Eli Lilly and Co. and Bristol-Myers Squibb Co. stopped enrolling new patients in a clinical trial of an experimental lung cancer drug over concerns about patients developing blood clots, the companies announced Wednesday morning.

The Phase 3 trial of necitumumab gave that drug in combination with Alimta, Lilly’s existing lung cancer drug, and cisplatin, a generic chemotherapy agent, to patients with advanced non-small lung cancer of a type called nonsquamous.

Lilly will continue to study necitumumab in a separate Phase 3 clinical trial, where it is being given in combination with Lilly cancer drug Gemzar and cisplatin. The patients in this second trial have non-small lung cancer of a different type, called squamous.

While stopping enrollment in one of the two Phase III trials is disappointing, the ... Phase III study of necitumumab in lung cancer continues," said Dr. Richard Gaynor, Lilly’s vice president of oncology product development, in a statement.  "Lilly remains committed to developing new medicines that can help treat this devastating disease."

Lilly and Bristol-Myers Squibb are sharing development costs of necitumumab and any potential revenues from the drug in United States, Canada and Japan. Lilly has exclusive commercialization rights in all other countries.

Lilly has had numerous drugs fail or be delayed in Phase 3 clinical trials over the past two years. The company is struggling to launch new drugs that can produce sales to offset a string of five blockbuster drugs that are beginning to face competition from generic copies as their patents expire over the next several years.

Those patent expirations could sap roughly $10 billion in annual revenue from Lilly’s books.