(Recasts, adds quotes, analyst comment)
LONDON, July 10 (Reuters) - The U.S. Food and Drug
Administration said on Friday it was unclear whether the
benefits of GlaxoSmithKline's experimental treatment for a
common form of blood cancer outweigh the risks ahead of a review
of a side-effect which affects the eyes.
Approval for belantamab mafodotin as a treatment for
multiple myeloma, a rival to Johnson & Johnson and
Genmab's Darzalex treatment, is seen as important for
GSK's growing oncology portfolio.
In submissions ahead of a meeting of the Oncologic Drugs
Advisory Committee (ODAC) on July 14, the FDA said it had
concerns about how belantamab mafodotin can cause deposits to
gather on the cornea, known as keratopathy.
The FDA highlighted the frequency of the side effect, its
severity, the lack of clear mitigation strategies and incomplete
data on whether it is reversible.
GSK is confident in the benefit/risk profile of the drug,
and proposes it should be managed through modifying or
interrupting the course of treatment.
"There is uncertainty whether the proposed dose modification
strategy is sufficient to mitigate the risks," a briefing
document published on the FDA's website said.
"It is not clear whether the benefit outweighs the risks of
ocular toxicity."
Broker Jefferies said that while it was usual for the
document to flag contentious issues, "our confidence is dented
by FDA's remarks".
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
keratopathy. 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 Darzalex.
GSK has other trials planned aimed at showing its benefits
in earlier stages of treatment.
(Reporting by Alistair Smout; Additional reporting by Ankur
Banerjee; Editing by Alexander Smith)
Glaxosmithkline (GSK)