Daratumumab is an investigational human CD38 monoclonal antibody used to treat patients with Multiple Myeloma. When initially testing my patient I thought the patient only had Rouleaux due to the multiple myeloma. I used the saline replacement technique which cleared up the patients 3 cell screen in immediate spin and 15 minutes using LISS. The AHG phase cells tested were all 1 plus. The solid phase panels showed no clear pattern with most donor cells being positive.
I was informed later that all red cells being tested must be DTT treated in order to prevent false positives. This includes the screening cells and red cells cross matched to the patient. All units given to the patient must be kell negative since DTT destroys the Kell antigen. This is a time consuming process. DTT treated screening cells do not last long (7 days). Further investigational studies are needed to extend DTT treated cells such as using red cell diluent.
Our lab has been given pheno-matched units which is time consuming and expensive as well. The blood bank must maintain a good dialogue with the hematologist performing these drug studies to adequately supply the patients with blood. Ideally one would phenotype the patient before the patient starts the daratumumab study or received blood within 90 days. The blood bank would know when the patient is being admitted into the hospital so that pheno-compatible units are available. Recently I have been asked if Daratumumab patients are DAT positive. 5 patients on Dara therapy were reviewed and found to be DAT negative. Some were positive using solid phase but were negative poly AHG.