Pancreatic cancer is
a notorious killer. With seven out of eight patients
dying within five years, it is the third leading cause of cancer deaths. A
new therapeutic mRNA vaccine has been developed which is showing
tremendous promise
in early-stage clinical trials. Of 16 trial patients, seven who received
the treatment have survived now for
six years
.
What needs more investigation: why did half the patients not respond to the
vaccine? And most importantly, can the result be reproduced in a larger
cohort?
What is promising: 1. The same approach is being tested on other
hard-to-treat cancers and is a harbinger of
personalized cancer treatment
(Sci Am archive.ph link). 2. There are minimal side effects and immunity to
the cancer appears to persist.
A detailed talk by lead researcher Vinod Balanchandran
on the road to the vaccine.
Balachandran, director of the Olayan Center for Cancer Vaccines at Memorial
Sloan Kettering, used deep-learning to analyze a sample of the patient's
tumour and identify the highest-profile neo-antigens for that patient.
Neo-antigens are abnormal protein fragments. They present themselves
on the surface of pancreatic cancer cells.
The computational process is a finely-tuned algorithmic approach that
delineates the "self" from the "non-self". The mRNA vaccine causes the
patient's body to produce these neo-antigens in great quantities triggering
an immune response.
The T-cells that are spawned home in on the neo-antigens and kill the
tumor cells. The vaccine essentially "lights up" the tumour so that the
immune system can see it.
Bottom line: Circumstantially, there are sound reasons why this treatment
will be proven definitively effective. Balachandran did a prior study of
long-term survivors of pancreatic cancer and found they had elevated levels
of T-cells that attacked high-profile neoantigens. His treatment mimics
that scenario.
Despite these promising results, we should keep in mind there have
been many false starts in the history of pancreatic cancer treatment.
Notably the
GVAX vaccine which showed 50% improvement in survival
rates in Phase 1 trials but no measurable effect in Phase 2.
On the other hand GVAX was a general vaccine, a "shot in the dark"
and not a personalized vaccine that homes in on cancer cells.
Previously (an earlier description of the trial result from last year).