Sampson says new therapies are critical. Over the past decade he and his research team have been working on several new vaccine strategies. The particular vaccine used in this study is called a peptide vaccine and was designed to stimulate the patient's immune systems to respond to a particular part of a protein on EGFRvIII.
Other brain tumor vaccine studies are in progress at other institutions with peptides drawn from the tumors and with heat shock proteins.
Researchers found that the vaccine (variously known as CDX-110 by Celldex Therapeutics, and Rindopepimut (PF-04948568) by Pfizer) stimulated an immune response in approximately half of the patients who received it. Six patients developed EGFRvIII-specific antibodies and three developed T-cell responses.
The data suggest that these responses are linked to increased survival time, "but the numbers are so small that we can not conclude this with any degree of certainty," says Amy Heimberger, MD, co-lead investigator, from MD Anderson.
Scientists were also able to examine pre- and post-vaccination tumor samples from 11 patients and found that when their tumors recurred, 82 percent lacked immunoreactivity, which Sampson says demonstrates that the vaccine had done its job in eliminating the most aggressive cells.
Sampson notes that the EGFRvIII vaccine may be worth further investigation because this growth factor is also found in other kinds of cancer cells, but not in normal tissue, making it a good target for intervention.
Bigner says that even though the study is small, the findings are intriguing and merit further study. "This appears to be a promising start, but the biological complexity of thes
|Contact: Michelle Gailiun|
Duke University Medical Center