 cycles. Results: RP2D was determined to be 48mg qd ZEN-3694 plus 0.75mg qd talazoparib. The most common AE for the Ph 1b/2 study was thrombocytopenia (TCP) (55% any grade, 34% G3/4), which was managed with dose holds and reductions. Dose intensity analysis showed average daily doses of ZEN-3694 and talazoparib could be maintained above 40mg and 0.5mg, respectively, over 8 cycles. Robust target engagement was demonstrated using BET-dependent and HRR transcripts assessed in paired tumor biopsies. Ph 2 portion of the trial met its primary endpoint with a CBR of 30% (11/37). For the Ph 1b/2 trial, investgator assessed ORR was 22% (11/50), including 2 CR, CBR was 35% (18/51) and the median DOR was 24 weeks. For the subset of TNBC at diagnosis patients (no history of HR+ disease), ORR was 32% (11/34), and CBR was 44% (15/34). Conclusions: Combination of ZEN-3694 and talazoparib demonstrated anti-cancer activity in pretreated mTNBC WT gBRCA1/2 patients. All confirmed responses were observed in TNBC at diagnosis patients, whose tumors are expected to be more sensitive to the combination due to their basal-like properties. The trial is being expanded to Ph. 2b to accrue an additional 80 TNBC at diagnosis patients. Clinical trial information: NCT03901469.

BRCA reversion mutations mediated by microhomology-mediated end joining (MMEJ) as a mechanism of resistance to PARP inhibitors in ovarian and breast cancer

5559

Background: PARP inhibitors exploit synthetic lethality in tumor cells with deficiency in homologous recombination repair (HRR). In line with this, most reported mechanisms of PARP inhibitor resistance restore HRR. Of multiple resistance mechanisms reported preclinically, reversion mutations in BRCA genes are the only confirmed mechanism of resistance to both platinum and PARP inhibitors in patients (pts) to date (Lin K et al. Cancer Discov 2019), with most studies focusing on ovarian cancer. MMEJ is an alternative DNA damage repair pathway, in which DNA polymerase θ (POLθ) has a key role; MMEJ has been suggested to play a role in BRCA reversion mutations (Tobalina L et al. Ann Oncol 2021). Methods: Targeted circulating tumor DNA (ctDNA) sequencing analyzed over 500 plasma samples collected at baseline and at progression to therapy in pts with ovarian or breast cancer and a mutation in BRCA1 and/or BRCA2 (BRCAm) who were treated with olaparib or chemotherapy in one of three Phase II/III clinical studies (LIGHT NCT02983799, SOLO3 NCT02282020, OlympiAD NCT02000622). Only pts with an original pathogenic BRCAm detected in ctDNA were evaluable. BRCA reversion mutations were identified using internal computational framework; DNA sequences surrounding BRCA reversion sites were analyzed for MMEJ signatures. Results: At baseline, in pooled data across treatment arms and across all available samples, BRCA reversion mutations were detected in 4/114 (3.5%) and 6/133 (4.5%) of breast and ovarian cancer pts, respectively, which may have developed on prior platinum therapy. At progression, BRCA reversion mutations were detected in 34/79 (43%) breast cancer pts and in 26/101 (26%) ovarian cancer pts who received olaparib, with at least 2/79 and 4/101 reversions already present at baseline, respectively. At progression, in the chemotherapy arm, BRCA reversion mutations were detected in 3/34 (9%) breast cancer pts and 1/29 (3%) ovarian cancer pts, with 2/34 and 0/29 reversions present at baseline, respectively. Reversion mutations varied in allelic frequency and were either present as single or multiple reversions, suggesting multiple events within the tumor were driving resistance. The location and type of reversion mutations reflected the functional importance of BRCA protein domains. A large proportion of BRCA reversion mutations (47/69 [68%] that were evaluable) were mediated by the MMEJ pathway based on the presence of MMEJ signatures around BRCA reversion sites. Conclusions: We detected BRCA reversion mutations in at least ̃40% of breast and ̃20% of ovarian cancer pts following treatment with olaparib. A large proportion of these reversion mutations are likely to have been mediated by MMEJ repair, suggesting that POLθ inhibitors in combination with platinum or PARP inhibitors might prevent or delay emergence of PARP inhibitor resistance. Clinical trial information: NCT02983799, NCT02282020, NCT02000622.

