Association between homologous recombination deficiency and time to treatment failure to platinum-based chemotherapy for pancreatic cancer by using the C-CAT database.

[BACKGROUND] Since homologous recombination deficiency (HRD) is relatively uncommon in pancreatic cancer (PC), its impact on time-to-treatment failure (TTF) among patients undergoing systemic chemotherapy for unresectable and recurrent PC remains uncertain.

[METHODS] Among patients with unresectable and recurrent PC enrolled in the Center for Cancer Genomics and Advanced Therapeutics (C-CAT) database by July 2023, a total of 1394 patients who underwent first-line chemotherapy with either gemcitabine plus nab-paclitaxel (GnP) or FOLFIRINOX (FFX) and received tissue-based CGP tests after disease progression were included in this study. HRD was defined as the presence of germline or somatic genetic mutations in homologous recombination repair (HRR)-related genes such as ATM, BARD1, BRIP1, BRCA1/2, CHEK2, CDK12, PALB, and RAD51C/D. We investigated the correlation between HRD and TTF among patients treated with GnP and FFX.

[RESULTS] First-line chemotherapy consisted of GnP in 69% of the cases and FFX in 31%. The CGP tests used were NCC OncoPanel and FoundationOne CDx in 26% and 74%, respectively. HRR-related genetic abnormalities were identified in 107 patients (7.6%): BRCA2 (n = 51), ATM (n = 34), BRCA1 (n = 9), PALB2 (n = 9), among others. In the GnP cohort, the median TTF was comparable between the HRD and non-HRD groups (5.3 vs 4.6 months, P = 0.44). Conversely, in the FFX cohort, it was significantly longer in the HRD group compared to the non-HRD group (7.3 vs. 4.7 months, p < 0.01).

[CONCLUSIONS] Our findings suggest that HRR-related genetic abnormalities might be predictive of TTF in platinum-based chemotherapy for PC.