BioCryst Pharmaceuticals and Presidio Pharmaceuticals have called off a proposed merger, the companies announced Friday.

BioCryst (Nasdaq: BCRX) and Presidio, which is based in San Francisco, said “terminating the merger was in the best interest of both companies and their respective shareholders at this time.”

The deal had been proposed in October.

“The termination of the transaction has been approved by the Boards of both companies,” BioCryst said in a statement.

“In association with the termination, both parties will release each other from all obligations with respect to the proposed transaction. Each company will bear its own legal and transaction fees.”

Presidio is a clinical stage specialty pharmaceutical firm focusing on antiviral therapeutics.

BioCryst recently terminated a Phase 3 trial of an intravenously administered influenza treatment for which it has received nearly $235 million in federal funding.