[TARC levels in lenalidomide-induced rash during multiple myeloma treatment].

Rash caused by lenalidomide, a key therapeutic agent for multiple myeloma (MM), often interferes with treatment continuation. This study investigated whether thymus and activation-regulated chemokine (TARC), a Th2-related chemokine, could serve as a biomarker for lenalidomide-induced rash. We evaluated patients treated with lenalidomide for MM at Takarazuka Municipal Hospital between January 2016 and October 2023. TARC levels were measured in patients who developed grade ≥2 rash. Clinical information, including blood test results, management of rash, and subsequent clinical course, was collected from medical records. Each episode was defined as one event consisting of three time points: before lenalidomide initiation, at rash onset (when TARC was measured), and at rash resolution. Fourteen events in eleven patients were analyzed. In all events, TARC levels were elevated at rash onset. In contrast, elevations in general inflammatory markers (white blood cell count, eosinophils, and C-reactive protein) or in lactate dehydrogenase, an indicator of atopic dermatitis, were observed in only a minority of events. These findings suggest that TARC may be a useful biomarker for identifying lenalidomide-induced rash and may aid in optimizing clinical management while maintaining treatment continuity.