SNY is defending its turf and NVS is cautiously invading; that's the only rough philosophy I can come up with to explain the apparent NVS malaise toward pricing.
NVS is (at least at launch) supply constrained - able to supply less* than half of the demand. It would be a waste to try and take more market share than they can supply. It would also reduce sales to both products if greater discounts were offered by NVS. Aggressive price competition in this situation is a lose/lose.