FDA hands Kamau Therapeutics RMAT designation for sickle cell therapy nula-cel

The FDA granted RMAT designation to nula-cel, Kamau's investigational stem cell medicine for sickle cell disease, the South San Francisco company said. The decision rests on preliminary clinical evidence from the ongoing Phase 1/2 RESTORE trial. Nula-cel already carries Fast Track and Orphan Drug designations.

In RESTORE, all three patients treated with the optimized manufacturing process hit transfusion independence with no vaso-occlusive events, according to Kamau. The two patients past the six-month follow-up mark show sickle hemoglobin below 20% — under the 30% threshold guidelines target for stroke prevention — with a predominantly adult hemoglobin profile.

RMAT status goes to regenerative therapies showing preliminary evidence they can tackle unmet needs in serious conditions. It buys designated treatments early and frequent FDA engagement, plus potential eligibility for priority review and accelerated approval.

"Pain crises matter, but between them, sickled cells continue damaging the body," said CEO Vali Barsan, MD, pointing to guidelines that call for exchange transfusions to keep sickle hemoglobin under 30% to prevent stroke. "We designed nula-cel to correct the root cause of sickle cell disease in a single treatment."

Chief Medical Officer Jacob Garcia, MD, said the designation opens the door to enhanced, more frequent FDA interactions. Kamau plans to request the comprehensive multidisciplinary RMAT meeting the agency recommended, aiming to align on a path to a registrational dataset, including possible priority review and endpoints for accelerated approval. More interim efficacy data from RESTORE is coming later this year.

Nula-cel works differently than therapies that induce fetal hemoglobin. It uses ex vivo homology-directed repair to correct the sickle mutation itself, converting it to the normal adult β-globin sequence, editing a patient's own long-lived stem cells outside the body and verifying each product's quality, identity, potency and safety before return. Because those cells self-renew, a single treatment is designed to deliver durable, potentially lifelong benefit.