FDA says to review side effect of GSK's multiple myeloma drug

LONDON, July 9 (Reuters) - The U.S. Food and Drug Administration on Friday said it would review GlaxoSmithKline's experimental treatment for multiple myeloma, a common form of blood cancer, for a reported side-effect which affects the eyes of patients.

Approval for belantamab mafodotin is seen as important for GSK's growing oncology portfolio, and it is currently being assessed by the U.S. drug regulator.

If approved, the drug could be a rival to Johnson & Johnson and Genmab's Darzalex treatment.

The FDA on Friday published submissions ahead of a meeting of the Oncologic Drugs Advisory Committee (ODAC) on July 14, where they will evaluate how belantamab mafodotin can cause keratopathy, a side-effect where deposits gather on the cornea of the eye.

"The concerns and uncertainties regarding the ocular toxicities raises questions about the overall benefit-risk profile of the belantamab mafodotin in the proposed patient population," a briefing document published on the FDA's website said.

"The FDA seeks input from the committee on whether the demonstrated benefit of belantamab mafodotin outweighs the risks in the proposed patient population with multiple myeloma."

In its mid-stage study DREAMM-2, nearly 100 patients were given the belantamab mafodotin at the dosage for which GSK has submitted for approval.

Of those patients, 27% experienced medically severe ketatopathy. One patient discontinued treatment due to the side effect but no patients experienced life threatening symptoms.

The trial was testing the drug, also known as GSK2857916, in patients who had received four to seven prior other treatments, including drug Darzalex.

GSK is confident in the benefit/risk profile of the drug, and believe it can be managed through modifying or interrupting the course of treatment.

GSK has other trials planned aimed at showing its benefits in earlier stages of treatment. (Reporting by Alistair Smout)