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Background Cancer patients are at risk of secondary therapy–related myeloid neoplasms (t-MNs). Acquired blood-specific mutations in clonal hematopoiesis (CH)–associated genes are t-MN risk factors, and their occurrence associated with cancer therapy and age. Patients with ovarian cancer (OC) showed a particularly high prevalence of CH–associated gene mutations, which may additionally be explained by the high proportion of a hereditary disease cause in this cancer entity. Methods We performed a retrospective analysis of 448 OC patients enrolled in the AGO-TR1 study; 249 were enrolled at primary diagnosis and 199 at platinum-sensitive recurrence. Analyses included the most frequently altered CH–associated genes (ASXL1, DNMT3A, GNAS, JAK2, PPM1D, SF3B1, SH2B3, SRSF2, TET2, TP53). Results were analyzed according to the BRCA1/2 germline (gBRCA1/2) mutation status. All statistical tests were 2-sided. Results Advanced age at blood draw and a high number of prior platinum-based chemotherapy lines were risk factors to acquire CH–associated gene mutations, with gene-specific effects observed. Binomial logistic regression suggested increased probabilities for gBRCA1/2 mutation carriers to acquire CH-associated PPM1D and TP53 gene mutations (PPM1D: odds ratio = 4.30, 95% confidence interval = 1.48 to 12.46, P = .007; TP53: odds ratio = 6.20, 95% confidence interval = 0.98 to 53.9, P = .06). This observation was due to a statistically significantly increased number of platinum-based chemotherapy lines in gBRCA1/2 mutation carriers vs noncarriers (PPM1D: mean [SD] = 2.04 [1.27] vs 1.04 [0.99], P Conclusions A positive gBRCA1/2 mutation status is not a risk factor to acquire CH–associated gene mutations. OC patients may benefit from monitoring CH–associated gene mutations, especially following carboplatin exposure. Future clinical studies are required to assess whether treatment regimen should be adapted according to individual t-MN risks.

IMPORTANCE: The GeparOcto randomized clinical trial compared the efficacy of 2 neoadjuvant breast cancer (BC) treatment regimens: sequential intense dose-dense epirubicin, paclitaxel, and cyclophosphamide (iddEPC) vs weekly paclitaxel and nonpegylated liposomal doxorubicin (PM) in patients with different biological BC subtypes. Patients with triple-negative BC (TNBC) randomized to the PM arm received additional carboplatin (PMCb). Overall, no difference in pathologic complete response (pCR) rates was observed between study arms. It remained elusive whether the germline variant status of BRCA1/2 and further BC predisposition genes are associated with treatment outcome. OBJECTIVE: To determine treatment outcome for BC according to germline variant status. DESIGN, SETTING, AND PARTICIPANTS: This retrospective biomarker study is a secondary analysis of the GeparOcto multicenter prospective randomized clinical trial conducted between December 2014 and June 2016. Genetic analyses assessing for variants in BRCA1/2 and 16 other BC predisposition genes in 914 of 945 women were performed at the Center for Familial Breast and Ovarian Cancer, Cologne, Germany, from August 2017 through December 2018. MAIN OUTCOMES AND MEASURES: Proportion of patients who achieved pCR (ypT0/is ypN0 definition) after neoadjuvant treatment according to germline variant status. RESULTS: In the study sample of 914 women with different BC subtypes with a mean (range) age at BC diagnosis of 48 (21-76) years, overall higher pCR rates were observed in patients with BRCA1/2 variants than in patients without (60.4% vs 46.7%; odds ratio [OR], 1.74; 95% CI, 1.13-2.68; P = .01); variants in non-BRCA1/2 BC predisposition genes were not associated with therapy response. Patients with TNBC with BRCA1/2 variants achieved highest pCR rates. In the TNBC subgroup, a positive BRCA1/2 variant status was associated with therapy response in both the PMCb arm (74.3% vs 47.0% without BRCA1/2 variant; OR, 3.26; 95% CI, 1.44-7.39; P = .005) and the iddEPC arm (64.7% vs 45.0%; OR, 2.24; 95% CI, 1.04-4.84; P = .04). A positive BRCA1/2 variant status was also associated with elevated pCR rates in patients with ERBB2-negative, hormone receptor–positive BC (31.8% vs 11.9%; OR, 3.44; 95% CI, 1.22-9.72; P = .02). CONCLUSIONS AND RELEVANCE: Effective chemotherapy for BRCA1/2-mutated TNBC is commonly suggested to be platinum based. With a pCR rate of 64.7%, iddEPC may also be effective in these patients, though further prospective studies are needed. The elevated pCR rate in BRCA1/2-mutated ERBB2-negative, hormone receptor–positive BC suggests that germline BRCA1/2 testing should be considered prior to treatment start. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02125344

