Cancer vaccine injected into tumour could kill all cancer cells

By Dr. Ananya Mandal, MDApr 9 2019Reviewed by Kate Anderton, B.Sc. (Editor)

Researchers have developed an experimental cancer vaccine that when injected into a single tumour can help trigger the immune system to kill the cancer cells circulating within the body. The results of the study titled, “Systemic clinical tumor regressions and potentiation of PD1 blockade with in situ vaccination,” were published in the latest issue of the journal Nature Medicine, this week, Monday.

The team of researchers say the vaccine essentially turns the tumour into “cancer vaccine factories” by teaching the immune cells to recognize the cancer cells. Once identification is done, the immune cells actively seek out all the cancer cells of the body and kills them. Lead study author Dr. Joshua Brody, director of the Lymphoma Immunotherapy Program at the Icahn School of Medicine at Mount Sinai in New York explained, “[We're] seeing tumors all throughout the body melting away.”

The team agrees that it is still premature to comment on the absolute success of this experimental therapy. They included 11 patients with non-Hodgkin's lymphoma in their study at Mount Sinai Hospital in Manhattan. Not all the patients responded to the treatment. However those of the patients that responded were in remission for a relatively long period of time, they explain. The team is testing the therapy in patients with head and neck and breast cancers now.

Lung cancer, 3D illustration showing malignant tumour. Image Credit: Kateryna Kon / Shutterstock

The researchers explain that this new immunotherapy involves the use of injections of two types of immunostimulants. It has three steps;

• Patient is given an injection of a small molecule that can call upon the immune cells called the dendritic cells into action within the tumour. These dendritic cells and T cells act as a ready army said Brody.
• Step 2 involves giving the patients low dose radiation therapy to kill the tumour cells. These cells now release proteins called antigens into the immune system. These proteins are recognised by the immune cells says Brody. The dendritic cells take up the antigens and show them to the T cells to help them learn. “Generals don't really fight wars, they make the plans,” Brody said calling the dendritic cells Generals to the T cell army.
• As step 3 another injection of the molecule is given to activate the dendritic cells. By now the T cells have been coached by the dendritic cells. Now they can go forth and kill the cancer cells of the body explains Brody.

Brody explained that this new therapy acts as a vaccine and boost the effects of an immunotherapy called “checkpoint blockade”. Both types of treatment are synergistic says Brody and they used them in lab mice. He hopes that this combination might help patients with cancers who are not responding to traditional immunotherapy.

In check point blockade, the brakes of the T cells are taken off so that they can aggressively target the cancer cells. On lab mice the team of researchers used both the vaccine and the check point blockade and saw a promising result in cancer cell killing with 75 percent mice being in remission from cancer after the experiment. “Here we demonstrate that increasing and activating cross-presenting [dendritic cells] at the tumor site can prime tumor-specific [T cells], restore efficacy of checkpoint blockade and yield superior anti-tumor immunity,” the authors wrote.

The team agrees that they need larger clinical trials and Food and Drug Administration (FDA) review and approval before safety and efficacy of this in-situ cancer vaccination becomes a reality. The research was funded by The Damon Runyon Cancer Research Foundation, the Cancer Research Institute and Merck. Celldex Therapeutics and Merck are currently making the immune stimulant PD-1 inhibitor Keytruda.