REUTERS: Gilead Sciences Inc said on Wednesday its experimental fixed-dose combination treatment for HIV proved as effective in a late-stage study as the company's widely used Truvada combo pill but with significantly less loss of bone mineral density and kidney function. The company has already sought U.S. and European marketing approval for the new combo pill nicknamed F/TAF, which is meant to be a safer replacement for Truvada, a cornerstone of HIV treatment that has been associated with slight declines in bone mineral density and kidney function.