US drugmakers Pfizer Inc and Nektar Therapeutics on Wednesday warned of cases of lung cancer in clinical trials of their inhaled insulin Exubera.
The findings led Nektar to announce it was abandoning its search for a new marketing partner for the troubled drug, effectively signaling Exubera's demise after entering the market in January 2006.
Pfizer, the world's largest pharmaceutical company, announced last October it stopped marketing Exubera, saying it did not meet customer needs or the financial expectations of the company.
The rise in lung cancer apparently linked to Exubera led Pfizer to update the medication's warning label to include information "about lung cancer cases observed in patients who used Exubera," the company reported in a statement.
It said that over the course of the clinical trial, six out of 4,740 Exubera-treated patients developed lung cancer, versus one of the 4,292 patients not treated with Exubera.
An additional case of lung cancer in an Exubera-treated patient was discovered after the drug's debut on the market following its approval by the US Food and Drug Administration.
The updated label states that all patients who developed lung cancer had a prior history of cigarette smoking, and that there were "too few cases to determine whether the development of lung cancer is related to the use of Exubera."
"Some patients continue to take Exubera, including those enrolled in extended transition programs or clinical trials," Pfizer chief medical officer Joe Feczko said in the statement.
"We are working closely with patients and their physicians to ensure the continued orderly transition from Exubera to alternative therapies," he added.
Nektar announced it was stopping all spending on the drug, including research and marketing.
"The concern over this new data analysis from ongoing clinical trials has resulted in the termination of all negotiations with potential partners," said Nektar president Howard Robin on the company's website.
Diabetes affects 230 million people worldwide, including 21 million in the United States, according to Pfizer. Exubera is a short-acting insulin breathed in through an inhaler that helps control high blood sugar in people with diabetes.