** UK-based drugmaker's shares up 1.8 pct at 1528.16pence on the London Stock Exchange; U.S.-listed shares up 2.11 pct at $46.92 premarket
** Company says melanoma drug, which combines two of GSK'sapproved treatments, significantly reduced risk of death inpost-approval study
** The drug, COMBI-d, was approved in January last year totreat patients with advanced melanoma that cannot be removed bysurgery
** Up to Thursday's close, company's stocks had fallen 5 pctin London and 11 percent in New York in the past 12 months