579 Background: The phase II trial WSG-ADAPT TN randomized triple-negative breast cancer (TNBC) patients to receive 12 weeks of neoadjuvant nab-paclitaxel (nab-pac) combined with carboplatin (carbo) vs gemcitabine (gem) and showed a substantial improvement of pathological complete response (pCR: ypT0/is, ypN0) with carbo (45.9% vs 28.7%). pCR had a strong favorable impact on iDFS after 3-year follow-up. Distribution of tumor mutations in BC-associated genes and impact of BRCA mutation status on pCR and outcome are analyzed here. Methods: NGS-based mutational analysis of BRCA1/2 and 18 further (potentially) BC-associated genes was performed on DNA derived from pretreatment FFPE samples (gem: n = 158, carbo: n = 108) using a customized gene panel. Variants with a variant fraction of ≥5% were included and classified according to IARC and ENIGMA guidelines. Results: In 42 of the 266 analyzed samples, at least one deleterious BRCA1/2-variant was found (15.8%; BRCA1 n = 37, BRCA2 n = 3, BRCA1+ BRCA2 n = 2) one of which displayed an additional STK11-mutation. In the BRCA1/2-negative cohort, a mutation in one of 14 further analyzed (potential) BC-risk genes was found in 19 samples (7.1%; BARD1 n = 3, CHEK2 n = 2, CDH1 n = 2, FANCM n = 3, PALB2 n = 5, RAD50 n = 1, RAD51C n = 1, RAD51D n = 1, XRCC2 n = 1; no deleterious mutations were found in ATM, BRIP1, MRE11A, NBN). At least one deleterious variant in TP53, PIK3CA, PTEN or MAP3K1 was seen in 89.1% (n = 237; TP53 n = 233, PIK3CA n = 22 PTEN n = 15, MAP3K1 n = 1). In 22 samples (8.3%) no deleterious mutation was identified in the analyzed genes. Overall, patients with tumor BRCA mutation (carbo n = 14, gem n = 28) had 45.2% vs 34.4% pCR (OR = 1.58, 95%-CI: 0.81-3.07, p =.18) without a mutation. pCR in the small group with mutation receiving carbo (n = 14) was 64.3% vs. 34.5% in all others (OR = 3.41, 95%-CI: 1.11-10.50; p =.03); direct comparison to BRCA-positive patients receiving gem (n = 28, 35.7%, OR = 3.2, 95%-CI: 0.85-12.36, p = 0.079) did not reach statistical significance. The results suggest that the strong favorable impact of pCR on iDFS is preserved even among BRCA-positive patients (n = 42, p =.07), as well as in the BRCA-negative subgroup (p

