Momenta Pharmaceuticals

(MNTA) - Get Report

shares fell Tuesday after the biotech company announced the Food and Drug Administration rejected its abbreviated new-drug application for a drug to treat and prevent blood clots.

The agency sent the company's partner Sandoz, a division of

Novartis

(NVS) - Get Report

, a non-approvable letter that said the application didn't adequately address the potential for immunogenicity of Enoxaparin Sodium Injection, a generic form of Lovenox.

The companies said the FDA recommended they meet with the office of generic drugs to determine what additional information could address the concern.

"We believe that we can address what we anticipate to be the FDA's concerns, based on our detailed characterization of enoxaparin and on the current medical and scientific literature,'' said Chief Executive Craig Wheeler.

Momenta fell $6.58, or 49%, to $6.80, and Novartis gained 47 cents, or 0.9%, to $53.04.