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 That is the verdict of experts following a presentation of a small
clinical study assessing the combination in patients with a variety
of solid tumors.
Oncologists and investors alike are keen to see if Avastin's
well-known ability to stop tumors from developing new blood vessels
might complement the effects of the new drug, which is designed to
help the body's immune system fight cancer cells.
The outcome is important for Roche, since Avastin counts for 13
percent of the company's sales and new immunotherapy medicines like
MPDL3280A - and similar rival products - might cannibalize this
business if there is no synergy.
Data presented at the European Society of Medical Oncology annual
congress in Madrid hinted at a possible effect, but was far from
conclusive.
Christopher Lieu of the University of Colorado Cancer Center
reported results for patients with advanced cancers treated with the
drug combination, with or without chemotherapy.
Tumor shrinkage was seen in a number of cancer types, including
kidney and colorectal cancers. One patient with kidney cancer given
the two drugs with chemotherapy experienced a complete response, or
disappearance of disease.
The overall response rate in 10 kidney cancer patients given
MPDL3280A and Avastin without chemotherapy was 40 percent, but only
8 percent in 13 colorectal patients. A separate group of colorectal
patients had around a 40 percent response rate when chemotherapy was
added to the drug mix.
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Some cancer doctors said the results suggested MPDL3280A and Avastin
might have a role in kidney cancer but this was more uncertain for
colorectal cancer, where chemotherapy alone can produce a response
rate of 40 percent or more.
"There may be synergies but we can't draw any firm conclusions from
the data so far," said Eric Van Cutsem of the University of Leuven,
who was not involved in the research. "We don't know if it is due to
the chemotherapy or due to the other drugs."
MPDL3280A is part of a closely watched class of drugs known as
anti-PD-L1 drugs, which work by blocking a tumor's ability to evade
the immune system's defenses.
(Editing by Aidan Martindale)
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