Yadav, Siddhartha

Abstract Introduction: ATRi and PARPi combinations kill tumor cells via synergistic modulation of complementary DDR pathways but clinical utility is limited by overlapping toxicities. A genome-wide CRISPR-Cas9 screen identified DDR alterations that sensitize tumors to the ATRi camonsertib (cam) plus PARPi. Based on preclinical models, tolerability and efficacy of cam plus PARPi given intermittently at low doses in pts with solid tumors with DDR alterations, including BRCA-mutated PARPi-resistant cancers, was evaluated. Methods: Pts (≥ 18 yrs) with relapsed/refractory (r/r) solid tumors with DDR alterations were treated with cam plus talazoparib (tala), niraparib (nira), or olaparib (ola) in 2 phase I trials (NCT04497116, NCT04972110). An adaptive BOIN design was used to optimize dose/schedule. Endpoints were safety, recommended phase II dose (RP2D), pharmacokinetics (PK), response (RECIST v1.1 [confirmed/unconfirmed], CA 125, or PSA), clinical benefit rate (CBR; RECIST/tumor marker response or treatment duration ≥ 16 wk), and ctDNA molecular response rate (MRR; best reduction in mean variant allele frequency [mVAF] ≥ 50%). Results: As of Nov 2022, 99 pts were enrolled (61 with ≥ 3 prior lines of therapy, 36 PARPi-pretreated); 43, 27, 29 pts in tala, nira, and ola combinations, respectively. Tumors included ovarian (n=20), prostate (n=13), breast (n=17), bile duct (n=3); most common genotypes were ATM (n=26), BRCA1 (n=19), and BRCA2 (n=33). Grade 3+ toxicities included reversible myelosuppression (neutropenia, anemia, and thrombocytopenia in 35%, 28%, and 14% of pts overall; 33%, 16%, and 11% at preliminary RP2Ds), fatigue (3%), and alkaline phosphatase increase (2%). Two pts discontinued treatment due to drug-related toxicity. Forty pts remain on therapy, up to 63 wks. Preliminary RP2Ds: cam 80 mg QD (d 5-7) + tala 0.25 mg QD, 1 wk on/1 wk off; cam 80 mg QD + nira 100 mg QD, 2 d on/5 d off; cam 50 mg QD + ola 100 mg BID, 3 d on/4 d off. As of abstract submission, response rate was 13% in 85 evaluable pts; CBR was 49%. Responders included pts with ovarian (n=6), bile duct (n=2), and breast, pancreatic, and carcinoma of unknown primary (n=1 each) cancers harboring alterations in BRCA1/2 (n=9), IDH1 (n=1), and ATM (n=1). Of 30 evaluable PARPi-pretreated pts, response rate was 23% and CBR was 52%. MRR was 64% (14/22 evaluable); change in mVAF correlated with a change in target lesion size (r=0.63, P=0.001). PK of each drug in the combination was consistent with respective monotherapy PK. Conclusion: Combination of cam plus PARPi at low doses on intermittent schedules was generally well-tolerated with clinical activity in DDR-aberrant tumors, including those pretreated with PARPi. RP2D optimization and translational correlative studies are ongoing. Citation Format: Timothy A. Yap, Siddhartha Yadav, Benjamin Herzberg, Benedito A. Carneiro, Elisa Fontana, Martin Højgaard, Michael J. Pishvaian, Ruth Plummer, Theresa L. Werner, Vaibhav Sahai, Stephanie Lheureux, Elizabeth K. Lee, Niharika B. Mettu, Gregory M. Cote, Joseph D. Schonhoft, Victoria Rimkunas, Ian M. Silverman, Marisa Wainszelbaum, Gerson Peltz, Adrian J. Fretland, Kezhen Fei, Danielle Ulanet, Insil Kim, Maria Koehler, Ezra Rosen, Michael Cecchini. Safety and efficacy of three PARP inhibitors (PARPi) combined with the ataxia telangiectasia- and Rad3-related kinase inhibitor (ATRi) camonsertib in patients (pts) with solid tumors harboring DNA damage response (DDR) alterations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT018.

