Investors should brace for dilution.Iovance Biotherapeutics (IOVA -0.19%) investors received great news earlier this year when the U.S. Food and Drug Administration granted it accelerated approval for the company's cell therapy treatment for advanced melanoma, Amtagvi. It gives the business a crucial product to build its operations around.Growth investors were initially bullish on the news, but in recent months, the stock has started to struggle. While there is a lot more optimism surrounding the company, i ...