After an unprecedented multi-year bull run, biotech is facing headwinds once again. Drug companies have become a target in an election year, putting pricing strategies under a microscope. Valuations have tumbled, drying up a fertile ground for IPOs. Yet biotech innovation continues apace, particularly in Boston. Gene editing has taken the scientific world by storm, and may soon reach human clinical testing. New ways of harnessing the immune system to battle cancer are being unlocked. Investments in neuroscience, long a drug development minefield, have picked up. And local venture firms are armed with new funds to spend on startups.