Cutaneous Toxicities of T-Cell-Redirecting Therapies in Multiple Myeloma: An EADV Task Force Position Paper and...

T-cell-redirecting immunotherapies, including bispecific antibodies and chimeric antigen receptor (CAR) T-cell therapies, have rapidly become major treatment options of relapsed or refractory multiple myeloma but are associated with a distinctive spectrum of cutaneous toxicities. Dermatologic manifestations are particularly prominent with GPRC5D-targeting agents, reflecting on-target, off-tumor activity against hard-keratinizing tissues, whereas BCMA-targeted bispecific antibodies and anti-BCMA CAR T-cell therapies are associated with milder and less phenotypically distinct cutaneous adverse events. Despite their clinical relevance, these toxicities remain inconsistently reported, and standardized definitions and management strategies are lacking. This European Academy of Dermatology and Venereology (EADV) Task Force "Dermatology for Cancer Patients" position paper, developed in collaboration with hematology units experienced in multiple myeloma care, reviews the mechanistic basis, clinical spectrum, and grading of cutaneous toxicities associated with T-cell-redirecting therapies. We propose a phenotype-driven, stepwise management framework organized around 4 principal patterns - barrier dysfunction and hyperkeratotic disease, inflammatory cutaneous eruptions, nail toxicity, and injection-site reactions- incorporating preventive strategies, baseline dermatologic assessment, and grade-adapted treatment algorithms.