Rocket Pharmaceuticals Pulls FDA Filing for Rare Blood Disorder Gene Therapy

A Rocket Pharmaceuticals gene therapy has reached the end of its regulatory journey before receiving an FDA decision. The company has withdrawn the submission for its therapeutic candidate for Fanconi anemia, a rare inherited blood disorder.

The voluntary withdrawal of the biologics license application (BLA) for mozafancogene autotemcel, known in development as RP-L201, follows a previously announced corporate reprioritization, the company said in a Friday regulatory filing. In July, Cranbury, New Jersey-based Rocket restructured operations, laying off about 30% of staff and turning the firm’s focus to cardiovascular programs it said offer the opportunity for creating near- and long-term value. With the restructuring, Rocket ceased any new internal spending on RP-L102 and withdrew the therapy’s regulatory submission in Europe.

In Fanconi anemia, the bone marrow does not create healthy blood cells and platelets, putting patients at greater risk of developing blood disorders and certain types of cancer. Treatments include drugs that stimulate the production of red and white blood cells. Another option is a bone marrow transplant.

RP-L102 is an ex vivo gene therapy made by using a lentiviral vector to modify a patient’s own stem cells early in the course of the disease. In a pivotal Phase 2 study, results showed eight of 12 evaluable patients maintained sustained genetic correction. The therapy was well tolerated. In the Friday regulatory filing, Rocket said its decision to withdraw the BLA was a business and strategic move and does not reflect any concerns about the safety or efficacy of RP-L102.

In a note sent to investors, Leerink Partners analyst Mani Foroohar said Rocket’s move was unsurprising as the company previously signaled deprioritization of RP-L102 and the broader lentiviral portfolio. Even so, Foroohar said there was some optimism that the Fanconi anemia gene therapy could be placed with a partner during or after the FDA’s review, as it would have given another company a commercial-ready asset.

“Management confirmed partnership discussions are ongoing, though BLA withdrawal signals tepid interest in lentiviral assets broadly,” Foroohar said.

Going forward, much of Rocket’s attention will focus on RP-A501, its gene therapy candidate for Danon disease, a rare inherited disorder that weakens heart muscle and leads to heart failure. This past May, Rocket reported a clinical trial fatality that was believed to be associated with a drug used as part of the pretreatment regimen for the gene therapy in the Phase 2 study. In August, the FDA lifted the clinical hold it had placed on the program; Rocket said it would proceed with a lower dose of RP-A501 and would no longer use the drug in the pretreatment regimen believed to have contributed to the patient death.

In Rocket’s report of second quarter 2025 financial results, the company said its cash position was $271.5 million as of June 30. Rocket expects this capital will last into the second quarter of 2027. That financial projection excludes potential regulatory approval of Kresladi, a gene therapy for leukocyte adhesion deficiency-I (LAD-I), a rare inherited immune disorder that makes children susceptible to recurrent bacterial and fungal infections that can become life-threatening.

Last June, the FDA turned down the BLA submission for Kresladi and asked for more information regarding chemistry, manufacturing, and controls. In the quarterly report, Rocket said it expects to resolve these issues by the end of 2025. Approval of Kresladi in LAD-I could come with a priority review voucher, which Rocket would be able to sell to bolster its finances.

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