Points to Consider Regarding Risk-Reducing Mastectomy in High-, Moderate-, and Low-Penetrance Gene Carriers

Risk-reducing mastectomy is considered a safe and effective surgical procedure in high-risk individuals with BRCA1/2 germline mutations. Multigene panels identify women with alterations in breast cancer susceptibility genes other than BRCA1/2. International guidelines classify these genes as high-, moderate-, and low-penetrance based on their associated relative risk for breast cancer. Classification of specific genes is not always concordant among guidelines, and the indications for risk-reducing mastectomy are not defined. In this opinion paper, we review some considerations to clarify these controversial points.

Breast Cancer Screening Strategies for Women With ATM, CHEK2, and PALB2 Pathogenic Variants: A Comparative Modeling Analysis

IMPORTANCE

Screening mammography and magnetic resonance imaging (MRI) are recommended for women with ATM, CHEK2, and PALB2 pathogenic variants. However, there are few data to guide screening regimens for these women.

OBJECTIVE

To estimate the benefits and harms of breast cancer screening strategies using mammography and MRI at various start ages for women with ATM, CHEK2, and PALB2 pathogenic variants.

DESIGN, SETTING, AND PARTICIPANTS

This comparative modeling analysis used 2 established breast cancer microsimulation models from the Cancer Intervention and Surveillance Modeling Network (CISNET) to evaluate different screening strategies. Age-specific breast cancer risks were estimated using aggregated data from the Cancer Risk Estimates Related to Susceptibility (CARRIERS) Consortium for 32 247 cases and 32 544 controls in 12 population-based studies. Data on screening performance for mammography and MRI were estimated from published literature. The models simulated US women with ATM, CHEK2, or PALB2 pathogenic variants born in 1985.

INTERVENTIONS

Screening strategies with combinations of annual mammography alone and with MRI starting at age 25, 30, 35, or 40 years until age 74 years.

MAIN OUTCOMES AND MEASURES

Estimated lifetime breast cancer mortality reduction, life-years gained, breast cancer deaths averted, total screening examinations, false-positive screenings, and benign biopsies per 1000 women screened. Results are reported as model mean values and ranges.

RESULTS

The mean model-estimated lifetime breast cancer risk was 20.9% (18.1%-23.7%) for women with ATM pathogenic variants, 27.6% (23.4%-31.7%) for women with CHEK2 pathogenic variants, and 39.5% (35.6%-43.3%) for women with PALB2 pathogenic variants. Across pathogenic variants, annual mammography alone from 40 to 74 years was estimated to reduce breast cancer mortality by 36.4% (34.6%-38.2%) to 38.5% (37.8%-39.2%) compared with no screening. Screening with annual MRI starting at 35 years followed by annual mammography and MRI at 40 years was estimated to reduce breast cancer mortality by 54.4% (54.2%-54.7%) to 57.6% (57.2%-58.0%), with 4661 (4635-4688) to 5001 (4979-5023) false-positive screenings and 1280 (1272-1287) to 1368 (1362-1374) benign biopsies per 1000 women. Annual MRI starting at 30 years followed by mammography and MRI at 40 years was estimated to reduce mortality by 55.4% (55.3%-55.4%) to 59.5% (58.5%-60.4%), with 5075 (5057-5093) to 5415 (5393-5437) false-positive screenings and 1439 (1429-1449) to 1528 (1517-1538) benign biopsies per 1000 women. When starting MRI at 30 years, initiating annual mammography starting at 30 vs 40 years did not meaningfully reduce mean mortality rates (0.1% [0.1%-0.2%] to 0.3% [0.2%-0.3%]) but was estimated to add 649 (602-695) to 650 (603-696) false-positive screenings and 58 (41-76) to 59 (41-76) benign biopsies per 1000 women.

CONCLUSIONS AND RELEVANCE

This analysis suggests that annual MRI screening starting at 30 to 35 years followed by annual MRI and mammography at 40 years may reduce breast cancer mortality by more than 50% for women with ATM, CHEK2, and PALB2 pathogenic variants. In the setting of MRI screening, mammography prior to 40 years may offer little additional benefit.

