Sam Rasty, chief operating officer of Homology Medicines (NASDAQ: FIXX), is leaving to join Platelet BioGenesis as president and CEO. In a securities filing, Bedford, MA-based Homology said Rasty’s last day will be July 12. Before joining Homology in 2016, Rasty was vice president and head of new products at Shire. Homology, a developer of genetic medicines, raised $144 million in an IPO last year. Cambridge, MA-based Platelet BioGenesis is developing a way to produce platelets from stem cells.