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C.S. is co-inventor of the patented AMIAT technology. C.S. and C.P.H. are both employees of imusyn GmbH & Co. KG.

INTRODUCTION: Administration of anti-CD38 antibodies is a state-of-the-art therapy for patients diagnosed with multiple myeloma. However, treatment with the currently approved anti-CD38 antibodies regularly results in widespread agglutination of red blood cells in indirect anti-human globulin tests (IAT), making the determination of irregular antibodies and timely transfusion of compatible blood a challenge.

Mezagitamab, a novel monoclonal anti-CD38 antibody, is currently under clinical investigation, not only for the treatment of multiple myeloma but also for other indications such as generalized myasthenia gravis.

METHODS: We tested mezagitamab against a range of test cells in the IAT and compared its interference to daratumumab. Additionally, we titrated mezagitamab to see if interference is likely to occur at the expected serum levels. Finally, we tested if DaraEx, a reagent containing Fab fragments of an anti-CD38 antibody, was able to eliminate the interference in the antigen masking indirect anti-human globulin test (AMIAT).

RESULTS: Mezagitamab also interferes with the indirect anti-human globulin test, with comparable titers but weaker reaction strengths than daratumumab. DaraEx is able to completely overcome this interference in the AMIAT.

CONCLUSIONS: Mezagitamab is likely to become a challenge for diagnostic laboratories once it will have been approved by the medical authorities. DaraEx treatment remains a simple and effective way to mitigate the interference of anti-CD38 antibodies.