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New ‘Cancer Vaccine’ Attacks Tumors From Within
A new method of brewing a cancer vaccine inside a patient’s tumor could harness the power of the immune system to destroy the disease.
Immune stimulants are injected directly into a tumor, which teaches the immune system to recognize and destroy all similar cancer cells throughout the body, said senior researcher Dr. Joshua Brody. He is director of the Lymphoma Immunotherapy Program at the Icahn School of Medicine at Mount Sinai in New York City.
“We’re injecting two immune stimulants right into one single tumor,” Brody said. “We inject one tumor and we see all of the other tumors just melt away.”
Eight out of 11 lymphoma patients in a small, early clinical trial experienced partial or complete destruction of the tumor that received the initial injection, according to the report published April 8 in the journal Nature Medicine.
The vaccine also halted overall cancer progression in six patients for three to 18 months, and caused significant regression or actual remission in three patients, the investigators found.
The results were solid enough that the research team is expanding its next clinical trial to include lymphoma, breast, and head and neck cancer patients, Brody said. That trial started in March.
Prior efforts at unleashing the immune system to fight cancer have focused on T-cells, which Brody calls the “soldiers” of the immune army because they directly attack harmful invaders in the body.
But the checkpoint inhibitors have typically only been able to help about one in five cancer patients significantly, “so there’s lots of room for improvement,” he added.
This new vaccine approach focuses on dendritic cells, which Brody calls the “generals” of the immune system’s army. Dendritic cells guide the response of T-cells to fight off invaders
Patients first received nine daily injections of an immune stimulant intended to “recruit” dendritic cells by teaching them how to recognize cancerous cells, the study authors said. The patients then received eight injections of a second stimulant that “activates” the dendritic cells, prompting them to instruct T-cells to hunt and destroy the now revealed cancer cells in the body.
Essentially, the method turns the injected tumor into a cancer vaccine factory, the researchers explained. The approach differs from traditional vaccines for the flu or measles because those are preventive, teaching the body beforehand how to fight off an infectious disease, Brody pointed out.
Lab tests involving mice show that this vaccine approach could be at least three times more powerful if combined with checkpoint inhibitors, Brody added. Because of this, patients in the new trial will receive both the vaccine and checkpoint inhibitors, the researchers said.
Susanna Greer, scientific director of clinical cancer research and immunology for the American Cancer Society, said that “priming” dendritic cells inside a person’s tumor to produce the best anti-tumor immune response “suggests a promising immunotherapy strategy.”
Dr. Catherine Diefenbach, director of clinical lymphoma at the NYU Langone Perlmutter Cancer Center in New York City, said the vaccine approach is “novel and extremely interesting,” and could help explain why checkpoint inhibitors usually don’t help patients with non-Hodgkin lymphoma. However, she noted that really only three of the 11 patients in the initial clinical trial had truly meaningful responses to the vaccine.
5 September, 2019