Phase I Trial of Intratumoral Injection of an Adenovirus Encoding Interleukin-12 for Advanced Digestive Tumors

Abstract

Purpose To evaluate the feasibility and safety of intratumoral injection of an adenoviral vector encoding human interleukin-12 genes (Ad.IL-12) and secondarily, its biologic effect for the treatment of advanced digestive tumors. Patients and Methods Ad.IL-12 was administered in doses ranging from 2.5 × 1010 to 3 × 1012 viral particles, to seven cohorts of patients with advanced pancreatic, colorectal, or primary liver malignancies. Patients were thoroughly assessed for toxicity, and antitumor response was evaluated by imaging techniques, tumor biopsy, and hypersensitivity skin tests. Patients with stable disease and no serious adverse reactions were allowed to receive up to 3 monthly doses of Ad.IL-12. Results Twenty-one patients (nine with primary liver, five with colorectal, and seven with pancreatic cancers) received a total of 44 injections. Ad.IL-12 was well tolerated, and dose-limiting toxicity was not reached. Frequent but transient adverse reactions, including fever, malaise, sweating, and lymphopenia, seemed to be related to vector injection rather than to transgene expression. No cumulative toxicity was observed. In four of 10 assessable patients, a significant increase in tumor infiltration by effector immune cells was apparent. A partial objective remission of the injected tumor mass was observed in a patient with hepatocellular carcinoma. Stable disease was observed in 29% of patients, mainly those with primary liver cancer. Conclusion Intratumoral injection of up to 3 × 1012 viral particles of Ad.IL-12 to patients with advanced digestive malignancies is a feasible and well-tolerated procedure that exerts only mild antitumor effects.