Can Belantamab mafodotin cause macro LDH?

Belantamab mafodotin (Belamaf), an anti-BCMA antibody-drug conjugate (ADC), is indicated for relapsed/refractory multiple myeloma (RRMM). This retrospective, single-center study evaluated 40 RRMM patients who received ≥2 Belamaf cycles between July 2019 and December 2024. Following treatment initiation, 27 patients (67.5%) exhibited elevated lactate dehydrogenase (LDH) levels. Six patients underwent comprehensive clinical evaluation and were diagnosed with Macro-LDH. LDH levels declined following Belamaf cessation in all affected individuals. Multivariate analysis revealed that a higher cumulative number of Belamaf cycles was significantly associated with elevated LDH (OR 1.11, 95% CI 1.0-1.2, p = 0.045). This study provides the first report of potentially Belamaf-associated Macro-LDH formation. Awareness of this benign phenomenon is essential to prevent unnecessary diagnostic investigations, thereby reducing patient burden and healthcare costs.