The power on Pembro! don't leave home without it (in head and neck cancers)!

Why not combine Pembrolizumab and Methotrexate in head and Neck cancer
and break them up into HPV positive and negative. There is reason to believe this combination would be just as powerful as any Cisplatin based treatment.

Wikipedia
"
Pembrolizumab (Trade name Keytruda formerly lambrolizumab;^[1]also known as MK-3475) is a drug marketed by Merck that targets the programmed cell death 1 (PD-1) receptor. The drug is intended for use in treating metastatic melanoma.^[2][3] Pembrolizumab was invented by Gregory Carven, Hans van Eenennaam and John Dulos at Organon Biosciences which later became Schering Plough Research Institute and then Merck & Co. ^[4]
On September 4, 2014 the US Food and Drug Administration (FDA) approved Pembrolizumab as a breakthrough therapy. It is approved for use following treatment with ipilimumab, or after treatment with ipilimumab and a BRAF inhibitor in patients who carry a BRAF mutation.^{[5]"   and "}Methorexate  acts by inhibiting the metabolism of folic acid.^[3] Methotrexate began to replace the more toxic antifolate aminopterin starting in the 1950s. The drug was originally synthesised by the Indian biochemist Yellapragada Subbarow and clinically developed by the American paediatrician Sidney Farber.^[6][7]
It is on the World Health Organization's List of Essential Medicines, a list of the most important medications needed in a basic health system.<sup>[8]'

Givem the relative tolerance of these two medications, one must surmise this combination of treatment to be the most tolerable yet effective in disease that seems so virally driven!  We are at the gate of excitement in cancer reaserch and cancer target therapy has just began!
The thing is treatment of locally head and neck cancer has left us hanging,   most people who treat this disease will notice that at the end of radiation  treatment most patient are left with residual mass.  And you keep scratching yourself...should we give additional chemotherapy, watch, of have some form of maintenance therapy?
A lot of patient end up being watched...would maintenance with pembro help survival  ?  How about Pembro+Methotrexate?</sup>