Incidence of brain metastases in patients with early HER2-positive breast cancer receiving neoadjuvant chemotherapy with trastuzumab and pertuzumab

The addition of pertuzumab (P) to trastuzumab (H) and neoadjuvant chemotherapy (NAC) has decreased the risk of distant recurrence in early stage HER2-positive breast cancer. The incidence of brain metastases (BM) in patients who achieved pathological complete response (pCR) versus those who do not is unknown. In this study, we sought the incidence of BM in patients receiving HP-containing NAC as well as survival outcome. We reviewed the medical records of 526 early stage HER2-positive patients treated with an HP-based regimen at Memorial Sloan Kettering Cancer Center (MSKCC), between September 1, 2013 to November 1, 2019. The primary endpoint was to estimate the cumulative incidence of BM in pCR versus non-pCR patients; secondary endpoints included disease free-survival (DFS) and overall survival (OS). After a median follow-up of 3.2 years, 7 out of 286 patients with pCR had a BM while 5 out of 240 non-pCR patients had a BM. The 3-year DFS was significantly higher in the pCR group compared to non-pCR group (95% vs 91 %, p = 0.03) and the same trend was observed for overall survival. In our cohort, despite the better survival outcomes of patients who achieved pCR, we did not observe appreciable differences in the incidence of BM by pCR/non-pCR status. This finding suggests that the BM incidence could not be associated with pCR. Future trials with new small molecules able to cross the blood brain barrier should use more specific biomarkers rather than pCR for patients' selection.

Abstract P2-13-06: Clinical implication of HER2 status change after neoadjuvant chemotherapy with Trastuzumab and Pertuzumab (HP) in patients with HER2-positive breast cancer

Background: Patients with early HER2-positive breast cancer (BC) and residual disease after HER2-targeted neoadjuvant chemotherapy (NAC) are at high risk of recurrence. It is estimated that 10-30% of HER2-positive breast cancers change HER2 status after trastuzumab alone, but the effects of adding pertuzumab on this phenomenon and clinical outcomes remain unclear. We previously reported a high rate (~50%) of HER2 status change after HP in a small subset of patients. Herein, we present an updated analysis incorporating pathological review of additional cases.Methods: We identified patients with HER2-positive BC who received NAC with pertuzumab and trastuzumab (NAC-HP) followed by surgery at our institution between September 1, 2013 to November 1, 2019. Patients with HER2 status performed either at MSKCC or outside institutions were included. Change in HER2 status on residual disease from baseline was evaluated. We defined HER2 positivity as immunohistochemistry (IHC) IHC3+ or IHC0-2+ FISH amplified (ratio ≥ 2 or ratio &lt; 2 and HER2 copy number ≥ 6 signals/cell). HER2-low was defined as IHC 1+ or 2+, FISH non-amplified. Disease free survival (DFS) and overall survival (OS) were analyzed using the Kaplan-Meier method. Differences between patients with concordant and discordance HER2 status were assessed using the log-rank test.Results: Of 525 patients receiving NAC with HP, 229 (44%) patients had residual disease post NAC-HP. Among these 229 patients, 141 had both pre and post NAC-HP HER2 status available and were included in this analysis. HER2 status on biopsy specimens was determined at MSKCC in 35/141 (25%) and at external institution in 106/141 (75%). The majority of patients (84%) received dose-dense AC-THP; the remainder received TCHP or other HP-based regimens. Most (96%) of patients continued HP after surgery, and 2 patients received T-DM1. Of the 141 patients, 84/141(60%) were found to be HER2 concordant, while 57 (40%) were found to be HER2 discordant. In 13/57 (23%) patients, HER2 expression was lost (IHC 0), while in 44/57 (77%) patients, HER2-low profile was detected (IHC 1+ in 31, and IHC 2+, FISH non-amplified in 13). Further details are reported in the table. Patients with HER2 discordance after NAC-HP had similar survival outcome compared with patients who remained HER2 concordant (5-years DFS: 92.3% versus 88.7%, p=0.49 and 5-yr OS 93.6% versus 88.4%, p=0.70).Conclusions: In a single center cohort, discordant HER2 status after NAC-HP appeared frequently without statistically significant impact on survival outcome, although this finding may be due to the small size and hence low statistical power. Of these, HER2-low profile is the most frequent post treatment HER2 status change. This raises the possibility that patients with change in HER2 status may have heterogenous expression of HER2 at baseline, and HER2-loss or low sub-clones survive as residual disease due to the selection pressure of HP. Alternatively, anti-HER2 therapy may suppress HER2 expression in surviving cells. These findings could inform studies of tailored approaches in the post-neoadjuvant setting based on the biological profile of residual disease.

