Oyster Therapeutics said it raised $60 million in an extension of its Series A round to develop orally delivered protein degraders targeting pathogenic tau forms in Alzheimer’s disease. The program uses a linker strategy designed to split after entering the body to improve brain penetration and selectively degrade disease-causing tau while sparing healthy isoforms. The company did not disclose a clinical timeline, but the financing underscores continued investor focus on tau beyond amyloid, particularly as multiple tau-lowering approaches have yet to deliver meaningful cognitive benefits. Oyster positions its targeted degradation approach as a potential complement—or alternative—to existing tau biology programs. Strategically, the funding comes as investors weigh modality differentiation in neurodegeneration and the durability of tau-targeting effects across clinical populations. It also adds competitive pressure for next-generation tau degraders and oral brain-delivered mechanisms. For the sector, Oyster’s financing highlights how degraders remain a key platform bet—especially where traditional binding-based therapies face constraints from tau’s biology and limited conventional drug “nooks and crannies.”