Tolerability and safety of EUS-injected adenovirus-mediated double-suicide gene therapy with chemotherapy in locally advanced pancreatic cancer: a phase 1 trial

Background and Aims: Locally advanced pancreatic cancer (LAPC) is challenging. Here, we aimed to evaluate the tolerability and safety of Ad5-yCD/mutTK(SR39)rep-ADP (Ad5-DS), a replication-competent adenovirus-mediated double-suicide gene therapy in combination with gemcitabine in patients with LAPC. Methods: Patients with newly diagnosed LAPC were enrolled in this single-center, open-label, 3 + 3 dose-escalation phase 1 trial. Ad5-DS was injected into the pancreatic mass with EUS-guided fine needles combined with oral 5-fluorocytosine and valganciclovir, and a standard dose of intravenous gemcitabine. The doses of Ad5-DS in cohorts 1 to 3 were 1 × 10¹¹, 3 × 10¹¹, and 1 × 10¹² viral particles (vp)/mL, respectively. Patients were observed for dose-limiting toxicity (DLT) for 8 weeks after Ad5-DS injection. Toxicity within 12 weeks, tumor response in 12 weeks, disease progression in 6.5 months, and detection of adenoviral DNA particles in 8 weeks were also assessed. Results: Among the 11 enrolled patients, 9 completed the evaluation period and 2 withdrew their consent. No DLT was reported; thus, the maximum tolerated dose was not reached. No additional toxicity was reported in 9 to 12 weeks. One patient showed a partial response and 8 showed stable disease at 12 weeks. Two patients showed disease progression at 6.5 months (median progression-free survival, 11.4 months). At 8 weeks, serum adenoviral DNA particles were detected in 4 patients (median, 55 days). Conclusion: A combination of intratumoral Ad5-DS and gemcitabine is safe and well tolerated in patients with LAPC. This warrants further investigation in a larger clinical trial. (Clinical trial registration number: NCT02894944.)