Britain's GSK seeks U.S approval for rival to J&J's multiple myeloma drug

(Reuters) - GlaxoSmithKline said on Monday it had applied for U.S. approval for its experimental multiple myeloma drug that showed meaningful response in nearly a third of patients, setting up a battle against Johnson & Johnson and Genmab's Darzalex.New data from the treatment, belantamab mafodotin, showed 30 of 97 patients experienced a reduction in their myeloma cells at the end of a mid-stage study, DREAMM-2.The trial was testing belantamab mafodotin, also known as GSK2857916, in patients..