I assume that IDIX has a right to reject any offer from NVS that it deems unsatisfactory.
That’s correct. If NVS had had zero interest in licensing IDX184, they presumably would’ve just said so and saved IDIX from wasting time negotiating. (This is what NVS did with IDX899, the HIV drug that was subsequently licensed to GSK.)
Still, NVS’ interest in Debio 025 makes it somewhat more puzzling to me that NVS did not make a strong enough offer to secure IDX184.