Many experimental cancer vaccines follow the same well-trodden path from the hype of an animal or early human study to the eventual disappointment of a late-phase fail. Yet the belief that one of the candidates will fulfill the vast potential of oncology vaccines remains.
The latest to excite with data from a small study is a personalized ovarian cancer vaccine trialed by the University of Pennsylvania. Researchers developed the vaccine using trial participants' own blood and tumor cells. The resulting injection--which took 7 days to make--was designed to recognize cancer and trigger an immune response to attack the tumor. Repeated doses of the vaccine were given in combination with Roche's ($RHHBY) Avastin, which limits blood supply to the tumor. The team outlined the process at the American Association for Cancer Research annual meeting.
Two-thirds of the 31 women who took part in the trial responded positively to the vaccine. In these cases, the vaccine elicited tumor-specific T cell responses against ovarian cancer antigens. Those who showed no response to the vaccine were given an adoptive T cell therapy as a second wave of treatment. The vaccine taught these T cells to attack tumors, amplifying the immune response. The disease stabilized in more than two-thirds of patients who took the second wave. In one case, total remission was achieved, but the cancer then returned and killed the patient.
The most dramatic improvement was seen in a woman who had relapsed twice and had three debulking surgeries before entering the trial. Since taking the vaccine, her cancer has been stable for almost four years. Most advanced ovarian cancer patients are dead within 5 years. If such an improvement can be replicated in other patients, the treatment could have a big impact on a cancer that kills more than 14,000 women in the U.S. each year. At the very least, the two-step vaccine-T cell treatment shows a potential approach to overcoming cancer's resistance mechanisms.
Avastin is among the drugs currently used to treat ovarian cancer. When it won approval in Europe last year, the Roche drug became the first new ovarian cancer treatment in 15 years. A potential immunotherapy for ovarian cancer--Eisai's monoclonal antibody farletuzumab--received a setback in January when it failed a Phase III trial. GlaxoSmithKline ($GSK), Merck ($MRK) and others are developing ovarian cancer drugs too.