Despite the obvious preclinical anti-tumor effects of PD-1 blockade and positive results from earlier trials in MM, phase III clinical trials involving combination therapy of PD-1 blockade with IMiDs were placed on hold by the FDA in 2017 due to increased rate of adverse effects observed in KEYNOTE-183 (NCT02576977) and KEYNOTE-185 (NCT02579863) [79]. This evidence concerns the gene PDCD1 and neoplasm.