PARP Inhibitors in Pancreatic Cancer with Homologous Recombination Repair Gene Mutations: A Single-Institution Experience.

Background: Limited data are available regarding the anticancer activity of PARP inhibitors (PARPis) in pancreatic cancer with mutations in HRR genes other than BRCA and PALB2 .
Methods: We retrospectively reviewed the clinical characteristics and outcomes of 48 patients with advanced pancreatic cancer harboring pathogenic germline and/or somatic HRR mutations who were treated with PARPis.
Results: Thirty patients had germline (g)HRR mutations only, twelve had somatic (s)HRR mutations only, and six had concomitant gHRR and sHRR mutations. The objective response rate (ORR) was 22%. The median progression-free survival (mPFS) and overall survival (mOS) were 6.9 and 11.5 months, respectively. Five patients received olaparib in the front-line setting due to borderline performance status. Their ORR was 20%, and their mPFS and mOS were both 11.3 months. The ORR was higher in patients with BRCA or PALB2 mutations (germline or somatic) than in those with non- BRCA / PALB2 mutations. Patients with somatic non- BRCA / PALB2 variants had a shorter mPFS. Patients with concomitant gHRR/sHRR mutations or gHRR mutations alone had a significantly longer mPFS than those with sHRR mutations only.
Conclusions: PARP inhibitors may be considered for patients with advanced pancreatic cancer harboring pathogenic alterations of BRCA who cannot tolerate standard chemotherapy. Maintenance PARPis can be considered in selected patients with non- BRCA /non- PALB2 HRR mutations.