Abstract Two recent studies have defined population-based risk of breast cancer (BC) due to pathogenic variants (PVs) in well-established BC susceptibility genes. Prior studies in high-risk BC cohorts identified variable BC risks based on the position and type of mutation in BRCA1 and BRCA2, and based on the type of mutation in ATM, CHEK2, and PALB2. Whether this variability holds true in the general population has not been evaluated. To determine the BC risks associated with mutations of different types and in different locations in BC susceptibility genes in the general population, we carried out case-control analyses of 32247 cases and 32544 controls in the CARRIERS study, including 12 US population-based studies, and case-control analyses, subset to mutation carriers. We used age-adjusted logistic regression to estimate odds ratios (OR), relative OR (rOR), and 95% confidence intervals (CI) for PVs in BRCA1, BRCA2, ATM, CHEK2, and PALB2. ORs were estimated using the full population of mutation carriers and noncarriers while rORs were estimated within subsets of individual gene mutation carriers. We identified 273 BRCA1, 421 BRCA2, 253 ATM, 351 CHEK2, and 148 PALB2 in women with BC and 35 BRCA1, 84 BRCA2, 139 ATM, 139 CHEK2, and 38 PALB2 variant carriers in those without BC. For BRCA1, we did not find differences in risk by mutation type or location. However, variants leading to nonsense mediated decay (NMD) predicted to have re-initiation at p.M128 had a non-statistical 3-fold higher risk for BC compared to those leading to NMD without re-initiation (rOR 3.1, 0.99-13.52, p = 0.0826). BRCA2 loss of function (LoF) mutations in exons 1-10 had a higher BC risk compared to LoF mutations in the exon 11 (rOR 2.7, 1.1-7.9, p=0.048) ovarian cancer cluster region (OCCR). We did not detect any differences in risk by mutation type or location in ATM, CHEK2, or PALB2. CHEK2 missense variants p.I157T (rOR 0.5, 0.4-0.7, p <0.001) and p.T476M (rOR 0.5, 0.3 - 0.8, p=0.005) were associated with lower BC risk relative to CHEK2 c.1100delC (OR 2.5, 2.0-3.3, p<0.001). The CHEK2 c.444+1G>A splicing variant was associated with highest BC risk among common CHEK2 variants (OR 4.2, 1.9-10.5, p<0.001), but was not statistically significantly different from c.1100delC (rOR 1.7, 0.8-4.3, p=0.230). In summary, we identified a higher BC risk for LoF variants in BRCA2, lower risk for CHEK2 missense mutations, and non-statistical higher risk for NMD/re-initiation BRCA1 variants and CHEK2 c.444+1G>A in this population-based study. Despite the large numbers included in the overall CARRIERS study, the number of PV carriers was relatively small, which may have limited the detection of associations. Nonetheless, we were able to detect genotype-risk associations that have implications for counseling women about their BC risk, and certainly for the development of individualized risks. Citation Format: Mwangala P. Akamandisa, Nicholas Boddicker, Chunling Hu, Siddhartha Yadav, Jeffrey N. Weitzel, Peter Kraft, Susan M. Domchek, Fergus J. Couch, Katherine L. Nathanson, for the CARRIERS Consortium . Mutation type and location in breast cancer susceptibility genes are associated with differential risk in the general population [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1183.

Abstract Purpose: Triple-negative invasive lobular carcinoma (TN-ILC) of breast cancer is a rare disease and the clinical outcomes and prognostic factors are not well-defined. Methods: Women with stage I-III TN-ILC or triple-negative invasive ductal carcinoma (TN-IDC) of the breast undergoing mastectomy or breast-conserving surgery between 2010 and 2018 in the National Cancer Database were included. Kaplan-Meier curves and multivariate Cox proportional hazard regression were used to compare overall survival (OS) and evaluate prognostic factors. Multivariate logistic regression was performed to analyze the factors associated with pathological response to neoadjuvant chemotherapy. Results: The median age at diagnosis for women with TN-ILC was 67 years compared to 58 years in TN-IDC (p<0.001). There was no significant difference in the OS between TN-ILC and TN-IDC in multivariate analysis (HR 0.96, p=0.44). Black race and higher TNM stage were associated with worse OS, whereas receipt of chemotherapy or radiation was associated with better OS in TN-ILC. Among women with TN-ILC receiving neoadjuvant chemotherapy, the 5-year OS was 77.3% in women with a complete pathological response (pCR) compared to 39.8% in women without any response. The odds of achieving pCR following neoadjuvant chemotherapy were significantly lower in women with TN-ILC compared to TN-IDC (OR 0.53, p<0.001). Conclusion: Women with TN-ILC are older at diagnosis but have similar OS compared to TN-IDC after adjusting for tumor and demographic characteristics. Administration of chemotherapy was associated with improved OS in TN-ILC, but women with TN-ILC were less likely to achieve complete response to neoadjuvant therapy compared to TN-IDC.

