CD38 and Miyoshi myopathy: Daratumumab treatment can also cause transient downregulation in CD38 expression and heterogenous responses.[32] As a result, there are efforts underway to improve daratumumab efficacy by increasing CD38 expression using treatments such as ATRA.[11, 12] In a proof‐of principle study to investigate the potential of [68Ga]Ga‐AJ206 to non‐invasively evaluate therapy induced changes in CD38 expression, we first treated four MM cell lines with ATRA and measured changes in CD38 expression.