Combining chemo & immuno in the treatment of metastatic head&neck canc

Have recent been diagnosed with stage 4 metastatic tonsil cancer that has spread bilaterally to the lymph nodes. A pet scan revealed a lesion on my sternum, so radiation was ruled out. I have had consultations with two medical oncologists, both of whom agree that immunotherapy, in particular Keytruda, may give the best chance of longer term control and possible remission with fewer debilitating side effects even though it is not yet common to use as a first line treatment.

One medical oncologist has proposed keytruda together with carboplatin and abraxine, arguing that immuno alone is insufficient, while the other suggests keytruda alone, stating that the toxicitity of combining both may be too high to tolerate and that the benefits of combining both are unproven.

I am relatively symptom free and physically strong (so far) so I am more inclined to go for a more aggressive treatment initially but I would like to hear any comments or advice others here may have.

FYI, my treatment will be in Singapore as I am an American residing in this part of the world and my insurance doesn't cover treatment in the US.