Abstract Background: Two poly (adenosine diphosphate-ribose) polymerase inhibitors (PARPi) are currently FDA-approved for the treatment of HER2-negative metastatic breast cancer (MBC) in carriers of germline pathogenic variants (PVs) in BRCA1 or BRCA2 (BRCA1/2). This study explores the clinical outcomes of MBC patients treated with a PARPi. Methods: In this retrospective study, we included MBC patients treated with a PARPi between January 2017 and February 2022 at Mayo Clinic (Minnesota, Arizona, Florida, and Mayo Clinic Health Systems). We used the Kaplan Meier method to estimate the time-to-treatment-failure (TTF) and the log-rank test to compare different subsets. In addition, predictors of TTF were identified in a multivariate cox-proportional hazard regression model, including age at PARPi initiation, race, ethnicity, histology, estrogen receptor (ER), progesterone receptor (PR), and HER2 expression of the tumor, the number of prior therapies, type of PARPi, and PV carrier status (germline BRCA1/2 or PALB2 vs. somatic BRCA1/2 vs. other). Results: Sixty-five patients treated with PARPi (olaparib: 51; talazoparib: 14) were included in the final analysis. Fifty-five patients were carriers of germline PVs in BRCA1 (n=24, 37%), BRCA2 (n=27, 42%) or PALB2 (n=4, 6%), whereas ten patients (15%) had no germline PVs but the tumor had a somatic mutation in the homologous recombination-related (HRR) genes (7 in BRCA1/2, 2 in ATM, and 1 in CDKN2A and CDH1). At the data cutoff, 48 (74%) patients had discontinued PARPi due to progression or death. Fifteen (23%) patients required a dose reduction due to side effects. Occurrence of grade ≥ 3 side effects: anemia in 8, fatigue in 4, neutropenia in 2, and thrombocytopenia in 2 patients. Eight (15.7%) patients in the olaparib group and seven (50%) patients in the talazoparib group required a dose reduction for side effects. No patient on olaparib required drug discontinuation due to side effects, whereas two patients on talazoparib were switched to olaparib due to cytopenias and could tolerate olaparib. Median TTF in the overall population was 8 months (95% confidence interval [CI]: 6.4 – 9.6), and there was no difference (p=0.64) in TTF between the olaparib and talazoparib groups. Median TTF in the germline BRCA1, BRCA2, and PALB2 PV carriers were 7, 8, and 11 months, respectively (p=0.57). Among patients with somatic BRCA1/2 mutations, the median TTF was 4 months. Numerically, patients with HER2-positive tumors (n=8) had a shorter TTF compared to HER2-negative tumors (Median TTF: 4 vs. 8 months, p=0.098). No significant difference in TTF was observed by ER or PR status of the tumor, age at initiation of PARPi, the number of prior therapies, and prior use of platinum-based chemotherapy or CDK4/6 inhibitors. In multivariate analysis, HER2 positivity (hazard ratio [HR]: 8.0, 95% CI: 2.2 – 29.4, p=0.002), somatic BRCA1/2 mutations (HR: 7.6, 95% CI: 1.2 – 50.0, p=0.03) and somatic mutations in other HRR genes (HR: 19.1, 95% CI: 3.1 – 118.6, p=0.002) were associated with worse TTF. Conclusions: In the real world, PARPi were well-tolerated with promising time-to-treatment-failure (TTF) benefits comparable to data from clinical trials. Notably, relatively shorter TTF was observed in patients with somatic BRCA1/2 and other HRR gene mutations and HER2-positive MBC. These findings improve our understanding of the role of PARPi in MBC and will help to guide treatment decisions with PARPi in the clinical setting. Citation Format: Nusrat Jahan, Jodi Taraba, Karthik V. Giridhar, Roberto A. Leon-Ferre, Amye J. Tevaarwerk, Elizabeth Cathcart-Rake, Ciara C. O’Sullivan, Prema Peethambaram, Timothy J. Hobday, Kathryn Ruddy, Lida A. Mina, Pooja Advani, Felipe Batalini, Matthew P. Goetz, Tufia C. Haddad, Fergus J. Couch, Siddhartha Yadav. Clinical outcomes of metastatic breast cancer patients treated with poly (adenosine diphosphate-ribose) polymerase inhibitors (PARPi): the Mayo Clinic 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 P4-01-22.

