IWG-MRT-ECNM response criteria for advSM. Normalization of 1 or more signs of hematologic and/or nonhematologic SM-related organ damage defines clinical improvement (CI). Refer to the published criteria (³⁶ ) that define the type and severity of SM-related organ damage that is eligible for CI assessment as well as specific criteria for progressive disease (PD). The IWG-MRT-ECNM definitions of “eligible organ damage findings” are distinct from the WHO definitions of “C findings.” Attainment of partial remission (PR) and complete remission (CR) is based on increasing improvement of the serum tryptase level and BM MC burden. For CI, PR, and CR, response duration must be at least 12 weeks. *Changes in MC burden refer to the BM and/or extracutaneous organ(s). ANC, absolute neutrophil count; diff, differential; Hb, hemoglobin; PD, progressive disease; SD, stable disease.