One pundit warns of apparent manufacturing issues with the company's melanoma drug.No investor likes it when one of their stocks is hit with a recommendation downgrade from an analyst. That was the dynamic behind Iovance Biotherapeutics' (IOVA -2.16%) more than 2% decline in value on Monday. A onetime Iovance bull has considerably cooled on the stock, and this triggered a bit of a sell-off for the biotech.Biotech bluesWell before market open today, Piper Sandler's Joseph Catanzaro reduced his recommendation ...