Abstract BACKGROUND: The OncotypeDX assay analyzes the expression of 21 genes, including HER2 and Grb7, to assess the predictive effect of chemotherapy in breast cancer recurrence among women with early-stage estrogen-receptor (ER) positive/HER2-negative breast cancer. In this study, we evaluate the distribution of recurrence score from the OncotypeDX assay based on the HER2 expression status by immunohistochemistry (IHC). METHODOLOGY: Utilizing the National Cancer Database, we identified adult women with a diagnosis of stage I – III ER+/HER2- invasive ductal carcinoma of the breast between the years 2010 and 2018. Recurrence scores were classified into low (&lt; 11), intermediate (11-26), and high risk (&gt;26); and the distribution of these recurrence scores cross-tabulated with different IHC scores of HER2 expression (0, 1+, and 2+) by IHC. Women with an IHC score of 2+ had to be negative for HER2 gene amplification by FISH. Multivariate logistic regression model adjusting for age, race, origin, progesterone receptor status, grade, and cancer stage was used to assess the odds of receiving a high OncotypeDx Score (≥26). RESULT: Among 198,931 women with ER+/HER2 negative breast cancer, 59,632 (30.0%) had HER2 IHC score of 0, 102,170 (51.4%) had IHC score of 1+, and 37,129 (18.6%) women were with IHC score of 2+. The median age at diagnosis of breast cancer among all three categories of HER2 expression was 59 years. The median recurrence score for women with IHC scores of 0,1+, and 2+ was 15, 15, and 16 respectively (p &lt; 0.001). A higher proportion of women with HER2 IHC score of 2+ had a high recurrence score compared to women with an IHC score of 0 (15.2% vs. 13%, p &lt; 0.001). In multivariate analysis, compared to women with HER2 IHC score of 0, women with HER2 IHC score of 2+/FISH negative were observed to have higher Odds (OR: 1.16; 95% CI: 1.11 – 1.20, p &lt; 0.001) of receiving high recurrence score. There was no significant difference in the odds of receiving a high recurrence score between women with IHC 0+ and 1+(OR: 0.99; 95% CI: 0.96 – 1.03, p 0.82). CONCLUSION: Women with a HER2 IHC score of 2+ were observed to have a higher odds of receiving high-risk recurrence scores as compared to women with IHC score of 0. This needs to be further correlated with the response to chemotherapy and the risk of recurrence. Citation Format: Anish Shah, Pravash Budhathoki, Suman Gaire, Utsav Joshi, Siddhartha Yadav. Influence of HER2 expression status in the distribution of recurrence score from the OncotypeDx assay among women with early-stage estrogen-receptor-positive/HER2-negative 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 P6-01-41.

