Western Regional Blog – BC, YK, AB, NWT and Nunavut
“The presence of germline and somatic HR mutations was highly predictive of primary platinum sensitivity (p=0.0002) and improved overall survival (p=0.0006)…”
Kathryn P. Pennington, Tom Walsh, Maria I. Harrell, Ming K. Lee, Christopher Pennil, Mara Rendi, Anne Thornton, Barbara M. Norquist, Silvia Casadei, Alexander Nord, Kathy J. Agnew, Colin C. Pritchard, Sheena Scroggins, Rochelle L. Garcia, Mary-Claire King, and Elizabeth M. Swisher
Purpose: Hallmarks of germline BRCA1/2-associated ovarian carcinomas include chemosensitivity and improved survival. The therapeutic impact of somatic BRCA1/2 mutations and mutations in other homologous recombination (HR) DNA repair genes is uncertain.
Experimental Design: Using targeted capture and massively parallel genomic sequencing, we assessed 390 ovarian carcinomas for germline and somatic loss-of-function mutations in 30 genes, including BRCA1, BRCA2, and 11 other genes in the HR pathway.
Results: 31% of ovarian carcinomas had a deleterious germline (24%) and/or somatic (9%)mutation in one or more of the 13 HR genes: BRCA1, BRCA2, ATM, BARD1, BRIP1, CHEK1, CHEK2, FAM175A, MRE11A, NBN, PALB2, RAD51C, and RAD51D. Non-serous ovarian carcinomas had similar rates of HR mutations to serous carcinomas (28% vs. 31%, p=0.6), including clear cell, endometrioid, and carcinosarcoma. The presence of germline and somatic HR mutations was highly predictive of primary platinum sensitivity (p=0.0002) and improved overall survival (p=0.0006), with median overall survival 66 months in germline HR mutation carriers, 59 months in cases with a somatic HR mutation, and 41 months for cases without an HR mutation.
Conclusions: Germline or somatic mutations in HR genes are present in almost one-third of ovarian carcinomas, including both serous and non-serous histologies.
Somatic BRCA1/2 mutations and mutations in other HR genes have a similar positive impact on overall survival and platinum responsiveness as germline BRCA1/2 mutations. The similar rate of HR mutations in non-serous carcinomas supports their inclusion in PARP inhibitor clinical trials.