Investors are misunderstanding when the biopharma company's flagship drug will begin generating meaningful reportable revenue.Iovance Biotherapeutics (IOVA -19.07%) shares are down to the tune of 18% today following Thursday evening's release of its first-quarter numbers. The sell-off clearly suggests investors didn't like everything they heard. The knee-jerk response to the news, however, looks past a critical detail regarding the report.An irrelevant quarterly reportIovance Biotherapeutics did $715,000 wo ...