BRCA1/2 germline mutations and response to PARP inhibitor treatment in lung cancer.

Abstract

e13007 Background: Germline mutations in BRCA1/2 (BReast CAncer genes 1 and 2), which are targets for PARP inhibitors in breast and ovarian cancer, have been previously identified in patients with non-small cell lung cancer (NSCLC). However, its prevalence and clinical outcomes to targeted therapy in NSCLC still remains unknown. Methods: We conducted a retrospective review of 9,324 Chinese NSCLC patients who underwent targeted next-generation sequencing (NGS) during 2015/11/01 and 2018/10/31. Patients with BRCA1/2 somatic and germline mutations were identified. We summarized their prevalence and explored their co-existing driver mutations. Then we initially reviewed the response to PARP-inhibitor targeted therapy in patient with BRCA2 germline mutation. Results: 459 (4.9%) patients are BRCA1/2 positive (germline/somatic mutation). Most patients are diagnosed with LUAD (372, 81.1%), with a median age of 63 years (range: 2-101). Slightly more male patients were carrying BRCA1/2 mutations (59.9%, 275 out of 459). The prevalence of BRCA1 and BRCA2 somatic mutations was similar (145, 1.56% vs. 169, 1.81%, p = 0.19). BRCA2 germline mutation was more common in lung cancer than BRCA1 germline mutation (148, 1.59% vs. 20, 0.21%, p < 0.0001). When specified to the common driver gene mutation subgroups, the prevalence of BRCA2 germline mutation is similar to the entire population (EGFR 1.79%; ALK 1.74%; KRAS 2.05%; BRAF 2.86%; ERBB2 0.93%; p > 0.05). K2729N is the most common BRCA2 germline mutation (41, 27.7%), followed by C315S (26, 17.6%), V2109I (12, 8.1%), R2108C (11, 7.4%), I2490T (10, 6.8%), T582P (5, 3.4%). About 20% patients with BRCA2 germline mutation carried at least one concomitant mutations of DNA repair genes, including MLH1, MLH3, MSH6, CHEK2, BARD1, BLM, BRCA1, MUTYH, RAD50, RECQL4 and XRCC1. One 56-year-old male LUAS patient, with germline BRCA2 rs80359490 frameshift deletion mutation (p.S1722Yfs*4), received the targeted therapy with PARP inhibitor Olaparib after multi lines therapies. This patient showed a great PR response to Olaparib, with a PFS of at least 6 months. Conclusions: BRCA1/2 germline mutations were rare in Chinese NSCLC patients. Patients with BRCA2 germline mutations might benefit from PARP-inhibitor treatment.