The prevalence of germ line mutations in non-BRCA1/2 genes associated with hereditary breast cancer (BC) is low, and the role of some of these genes in BC predisposition and pathogenesis is conflicting. In this study, 5589 consecutive BC index patients negative for pathogenic BRCA1/2 mutations and 2189 female controls were screened for germ line mutations in eight cancer predisposition genes (ATM, CDH1, CHEK2, NBN, PALB2, RAD51C, RAD51D, and TP53). All patients met the inclusion criteria of the German Consortium for Hereditary Breast and Ovarian Cancer for germ line testing. The highest mutation prevalence was observed in the CHEK2 gene (2.5%), followed by ATM (1.5%) and PALB2 (1.2%). The mutation prevalence in each of the remaining genes was 0.3% or lower. Using Exome Aggregation Consortium control data, we confirm significant associations of heterozygous germ line mutations with BC for ATM (OR: 3.63, 95% CI: 2.67-4.94), CDH1 (OR: 17.04, 95% CI: 3.54-82), CHEK2 (OR: 2.93, 95% CI: 2.29-3.75), PALB2 (OR: 9.53, 95% CI: 6.25-14.51), and TP53 (OR: 7.30, 95% CI: 1.22-43.68). NBN germ line mutations were not significantly associated with BC risk (OR: 1.39, 95% CI: 0.73-2.64). Due to their low mutation prevalence, the RAD51C and RAD51D genes require further investigation. Compared with control datasets, predicted damaging rare missense variants were significantly more prevalent in CHEK2 and TP53 in BC index patients. Compared with the overall sample, only TP53 mutation carriers show a significantly younger age at first BC diagnosis. We demonstrate a significant association of deleterious variants in the CHEK2, PALB2, and TP53 genes with bilateral BC. Both, ATM and CHEK2, were negatively associated with triple-negative breast cancer (TNBC) and estrogen receptor (ER)-negative tumor phenotypes. A particularly high CHEK2 mutation prevalence (5.2%) was observed in patients with human epidermal growth factor receptor 2 (HER2)-positive tumors.

573 Background: GeparOcto compared the efficacy of two neoadjuvant treatment (NAT) regimens in high-risk early breast cancer (BC): Sequential intense dose-dense epirubicin, paclitaxel, and cyclophosphamide (iddEPC) and weekly paclitaxel plus non-pegylated liposomal doxorubicin (PM), plus carboplatin (PMCb) in triple-negative BC (TNBC). There was no difference in pathologic complete response (pCR) rates (Schneeweiss et al. Eur J Cancer 2019). Here, we stratified pCR rates according to germline mutation status. Methods: Germline (g) mutation analysis of BRCA1/2 and 16 further BC predisposition genes in 914 patients (pts) enrolled (393 pts with TNBC, iddEPC n = 194, PMCb n = 199; 156 pts with HER2-/HR+ BC, iddEPC n = 75, PM n = 81; and 365 pts with HER2+ BC, iddEPC n = 182, PM n = 183). Results: The gBRCA1/2 mutation prevalence was 17.6% in TNBC, 14.1% in HER2-/HR+ BC and 1.4% in HER2+ BC. Overall, pts with gBRCA1/2 mutations achieved higher pCR rates than gBRCA1/2 wildtype pts (60.4% vs 46.7%, OR 1.74, P = 0.012), with more pronounced effects in the PM(Cb) arm (68.1% vs 45.7%, OR 2.53, P = 0.005). Among gBRCA1/2 wildtype pts, 76 carried mutations in non- BRCA1/2 predisposition genes. pCR rates were similar to those observed in pts without any mutation. Conclusions: Pts with gBRCA1/2 mutations benefitted most from NAT with highest pCR rates achieved in the gBRCA1/2 TNBC / PMCb group. The role of Cb for NAT of gBRCA1/2 TNBC should be further explored. Clinical trial information: NCT02125344. [Table: see text]

RAD51C is an integral part of the DNA double-strand repair through homologous recombination, and monoallelic mutations were found in ~1.3% of BRCA1/2-negative breast cancer (BC) and/or ovarian cancer (OC) families. Several studies confirmed the occurrence of RAD51C mutations predominantly in BC and/or OC families, although with varying frequencies, clearly establishing RAD51C as a cancer-predisposing gene. There is ongoing debate whether pathogenic RAD51C alterations increase the relative risk for BC in addition to that for OC, which was estimated to be 5.88 (95% confidence interval = 2.91 to 11.88; P = 7.65 × 10(-7)).