While smoking and lung cancer have always been closely linked, recent advances in research have begun to unravel the genetic code behind the disease. Pfizer is revolutionizing treatment for lung cancer patients by targeting the genetic mutations that cause a rare form of this disease called non–small cell lung cancer (NSCLC).
Xalkori (crizotinib), an oral medication used to treat ALK-positive patients with late-stage NSCLC, was approved by the FDA on Friday. In a teleconference on Tuesday, a team of Pfizer’s researchers and lung cancer specialists explained that even though the drug treats a limited number of lung cancer patients, the drug will only go to the patients who stand to benefit from the drug, thereby maximizing its efficiency by eliminating mass use of the drug in populations where it is not effective.
Estimates vary on exactly how many NSCLC patients exhibit the ALK mutation. Data presented at the American Society of Clinical Oncologists meeting earlier this year placed the estimate somewhere around 8%, while Pfizer’s estimates put that number closer to 3% to 5%. At the teleconference, Mark G. Kris, MD, chief of the Thoracic Oncology Service at Memorial Sloan-Kettering Cancer Center in New York City, said that between 6000 and 11,000 patients in the United States with the ALK mutation are diagnosed annually.
To identify which patients are best served by Xalkori, patients are required to undergo a genetic test. The Vysis ALK Break Apart FISH Probe Kit, developed by Abbott Laboratories, is the first test of its kind to identify patients with an abnormal ALK gene. The test will cost about $250 to administer to each patient, roughly in line with similar genetic testing kits, according to Garry Nicholson, President and General Manager of the Pfizer Oncology Business Unit.
Despite being able to only help a minority of lung cancer patients, the specialists at the conference suggested widespread testing. “I would caution against any kind of patient profiling,” Kris said. “I think, in general, you need to test everyone [with lung cancer].”
Representatives from Pfizer estimated that each month of therapy will cost a patient $9600. Patients take Xalkori orally twice daily. A maximum dosage has not been determined, but some patients who started taking Xalkori during clinical trials have been taking the drug for more than a year.
The drug’s approval was based on a number of encouraging studies. Earlier this year, the drug showed marked antitumor activity in a study presented at the 14th World Conference on Lung Cancer in Amsterdam. In early phase II results from the single-arm, open-label PROFILE 1005 trial, 51% of 133 patients who had undergone prior chemotherapy who were treated with crizotinib exhibited an overall response, including 1 patient who experienced a complete response. At 12 weeks into the trial, the disease control rate was 74%, indicating that a proportion of participants achieved stable disease, or partial or complete responses.
Further studies confirmed crizotinib’s effectiveness in treating patients with NSCLC. Two multicenter trials enrolling 255 patients with late-stage ALK-positive NSCLC demonstrated 50% and 61% median objective response rates and mediation duration of response of 42 and 48 weeks, respectively.
However, no one from Pfizer could provide any estimates on how Xalkori affects a patient’s overall survival. Mace Rothenberg, MD, Senior Vice President of Clinical Development, and Medical Affairs in the Oncology Business Unit at Pfizer, said studies to assess how the drug affects overall survival and progression-free survival are currently underway, but no data are available yet, as the trials are currently ongoing.