From clinical cancer research: Rethinking Therapeutic Cancer Vaccine Trials

Ongoing therapeutic cancer vaccine trials have yet to show evidence of
vaccines spurring a patient’s immune system to shrink tumors — yet
patients who receive these vaccines in trials tend to live longer and
respond better to subsequent treatment. In the July 1 issue of Clinical
Cancer Research, a journal of the American Association for Cancer Research,
a team of National Cancer Institute researchers asks a fundamental question:
Are we looking at cancer vaccine trials the wrong way?”

In a review of five prostate cancer vaccine trials, NCI researchers offer
evidence that patients who receive vaccines may respond better to subsequent
chemotherapy or hormone treatment. The specific results or endpoints
of these clinical trials, however, were not the long term survival of
patients, but rather the degree to which the vaccine caused tumors to
shrink. According to the researchers, since they didn’t achieve their
primary endpoints, these vaccines may be abandoned as dead-ends, despite
their real therapeutic value in terms of prolonging patient survival.

Clinical data are providing evidence that patients are living longer
following vaccination, despite the fact that trials do not show the
vaccines can induce the immune system into shrinking tumors, said Jeffrey
Schlom, Ph.D., chief of the Laboratory of Tumor Immunology and Biology at
the National Cancer Institute. The data suggests that the scientific
community and regulatory committees ought to rethink the design of clinical
vaccine trials and our current approach to measuring the effectiveness of a
cancer vaccine.§

According to the researchers, it may be more helpful to think of the
effectiveness of a vaccine in ter