Despite reporting a Phase 3 win this summer, Pfizer terminated its hemophilia A gene therapy pact with Sangamo Therapeutics in a move that cast a pall on the California biotech’s future.
In response to Monday’s news about giroctocogene fitelparvovec, Sangamo’s shares $SGMO tumbled about 50% in Tuesday morning trading.
The struggling biotech said earlier this month that it had just enough money to make it to the middle of 2025 after inking a potentially company-saving deal with Astellas. Its financial future is now far less certain. Sangamo had still expected up to $220 million more in regulatory and commercial milestones from Pfizer as part of their tie-up, which began in 2017 with $70 million upfront.
Sangamo said Monday it will seek out “all options to commercialize” the gene therapy, including finding a new partner.
“While we were surprised and extremely disappointed by Pfizer’s decision to end our collaboration so close to the anticipated BLA and MAA submissions, especially given the compelling pivotal clinical trial data, we appreciate their collaboration in leading a robust and successful clinical development program and for advancing the asset to this important stage,” Sangamo CEO Sandy Macrae said in a statement.
Pfizer’s pullback occurs just weeks after it presented more data from the Phase 3 study at the American Society of Hematology’s annual meeting.
The New York pharma giant, which got two hemophilia drugs approved this year, attributed the deal’s termination to market factors, an “extensive analysis” of clinical data, feedback from experts and “the slow uptake of hemophilia A gene therapy in patients with moderate-to-severe disease,” a spokesperson said in an email.
Earlier this year, Pfizer received FDA approval for Beqvez, its hemophilia B gene therapy, and Hympavzi, a once-weekly medicine for hemophilia A or B.
“We believe there is limited interest in an additional gene therapy option in this patient population at this time,” the spokesperson added.
The other gene therapy in question is BioMarin’s Roctavian, which has had a patchy uptake since being approved in August 2023 and has since led the drugmaker to reconsider its commercial plans for the gene therapy. At the time of Sangamo and Pfizer’s Phase 3 readout in July, questions circled around whether the duo could make a mark in the field given Roctavian’s precedent.
Roche also recently terminated a Phase 3 trial for a hemophilia A gene therapy, though it said it’s working on a new candidate.
Meanwhile, Sangamo said it needs more money to finance a Phase 1/2 study next year for ST-503 for idiopathic small fiber neuropathy and to move a prion disease program forward. It also said it’s in “advanced business development discussions” surrounding its Fabry gene therapy program.

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