Optimizing transfusion management of multiple myeloma patients receiving daratumumab-based regimens

Risk of new alloimmunization in patients on anti-CD38 treatment using tube LISS-IAT method

BACKGROUND

Daratumumab is a monoclonal antibody that targets CD38, a transmembrane protein expressed on many cells including RBCs and to a greater extent on myeloma cells. It has been used for treatment of multiple myeloma and autoimmune diseases. Transfusion management of patients on such therapy can be challenging as these drugs cross-react with RBC surface antigens and cause panreactivity.

MATERIAL AND METHODS

A retrospective study of the 68 patients treated with anti-CD38 from 2018-2023 was carried out. Data regarding transfusion history and antibody screens were analyzed. Depending whether they had immunohematological work-up before or during the treatment- DAT, antibody screen (CAT and tube), RBC pheno/genotyping and serologic cross-matches (CAT and tube) were performed for each patient. All cases with positive CAT IAT were retested in LISS-tube and cross-matches were performed with phenotypically matched units in LISS-tube.

RESULTS

Antibody screen has shown panagglutination with all panel cells with low and variable agglutination intensity (weak to 2 +). Panagglutination remained positive for 1 - 6 months after drug cessation. Positive DAT was seen in 60,6% patients, while autocontrol was negative. Ficin treated panel-cells eliminated nonspecific reactivity. LISS-tube antibody screen and cross-matches were negative for all patients, apart from 3 patients who had preexisting antibodies. No new antibodies were detected during the course of the study.

CONCLUSION

Among study group there were no newly identified alloantibodies, meaning that the policy of transfusing them with matched RBCs and performing IAT/cross-matches in tube is a safe and effective policy according to the findings of this study.

Long-term storage protocol of reagent red blood cells treated with 0.01M dithiothreitol (DTT) for pre-transfusion testing of patients receiving anti-CD38 therapy, daratumumab

OBJECTIVE

Use red blood cell stabilizer to store the antibody screening and antibody identification reagent red blood cells (RBCs) treated with 0.01 mol/L DTT and investigate its value in the pre-transfusion examinations of patients treated with daratumumab.

METHOD

Determined the optimal incubation time for the 0.01 mol/L DTT-treated RBCs method by evaluating the effect of treatment at different time points. Added ID-CellStab to store DTT-treated RBCs, determined the maximum shelf life of reagent RBCs by monitoring the hemolysis index, and assessed changes in the antigenicity of blood group antigens on the surface of RBCs during storage with antibody reagents.

RESULT

A protocol for long-term storage of reagent red blood cells treated with the 0.01 mol/L DTT method was established. The optimal incubation time was 40-50 min. RBCs could be stored stably for 18 days after adding ID-CellStab. The protocol was able to eliminate pan-agglutination caused by daratumumab, with no significant changes in the antigens of most blood group systems, except for some attenuation of K antigen and Duffy blood group system antigens during the storage period.

CONCLUSION

The storage protocol of reagent RBCs based on the 0.01 mol/L DTT method does not affect the detection of most blood group antibodies and retains a certain degree of detection ability for anti-K antibodies, allowing patients treated with daratumumab to quickly perform pre-transfusion examinations, making up for the shortcomings of currently commercial reagent RBCs.

Case report: Daratumumab treatment in pre-transplant alloimmunization and severe hemolytic anemia

Daratumumab, a CD38 monoclonal antibody that has been FDA-approved to treat multiple myeloma, has acquired popularity and is used off-label for both auto- and alloantibody mediated disorders, particularly in refractory/resistant circumstances. Much of the published data for its use in pediatric blood disorders has been in post-transplant autoimmune cytopenias. Here we describe three patients in whom daratumumab was used outside of post-transplant autoimmune cytopenias, highlighting further potential uses of this medication.

Efficient neutralization of daratumumab in pretransfusion samples using a novel recombinant monoclonal anti-idiotype antibody

BACKGROUND

Anti-CD38 antibodies such as daratumumab (DARA) are critical therapies for multiple myeloma and other diseases. Unfortunately, anti-CD38 antibodies cause panreactivity in indirect antiglobulin tests (IATs), complicating blood compatibility testing. The anti-CD38 interference is most often mitigated by treating reagent red blood cells (RBCs) with dithiothreitol (DTT). However, when using the DTT method, not all RBC antibody specificities can be detected (e.g., anti-K), and the DTT method is impractical for some transfusion services. We evaluated the ability of a new anti-idiotype antibody to neutralize DARA in vitro and eliminate the anti-CD38 interference.

STUDY DESIGN AND METHODS

A recombinant monoclonal rabbit anti-DARA idiotype antibody ("anti-DARA") was generated. The ratio of anti-DARA required to neutralize DARA in spiked samples was evaluated in IATs performed in gel. IATs performed in tube were used to demonstrate that anti-DARA allows alloantibody detection in the presence of DARA. Plasma samples from 29 patients receiving DARA were treated with a fixed quantity of anti-DARA (120 μg) before performing antibody detection tests (screens) in tube.

RESULTS

Anti-DARA used at or above a 1:1 ratio with DARA eliminated the DARA interference with IATs. Anti-DARA allowed detection of both alloanti-E and alloanti-K in the presence of DARA. In 27/29 (93.1%) clinical samples, 120 μg anti-DARA was sufficient to neutralize the DARA in 100 μl patient plasma.

DISCUSSION

An anti-DARA:DARA ratio as low as 1:1 is sufficient to neutralize DARA in solution. A fixed amount of anti-DARA eliminates the anti-CD38 interference in most patient samples.