Near the end of the 19th century, a physician by the name
of William Coley made the first attempt to stimulate the immune system to help
improve a cancer patient’s condition. At the time, it was a radical idea, met
with skepticism and scorn, despite Coley reporting some good results.
Modern immunology shows that Coley’s principles of immune
stimulation were indeed on target, and today the field of cancer immunology has
become a highly sophisticated specialty. Indeed, cancer vaccines have caught
the imagination of the public and of researchers who are investigating and
developing these vaccine therapies. But the clinical translation of cancer vaccines
into effective treatments has been challenging. Nonetheless, there have been
some incredible breakthroughs.
Overcoming Challenges
One of the challenges is that pancreatic cancer tumors
don’t typically respond to immunotherapy. That’s because these tumors develop
deep within the body and surround themselves with a tough, fibrous capsule
that’s difficult for drugs to pierce. This fibrous capsule also wards off the
immune system’s T cells, our so-called “fighter” cells, which attack foreign
invaders and cancer cells within the body.
Plus, pancreatic tumors are immunosuppressive. This means
that their microenvironment—all the cells that make up the tumor—creates a
barrier to effective immune surveillance by T cells. T cells are somewhat
tolerant of cancer cells and cancer cells are also smart and are able to evade
the immune response.
Next step for immunotherapy for pancreatic cancers, and
one way to achieve this is to reprogram the tumor microenvironment to better
mount a more robust anti-cancer immune response.
GVAX - Vaccine for Pancreatic Cancer Treatment
Developed by Elizabeth Jaffee, M.D., and Daniel Laheru,
M.D., this novel vaccine, called GVAX, supercharges the immune system and
causes immune cells, which tend to be tolerant of cancer, to seek out and kill
pancreatic cancer cells throughout the body.
The vaccine uses pancreatic cancer cells that have been
treated with radiation to inhibit their ability to grow. These cells have also
been genetically altered to secrete a molecule called GM-CSF. This molecule
acts as a lure to attract immune system cells to the site of the tumor vaccine
where they encounter proteins called antigens on the surface of the radiated
cells. Then, these newly armed immune cells patrol the rest of the patient's
body to destroy any circulating pancreas cancer cells still remaining.
Since pancreatic cancer is often found in areas outside
of the pancreas, the vaccine could allow physicians to target microscopic
cancer cells that could escape other therapies. This vaccine is being tested in
clinical trials. Currently, trials are focusing on not only identifying and
overcoming the immune pathways unique to pancreatic cancer, but also on using a
T cell activating vaccine to try to prime the immune system to fight back.
Sources and Additional Information:
https://letswinpc.org/research/overcoming-challenges-vaccine-immunotherapy/
https://cdrjournal.com/article/view/3441
