US drugmakers Pfizer Inc and Nektar Therapeutics warned on Wednesday 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.