Pre NAC-HP HER2 statusNPost NAC-HP HER2 statusNDiscordantN=57IHC 3+: 19IHC0: 4IHC1+: 9IHC2+ FISH not ampl: 6IHC 0-2+ FISH ampl: 38IHC0: 9IHC1+: 22IHC2+ FISH not ampl: 7Concordant N= 84IHC 3+: 59IHC 3+: 47IHC 0- 2+ FISH ampl: 12IHC 0-2+ FISH ampl: 25IHC 3+: 4IHC 0- 2+ FISH ampl: 21

Citation Format: Emanuela Ferraro, Anton Safonov, Hanna Y Wen, Edi Brogi, Mithat Gonan, Andrea V. Barrio, Pedram Razavi, Sarat Chandarlapaty, Shanu Modi, Andrew D. Seidman, Larry Norton, Mark E. Robson, Chau T. Dang. Clinical implication of HER2 status change after neoadjuvant chemotherapy with Trastuzumab and Pertuzumab (HP) in patients with HER2-positive breast cancer [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 P2-13-06.

Abstract P4-08-01: Effectiveness of electroacupuncture versus auricular acupuncture in breast cancer survivors with chronic musculoskeletal pain: The PEACE randomized clinical trial

Introduction: Chronic musculoskeletal pain is common and debilitating among breast cancer survivors. Recently, the Personalized Electroacupuncture (EA) versus Auricular Acupuncture (AA) Comparative Effectiveness (PEACE) trial demonstrated that both acupuncture methods improved pain control better than usual care (UC) in cancer survivors. However, the comparative effectiveness between EA and AA among breast cancer survivors, specifically, for chronic musculoskeletal pain is unknown. Here, we report the results of breast cancer survivors enrolled in the PEACE trial. Methods: PEACE is a three-arm, parallel, single center randomized trial investigating the effectiveness of EA and AA versus UC for chronic musculoskeletal pain in 360 cancer survivors. Patients in both EA and AA received ten weekly treatments. Patients in UC could receive ten EA treatments after week 12. The primary endpoint was the change in mean Brief Pain Inventory (BPI) pain intensity from baseline to week 12; change from baseline to week 24 was a secondary endpoint. We analyzed the subset of trial participants with a primary diagnosis of breast cancer (46%). We conducted constrained linear mixed model analyses, which constrained all arms to have a common pre-randomization baseline mean. Model-based mean estimates at weeks 12 and 24 were compared between arms using model contrasts. Results: Among the 165 breast cancer survivors, mean (SD) age was 60.3 (11.0) years, 35.8% were non-white, and mean time since cancer diagnosis was 5.4 (6.5) years. Patients had been experiencing pain for 5.6 (7.3) years, with baseline mean pain severity of 5.35 (95% CI: 5.04, 5.66). 86.7% had a prior history of surgery, 43.0% chemotherapy, 64.8% radiotherapy, and 50.3% endocrine therapy. The common locations of pain were lower back (24.2%), knee/leg (23.6%), and shoulder/arm/elbow (13.9%). 107 (66.9%) patients were taking pain medication. At week 12, the BPI pain severity score was 2.69 (2.26. 3.13) in EA, 3.60 (3.17, 4.02) in AA, and 5.06 (4.47, 5.65) in UC. The change in mean BPI intensity score from baseline was -2.65 (-3.06, -2.25), -1.75 (-2.15, -1.35), and -0.29 (-0.86, 0.28) in EA, AA, and UC, respectively (Table 1). At week 24, the mean BPI pain severity was 2.84 (95% Confidence Interval [CI]: 2.40, 3.28) in EA and 3.67 (95% CI: 3.23, 4.10) in AA. EA reduced pain severity significantly more than AA at both week 12, (-0.90 [-1.45, -0.36], p =0.001) and week 24 (-0.82, [-1.38, -0.27], p=0.004). Minimal toxicities were reported. Conclusions: While both EA and AA were associated with clinically meaningful and persistent reduction of pain among breast cancer survivors, EA was more effective than AA at reducing pain severity. Breast cancer survivors with chronic musculoskeletal pain may consider EA.

