GSK Plc shares tumbled after its blood cancer drug failed to secure the backing of a panel of US regulatory advisers, putting its approval in doubt.

The British pharmaceutical company said combinations for its Blenrep drug were evaluated in adults with relapsed or refractory multiple myeloma who have previously received at least one line of therapy.

The U.S. FDA's panel of independent advisers on Thursday recommended against GSK's blood cancer drug Blenrep, citing concerns about previously documented risks of eye-related side effects, sending the British drugmaker's U.