Merck & Co. has agreed to acquire auto immune drug developer Pandion Therapeutics for US$60 per share, representing a total transaction value of US$1.85 B and a notable 134% premium over Pandion’s share price before the deal was announced. Pandion’s lead candidate, PT101, is an engineered IL-2 mutein fused to a protein backbone designed to selectively activate and expand regulatory T cells for the potential treatment of ulcerative colitis and other autoimmune diseases.