Abstract Background: HER2-positive invasive lobular carcinoma (ILC) of the breast is a rare entity. Treatment decisions for HER2-positive lobular breast cancer are often extrapolated from the HER2-positive ductal subtype of breast cancer but the clinical outcomes and prognostic factors are not well defined. Methodology: Women with a diagnosis of stage I to III HER2-positive ILC or invasive ductal carcinoma (IDC) of the breast between 2010 and 2018 were identified from the National Cancer Database. Baseline characteristics were compared between ILC and IDC using Chi-square test for categorical variables and the Mann-Whitney U test for continuous variables. Five-year overall survival (OS) was estimated by the Kaplan Meir method. Multivariate cox proportional hazards regression model including age, race, ethnicity, Charleston Deyo score, grade, TNM stage, and treatment modalities such as type of surgery, chemotherapy, and radiation was used to identify factors associated with OS in HER2-positive ILC. In a subset of patients receiving neoadjuvant chemotherapy, the odds of achieving a complete pathological response were compared between women with ILC and IDC in a multivariate logistic regression model adjusting for age, race, ethnicity, Charleston Deyo score, grade, and clinical stage. Results: A total of 4,197 women with HER2-positive ILC and 116,984 women with HER2-positive IDC were included in the final analysis. The median age at diagnosis was 63 years for women with HER2-positive ILC and 56 years for women with HER2-positive IDC (p&lt; 0.001). The five-year OS among women with HER2-positive ILC was 93.1%, 90.8%,and 78.8% in TNM stages I, II, and III respectively. In multivariate analysis, a significant difference in difference in overall survival was not observed between women with HER2 positive ILC and IDC (Hazard Ratio [HR]: 1.0, 95% Confidence Interval [CI]: 0.9 - 1.1, p=0.55). Among women receiving neoadjuvant chemotherapy, a complete pathological response was observed in 31.7% of women with HER2-positive ILC and 42.7% of HER2-positive IDC. In multivariate analysis, there was no difference in odds of achieving a complete pathological response to neoadjuvant chemotherapy between HER2-positive ILC and IDC (Odds Ratio [OR]: 0.8, 95%CI: 0.7 - 1.0, p=0.12). Higher odds of complete pathological response in HER2-positive ILC were observed for women with estrogen-receptor negative (OR: 2.0, 95% CI: 1.1- 3.8), p= 0.02) and progesterone-receptor negative (OR 2.4, 95%CI: 1.5- 3.7), p&lt; 0.001) tumors. The five-year OS for women with a complete pathological response, partial response, and no response after neoadjuvant chemotherapy in HER2-positive ILC were 89.6%, 84.9%, and 77.3% respectively (p=0.01). Conclusion: This study demonstrates that HER2-positive ILC has comparable clinical outcomes to HER2-positive IDC and response to neoadjuvant chemotherapy correlates with OS in HER2-positive ILC. These findings lend support to the current practice of treating HER2-positive ILC and IDC in a similar manner. Citation Format: Suman Gaire, Pravash Budhathoki, Utsav Joshi, Anish Shah, Grace M. Choong, Siddhartha Yadav. Clinical outcomes of loco-regional HER2-positive invasive lobular carcinoma of the breast [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 P4-06-04.

Abstract Background: - Low levels of HER2 expression among women with HER2-negative breast cancer is an emerging target. In addition, prior studies have suggested that low levels of HER2 expression might confer resistance to chemotherapy among women with triple-negative breast cancer (TNBC). In this study, we assess the response to neoadjuvant chemotherapy among women with TNBC with varying degrees of HER2 expression. Methodology: - Utilizing the National Cancer Database, we identified adult women treated with neoadjuvant chemotherapy for a diagnosis of clinical TNM stage I to III triple-negative invasive ductal carcinoma of the breast between the years 2010 and 2018. Baseline characteristics were compared between HER2 immunohistochemistry (IHC) scores of 0, 1 +, and 2+ (Women with HER2 2+ expression had to be negative for amplification in the HER2 gene by FISH) using Chi-square for categorical variables. The odds of achieving a complete pathological response were compared among women with different HER2 expression statuses in a multivariate logistic regression model adjusting for age, race, ethnicity, grade of the tumor, and clinical TNM stage at diagnosis. A multivariate cox proportional hazards regression model was used to identify the prognostic effect of HER2 expression on overall survival (OS) adjusting for age at diagnosis, race, ethnicity, grade of tumor, and clinical TNM stage at diagnosis. Results: - A total of 11,038 women with HER2 IHC score of 0, 8,718 women with a score of 1+ and 2,700 women with a score of 2+ were included in the final analysis. The median age at diagnosis was 52 for women with a HER2 IHC score of 0, 53 for women with a HER2 IHC score of 1+ and 54 for women with an IHC score of 2+/FISH negative. The rates of complete pathological response among women with HER2 IHC scores of 0, 1+, and 2+ were 39.5%, 38.1%, and 36.1% respectively. In multivariate analysis, a significant difference in the odds of achieving complete pathological response was not observed for women with HER2 1+ (OR: 1.1, 95% CI: 0.95-1.20, p = 0.3) or HER2 2+ (OR: 0.9, 95% CI: 0.7-1.0, p = 0.1) tumors compared to women with HER2 IHC score of 0. In multivariate Cox regression analysis, women with TNBC with HER2 IHC score 2+ were found to have a better OS (Hazard Ratio [HR]: 0.88, 95% CI: 0.80-0.97, p = 0.01) compared to women with HER2 IHC score of 0 whereas a significant difference in OS was not observed between women with HER2 IHC scores of 0 and 1+ (HR: 0.95, 95% CI: 0.89–1.01, p = 0.1). Conclusion: - This study demonstrates that HER2 expression status does not influence the rates of complete pathological response to neoadjuvant chemotherapy in women with TNBC. However, women with HER2 IHC score of 2+ were found to have a favorable prognosis, which needs to be evaluated further in future studies. Citation Format: Pravash Budhathoki, Anish Shah, Suman Gaire, Utsav Joshi, Siddhartha Yadav. Response to neoadjuvant chemotherapy among women with triple-negative breast cancer by HER2 expression status [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 P4-06-05.

