A phase 1 study of 11 patients with glioblastoma who received injections of an investigational dendritic cell vaccine targeting a cytomegalovirus (CMV) protein in conjunction with temozolomide, a first-line chemotherapy agent, showed the combination was well tolerated and resulted in unexpectedly significant increases in survival. Published on April 14, 2017, in Clinical Cancer Research, the study highlighted that 4 of the 11 participants survived for more than 5 years post-diagnosis, a notable outcome given the median survival rate of nearly 15 months with current standard treatments.
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Tolerance and Adverse Effects: The combination therapy was generally well tolerated. No treatment-limiting adverse events related to the cellular portion of the vaccine were reported. However, known adverse effects of temozolomide, such as nausea, lymphopenia, thrombocytopenia, and fatigue, were observed. One participant experienced a grade 3 vaccine-related allergic reaction to the GM-CSF component but continued treatment without GM-CSF and had no further adverse events.
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Study Insights: Kristen Batich, MD, PhD, the study's lead author, emphasized the study's focus on targeting a protein on glioblastoma tumors and the potential for combining the vaccine with a more intense chemotherapy regimen to promote a strong, cooperative benefit. The approach leverages the immune deficiency caused by temozolomide to optimally introduce the vaccine therapy, directing the immune system to specifically attack the tumor.
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Clinical Outcomes: The study reported a median tumor recurrence time of 25 months, significantly longer than the 8 months typically observed with standard treatment. John Sampson, MD, PhD, the study's senior author, noted the promising clinical outcomes but cautioned that the study was small and used historical comparisons rather than randomized treatments. He advocated for further study in larger, controlled clinical trials.
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Future Research: The research team has received approval to launch a new study comparing the standard dose of temozolomide with the dose-intensified regimen in combination with the vaccine, aiming to further explore this promising therapeutic approach.
