The blockade of MCT4 expression has been shown to represent a novel treatment target in glioblastoma, large B‐cell lymphoma, and multiple myeloma.25, 26, 27 For these reasons, and because MCT4 has the capacity to alter the microenvironment in tumors, we felt we had a compelling reason to investigate the effect of MCT4 on NK cells. This evidence concerns the gene SLC16A3 and AL amyloidosis.