US FDA places clinical hold on Regenxbio’s rare disease program

Jan 28 (Reuters) – Regenxbio said on Wednesday the U.S. Food and Drug Administration has placed a clinical hold on two of its experimental gene therapy programs for rare childhood diseases, sending its shares plummeting 30% premarket.

The company’s experimental gene therapy RGX-111 was placed on clinical hold after a brain tumor was found in one trial participant, the company said.

The tumor was discovered during a routine brain scan of a five-year-old child who had received the treatment about four years earlier, the company said.

RGX-111 is being developed as a treatment for Hurler syndrome, a rare autosomal recessive lysosomal storage disorder. It is estimated to occur in 1 in 100,000 births.

Another therapy, RGX-121, being developed as a one-time treatment of MPS II or Hunter Syndrome, was also put on clinical hold by the FDA citing similarities between the two programs and a potentially shared risk.

“We are surprised by FDA’s decision to place our RGX-121 program on hold while the investigation of this single, inconclusive incident in RGX-111 continues,” said Curran Simpson, CEO of Regenxbio.

The company said no other tumors have been reported among the nine other patients treated with RGX-111, or among 32 patients treated with RGX-121.

The company said it has not yet received the full clinical hold letter and awaits additional details from the FDA.

(Reporting by Padmanabhan Ananthan in Bengaluru; Editing by Shailesh Kuber)