Table 1.Changes in BPI Pain Intensity from BaselineBPI Pain IntensityUCEAAAEA vs AAChange from baselineChange from baselineDifference from UCChange from baselineDifference from UCDifference between EA and AAWeek 12Mean (95% CI)-0.29 (-0.86, 0.28)-2.65* (-3.06, -2.25)-2.37*(-3.05, -1.68)-1.75* (-2.15, -1.35)-1.46* (-2.14, -0.78)-0.90* (-1.45, -0.36)*p≤0.001

Citation Format: Wanqing Iris Zhi, Jun J Mao, Raymond E Baser, Susan Q Li, Vicotria S Blinder, Larry Norton, Andrew D Seidman, Mark E Robson, Ting Bao. Effectiveness of electroacupuncture versus auricular acupuncture in breast cancer survivors with chronic musculoskeletal pain: The PEACE randomized clinical 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 P4-08-01.

Abstract GS3-03: Genomic analysis of 733 HER2+ breast cancers identifies recurrent pathways alterations associated with anti-HER2 resistance and new therapeutic vulnerabilities

Background:The introduction of anti-HER2 therapies, trastuzumab and pertuzumab (HP) to the treatment of metastatic HER2-positive breast cancer has had a transformational impact on the outcomes for this disease. Nevertheless, disease progression is ultimately observed in most patients within 3 years carrying the potential for morbidity and potentially more toxic therapies. To identify selective strategies to prevent disease progression, we sought to elucidate mechanisms of resistance to anti-HER2 therapies by analyzing a large cohort of genomically and clinically annotated HER2+ breast cancers. Methods: Patients with advanced HER2+ breast cancer who underwent prospective clinical tumor sequencing utilizing MSK-IMPACT assay between April 2014 and February 2021 were included in the analysis. Clinical HER2 positivity was defined as per ASCO/CAP guidelines. Cox proportional hazard models were used to determine the association between genomic alterations and progression-free survival (PFS) on 1st line HP and taxane-based therapy (THP). Only patients with a sequenced pre-treatment tumor sample were included in the survival analysis. Recurrent mutations identified were modeled in HER2+ breast cancer cell lines using short hairpin RNAs and CRISPR/Cas9, and the sensitivity of these isogenic pairs to HER2-targeted therapies was evaluated via metabolic and colony formation assays of cell proliferation. Results: We identified 733 ERBB2-amplified primary (n=385) and metastatic (n=348) that underwent sequencing. Concurrent PIK3CA mutations were identified in 30% of the tumors. Pathogenic activating alterations involving the MAPK pathway were observed in 12.8% of tumors with the most frequent alterations being NF1 loss, ERBB2 and RAS activating mutations. MAPK alterations were significantly enriched in the metastatic tumors (16.6%) compared to the treatment-naïve primaries (9.8%, p=0.020). The outcome analysis included 145 patients with advanced clinically HER2+ breast cancer whose tumors were sequenced prior to starting 1st line THP. Twenty percent (29/145) of tumors did not show genomic ERBB2 amplification as detected by NGS and had a significantly worse outcome (median PFS of 9.4 months [95% CI 5.5-19] and 23 months [95% CI 17-30], respectively; p=0.015). PIK3CA mutations were also associated with a shorter PFS (mutant: 13 months [95%CI: 7.7-18] vs wild type: 23 months [95%CI 17-16], p=0.0013). We further found reduced PFS in MAPK altered tumors (median PFS 9.9 months; 95% CI: 5.5-17) compared to the rest of the population (median PFS 21 months; 95% CI: 17-30; p=0.01). On multivariable analysis adjusted for estrogen receptor status, and presence of PIK3CA/AKT1/PTEN mutations and genomic ERBB2 amplification, MAPK pathway alterations were independently associated with worse outcome (HR: 2.25; 95% CI: 1.29, 3.93; multivariate p = 0.0043). To establish a causal role for MAPK alterations in reducing efficacy of anti-HER2 therapy, we depleted NF1 expression or expressed mutant KRAS or BRAF in a panel of HER2+ breast cancer cell lines. Consistently, MAPK-altered cell lines exhibited resistance to FDA approved HER2 inhibitors in vitro and in vivo. Conclusions: This clinicogenomic analysis of mechanisms of resistance to anti-HER2 therapy demonstrated that PIK3CA activating mutations and lack of genomic ERBB2 amplification as detected by tumor sequencing are associated with shortened PFS on HP-based therapy. Our analysis uniquely identified MAPK pathway alterations as additional potential drivers of resistance to anti-HER2 therapy. Inhibition of the PI3K or MAPK pathway in such tumors may represent a new therapeutic strategy to extend H/P benefit.

