Daratumumab is a wonder drug for multiple myeloma patients, but it can make blood transfusions a little tricky! By the end of this video from our Transfusion Medicine Essentials course, you'll understand how the anticancer drug, daratumumab, interferes with blood typing and the implications of this effect.
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[00:00:00] In recent years, a monoclonal antibody called daratumumab has emerged as a new treatment option for relapsed or refractory multiple myeloma. Daratumumab is directed against the antigen CD38, which is highly expressed in myeloma cells. However, CD38 is also weakly expressed on red blood cells. That is why the presence of daratumumab in the patient serum has a major influence on pre-transfusion testing.
[00:00:30] It interferes with reagent and donor blood cells used in antibody screening as well as in crossmatching and also may affect the results of a direct antiglobulin test. What we see in all three of these tests, in the presence of daratumumab, is agglutination even when it shouldn't be there. We call this panagglutination. So basically, we see false positive results. Two major problems arise from this interference. One is that panagglutination can mask the presence
[00:01:00] of clinically relevant alloantibodies, which in turn might induce serious transfusion reactions. The other problem is that procedures to eliminate these interferences lead to delays in issuing RBC units, which might also harm the patient. So what can we do about it? How can you help improve the situation? First of all, communication between the clinicians and the transfusion lab staff is essential. Current recommendations advised performing an array of tests on the myeloma patient’s blood samples before
[00:01:30] daratumumab therapy started. These tests include blood typing with an extended RBC phenotype or genotype, antibody screen, and direct antiglobulin test. The patient should also be provided with an alert card that states that he or she is a daratumumab patient. This card should be presented to every healthcare provider prior to any treatment. What happens if the patient needs a blood transfusion during therapy? In this case, the lab must be informed about the administration of their
[00:02:00] daratumumab, first, before the transfusion. Before performing any lab tests, the lab staff will then treat both the test and donor cells with the special chemical called DTT, which destroys CD38 on the cells. This should eliminate any interferences made by daratumumab. However, this is a time consuming and quite labor intensive procedure. So it's best to plan a patient's transfusion as early as possible to avoid any delays. If cell treatment with DTT does not
[00:02:30] work, you still have a positive crossmatch, but your patient urgently needs blood. You can alternatively order blood units that are matched not only according to the ABO and rhesus blood group but also other blood groups. That way there is a better chance that you will avoid immunization. However, this level of matching takes time, depends on the availability of specifically matched blood product and is more expensive. What happens after daratumumab therapy is discontinued.
[00:03:00] Since panagglutination can occur for up to six months after discontinuation of their daratumumab therapy, it is important to inform the lab staff that the patient had been previously treated with their daratumumab in this time period. A number of promising alternative options, for preventing the effects of daratumumab on agglutination which are simpler and faster than DTT treatment, are currently in the works but none of these are yet available for clinical use. Daratumumab is a promising new agent in the fight
[00:03:30] against myeloma. However, the downside is its interference with important pre-transfusion tests. So don't forget to plan ahead and communicate with your transfusion lab.