10 Promising Therapeutic Vaccines

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by Deborah Erickson

Scientists have long figured it should be possible to rev up the immune system on command, to give the body's own natural defenses an extra surge of power to attack tumors and fight diseases. But decades of working on the challenge have seen many promising clinical trials of potential "immune modulators," "immune stimulators" and "therapeutic vaccines" end in disappointment.

Now there is evidence that therapeutic vaccines actually can work. Therapeutic vaccines are meant to combat existing disease rather than offer lasting protection against infection, as traditional vaccines do. The FDA approved the first therapeutic vaccine in April 2010. Dendreon's Provenge (sipuleucel-T) was shown to extend life about four months in men with a certain type of metastatic prostate cancer. The vaccine provokes an immune response against a particular antigen, or identifying molecule, found on most prostate cancer cells.

Provenge is stimulating more than patients' immune systems: Investors, clinicians and companies of all sizes are encouraged by the proof that immune-enhancing treatments can benefit patients with relatively few side effects, and command premium pricing in the marketplace. A course of Provenge treatment costs $93,000. Ever-expanding understanding of molecular biology and immunology is also stirring up fresh hope, giving rise to a range of treatment candidates with mechanisms unknown or inaccessible even a decade ago.

Here, FierceVaccines spotlights 10 therapeutic vaccines now being tested in humans and generating buzz. Those for cancer get the most attention, in part because their anticipated gentleness stands in such stark contrast to the known toxicities of conventional chemotherapies. The idea of immune stimulation at last proven effective in oncology is also inspiring researchers in indications beyond the long-pursued "big" infectious diseases like HIV and hepatitis. Because one of the key hurdles in developing therapeutic vaccines has been training the immune system how to recognize and destroy "bad" cells, it's possible that vaccines able to help the body fight one type of tumor or disease may be tailored for other purposes. So we include in our list several potentially pioneering therapeutic vaccines unrelated to cancer.