Angiogenesis, the formation of new blood vessel from existing vessels, is essential for tumor growth and metastasis. Antiangiogenic therapies inhibit the growth of genetically stable endothelial cells, and most tumors should starve to death with little acquired resistance. Endostatin has been shown to block endothelial cell proliferation, survival, and migration. Antitumor activity of endostatin protein has been demonstrated in various murine and human tumors in animal model studies without any detectable toxicity. Endostatin gene therapy could directly express the highly bioactive protein in vivo by means of the mechanism of eukaryotic expression system as post-translational modification and folding, as well as overcoming the challenge of the long-term storage and the cumbersome daily administration of endostatin protein.

E10A is a replication-deficient recombinant adenovirus containing a wild-type human endostatin transgene constructed from serotype 5 adenovirus (Ad5). Preclinical studies demonstrated that intratumoral injection of E10A provided significant tumor growth inhibition and sustained elevation of endostatin in blood and tumor tissue in hepatocellular carcinoma, nasopharyngeal carcinoma, and tongue cancer animal models. A Phase I clinical trial of E10A we conducted showed that repetitive intratumoral injection of E10A resulted in a small and sustained elevation of endostatin in blood and had a mild antitumor activities with very limited toxicity. The major toxicity was transient and manageable fever. A randomized Phase III trial in nonsmall-cell lung cancer showed endostatin improved response rate and time to tumor progression in combination to chemotherapy. Therefore, we designed a randomized phase II trial to explore the safety and effectiveness of E10A combined with chemotherapy in the treatment of patients with head and neck cancer.