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Immune Stimulator Improves Survival in Pancreatic Cancer

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When the agent CRS-207, which stimulates the immune system, is added to the vaccine GVAX, survival is improved among patients with advanced pancreatic cancer. These results were recently published in the Journal of Clinical Oncology.

GVAX is a type of vaccine that stimulates the immune system to fight pancreatic cancer cells. Researchers continue to evaluate ways in which to further improve immune responses with GVAX, as pancreatic cancer responds poorly to standard chemotherapy and/or radiation therapy.

Researchers recently added the immune stimulator CRS-207 to GVAX to evaluate its potency in further stimulating the immune system. CRS-207 contains mesothelin, a protein which tends to be overabundant on pancreatic cancer cells, attached to the bacteria Listeria monocytogenes. The bacteria is inactivated through laboratory processes so that patients are not infected; however, the presence of the bacteria evokes further immune responses. The immune cells also recognize the mesothelin that is attached to the Listeria as foreign, and mounts an attack against mesothelin – the same proteins found on the cancer cells. Ultimately, this stimulates the immune cells to attack the cancer cells.

The trial evaluating CRS-207 included 90 patients with advanced pancreatic cancer that had received prior therapy. One group of patients was treated with the GVAX vaccine, while the other group received GVAX plus CRS-207.

Overall survival was 6.1 months for those treated with CRS-207/GVAX, compared with 3.9 months for those treated with GVAX only.
Among patients who received at least 3 doses of their respective treatment, overall survival was 9.7 months for those treated with GVAX/CRS-207, compared with only 4.6 months for those treated with GVAX only.
The most common serious side effects were transient fevers, abnormal immune cell levels, fatigue and elevated liver enzymes.
The researchers concluded that “prime/boost with Cy/GVAX and CRS-207 extended survival for patients with pancreatic cancer, with minimal toxicity”.

Reference: Le C, Wang-Gillam A, Picozzi V, et al. Safety and Survival With GVAX Pancreas Prime and Listeria Monocytogenes–Expressing Mesothelin (CRS-207) Boost Vaccines for Metastatic Pancreatic Cancer. Journal of Clinical Oncology. Published online before print January 12, 2015, doi: 10.1200/JCO.2014.57.4244 JCO