Abstract Background: Circulating tumor DNA (ctDNA) are short DNA sequences shed by tumor cells into the systemic circulation. Studies have shown potential utility of the test to predict relapse or recurrence following treatment in solid tumors, but sensitivity and specificity have varied widely, ranging from 19-100% and 80-100% respectively, in breast cancer specifically. Moreover, literature describing the utility of monitoring dynamic changes in ctDNA trends is limited. We aim to evaluate the correlation between ctDNA test, both single test as well as dynamic trends in value over time, with imaging findings. Methods: We retrospectively analyzed the medical records of all adult patients diagnosed with breast cancer who underwent ctDNA testing at the hematology-oncology clinic at William Beaumont - Royal Oak and Troy Hospitals, Michigan, from August 2017 to June 2022. Patients who had ctDNA testing done but did not have imaging to correlate it with were excluded from the study. We calculated the sensitivity and specificity of a single positive ctDNA test to detect disease progression or residual disease on imaging. In patients with multiple ctDNA tests, we calculated the sensitivity and specificity of dynamic trends in ctDNA values to detect progression, regression, or absence of disease on imaging. Moreover, we calculated the lead time for positive ctDNA results to detect disease progression compared to imaging. Results: Nineteen patients were included in the study, with 34 total ctDNA test results, each utilized as a separate data point to compare with corresponding imaging findings (Table 1). Ten out of the 19 patients had multiple(&gt;=2) ctDNA test results reported, with a total of 15 pairs of ctDNA values and each pair was analyzed separately as up trending (N=7), down trending (N=4), or persistent negative (N=4) to compare with a corresponding pair of imaging findings (Table 2). The median age at diagnosis was 55 years, and 94.7% were female. At diagnosis, majority of patients (68.4%) had either stage III or IV disease. Our primary endpoint, the correlation of single positive ctDNA result with imaging showing either progression or residual disease, showed a sensitivity and specificity of 100% and 93.3%, respectively. Secondarily, serial ctDNA trend analysis in ten patients revealed both sensitivity and specificity of 100% for up-trending ctDNA values to detect progression, down-trending to detect regression, and persistent negative results to detect absence of disease on imaging, respectively. The positive ctDNA results detected disease progression with a median lead time of 44.5 days compared to imaging. Conclusion: Given the high sensitivity and specificity to detect disease progression and regression in breast cancer patients by single ctDNA results and dynamic ctDNA trends in our study, we conclude that this may be a valid way to reliably monitor for changes in disease status before they become evident in imaging studies. Further clinical studies are required to prove the utility of ctDNA to detect changes in disease status and to guide therapeutic interventions in breast cancer. Table 1. Correlation of single ctDNA result with imaging findings. Table 2. Correlation of dynamic trends in ctDNA values with imaging findings. Citation Format: Ujjwal Karki, Bipin Ghimire, Emma Herrman, Siddhartha Yadav, Mohammad Muhsin Chisti. Detection of progression or regression of breast cancer by circulating tumor DNA (ctDNA) [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-05-07.

