Two experimental drugs that “reveal” hiding
cancer cells to the body’s immune system show striking promise in the treatment
of advanced, metastatic melanoma.
by John
Tyburski
Copyright © Daily
Digest News, KPR Media, LLC. All rights reserved.
Preliminary
results of two international trials on experimental treatments for advanced
stage skin cancer were presented this week at the American Society of Clinical
Oncology (ASCO) Annual Meeting in Chicago. Two experimental drugs,
pembrolizumab and nivolumab, target the means by which cancer cells remain
hidden from the body’s immune system
If it
detects them, the immune system destroys cancer cells, but cancer cells
typically go undetected because they “hide” from the immune system’s
surveillance system. In one trial of 411 patients on pembrolizumab (previously
known as MK-3475) with advanced melanoma, an aggressive and stubborn form of
skin cancer that has spread to other organs of the body, 69 percent survived at
least one year. For years the average survival for advanced melanoma was only
about six months.
Pembrolizumab
is also being looked at in the treatment of other forms of cancer.
“Pembrolizumab
looks like it has potential to be a paradigm shift for cancer therapy,” said
Dr. David Chao of the Royal Free London NHS Foundation Trust and scientist on
the trial. Chao has another ongoing trial of the drug in treatment for lung
cancer.
The other
trial involves the combination of Nivolumab with ipilimumab, licensed
immunotherapy drug already used in cancer treatment. Among 53 melanoma patients
in the trial, 85 percent survived one year, and 79 percent survived an
additional year for a total of two years of life after diagnosis with
metastatic melanoma.
“I am
convinced that this is a breakthrough in treating melanoma,” said John Wagstaff
of Swansea College of Medicine in the UK. “The trial is still ‘blinded’ so we
don’t know what treatments the patients are getting, but we have seen some
spectacular responses.”
The results
for both trials represent Phase I findings. Larger Phase II and III studies are
necessary before these results can be interpreted with confidence.
Both
pembrolizumab and novolumab are monoclonal antibodies that were generated
against specific protein targets found on cancer cells. Pembrolizumab was
developed by Merck to attack the programmed cell death-1 (PD-1) receptor.
Nivolumab was developed by Bristol-Myers Squibb (BMS) and blocks ligand
activation of PD-1 receptor. The approved drug Ipilimumab is also BMS-developed
monoclonal antibody that inhibits the CTLA-4 receptor that normally attenuates
immune system activity.
The 2014
ASCO Annual Meeting abstracts are available online to
the public.
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