Pfizer scraps Phase III melanoma drug trial

Shares fall 2 percent in wake of setback

Amy Swinderman
NEW YORK—Shares of Pfizer Inc. slumped last week following the company's announcement that it will discontinue a Phase III clinical trial of an experimental drug for advanced melanoma.

Pfizer discontinued its Phase III clinical trial of tremelimumab in patients with advanced melanoma after a review of interim data showed it was no better than standard chemotherapy, the company said in a statement.

Tremelimumab was thought to stimulate patients' immune systems to attack their tumors and had been shown to induce durable tumor responses in patients with metastatic melanoma in Phase I and II clinical studies. But the Phase III trial—called A3671009— compared tremelimumab to temozolomide, or standard chemotherapy, in patients with advanced melanoma and found it did not demonstrate superiority.

"Although this outcome is disappointing, Pfizer remains committed to investigating new treatment options for patients with melanoma," said Dr. Charles Baum, vice president of Pfizer Global Research and Development.

The study's full data is being analyzed, and more details are expected to be available at the upcoming American Society for Clinical Oncology Annual Meeting in June.

News of the setback sent Pfizer's shares down about 2 percent, to $20.90, from their New York Stock Exchange close of $21.38. Tempering the bad news, Pfizer also announced that its cholesterol drug Lipitor has shown surprisingly good results on patients with chronic angina. Shares soon recovered to $21.05.

Pfizer has experienced pipeline setbacks in other areas. In December 2006, the company discontinued development of torcetrapib, a drug that increases production of HDL, or "good cholesterol," after studies showed an increased risk of death. Pfizer has lost nearly $1 billion in investments on the failed drug, and as stocks plummeted, the company moved to accelerate cost cuts and search for partnerships and acquisitions to help boost future growth.

But this latest setback may have ramifications for a similar antibody called ipilimumab (MDX-010) that Princeton, N.J. biopharmaceutical company Medarex Inc. is developing with partner Bristol-Myers Squibb Co., according to some analysts. Shares in Medarex fell 18 percent following Pfizer's nixed the trial, depriving Medarax of potential royalties on sales.

"While there are a lot of differences between the two products, there are also a lot of similarities," Susquehanna Financial Group Analyst Jason Kolbert told Forbes. "As such, this news lowers our already low confidence that Medarex will be successful to file MDX-010 based on the current trial data."

Medarex responded with a statement clarifying that ipilimumab and tremelimumab are different molecules. The company also said three studies of its Phase II program were suggestive of its drug's potential for clinical anti-tumor activity, and its Phase III program is designed differently from Pfizer's trial. Medarex shares climbed about 2 percent shortly after it issued this clarification statement.

Medarex also said it is firmly moving forward with development of ipilimumab along with partner BMS.

But Kolbert and other analysts remain skeptical of Medarex's chances for success. In December, Medarex and BMS released results for ipilimumab studies that failed to meet endpoints to shrink tumors in at least 10 percent of the study's 155 patients. Patients also experienced serious side effects, including rashes, diarrhea and hepatitis.

"The Pfizer news plus MDX-010's own lackluster efficacy results and difficult side-effect profile are problems," Kolbert told Forbes. "We come to the conclusion that while a significant part of the ipilimumab program has already been written off by the Street, there is little reason to believe that this program will rebound in the near term."

Baum, who heads Pfizer's Oncology Therapeutic Area, said Pfizer also will not abandon tremelimumab.

"We continue to focus on additional studies involving tremelimumab alone and in combination with other therapies which are currently ongoing in patients with several types of cancer," he said. "We have a robust pipeline within Pfizer Oncology and we remain committed to the discovery and development of novel cancer treatments."

Amy Swinderman

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