Wells Fargo analyst Jim Birchenough notes that shares of Bluebird Bio have been under pressure following announced departure of the company's Chief Strategy Officer Jeff Walsh and more broadly on concerns regarding late stage programs for BCMA CAR-T therapeutic bb2121 and Lentiglobin gene therapy for beta thalassemia and sickle cell disease. Following his discussion with the company, the analyst believes the departure was planned for some time, represents a natural transition to requirements of a commercial stage company and has no read-through to outcome of bb2121 KarMMa Phase 3 for bb2121, ZYNTEGLO gene launch for beta thalassemia in Europe and expectations for LentiGlobin gene therapy in Sickle Cell Disease. Birchenough has an Outperform rating and $242 price target on the shares.