Abstract Purpose To estimate the risk of contralateral breast cancer (CBC) among women in the general population with germline pathogenic variants (PVs) in ATM, BRCA1, BRCA2, CHEK2, and PALB2. Methods Among 15,104 prospectively followed women within the CARRIERS study treated with ipsilateral surgery for invasive breast cancer, a subset of 14,237 women were identified from population-based studies. The risk of CBC was estimated for PV carriers in each gene compared to women without PVs in a multivariate proportional hazard regression analysis accounting for the competing risk of death and adjusting for patient and tumor characteristics. The primary analyses focused on the overall cohort and on women from the general population. Secondary analyses examined associations by race/ethnicity, age at primary breast cancer diagnosis, menopausal status, and tumor estrogen receptor status. Results Germline BRCA1, BRCA2, and CHEK2 PV carriers with breast cancer were at significantly elevated risk (Hazard ratio ≥ 1.9, p&lt; 0.05) of CBC, whereas only the PALB2 PV carriers with ER-negative breast cancer had elevated risks. In contrast, ATM PV carriers did not have significantly increased CBC risks. African American PV carriers had similarly elevated risks of CBC as non-Hispanic White PV carriers. Among premenopausal women, the 15-year cumulative incidence of CBC was &gt;20% for BRCA1, BRCA2 and CHEK2 PV carriers with breast cancer, and for PALB2 PV carriers with ER-negative breast cancer. The 15-year cumulative incidence of CBC among postmenopausal PV carriers was &lt; 20% for PV carriers in any of the 5 genes. Conclusions Women diagnosed with breast cancer and known to carry germline PVs in BRCA1, BRCA2, CHEK2, or PALB2 are at substantially increased risk of CBC and may benefit from enhanced surveillance and risk-reduction strategies. Citation Format: Siddhartha Yadav, Nicholas J. Boddicker, Jie Na, Eric C. Polley, Chunling Hu, Steven N. Hart, Rohan D. Gnanaolivu, Nicole Larson, Carolyn Dunn, Susan Holtegaard, Huaizhi Huang, Lauren R. Teras, Alpa V. Patel, James V. Lacey Jr., Susan Neuhausen, Leslie Bernstein, Elena Martinez, Christopher Haiman, Fei Chen, Kathryn Ruddy, Janet Olson, Esther John, Allison W. Kurian, Dale P. Sandler, Katie M. O’Brien, Jack A. Taylor, Clarice R. Weinberg, Hoda Anton-Culver, Argyrios Ziogas, Gary R. Zirpoli, David E. Goldgar, Katherine L. Nathanson, Susan Domchek, Julie R. Palmer, Jeffrey Weitzel, Peter Kraft, Fergus J. Couch. Population-based Estimates of contralateral Breast Cancer Risk among Carriers of Germline Pathogenic Variants in ATM, BRCA1, BRCA2, CHEK2, and PALB2 [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 GS4-04.

PURPOSE To estimate the risk of contralateral breast cancer (CBC) among women with germline pathogenic variants (PVs) in ATM, BRCA1, BRCA2, CHEK2, and PALB2. METHODS The study population included 15,104 prospectively followed women within the CARRIERS study treated with ipsilateral surgery for invasive breast cancer. The risk of CBC was estimated for PV carriers in each gene compared with women without PVs in a multivariate proportional hazard regression analysis accounting for the competing risk of death and adjusting for patient and tumor characteristics. The primary analyses focused on the overall cohort and on women from the general population. Secondary analyses examined associations by race/ethnicity, age at primary breast cancer diagnosis, menopausal status, and tumor estrogen receptor (ER) status. RESULTS Germline BRCA1, BRCA2, and CHEK2 PV carriers with breast cancer were at significantly elevated risk (hazard ratio > 1.9) of CBC, whereas only the PALB2 PV carriers with ER-negative breast cancer had elevated risks (hazard ratio, 2.9). By contrast, ATM PV carriers did not have significantly increased CBC risks. African American PV carriers had similarly elevated risks of CBC as non-Hispanic White PV carriers. Among premenopausal women, the 10-year cumulative incidence of CBC was estimated to be 33% for BRCA1, 27% for BRCA2, and 13% for CHEK2 PV carriers with breast cancer and 35% for PALB2 PV carriers with ER-negative breast cancer. The 10-year cumulative incidence of CBC among postmenopausal PV carriers was 12% for BRCA1, 9% for BRCA2, and 4% for CHEK2. CONCLUSION Women diagnosed with breast cancer and known to carry germline PVs in BRCA1, BRCA2, CHEK2, or PALB2 are at substantially increased risk of CBC and may benefit from enhanced surveillance and risk reduction strategies.