VACCINE BOOSTS SURVIVAL IN GLIOBLASTOMA

A novel vaccine appears to extend survival in glioblastoma multiforme (GBM), according to results from a small, single-group study published online December 21 in Neuro-Oncology.

The trial involved 41 patients with recurrent GBM who received a series of vaccinations with Prophage Series G-200 (Aegnus Inc), starting at a median of a month after surgical resection. Six months after surgery, 90.2% of these patients were still alive, and at 12 months, 29.3% of patients were still alive.

The median overall survival in the study was 11 months, which is longer than the current expected survival of between 3 and 9 months.

The study's senior author, Andrew Parsa, MD, PhD, emphasized that the primary endpoint of the study was overall survival at 6 months. However, several patients had survived longer than that. "There are a few patients, about 10%, who are still alive and disease-free after 3 years," said Dr. Parsa, who is professor and chair, Department of Neurological Surgery, Northwestern University Feinberg School of Medicine, Chicago, Illinois.

"We can't say for sure that it is the vaccine that is keeping them alive," he told Medscape Medical News. "[A] randomized trial is the only way to tell us that. But we are delighted with the results, and we are encouraged that it did provide the foundation for a randomized trial that will be funded by the National Cancer Institute."

The vaccine appears to be very safe, and these are very "provocative preliminary results," explained Dr. Parsa. "They may signal an efficacy that correlated with overall survival."

GBM is the most common primary brain malignancy, and despite advances in treatment, the prognosis continues to remain poor. Immunotherapy offers the promise of improving outcomes, which has prompted the development of novel vaccines. As previously reported by Medscape Medical News, another early trial recently yielded promising results, encouraging further investigation in larger trials.

The vaccine used in this study is heat-shock peptide protein complex 96 (HSPPC-96). Heat-shock proteins function as intracellular chaperones and can be used to deliver a variety of tumor antigens to antigen-presenting cells for immune stimulation, the researchers explain.

Met Primary Endpoint

Study participants received a median of 6 vaccinations (range, 1 - 15), with 3 patients receiving less than the protocol minimum of 4 vaccinations. All were followed-up until death or closure of the analysis (January 12, 2013), and none were lost to follow-up.

In the intent to treat population, the median progression free survival was 19.1 weeks, with a 6-month progression-free survival of 29.3%. The median overall survival was 42.6 weeks and a 6-month overall survival of 90.2%; overall survival was 29.3% at 12 months

The toxicity associated with the vaccine was minimal, note the authors, and was primarily related to injection-site reactions. Only a single patient experienced grade 3 fatigue, which was possibly related to the vaccine. There were no grade 4 adverse events or deaths attributable to the vaccine, but 17 serious events (grade 3 - 4) were associated with the surgical resection (consistent with known risks of a craniotomy for GBM). A single death occurred that was caused by a delayed subdural hematoma but was unrelated to the vaccine.

The study was supported by the National Cancer Institute Special Program of Research Excellence, American Brain Tumor Association, National Brain Tumor Society, and Accelerated Brain Cancer Cure, Inc. The authors have disclosed no relevant financial relationships.

Neuro-Oncol. Published online December 12, 2013. Abstract