Clinical trial design for adenoviral gene therapy products

Two adenoviral gene therapy products have now been approved for clinical use in China, and elsewhere at least four products are in phase III clinical trials. The adenovirus vector is the most commonly used vector for clinical gene therapy due to its high rate of gene transfer in vivo. However, the clinical efficacy of this vector has yet to be proven, despite over 300 clinical trials that have shown it to be well-tolerated and efficient in gene transfer. Recent studies in China have reported improved efficacy of an adenoviral gene therapy product in combination with radiotherapy and/or chemotherapy for the treatment of several types of cancer. There are now at least three phase III clinical trials for adenoviral cancer gene therapy that are ongoing in the U.S., and two of these call for combination therapy with either chemotherapy or radiation. In addition, in the European Union, one adenoviral gene therapy product for malignant glioma in combination with surgery showed a therapeutic benefit in the preliminary results of a phase III trial. This product, when applied as just one component of a multimodality approach, along with surgery, radiation and/or chemotherapy, holds some promise for proving the clinical efficacy of adenovirus vectors.