Daratumumab: Therapeutic asset, biological trap!

Objectives: Recently, daratumumab has been included in the therapeutic strategies for myeloma patients. This molecule is an antibody directed against CD38, strongly expressed on plasma cells. Nevertheless, as CD38 is also present on erythrocyte membrane, daratumumab interferes with immunohaematological tests, complicating the selection of compatible blood.
Methods: A total of 14 patients treated by daratumumab have been followed in our transfusion laboratory. Among them, 11 have been transfused. Dithiotreitol (DTT) has been used to inhibit the daratumumab's interference, in the pre-transfusion tests (irregular antibody screening and cross-match).
Results: The red blood cell treatment with DTT has been very efficacious to inhibit the daratumumab's interference in 13 patients out of 14. Some precautionary measures had to be taken into account, especially the pH and the storage conditions. An extended pheno/genotype was an additional security element in the selection of compatible blood. To simplify and to optimize the laboratory practices, a decisional flow chart has been written.
Conclusion: DTT red blood cell treatment is very useful and efficacious in the pre-transfusion tests of patients treated with daratumumab. It allows to avoid the selection of blood bags only on the basis of an extended pheno/genotype, what is more secure and more ethical with respect to other at higher risk patients. A clear decisional flow chart allows a quality assurance gait. Collaboration with physicians is essential.
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