NEW CANAAN, CT— Cancer vaccines present an elusive goal, yet one that is increasingly within reach for biomedical researchers. Their hope is to offer physicians and cancer patients more and better therapy options than radiation and chemotherapy. The advancement of cancer vaccine research, from the bench to clinical trials, was the focus of the Sabin Vaccine Institute’s 5th Annual Colloquium on Cancer Vaccines and Immunotherapy held this past March 5-8 at Walker’s Cay in the Bahamas.
According to H.R. Shepherd, chairman of the Sabin Vaccine Institute, this year’s colloquium generated immense energy toward progress on cancer vaccine research and immunotherapy advances. Dr. Shepherd is a proponent of vaccines as therapeutic agents against many forms of cancer, having been treated successfully with BCG vaccine (traditionally a tuberculosis vaccine), which is a non-specific immuno-suppressant that has found a place in the treatment of bladder cancer. Colloquium participants were challenged by Dr. Shepherd’s refrain, “Why are there so few vaccines, and why does it take so long to develop them?”
Forty of the world’s leading scientists, medical researchers, and thought leaders convened for the think-tank sessions on the island where former President Richard Nixon first declared the War on Cancer in 1973. Their discussion topics ranged from underlying mechanisms of immunity to clinical results, including such concepts as immunocompetence to immunosuppression. “Fundamental to the presentations was the idea that academia, industry, and the government can better work together to circulate information and produce more potent and effective cancer treatments,” said Dr. Shepherd.
The plenary lecture provided by Dr. Guido Forni from the University of Turin addressed prophylactic cancer vaccines. His proposal was both simple and fascinating: Since the stimulation of anti-tumor immune responses following vaccination seems most successful in the initial stages of cancer, is it possible to use vaccines to prevent disease? The underlying tenets of immunoprevention maintain that cancer formation occurs slowly, this slowness provides a time window of opportunity during which a meaningful response could be induced, the capacity to induce a response lessens as cancer progresses, and the reason that the response lessens is increased suppression of immune cells that correlates with tumor stage. Data Dr. Forni presented showed that survival was “barely improved” in vaccinated mice bearing tumors only 24-72 weeks old, as compared with pretreatment of normal mice.
In rounds of presentations spanning the three-day meeting, encouraging signs pointed to tangible progress towards a prescribable treatment therapy. Participants provided evidence that in vitro and animal models can be used to design treatment regimens and remove less promising vaccines from further development. The timing of administration and immune status of a patient is as important to achieving therapeutic benefit as the components of a vaccine, according to some evidence.
The colloquium targeted four areas of investigation, each aimed as much at why so many patients do not respond to treatment as at data supporting why some do:
- Models for Cancer Vaccines and Strategies to Enhance the CD8+ T Cell Tumor Response
- Immune Response to Tumors
- Developing New Targets and Constructs for Cancer Vaccines
- Clinical Trials and Immune Monitoring
- Escape from Immunological Destruction
The 40 colloquium participants included approximately 20 participants from biomedical research departments at several of the nation’s leading universities as well as from Italy and Canada; 10 pharmaceutical industry researchers; members of biological research institutes and government research laboratories, and independent researchers. This year’s colloquium was co-chaired by W. Martin Kast, PhD, professor of microbiology and immunology and pharmacology at Loyola University Chicago; and Malcolm S. Mitchell, MD, program leader, Biological Therapy, Karmanos Cancer Institute, Wayne State University, Detroit.
More speakers than ever before had clinical trials either underway or under concerted development. A continuous pipeline of vaccines into clinical trials is essential, since proof-of-principle in cancer patients is essential if these biologics are to be approved by regulatory agencies and made available as alternatives to chemotherapy and radiation. If the cancer vaccine development described at Walker’s Cay is even partially successful, the day will come sooner when a doctor no longer need tell a cancer patient, “There is nothing more we can do.”
The mission of the Albert B. Sabin Vaccine Institute is to save lives by stimulating development of new vaccines and increasing immunization rates throughout the world. Founded in 1993, the Institute pursues Dr. Albert Sabin’s vision of a world protected from disease by vaccines. Sabin Institute colloquia convene leaders in academia, government, industry, and philanthropy to explore solutions to problems in vaccine research and development, and promote dialogue to prevent infectious diseases and treat cancer. As an immunization advocate, it helps policy makers shape sound public health policies and informs the public about the importance of vaccinations. The Sabin Institute’s Hookworm Vaccine Initiative is working to develop a vaccine to prevent an infection that afflicts more than one billion individuals, and is a leading cause of anemia and malnutrition in the developing world.