Cutaneous Toxicities of Anti-GPRC5D Bispecific Antibodies for Multiple Myeloma: Retrospective Study.

Talquetamab, a bispecific antibody, has a high efficacy in multiple myeloma (MM), with common dermatologic adverse events. We aim to describe the real-world burden of cutaneous toxicities. A retrospective study of MM patients treated with talquetamab between March 2021 and February 2026. Demographic and clinical data were extracted from electronic health records. Cutaneous, nail, and mucosal toxicities attributed to talquetamab were recorded. Of 32 patients (mean age 61.4 years; 59.4% male), 28 (87.5%) developed cutaneous adverse events. A total of 87 dermatologic events were recorded. Most frequent manifestations were exanthema (37.5% of cutaneous events), xerosis (33.3%), and palmoplantar involvement (46.9% of patients). Nail toxicity affected 75% of the cohort, predominantly onychomadesis. Mucositis affected 34.4%, with a tendency to occur earlier compared with cutaneous and nail toxicities. Dermatologic evaluation was associated with therapeutic management of adverse events (95.8% vs. 69.9%, p = 0.0098). No patient required permanent talquetamab discontinuation due to mucocutaneous toxicity. Median time to resolution was 50 days. Talquetamab is associated with a high burden of mucocutaneous toxicity. Early dermatologic assessment enables accurate diagnosis and effective management. These findings expand the clinicopathological spectrum of talquetamab toxicity and highlight the importance of interdisciplinary care.