ASCO '13: More Data on Bristol's Immune-Boosting Melanoma Drug

CHICAGO ( TheStreet) -- Bristol-Myers Squibb's ( BMY) immune system-boosting drug nivolumab produced long-lasting tumor shrinkage patients with advanced melanoma, according to updated results from an early-stage study.

The response to Nivolumab was three times better than what's typically seen with Bristol-Myers' first-generation melanoma drug Yervoy, approved in 2011.

Nivolumab belongs to a new class of drugs that work by dismantling a cloaking mechanism used by cancer cells to hide from a patient's immune system. Bristol-Myers and Merck ( MRK) are each developing drugs that target this PD-1 receptor on T cells, while Roche ( RHHBY) is working on a similar drug known as an anti-PDL-1 antibody.

The potent, tumor-killing efficacy of these drugs across many different types of tumors -- lung, kidney, breast as well as skin cancer -- is generating a lot of buzz at this year's American Society of Clinical Oncology (ASCO) annual meeting.

Yervoy and nivolumab could generate peak sales of $6 billion for Bristol-Myers, analysts and investor surveys indicate. The blockbuster potential for this new crop of cancer immunotherapy has been a big contributor to the 41% increase in Bristol-Myers' stock price this year. Bristol-Myers shares closed Friday at $46.01.

More data on Merck's drug, known as lambrolizumab, will be released Sunday morning at the ASCO meeting.

In the phase I study, 107 patients with advanced, stage IV melanoma were treated with five different doses of Bristol-Myers' nivolumab. Twenty-five percent of the patients had already been treated with three or more prior therapies, and 63% had two or more.

Overall, 31% of the nivolumab-treated patients reported clinically meaningful tumor shrinkage. The median overall survival across all nivolumab doses was 16.8 months and 43% of patients were still alive at two years of follow up.

The study lacked a control arm so the nivolumab survival data cannot be compared directly against another drug or a placebo. However, Yervoy typically produces tumor shrinkage rates of 5-10% and a median overall survival of 10 months in patients with advanced melanoma.

Seventeen melanoma patients in the study were treated with a 3 mg of nivolumab, which Bristol-Myers has already identified as the most effective dose to use in phase III studies already underway. The overall response rate in these patients was 41% with a median overall survival of 20.3 months.

Long-term follow-up results from early-stage studies of nivolumab in non-small cell lung cancer and kidney cancer are being presented on Monday at the ASCO annual meeting.

Bristol-Myers is also investigating the combination of nivolumab and Yervoy. In one early-stage study, the two-drug combination produced a tumor shrinkage rate of 50 percent in melanoma patients.

Merck and Roche will also be presenting updates results on their respective PD-1 and anti-PDL-1 drugs during the ASCO meeting.

-- Reported by Adam Feuerstein in Chicago.

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Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback; click here to send him an email.

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