Researchers at the Johns Hopkins Kimmel Cancer Center have developed and tested a vaccine that triggered the growth of immune cell nodules within pancreatic tumors, essentially reprogramming these intractable cancers and potentially making them vulnerable to immune-based therapies.
In their study described in the June 18 issue of Cancer Immunology Research, the Johns Hopkins team tested the vaccine in 39 people with pancreatic ductal adenocarcinomas (PDAC), the most common form of pancreatic cancer. The disease becomes resistant to standard chemotherapies and is particularly lethal, with fewer than 5 percent of patients surviving five years after their diagnosis.
PDACs do not typically trigger an immune response against the cancer cells that comprise, but with the help of a vaccine developed by Johns Hopkins researcher Elizabeth Jaffee, M.D., the scientists were able to "reprogram" tumors to include cancer-fighting immune system T cells.
The vaccine, known as GVAX, consists of irradiated tumor cells that have been modified to recruit immune cells to a patient's tumor. The researchers tested GVAX in combination with an immune modulator drug called cyclophosphamide, which targets a type of immune cell, called Tregs, that typically suppresses the immune response of certain T cells that destroy cancer.
The reprogramming is designed to make the tumors more vulnerable to other immune-modulating drugs that have been useful in fighting other cancers, said Jaffee, The Dana and Albert "Cubby" Broccoli Professor of Oncology at the Johns Hopkins University School of Medicine.
Jaffee and colleague, Lei Zheng, M.D., say the vaccine could potentially convert many types of tumors to a state where immunotherapies can have a much larger impact.
For example, Jaffee says, in certain melanomas, "we've tested immunotherapies that target T cells and have found a 10-30 percent response in cancers that naturally have the abili
|Contact: Michelle Potter|
Johns Hopkins Medicine