i would think that if DCVax-L ie approved, even if Merck owns the company, I don't think they could refuse to sell it unless Keytruca is bought at the same time. On the other hand, if they actually created a third product which combined DCVax-L and Keytruda, that would be a new drug and they'd have patent coverage for the new product. Even with that, I don't know that they could refuse to sell the DCVax-L by itself.
Gary