by W. Crews, M.D., Medical Director of Laboratory Services, Carter BloodCare
When DARZALEX® (daratumumab or DARA) was approved by the FDA in November 2015, the transfusion service/blood banking community was quickly front and center with the newest monoclonal antibody treatment. Shortly after receiving FDA approval, it was discovered that DARA caused interference with the antibody screen during pre-transfusion testing.
DARA is an anti-CD38 monoclonal antibody used in the treatment of multiple myeloma. CD38 is weakly expressed on the surface of red blood cells. Patients undergoing treatment with DARA who require an antibody screen will exhibit in vitro panreactivity due to DARA, in the patient’s plasma, binding to CD38 on the surface of reagent red blood cells.
Since CD38 is susceptible to dithiothreitol (DTT) treatment, it was determined these patients could be safely transfused by treating the screening red cells with DTT, which disrupts the CD38 protein on the red cell. DTT also destroys antigens in the Kell blood group; so, if the antibody screen was negative, red cell units negative for the K antigen should be issued.
Another way to mitigate the interference caused by DARA is to perform a phenotype or genotype prior to the patient beginning treatment. If the patient has already been started on DARA, a genotype can still be performed. Knowing the patient’s phenotype or genotype, and informing the blood bank that the patient is currently receiving DARA greatly reduces the turnaround time for providing crossmatch-compatible units.
Since December 2015, Carter BloodCare has performed over 150 workups on 53 patients while they were undergoing treatment with DARA. An abstract poster describing Carter BloodCare’s experience with DARA was presented at the 2016 AABB annual conference and can be viewed here.