These are all reasonable options. There are no direct comparisons, so the preferred option for me would depend at least in part of patient combordities and ability to tolerate these regimens. Starting with Carbo/Gem may give the patient an extra line of therapy, and if the patient has a response or stable disease, then maintenance Avelumab would be an option that has shown a solid median overall survival of 21 months (from start of Avelumab, so it would be even longer from start of Carbo/Gem). However, Carbo/Gem could be challenging in terms of tolerability for many patients in their mid/late 70s, so patient fitness for chemotherapy should be carefully considered. Furthermore, there is the current carboplatin shortage in the United States, which may factor into things when there are non-carboplatin alternatives. Pembrolizumab/Enfortumab combination is appealing as well given the high response rates and recent long-term (4 year follow-up) data from EV-103 presented at ASCO reported a median overall survival of 26 months. We do not know if Pembrolizumab/Enfortumab combination is better than sequential Pembrolizumab followed by Enfortumab vedotin, so if the patient is wary of excess side effects, Pembrolizumab alone is a reasonable option. However, if the patient is symptomatic from disease or has a large burden of disease in which there may be a need to maximize chance of response, I would favor combination therapy Pembrolizumab/Enfortumab over Pembrolizumab monotherapy.