By Peter Loftus
CHICAGO--A new crop of cancer immunotherapy drugs is showing
promise in a widening range of tumor types, while researchers home
in on ways to predict which patients are likely to benefit most
from the drugs.
Studies released Friday at the annual meeting of the American
Society of Clinical Oncology showed drugs from Bristol-Myers Squibb
Co. and Merck & Co. were effective in shrinking tumors in
patients with cancers of the lung, liver, head and neck. The drugs,
Bristol's Opdivo and Merck's Keytruda, were previously approved to
treat the skin cancer melanoma, while Opdivo has also been approved
to treat a type of lung cancer.
Other studies have shown potential for the new wave of
immunotherapy drugs to treat cancers of the blood, bladder, kidney
and breast. Some of the findings need to be confirmed in larger
studies, and these uses haven't been approved by regulators.
Goldman Sachs estimates the market for immunotherapy drugs could
reach $40 billion to $50 billion in annual sales, fueled by their
use in a broad range of cancers. The drugs also are costly--about
$150,000 per patient if used for a year for each of Opdivo and
Keytruda.
Opdivo and Keytruda are known as PD-1 inhibitors, and they work
by lifting a natural brake on the body's immune system, which
allows immune cells to destroy cancer cells. Similar drugs are
being developed by Roche Holding AG, AstraZeneca PLC and a
partnership between Pfizer Inc. and Merck KGaA.
Opdivo was approved in March to treat a type of lung cancer
called squamous non-small cell lung cancer. On Friday, researchers
presented results of a study that could support widening its use to
include treating a more common form of lung cancer, known as
non-squamous non-small-cell lung cancer.
The late-stage study showed that patients receiving Opdivo had a
median overall survival of 12.2 months, versus 9.4 months for
patients taking a comparator drug, the chemotherapy docetaxel,
according to an ASCO summary of the results. Adverse events
associated with Opdivo included fatigue and nausea but were
generally less severe than in patients taking docetaxel.
Bristol in April stopped the study early because of the superior
efficacy of Opdivo, allowing patients who had been taking docetaxel
to switch to Opdivo.
Certain biological markers in patients might be able to help
predict which ones respond best to the drugs. The benefit from
Opdivo even greater in patients whose tumors had significant
expression of a substance called PD-L1, which interacts with PD-1
on immune cells.
Among these patients, the median overall survival of those
taking Opdivo was 17 months versus 9 months for docetaxel. In
contrast, there was no significant survival difference between the
drugs in patients whose tumors had less than 1% PD-L1 expression
levels.
"We know that every patient who receives an immunotherapy is not
going to respond," so it is important to find ways to try to
predict who will, said Lynn Schuchter, chief of the division of
hematology-oncology at the University of Pennsylvania.
Bristol and other companies are developing diagnostic tests to
assess PD-L1 expression, which they say can help doctors predict
which patients might respond best to the drugs.
Bristol shares dropped 6.6% to $64.60 Friday after the study
results were released. Some analysts said absence of a benefit in
patients whose tumors had low PD-L1 expression was disappointing,
and could make Opdivo more vulnerable to competition from other
immunotherapy drugs. Merck shares rose 2% to $60.89.
In a separate study of Merck's Keytruda, patients with
colorectal and other gastrointestinal tumors, who had a certain
genetic trait, had a higher tumor-shrinkage rate than patients who
didn't have this trait. The genomic marker is called "mismatch
repair deficiency," which leads to an accumulation of genetic
mutations in a tumor. Researchers who led the study suggested the
genetic marker could be useful in predicting responses to
immunotherapy in additional tumor types.
"Our results show an approach for the treatment of a specific
class of tumors that is based solely on genetic status that is,
without regard to the underlying tumor type," the researchers wrote
in an article the New England Journal of Medicine published online
Friday.
In a small, early-stage study released Friday, Bristol's Opdivo
shrank tumors significantly in 19% of patients with advanced liver
cancer, and 62% of patients were alive one year after starting
treatment. The average overall survival for advanced liver cancer
is 10 to 11 months, according to ASCO. The most common reported
adverse events in the Bristol-funded study included abnormal liver
enzymes and rash.
In another study, about 25% of patients with advanced head and
neck cancer experienced significant tumor shrinkage after taking
Merck's Keytruda, with side effects including fatigue and rash.
Initial results from the study, in a smaller group of patients, had
shown a tumor-shrinkage rate of about 18%.
Write to Peter Loftus at peter.loftus@wsj.com
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