Novartis AG's deal with Enanta Pharmaceuticals Inc. gives the pharma two angles for targeting HCV that act directly and indirectly against the non-structural protein 5A. The combination of Enanta's direct inhibitor with the pharma's alisporivir cyclophilin inhibitor, which blocks the host protein's interaction with NS5A, should tamp down resistance better than either alone.

The pharma paid $34 million up front last month for exclusive, worldwide rights to Enanta's EDP-239, which has an open IND with FDA and is ready to begin Phase I testing. The biotech is eligible for up to an additional $406 million in milestones, plus tiered double-digit royalties.