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Cancer Vaccines Facing Difficult Clinical Trial Challenges; Greystone Associates Cites Enrollment, Endpoint, and Protocol Issues

Posted on: Monday, 20 March 2006, 09:00 CST

Therapeutic cancer vaccines continue to grab our attention, as the number of market participants and vaccine candidates expands. In spite of the market hype and wishful thinking, the results of clinical trials for cancer vaccines to date have been mixed and often disappointing. While the challenge of creating and successfully proving the efficacy of a vaccine that can effectively treat America's second-deadliest disease is perhaps without medical precedent, a close look at the dynamics and regulatory environment of the clinical trial process provides insight into possible reasons why the first approvable, truly therapeutic cancer vaccine may still be years away.

Clinical trial endpoints for cancer vaccines include criteria on tumor shrinkage, delayed time to progression, immunologic end points, and molecular markers - endpoints that can not be measured with true analytical accuracy or precision among patients. This error factor is compounded by the often small trail populations that result from the narrow focus of many cancer vaccine disease targets. Up to this point, evidence of immunologic response and clinical responses in small patient populations, correlation between immunologic response and clinical response has been difficult to demonstrate.

Often, the enrollment issue is exacerbated because the complexities of vaccine preparation - for example, autologous vaccines which must rely on the availability of fresh patient tumor cells for preparation at a central laboratory on an individual patient basis - limits sponsors to offering a given trial in only a handful of centers.

Most cancer vaccine clinical trails involve patients with advanced-stage disease who have already endured at least one round of chemotherapy. Such immune- compromised patients cannot be expected to provide an accurate assessment and representative outcome for a therapy designed to work by boosting immunity.

"Cancer vaccines are playing by rules which in some ways place them at a distinct disadvantage relative to the therapeutic value they have been designed to deliver," explains George Perros, Greystone Associates Managing Director. "These issues, which will require a strong working relationship between vaccine developers and key FDA and NCI decision makers to resolve, must be addressed if the promise of cancer vaccines is to be fully realized."

These findings are contained in a new and comprehensive report: Therapeutic Cancer Vaccines: Platforms, Players and Prospects. The report contains in-depth analysis of cancer vaccine development and clinical trial activities and prospects for more than three dozen market sector participants.

More information is available at http://www.greystoneassociates.org/Cancer_Vaccines.htm

About Greystone

Greystone Associates is a medical and healthcare technology consulting firm providing services in strategic planning, venture development, product commercialization, and technology assessment.

Source: Business Wire

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