Carly Schwartz

Pancreatic cancer (PC) is broadly resistant to immune checkpoint blockade, although a subset of homologous recombination-deficient (HRD) tumors exhibits durable immune engagement. The genomic features that distinguish these immune-responsive tumors from immune-inert HRD tumors remain poorly understood. Here we identify a microhomology-mediated end joining (MMEJ) repair scar, the MMEJ Deletion Footprint (MDF), as a genomic readout of POLQ-associated error-prone repair that enriches for frameshift indels. Across the multi-omic discovery cohort integrating tumor genomics, single-nucleus transcriptomics and spatial immune profiling, MDF-high HRD PC exhibited increased frameshift-indel-derived neoantigens and interferon programs. MDF was further associated with remodeling of the myeloid compartment toward MHC II-high dendritic cell-like antigen-presenting macrophage states and the immune synapse architecture marked by increased spatial interaction between APC-like macrophages and cytotoxic CD8 ⁺ T cells. These tissue-level features aligned with a functional trajectory shift of CD8 ⁺ T cells, consistent with effective anti-tumor immunity and was associated with favorable clinical outcomes of patients. Together, our findings position MMEJ-linked repair scarring as actionable biology that connects an HRD genotype to immune organization and suggests rational immunotherapy combinations that may enhance antigen presentation and myeloid activation to extend durable benefit in HRD-lineage cancers.

Supplementary Figure S1 from A Phase II Trial of an Extended-Release siRNA Implant Targeting KRASG12D/V in Locally Advanced Pancreatic Cancer

Study Representativeness Table

Purpose: Locally advanced pancreatic cancer (LAPC) accounts for 30% of pancreatic cancers. We assessed the efficacy and safety of a novel extended-release siRNA targeting KRASG12D/V mutations (siG12D-LODER) combined with chemotherapy in LAPC. Patients and Methods: This two-cohort, phase II multicenter, open-label study (NCT01676259) evaluated siG12D-LODER with chemotherapy in patients with LAPC, regardless of KRAS status. In cohort 1, patients were randomized to siG12D-LODER plus gemcitabine/nab-paclitaxel (arm 1) or gemcitabine/nab-paclitaxel alone (arm 2). In cohort 2, patients with LAPC or borderline resectable disease received siG12D-LODER plus standard chemotherapy (modified FOLFIRINOX or gemcitabine/nab-paclitaxel) in a single-arm, nonrandomized design. Primary endpoints were overall survival (OS) for cohort 1 and objective response rate (ORR) for cohort 2. Secondary endpoints included progression-free survival, duration of response, OS (cohort 2), and ORR (cohort 1). Results: Across two cohorts, 59 patients were enrolled. In cohort 1, the median OS in the modified intent-to-treat (mITT) population unselected for KRAS status was 22.7 months for siG12D-LODER + gemcitabine/nab-paclitaxel versus 21.9 months for chemotherapy alone (P > 0.05). Among patients with KRASG12D/V mutations, OS was 22.7 versus 13.5 months [HR, 0.59; 95% confidence interval (CI), 0.18–1.96; P = 0.39]. In cohort 2, ORR was 31.6% (95% CI, 0.13–0.57) in the mITT (unselected for KRAS); in the G12D/V subgroup, ORR was 57.1%, similar to 63.6% in cohort 1. Treatment-emergent adverse events were mainly procedure related, including grade 1/2 gastrointestinal events and higher infection rates in the intervention arm. Conclusions: siG12D-LODER plus chemotherapy is safe, tolerable, and warrants further investigation in KRASG12D/V-mutant LAPC.