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Pfizer Lung Cancer Drug Hits Target

Pfizer's crizotinib targets a specific genetic mutation to boost response in lung cancer patients.

Follow all the action from the American Society of Clinical Oncology (ASCO) annual meeting in real time at Adam Feuerstein's ASCO live blog.

CHICAGO (

TheStreet

) --An experimental

Pfizer

(PFE) - Get Report

drug targeting a specific genetic mutation in lung cancer shrank tumors in more than 50 percent of patients with advanced disease, according to results from an expanded, early-stage study.

Researchers on behalf of Pfizer are presenting data from the phase I study of the drug, known as crizotinib, at Sunday's plenary session of the

American Society of Clinical Oncology

(ASCO) annual meeting.

Based on the positive results so far, Pfizer has already started a pivotal phase III study testing crizotinib in patients with advanced non-small cell lung cancer.

Drugs completing early phase I studies don't typically get top billing at the ASCO meeting. Crizotinib is an exception because the drug exemplifies the promise of personalized medicine in which drugs can be developed that target specific genetic variations in a tumor. This can help doctors identify and tailor treatment to patients who will benefit most from the highly targeted drug.

Crizotinib works by tamping down an enzyme known as anaplastic lymphoma kinase (ALK) that helps cancer cells grow. The ALK enzyme is produced when two genes, including ALK, are fused together. About one in 20 lung cancer patients have so-called ALK-positive tumors, according to Pfizer.

The phase I study enrolled 82 patients with advanced non-small cell lung cancer containing the ALK gene fusion. After treatment with crizotinib, 57 percent of patients reported clinically significant tumor shrinkage. When patients with tumors that stopped growing or shrank less were included, the overall disease control rate was 87 percent in the study.

"Many of these patients had received three or more prior treatments, and we would expect only about 10 percent to respond," said lead investigator Dr. Yung-Jue Bang, professor at Seoul National University College of Medicine in Seoul, Korea. "These results are quite dramatic, and represent an important improvement over what we would see with standard chemotherapy for patients with metastatic disease."

Understanding the role that the ALK gene plays in tumors accelerated the development of crizotinib and allowed Pfizer to advance the drug from a phase I study in 2007-2008 to a pivotal phase III study in 2009, says Dr. Mace Rothenberg, senior vice president of clinical development at Pfizer Oncology.

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"We've been talking about personalized medicince for more than 10 years. It's a tough thing to do, but when you can identify specific subsets of patients based on the biology of a tumor, you can develop therapies most likely to help them."

Abbott Laboratories

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is working with Pfizer to develop a test that can detect the presence of the ALK gene fusion in patients. Armed with the test, doctors can determine which patients are most likely to benefit from crizotinib.

The challenge for Pfizer and Abbott, however, will be to convince the U.S. Food and Drug Administration to approve crizotinib and the ALK gene test simultaneously.

"The FDA is not really set up to do this sort of thing, so we're forging new relationships at the agency to make sure everyone is on the same page," said Pfizer's Rothenberg.

Pfizer began the phase III study of crizotinib in second-line lung cancer patients in December 2009. The study expects to enroll about 320 patients.

Pfizer estimates that there are between 7,500 and 10,000 ALK-positive lung cancer patients in the U.S, with about 40,000 such patients worldwide.

-- Reported by Adam Feuerstein in Boston.

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Follow all the action from the American Society of Clinical Oncology (ASCO) annual meeting in real time at Adam Feuerstein's ASCO live blog.

Adam Feuerstein writes regularly for TheStreet.com. In keeping with TSC's editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet.com. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback;

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