PTC Therapeutics Inc. has signed an exclusive global license and collaboration agreement with Novartis Pharmaceuticals Corporation, a subsidiary of Novartis AG, for its PTC518 Huntington’s disease program, which includes related molecules.   Under the agreement, PTC will receive an upfront payment of $1.0 billion, up to $1.9 billion in development, regulatory and sales milestones, a profit share in the U.S., and double-digit tiered royalties on ex-U.S. sales.   “PTC518 is the lea...