PARIS - The first results of Phase II clinical trials of a p53 gene therapy for head and neck cancers conducted by RPR Gencell, the gene therapy division of the pharmaceutical company Rhtne-Poulenc Rorer, of Collegeville, Pa., show the therapy reversed or arrested tumor growth in some patients.

Three studies of a single-agent, intra-tumoral therapy targeting the p53 gene were carried out on a total of 170 patients with recurrent squamous cell carcinoma of the head and neck. In the largest of these studies, 106 patients, over 40 percent of whom had tumors that were progressive despite having received one or more combinations of chemotherapy and/or repeat radiation therapy, were injected with this agent following one of two treatment schedules. Of the 90 patients that were evaluable for antitumor activity, five (or six percent) showed complete or partial tumor response, while in 18 (20 percent) tumor growth was stabilized for a period of two to 11 months. Antitumor activity was also demonstrated in the other two trials, in which three dosing schedules were tested (ranging from one to six days per month).

Study investigator John Nemunaitis, regional director of PRN Research Inc., welcomed these results as "good news," since no treatment to date has ever improved the survival rate of patients with recurrent head and neck cancer. "We look forward to moving into Phase III trials to further test the efficacy of this treatment," he said. The treatment was also found to be well tolerated, showing minimal toxicity in all patients. The most commonly reported adverse events were pain at the injection site and fever, but both were found to be manageable and self-limited.

The agent utilized was RPR/INGN 201, a common adenovirus (the cold virus) that was re-engineered to be non-replicating and deliver a normal p53 gene into the cancer cells. The therapeutic material was provided by Gencell's collaborator, Introgen Therapeutics, Inc., which had earlier carried out Phase I trials of the therapy.