Stem cell transplants have improved treatment of patients with chronic lymphocytic leukemia (CLL), but the risk of relapse remains. Advances are needed to extend 5-year progression-free survival rates beyond the currently achieved 64%, and Dana-Farber thinks a vaccine could help.
Dana-Farber Cancer Institute researchers trialed the use of a personalized tumor vaccine made up of a patient's own inactivated leukemia cells and an immune stimulant. After receiving up to 6 doses of the vaccine, the patients' transplanted immune systems appeared better equipped to control the cancer. In a paper published in The Journal of Clinical Investigation, the researchers estimate the 18 patients who received the vaccine have a two-year progression-free rate of 82%. CD8+ T cells in vaccinated patients reacted against autologous tumor cells by increasing secretion of interferon-gamma, a cytokine that promotes anticancer activities.
While Dana-Farber is encouraged by the data, the Phase I trial was small, and the long-term fate of the participants is still unclear. Further randomized clinical studies that enroll more patients are needed to assess the effectiveness of the vaccine. Even at this stage though, the research adds to mounting evidence that whole tumor cell-based vaccination can help patients with cancers of the blood, bone marrow and lymph nodes.
The nature of the vaccine could limit its commercial use though. Like Dendreon's ($DNDN) Provenge, the vaccine trialed by Dana-Farber is tailored to each patient. This pushed the cost of three infusions with Dendreon's prostate cancer drug up to $93,000. The cost is one of several factors that has limited uptake of the product since it won FDA approval in 2010. And even at this price, Dendreon has suffered because the cost of making the vaccine depresses its profit margins. The leukemia vaccine could face similar problems if it reaches the market.
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