To investigate the therapeutic potential of an interleukin-21-expressing recombinant oncolytic influenza virus (rOV-IL-21) in pancreatic cancer.

Viral replication, IL-21 expression, and cytotoxicity of rOV-IL-21 in pancreatic cancer cells were evaluated by hemagglutination assay and CCK-8 assay. A subcutaneous pancreatic cancer model was established in C57BL/6 mice, and tumor growth was monitored. Flow cytometry was used to assess intratumoral immune activation. In vivo safety was evaluated by monitoring body weight, serum ALT/AST levels, and histopathological changes in major organs. ANOVA analysis was used for comparisons among multiple groups, and Tukey multiple comparison test was used for pairwise comparisons between groups. Two-factor repeated measures analysis of variance (ANOVA) was used for comparisons involving time and treatment doses.

rOV-IL-21 can stably replicate and efficiently express IL-21 in pancreatic cancer cells, exhibiting a pronounced dose-dependent cytotoxic effect. In the syngeneic subcutaneous tumor model established with KPC pancreatic cancer cells, rOV-IL-21 significantly inhibited tumor growth (P < 0.001) and prolonged the survival of mice (P = 0.001 8) . Flow cytometric analysis of tumor-infiltrating immune cells showed that rOV-IL-21 enhanced the cytotoxic function of CD8⁺ T cells, with significantly increased proportions of GzmB⁺ CD8⁺ T cells [ (19.23 ± 1.46) % vs (7.53 ± 2.28) %, P < 0.05] and reduced proportions of exhausted CD8⁺ T cells [ (3.47 ± 0.52) % vs (14.54 ± 5.91) %, P < 0.05]when compared with control groups. There were no significant differences in serum ALT or AST levels between the rOV-IL-21 and control groups (P > 0.05) .

rOV-IL-21 demonstrates favorable safety and potent antitumor efficacy in pancreatic cancer models, which is associated with enhanced cytotoxic function of intratumoral CD8⁺ T cells. These findings support rOV-IL-21 as a promising oncolytic virus-based immunotherapeutic strategy for pancreatic cancer.