Vertex Pharmaceuticals (VRTX -0.04%) has been one of the hottest growth stocks to own within the healthcare industry. The company has a dominant cystic fibrosis (CF) business, and it has been expanding into other areas as well. Last year, Vertex's shares rose by just under 41%, easily outperforming the S&P 500, which increased by a still-respectable 24%.Can this biotech continue rallying after posting its latest earnings numbers, or has it become too expensive?Vertex's growth rate is slowing downOn Feb. 5, ...