PDCD1 and acute myelomonocytic leukemia M4: Yet, ICI mechanisms of action have proven complex and many theories explaining non-response or hyperprogression have been developed, including ‘tumor-intrinsic PD-1 signaling.’ Kim et al. [13] reported a case of acute myelomonocytic leukemia (AMML) after three cycles of pembrolizumab for NSCLC.