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May 14 (Reuters) - Roche Holding's drug from a closely watched new class of cancer immunotherapies showed promise against advanced bladder cancer in a small, early stage study, according to data released on Wednesday.
Roche has previously released data from studies testing the drug, MPDL3280A, against advanced melanoma, lung and kidney cancers, helping to generate excitement among physicians and healthcare investors for the class of medicines that help the body's immune system fight disease. The study was the first to test this type of immunotherapy against advanced bladder cancer.
The biotech drug, known as a PDL1 inhibitor, is an antibody that blocks a tumor's ability to camouflage itself so that it can be recognized and attacked by the immune system.
Anti-PDL1 drugs, and related anti-PD-1 drugs being developed by Merck & Co, Bristol-Myers Squibb Co and others, are viewed as one of the most important new mechanisms to fight cancer. Wall Street has forecast multibillion-dollar sales for the medicines once they win regulatory approval.
Among 20 patients with advanced bladder cancer whose tumors were found to be PD-L1 positive, the tumors shrank by at least 30 percent for 10 of them, for a 50 percent response rate, according to a brief summary of data that will be presented at the upcoming American Society of Clinical Oncology (ASCO) meeting in Chicago.
Sandra Horning, Roche's chief medical officer, told Reuters: "A 50 percent response rate is quite remarkable and it certainly compares favorably with what we and others have seen with immunotherapy for other tumor types."
One of those 10 patients had a complete response, showing no sign of the cancer after at least six weeks of treatment.
The response rates could increase over time, as similar therapies have been shown to help the immune system learn to attack cancer cells long after treatment begins. All of the 10 patients were still responding at the time the data had to be submitted, researchers said.
The median time to response was 43 days, which was considered fairly swift, as it typically takes the immune system longer to make a dent against cancer compared with the body's reaction to harsher treatments, such as chemotherapies, or targeted drugs.
"To see an early response with immunotherapy is a very notable finding," Horning said.
There were no immune system-related side effects reported and only one patient experienced a side effect deemed to be serious, which was fatigue-related, the company said.
Roche is using a diagnostic test to identify tumors that are deemed PD-L1 positive in an effort to select patients most likely to benefit from the drug.
PD-L1 positive means that the PD-L1 protein is expressed on the surface of cancer cells or immune cells present in the tumor. If little or no PD-L1 is present, the patient is considered PD-L1 negative.
The company will also present results from PD-L1 negative patients in the study at the May 30-June 3 ASCO meeting, as well as updated longer-term follow-up data and results from more patients that were not yet available.
The American Cancer Society estimates that nearly 75,000 new cases of bladder cancer will be diagnosed in the United States and about 15,600 Americans will die from the disease in 2014. (Reporting by Bill Berkrot; Editing by Dan Grebler)