Rocket Pharma shares fall despite FDA nod for childhood disorder treatment

By Kamal Choudhury

March 27 (Reuters) - Rocket Pharmaceuticals' RCKT.O shares tumbled over 20% to a one-month low on Friday as investors focused on potential hurdles to uptake for its gene therapy, which won a first-of-its-kind approval in the U.S. to treat a rare and often fatal immune disorder in children.

The shares had initially risen over 10% on the news.

The drug, Kresladi, is indicated for severe Leukocyte Adhesion Deficiency-I, which prevents white blood cells from reaching infection sites, leaving patients vulnerable to serious diseases.

There had previously been no treatment approved by the U.S. Food and Drug Administration specifically for the disease. About 75% of untreated patients die before the age of two unless they receive a stem cell transplant.

BofA analyst Jason Zemansky said that although the approval is a clear win for patients, investors are disappointed as practical hurdles may limit the number of patients treated. "But that shouldn’t detract from Rocket’s accomplishments," he said.

Wedbush analyst Yun Zhong called the share price reaction "unwarranted," suggesting the decline may be tied to the management's comments that the company does not plan to actively market Kresladi.

Rocket said it plans a limited phased launch and the drug is expected to be commercially available in the fourth quarter of 2026 at a small number of specialized treatment centers.

The company is engaging with insurers ahead of the launch to secure reimbursement, but has not yet disclosed prices.

Jefferies analyst Andrew Tsai said the selloff likely reflects "not everyone being super aware" that the approval was never meant to drive meaningful sales.

The FDA granted accelerated approval for the therapy on Thursday, based on a surrogate endpoint measuring improved immune cell function.

The decision comes under Vinay Prasad, the FDA's head of biologics who is set to leave the agency at the end of April, and has previously expressed skepticism toward surrogate endpoints.

The approval also includes a Rare Pediatric Disease Voucher, which companies can sell or use to expedite review of another drug.