Citation Format: Emanuela Ferraro, Alison Smith, Anton Safonov, Paulino Tallon De Lara, Cristina Bernado', Enrique J. Arenas Lahuerta, Joaquín Arribas, David Solit, Jorge S. Reis-Filho, Neal Rosen, Larry Norton, Shanu Modi, Mark E. Robson, Chau T. Dang, Giuseppe Curigliano, Sarat Chandarlapaty, Pedram Razavi. Genomic analysis of 733 HER2+ breast cancers identifies recurrent pathways alterations associated with anti-HER2 resistance and new therapeutic vulnerabilities [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 GS3-03.

Abstract OT2-04-01: Circulating tumor DNA-guided adaptive therapy escalation in ER+ MBC: A phase 1b study with letrozole, palbociclib and onapristone ER

Background: Extended release onapristone (onapristone ER) is a progesterone receptor (PR) antagonist that inhibits hormone-mediated PR activation and stabilizes PR association with corepressors, resulting in an antineoplastic effect when applied alone or in combination with antiestrogen therapy to breast cancer cells in vitro. Recent preclinical studies further suggest that onapristone adds to inhibition of cell proliferation when combined with CDK4/6 inhibitors and fulvestrant. Elevations in ctDNA can precede overt disease progression by a matter of months in metastatic breast cancer and may represent an opportunity for proactive therapeutic intervention. Trial Design: This is an investigator initiated open-label, single institution phase 1b study of onapristone ER added as escalation therapy in patients with ER+, PR+, HER2 negative MBC, who have detectable ctDNA after six months of treatment with letrozole and palbociclib in the first line. The study is supported by Context Therapeutics and will involve two stages. Stage 1 is a dose escalation/de-escalation phase of 18 patients maximum, in which the safety and recommended phase 2 dose (RP2D) will be established for onapristone ER when used in combination with letrozole and palbociclib. In stage 2, the dose expansion phase, the RP2D of onapristone will be combined with letrozole and palbociclib in 10 patients to further explore the tolerability of the regimen. ctDNA will be collected serially while patients are on this triplet therapy. Eligibility Criteria: This study will enroll patients with radiologically measurable or evaluable metastatic or unresectable ER+/PR+/HER2-negative MBC in whom a tumor-derived somatic mutation can be detected in ctDNA at a variant allele fraction of 0.5% or greater after 6 months (+/- 4 weeks) of treatment with first line letrozole and palbociclib without progression, using our in house CLIA certified MSK-ACCESS assay. Adequate organ function and functional status for enrollment are stipulated in the protocol. Specific Aims: The primary objective of this study is to define the safety, tolerability, and recommended phase 2 dose of onapristone ER used in combination with letrozole and palbociclib. Secondary objectives include to investigate ctDNA response rate of the triplet therapy regimen, to gather early data regarding the 6-month clinical benefit rate , overall response rate , and progression free survival of this triplet escalation therapy regimen in high risk ctDNA+ patients, and to evaluate the pharmacokinetics of Onapristone ER when used in combination with letrozole and Palbociclib. Exploratory objective include to describe ctDNA dynamics during antiprogestin therapy escalation in ER+ MBC, as well as the molecular features present in responders vs. non-responders using ctDNA and pre-treatment tissue. Target Accrual: The total planned cohort for the phase I dose escalation is a maximum of 18 patients across 3 dose levels, and the total planned cohort for the dose expansion is 10 patients, with an anticipated maximum total of 28 patients. We will allot for 5 additional patients to account for inevaluability during the dose escalation and expansion portions of the trial. The trial will be open to enrollment at MSKCC in July 2021.

Citation Format: Joshua Z Drago, Elaine M Walsh, Mithat Gonen, Michael F Berger, Mark E Robson, Sarat Chandarlapaty, Pedram Razavi, Komal Jhaveri. Circulating tumor DNA-guided adaptive therapy escalation in ER+ MBC: A phase 1b study with letrozole, palbociclib and onapristone ER [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 OT2-04-01.

Genomic characterization of metastatic patterns from prospective clinical sequencing of 25,000 patients

Metastatic progression is the main cause of death in cancer patients, whereas the underlying genomic mechanisms driving metastasis remain largely unknown. Here, we assembled MSK-MET, a pan-cancer cohort of over 25,000 patients with metastatic diseases. By analyzing genomic and clinical data from this cohort, we identified associations between genomic alterations and patterns of metastatic dissemination across 50 tumor types. We found that chromosomal instability is strongly correlated with metastatic burden in some tumor types, including prostate adenocarcinoma, lung adenocarcinoma, and HR+/HER2+ breast ductal carcinoma, but not in others, including colorectal cancer and high-grade serous ovarian cancer, where copy-number alteration patterns may be established early in tumor development. We also identified somatic alterations associated with metastatic burden and specific target organs. Our data offer a valuable resource for the investigation of the biological basis for metastatic spread and highlight the complex role of chromosomal instability in cancer progression.

