DNA Repair Gene Associated with Clinical Outcome of Epithelial Ovarian Cancer Treated with Platinum-based Chemotherapy

10 Background: DNA repair gene mutations are important molecular alterations in prostate cancer pathogenesis. Germline mutations in DNA repair genes, particularly BRCA2, were recently recognized as associated with metastatic prostate cancer and may also be particularly sensitive to platinum based chemotherapy and PARP inhibitor therapy. We sought to characterize alterations in DNA repair pathway genes in both primary and metastatic prostate tumors. Methods: We studied the distribution of DNA repair gene mutations in 936 prostate cancers harvested from localized and metastatic tumors. Tumor DNA underwent hybrid capture for all coding exons of 395 cancer-related genes plus select introns from 19 or 31 genes frequently rearranged in cancer and sequenced to a median exon coverage depth of >500x using Illumina sequencing and were analyzed for base substitutions/insertions, copy number alterations and rearrangements. We utilized two described lists of genes involved in DNA repair : our own in-house list of 74 (UCD) and a list of 20 DNA repair genes associated with cancer predisposition syndromes utilized in a recent publication by Pritchard et al. We further stratified the frequency of mutations by tissue site (prostate versus metastases). Results: We identified 228/936 unique samples with at least one likely functional mutation in a DNA repair gene (24.4%). Mutations were identified in 20.1% of prostate tumors (13% UCD, 18.4% Pritchard et al.) and in 18.8% of bone metastases. The highest rates of DNA repair mutations were found in visceral metastases including brain, pelvis and liver, higher than either prostate tissue or bone sites (p=<0.01). The most commonly (≥1% of samples) mutated genes in the DNA repair pathways are: BRCA2 (11.43%), ATM (5.77%), MSH6 (2.46%), MSH2 (2.14%), ATR (1.60%), MLH1 (1.28%), and BRCA1(1.18%). Conclusions: DNA repair gene mutations are more common in metastatic than localized prostate tumors. Visceral metastases appear enriched for these mutations compared with localized tumors or bone metastases. Genomic profiling may identify prostate cancers potentially sensitive to platinum-based chemotherapy or PARP inhibition.

Download Full-text

TRITON2: An international, multicenter, open-label, phase II study of the PARP inhibitor rucaparib in patients with metastatic castration-resistant prostate cancer (mCRPC) associated with homologous recombination deficiency (HRD).

Journal of Clinical Oncology ◽

10.1200/jco.2018.36.6_suppl.tps388 ◽

2018 ◽

Vol 36 (6_suppl) ◽

pp. TPS388-TPS388 ◽

Cited By ~ 7

Author(s):

Wassim Abida ◽

Alan Haruo Bryce ◽

Arjun Vasant Balar ◽

Gurkamal S. Chatta ◽

Nancy Ann Dawson ◽

...

Keyword(s):

Prostate Cancer ◽

Dna Repair ◽

Homologous Recombination ◽

Objective Response ◽

Specific Antigen ◽

Nodal Disease ◽

Repair Gene ◽

Dna Repair Gene ◽

Platinum Based Chemotherapy ◽

Brca1 Brca2

TPS388 Background: Up to 25% of patients with advanced prostate cancer, including mCRPC, have a deleterious germline or somatic mutation in BRCA1, BRCA2, ATM or another homologous recombination (HR) DNA repair gene that can serve as a molecular marker to select those who may respond to poly(ADP-ribose) polymerase inhibitors (PARPis). PARPis are lethal to cells with HRD, and PARPi treatment has shown preliminary evidence of an antitumor effect in patients with mCRPC who harbor a mutation in an HR DNA repair gene (Mateo et al. N Engl J Med. 2015;373:1697-708). These data provide a compelling rationale for evaluating rucaparib, a potent PARP1, PARP2 and PARP3 inhibitor, in patients with mCRPC associated with HRD. Methods: TRITON2 (NCT02952534) is a phase 2 study evaluating rucaparib 600 mg BID in patients with mCRPC. Patients with a deleterious germline or somatic BRCA1, BRCA2 or ATM mutation (per prior local test or central test during screening) will be enrolled into 1 of 2 cohorts based on the presence or absence of measurable visceral and/or nodal disease. An exploratory cohort will enroll patients with an alteration in any of 12 other prespecified HR genes (eg, RAD51C, RAD51D and PALB2), with or without measurable visceral and/or nodal disease. Patients must have progressed on androgen receptor signaling–directed therapy and 1 prior taxane-based chemotherapy for mCRPC. Patients who received prior treatment with a PARPi, mitoxantrone, cyclophosphamide or platinum-based chemotherapy are excluded. The primary endpoint is objective response rate measured using modified RECIST v1.1/PCWG3 for patients with soft-tissue disease and prostate-specific antigen response for patients with nonmeasurable disease. Secondary endpoints include duration of response, radiographic progression-free survival, overall survival, clinical benefit rate and safety. Pretreatment blood samples collected from all patients will enable development of a plasma-based companion diagnostic to select patients who may benefit from rucaparib treatment. Patients (≈160) will be enrolled at > 100 sites worldwide. Clinical trial information: NCT02952534.

Download Full-text