How would you treat a patient with metastatic NSCLC on pembrolizumab with a sustained complete response, now with 2 isolated small liver lesions?

I am unaware of any "level 1" evidence for this approach, much of our data is anecdotal, however there is certainly reasonable experience of treating "oligo-progressive" disease with local therapies.  While there is more experience in adrenal and CNS metastatic disease, I would think that a local therapy option for hepatic progressive disease is reasonable.  The choice of therapy (RFA or SBRT) would be a discussion in tumor board, and dependent (to some extent) on local expertise, anatomy, and similar considerations.  I would probably continue Pembrolizumab after completion of local therapy, presumably to complete two years, and assuming that all disease continued to be controlled at that time, would have a discussion of stopping therapy with close monitoring.