KRAS mutational landscape and immune microenvironment features in pancreatic cancer: Implications for targeted and combination therapeutic strategies.

e16406 Background: The poor prognosis of pancreatic cancer and its high prevalence of KRAS mutations have made KRAS alterations a major focus of clinical research. Although KRAS-targeted inhibitors approved in other solid tumors, such as sotorasib and the combination of avutometinib plus defactinib, have shown clinical activity in pancreatic cancer, durable benefit remains limited. Combination strategies may therefore provide additional therapeutic opportunities. This study aimed to characterize KRAS mutational features and the immune microenvironment in a real-world pancreatic cancer cohort to inform the development of KRAS-targeted and combination treatment approaches. Methods: Next-generation sequencing (NGS) was performed in 93 pancreatic cancer patients to characterize genomic alterations. All samples underwent multiplex immunofluorescence (mIHC) to evaluate the tumor immune microenvironment. Ten immune markers were quantified with APTime Pathology Analysis Software, including T cells, B cells, macrophages, NK cells, and tertiary lymphoid structures. Results: KRAS alterations were identified in 79.6% (74/93) of patients, including 69 single-nucleotide variants and 5 copy number amplifications. The most frequent mutation subtype was G12D (55.3%), and 94.7% of KRAS variants were located in exon 2, consistent with canonical activating mutations. Only three patients harbored KRAS variants of unknown clinical significance, two of whom also carried common KRAS hotspot mutations. The most frequent co-altered genes in KRAS-mutant tumors were TP53 (9.7%) and CDKN2A (5.9%), both of which have been associated with immune-related features in prior studies. All tumors were microsatellite stable. No significant differences were observed between KRAS-mutant and wildtype tumors in tumor mutational burden (median: 4.2 vs 3.4 mut/Mb, P = 0.6) or HRD score (median: 13 vs 5, P = 0.2). However, immune microenvironment analysis revealed that KRAS-mutant tumors had significantly higher levels of M1 macrophages in the tumor stroma ( P = 0.006), PD-L1⁺CD68⁺ cells in the stroma ( P = 0.03), and PD-L1⁺CD68⁺ cells in the tumor compartment ( P = 0.02) compared with KRAS-wildtype tumors. Overall, KRAS-mutant tumors exhibited a more immune-active microenvironment. Conclusions: KRAS mutations are highly prevalent in pancreatic cancer and are predominantly canonical pathogenic variants, supporting strong potential for targeted therapeutic intervention. Although KRAS-mutant tumors did not demonstrate advantages in TMB or MSI, they exhibited enriched M1 macrophage and PD-L1⁺CD68⁺ immune populations, suggesting a more favorable immune microenvironment. These findings support the rationale for exploring KRAS-targeted therapies in combination with immunomodulatory strategies in pancreatic cancer.