H.C. Wainwright analyst Debjit Chattopadhyay says the resignation of ImmunoGen (IMGN) CFO David Johnston after the executive was found guilty for civil securities fraud has little to do with the execution of his current responsibilities, but a reflection of his tenure with Aveo Pharmaceuticals (AVEO) pharmaceuticals between 2007 and 2012. Given that a potential guilty verdict was always a possibility, the analyst anticipates a potential replacement "in the not so distant future." With ImmunoGen having made "significant strides" over the past five years, and now closer to commercialization with mirvetuximab Phase 3 readout anticipated during the first half of 2019, any potential replacement might come with prior oncology commercialization experience, and might be a better fit with future needs of the company, Chattopadhyay tells investors in a research note titled "Water Under the old AVEO Bridge." He admits, however, that the resignation is publicity ImmunoGen "could have done without." Chattopadhyay keeps a Buy rating on ImmunoGen with an $18 price target.