Targeted BRCA1/2 population screening among Ashkenazi Jewish individuals using a web-enabled medical model: An observational cohort study

PURPOSE

This study aimed to evaluate uptake and follow-up using internet-assisted population genetic testing (GT) for BRCA1/2 Ashkenazi Jewish founder pathogenic variants (AJPVs).

METHODS

Across 4 cities in the United States, from December 2017 to March 2020, individuals aged ≥25 years with ≥1 Ashkenazi Jewish grandparent were offered enrollment. Participants consented and enrolled online with chatbot and video education, underwent BRCA1/2 AJPV GT, and chose to receive results from their primary care provider (PCP) or study staff. Surveys were conducted at baseline, at 12 weeks, and annually for 5 years.

RESULTS

A total of 5193 participants enrolled and 4109 (79.1%) were tested (median age = 54, female = 77.1%). Upon enrollment, 35.1% of participants selected a PCP to disclose results, and 40.5% of PCPs agreed. Of those tested, 138 (3.4%) were AJPV heterozygotes of whom 21 (15.2%) had no significant family history of cancer, whereas 86 (62.3%) had a known familial pathogenic variant. At 12 weeks, 85.5% of participants with AJPVs planned increased cancer screening; only 3.7% with negative results and a significant family history reported further testing.

CONCLUSION

Although continued follow-up is needed, internet-enabled outreach can expand access to targeted GT using a medical model. Observed challenges for population genetic screening efforts include recruitment barriers, improving PCP engagement, and increasing uptake of additional testing when indicated.

Germline Variants Identified in Patients with Early-onset Renal Cell Carcinoma Referred for Germline Genetic Testing

BACKGROUND

Despite guidelines recommending genetic counseling for patients with early-onset renal cell carcinoma (RCC), studies interrogating the spectrum of germline mutations and clinical associations in patients with early-onset RCC are lacking.

OBJECTIVE

To define the germline genetic spectrum and clinical associations for patients with early-onset RCC diagnosed at age ≤46 yr who underwent genetic testing.

DESIGN, SETTING, AND PARTICIPANTS

We retrospectively identified patients with early-onset RCC who underwent germline testing at our institution from February 2003 to June 2020.

OUTCOME MEASUREMENT AND STATISTICAL ANALYSIS

The frequency and spectrum of pathogenic/likely pathogenic (P/LP) variants were determined. Clinical characteristics associated with mutation status were analyzed using two-sample comparison (Fisher's exact or χ2 test).

RESULTS AND LIMITATIONS

Of 232 patients with early-onset RCC, 50% had non-clear-cell histology, including unclassified RCC (12.1%), chromophobe RCC (9.7%), FH-deficient RCC (7.0%), papillary RCC (6.6%), and translocation-associated RCC (4.3%). Overall, 43.5% had metastatic disease. Germline P/LP variants were identified in 41 patients (17.7%), of which 21 (9.1%) were in an RCC-associated gene and 20 (8.6%) in a non-RCC-associated gene, including 17 (7.3%) in DNA damage repair genes such as BRCA1/2, ATM, and CHEK2. Factors associated with RCC P/LP variants include bilateral/multifocal renal tumors, non-clear-cell histology, and additional extrarenal primary malignancies. In patients with only a solitary clear-cell RCC, the prevalence of P/LP variants in RCC-associated and non-RCC-associated genes was 0% and 9.9%, respectively.

CONCLUSIONS

Patients with early-onset RCC had high frequencies of germline P/LP variants in genes associated with both hereditary RCC and other cancer predispositions. Germline RCC panel testing has the highest yield when patients have clinical phenotypes suggestive of underlying RCC gene mutations. Patients with early-onset RCC should undergo comprehensive assessment of personal and family history to guide appropriate genetic testing.

PATIENT SUMMARY

In this study of 232 patients with early-onset kidney cancer who underwent genetic testing, we found a high prevalence of mutations in genes that increase the risk of cancer in both kidneys and other organs for patients and their at-risk family members. Our study suggests that patients with early-onset kidney cancer should undergo comprehensive genetic risk assessment.