US FDA advisers to determine need for more studies of Vertex/CRISPR gene therapy

By Sriparna Roy

(Reuters) -The U.S. Food and Drug Administration’s staff reviewers on Friday asked the regulator’s advisory panel to consider the need for additional studies for Vertex Pharmaceuticals and CRISPR Therapeutics’ sickle cell disease gene therapy.

The therapy, called exagamglogene autotemcel or exa-cel, uses new gene editing CRISPR technology, and is the first-of-its-kind product to reach the FDA for an approval decision.

The FDA’s reviewers said this type of gene editing raises concerns about “off-target” unintended genomic alterations, and can potentially cause other side effects. They, however, did not raise any concerns about the therapy’s efficacy.

The small genetic sample size used in the therapy’s lab analysis may not be sufficient for safety assessment as that did not capture the diversity of the entire U.S. population for sickle cell disease, the FDA staff said.

They said it was not clear if the analysis conducted by the company to assess the off-target risk was adequate.

The FDA appears to be focusing on the risks around the technology, said RBC analyst Luca Issi. He said the FDA’s concerns appeared benign and expects additional studies only after the therapy is approved.

Vertex and CRISPR Therapeutics are seeking to gain approval for the therapy to treat the inherited red-blood-cell disorder that causes the cells to become sickle-shaped due to abnormal levels of hemoglobin in the body.

If approved, the therapy will potentially offer patients a one-time treatment option, versus frequent blood transfusion or once-daily drugs such as Pfizer’s Oxbryta.

An independent panel is set to meet on Tuesday to discuss the off-target analysis and if additional lab studies are needed.

The FDA will decide on the therapy’s use in patients aged 12 years and older by Dec. 8.

Shares of CRISPR Therapeutics and Vertex were flat in early trading.

(Reporting by Sriparna Roy in Bengaluru; Editing by Shinjini Ganguli)