Here's why a gene therapy product originally developed at CHOP spinout Spark Therapeutics was shelved by Pfizer.

Pfizer (NYSE:PFE) has decided to end R&D and marketing activities related to Beqvez, a one-time gene therapy the company has developed with Roche’s (OTCQX:RHHBY) (OTCQX:RHHBF) Spark Therapeutics for hemophilia B,

Pfizer said on Thursday it will end global development of its hemophilia gene therapy, Beqvez, citing soft demand from patients and their doctors. Beqvez was approved in the U.S. last year, for the treatment of adults with moderate to severe hemophilia B.