To dispute the point of poor efficacy, speakers from Transgene, Onyvax (www.onyvax.com), and Oxxon Therapeutics (www.oxti.com) presented encouraging clinical trial data on their vaccines. Dr. Bonnefoy discussed TG 4001, Transgene’s human papilloma virus (HPV) vaccine to treat cervical cancer. This has a modified virus ankara (MVA) nonpropagating, attenuated vaccinia virus backbone into which is engineered DNA for cervical cancer-associated antigens (HPV16) and interleukin 2 (IL2), a cytokine adjuvant that stimulates immune responses.
In a Phase II trial of 21 women with cervical cancer lesions, six months post-TG 40101 vaccination, 10 women had no lesions and did not need surgery, according to Dr. Bonnefoy. “If we can avoid doing cone biopsies, as this study indicates, then TG 4001 will be a great product.”
Joerg Schneider, Ph.D., vp of research and cofounder of Oxxon Therapeutics, presented the firm’s Hi-8™ MEL DNA vaccine for the treatment of melanoma. This vaccine is a two-step process where a plasmid DNA vaccine (DNA.mel3) expressing seven epitopes derived from five melanoma antigens is injected, followed by a second injection of an MVA based vector (MVA.mel3) expressing the same epitopes as the plasmid.
Using this two-step prime boost approach increases the immune response by as much as 10 times, says Dr. Schneider. In a Phase II trial, where 41 patients were given both DNA vaccines sequentially, 27 patients had an immune response, and those that responded had a median survival of 86 weeks compared to 37 weeks for nonresponders.
Stephen Ward, Ph.D., head of process development at Onyvax, talked about a cell-based vaccine, ONY-P1, for treating hormone-resistant prostate cancer. ONY-P1 contains nonpatient-specific prostate cancer cells mixed with the vaccine BCG (used for the treatment of superficial bladder cancer as well as controlling tuberculosis) as an adjuvant. Dr. Ward presented Phase II data that showed that among the 26 patients treated with ONY-P1, there was a median of 58 weeks progression-free survival compared to historical controls of approximately 29 weeks without treatment, and 11 of these patients showed a decrease in their prostate-specific antigen levels over time.“On the basis of these encouraging results, we are going ahead with a further randomized Phase II, placebo-controlled trial of 75 patients,” said Dr. Ward.