PARPi would fall into my proven drug category. Still, it is theoretical not proven in clinic. Data from several PARPi in combination with anti-PD1 had been presented, it is mixed but interesting nevertheless. It wasn’t as apparent as anti-PD1 in combination with chemo/TKI based on earlier data. It might take time to work or find right indications and settings etc, but definitely worth of exploring further. MRK deal with AZN on PARPi probably was a lower risk bet on PARPi beyond monotherapy alone.
The thing with TKIs is that they tend to be cytostatic rather than cytotoxic
I think most people now believe there is cell killing with TKIs too. When you disrupt the mutation driving the cancer apoptosis may kick in. even without the cell killing causing release of neoantigens TKIs are so effective when there is large tumor burden that they can potentially be used to debulk the tumors initially before checkpoints. I've read that this is often the case when deciding between a TKI and PD-1 for BRAF mutated melanoma for example if you don't think the patient can wait for the checkpoint to start working
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