Duke University Medical Center Durham, North Carolina, United States
Background/Case Studies: Daratumumab, an anti-CD38 monoclonal antibody used in the treatment of multiple myeloma, interferes with pretransfusion testing by binding to CD38 on reagent red blood cells. This binding causes panreactivity in antibody screens (ABSC), which can mask underlying alloantibodies and complicate compatibility testing. While interference during active treatment is well documented, its re-emergence after autologous stem cell transplant (ASCT) is less understood. This is especially complex when patients receive daratumumab during stem cell collection, discontinue treatment, and initially show a negative antibody screen before developing renewed reactivity post-ASCT. This case series explores this phenomenon of post-treatment anti-CD38 reemergence and its implications for transfusion management.
Study
Design/Methods: A retrospective chart review was performed at a single institution. Included patients had documented anti-CD38 reactivity persisting over 6 months after their last daratumumab dose and had undergone ASCT. Data included dates of daratumumab administration, stem cell collection and transplant, and changes in antibody screen results. Patients with incomplete records were excluded.
Results/Findings: Of 10 patients with complete data, 2 had negative antibody screens before ASCT followed by positive screens post-reinfusion. The remaining 8 were excluded: 6 (75%) had persistent interference due to recent therapy, and 2 (25%) received daratumumab throughout the peri-transplant period.
In the 2 included cases, one was antibody screen-negative for 1 week (3 days), and the other for 13 months (381 days) before ASCT. Both exhibited panreactivity in gel and PEG-based antibody screens post-transplant but were nonreactive with DTT-treated reagent cells, indicating anti-CD38 interference.
Additional testing of the newly positive antibody screens using group O pooled cord cells was also nonreactive. Testing patient red cells with plasma from ABO-compatible daratumumab-treated patients (negative DAT, no recent transfusions) also demonstrated nonreactivity, further confirming the reemergent panagglutination was due to anti-CD38 following ASCT. Reactivity resolved within an average of 9 days (7 and 11 days respectively). These findings suggest that hematopoietic progenitor cell products collected during daratumumab treatment can carry residual drug, leading to transient reappearance of serologic reactivity upon reinfusion.
Conclusions: In patients receiving daratumumab at time of stem cell collection, the medication can persist in the final stem cell product. Reinfusion of this product during autologous stem cell transplant may lead to a short-lived positive antibody screen, requiring anti-CD38 mitigation to facilitate subsequent serologic testing and RBC transfusions.
