The phase 2 POLAR trial investigated maintenance treatment with pembrolizumab and olaparib in 63 patients with metastatic pancreatic cancer who had achieved disease control after platinum-based chemotherapy.[1] Patients were divided into three groups: group A (33 patients with BRCA1/2 or PALB2 HRD mutations), group B (15 patients with other HRD mutations), and group C (15 platinum-sensitive patients without HRD mutations).[1] In group A, the objective tumor response was 35% (95% CI: 15-59%) and the progression-free rate at 6 months was 64% (95% CI: 49-82%), which did not meet the primary study objectives.[1] Median progression-free survival was 8.3 months (95% CI: 5.3-not reached) in group A, 4.8 months (95% CI: 4-12) in group B, and 3.3 months (95% CI: 1.9-4.8) in group C.[1] In the 17 surviving patients, the median follow-up was 26.0 months (range 1.4-52.5) and the overall survival rate at 2 years was 56% (95% CI: 41-76).[1] Preclinical analyzes showed that a molecular response in circulating cell-free DNA, a high density of tumor-infiltrating lymphocytes, and a higher number of frame incisions and neoantigens were associated with sustained benefit, especially in HRD tumors.[1] The results support precision immunotherapy in selected subgroups of patients with pancreatic cancer.[1]