Biotechnology company MannKind Corp. said Thursday that it is suspending partnership discussions for its inhalable insulin drug candidate following Pfizer Inc.'s warning of a potential lung cancer risk for its own inhaled insulin drug.
MannKind said it believes that Technosphere Insulin, which is in late stage trials, will not be valued appropriately until data confirms that the drug is safe and effective. The company said it plans to continue its clinical trials.
On Wednesday, Pfizer said it updated the U.S. product labeling for Exubera Inhalation Powder to include a warning about lung cancer cases observed in patients who used the inhaled insulin treatment.
Over the course of Exubera's clinical trial program, six of the 4,740 patients treated with Exubera developed lung cancer, compared with 1 of the 4,292 patients not treated with the drug. There was also a post-marketing report of lung cancer in one Exubera-treated patient.
On Thursday, MannKind noted that Pfizer said all patients who developed lung cancer had a prior history of cigarette smoking, and that there were too few cases to determine whether the cancer is related to use of Exubera.
MannKind said preclinical studies of Technosphere, including a two-year carcinogenicity study in rats, have not shown a cancer risk. The company said it also recently completed a six-month carcinogenicity study in mice that are prone to cancer. MannKind said it plans to complete its analysis later this quarter but has not seen evidence of cancer in animals treated with the drug for 26 consecutive weeks.
Also, MannKind said its clinical program has not shown a higher incidence of lung cancer in Technosphere patients than expected in the general population.
MannKind also has faced questions about the market viability of inhaled insulin. Pfizer discontinued Exubera in October 2007 after lackluster sales. Last month, Alkermes Inc. said its partner Eli Lilly and Co. planned to stop development of its experimental AIR inhaled insulin.
MannKind shares gained 3 cents to $2.38 early Thursday.