Hi all, 

I'm a fairly new tech and I have a question regarding testing methods on patients that are actively on DARA. My hospital currently uses gel as its primary testing method. DARA patients, of course, are panreactive 1-2+ throughout both in the ABSC and the ABID panel. My current policy is to perform a DTT-treated screen and treat units if they need a transfusion. We provide K matched units and perform AHG XMs on treated RBCs. Many of these patients are surprise patients and there is frustration from providers when we tell them that the work up will take a few hours. 

 

I never want to jeopardize patient safety, however, I'm wondering if there is a more efficient way to work up patients on DARA. Is it possible to repeat the ABSC in tube using both PEG and LISS? I have found that some PEG and LISS screens are negative. Would having 2 negative ABSCs in tube support that the reactivity in gel is interference from DARA? 

My experience with DARA patients is panagglutination with tube testing, both in LISS and PEG. This may be manufacturer dependent. For a first time patient we need to serologically explain the gel reactivity even if the tube was negative. For subsequent visits negative reactivity in tube would be sufficient. I suggest you discuss with your pathologist to see what they are willing to accept. Other BB have different policies with regards to DARA patients, which I hope will be described.    

We have educated our multiple myeloma specialists to send a type and screen before administering the first dose of a daratumumab (Darzalex).  Our standard operating procedure is to have a panel of three cord blood cells (we have a large OB service) that is a laboratory developed test of sorts.  Cord cells do not express CD38 at interfering levels.

As it turns out we have made more of an issue of this than it warrants.  Patients who have negative antibody screens essentially never develop new antibodies to red cells after being started on daratumumab probably because it potential inhibits B cells function.  Minimal B cell function apparently yields little ability to make antibodies to red cell antigens, which are relatively weak alloantigens, especially when there is no adjuvant or inflammation in the recipient.  That said, a manufacturer is making a soluble CD38  analog that will inhibit the anti-CD38 activity and make testing easier from what I've read.  DTT treatment is also reasonable.  But the good news is that patients on this drug do not make new antibodies. There are literature references to this, and we have probably tested about 500 patients with no new alloantibodies. Mostly non-transfused patients, obviously.

Once our patients show panreactivity in GEL, we automatically switch them to PEG screens which are negative 95% of the time.  We stop doing gel all together.

We don't test with DTT treated cells until the PEG screen comes up pos.  Then, if the screen is NEG with DTT treated cells, we give K neg units with a signed release.

@Bet'naSBB Thank you. This is what I think our workflow should be as well. I’ll consult with management.

We sometimes find them negative in PEG.  If that or a DTT treated screen is negative, we give units as electronic crossmatched (K matched if DTT used).  Anti-CD38 is not a clinically significant antibody, and we have a negative DTT screen we can turn out which makes the computer happy. 

On 4/29/2025 at 7:46 AM, Neil Blumberg said:

a manufacturer is making a soluble CD38 analog that will inhibit the anti-CD38 activity and make testing easier from what I've read.  

Can we purchase this in the US yet?  What company is making it?

Not yet available. Being developed by Grifols.  Probably months to a year away from FDA approval.  You can contact them about becoming a testing site for licensure I'd guess.  Until it's licensed you won't be able to use it in patient care, just research/validation.

Is anyone performing their patient testing as described in the attached paper? Uses a lower concentration of DTT in gel that does not denature Kell, Lutheran, Cartwright, and JMH antigens but yet still eliminates the panagglutination due to anti-CD38.

DTT gel testing (DARA) New Method.pdf

oops

Edited June 27Jun 27 by SbbPerson
error

I have never understood why we are using DDT instead of trypsin? I do realize that DDT is somewhat easier to use than trypsin, but the Kell problem is eliminated. M & N require looking at, but I will take that trade. In the Southeast we also look out for Jsb as quite a few Jsb- people live here.

11 hours ago, jtemple said:

I have never understood why we are using DDT instead of trypsin? I do realize that DDT is somewhat easier to use than trypsin, but the Kell problem is eliminated. M & N require looking at, but I will take that trade. In the Southeast we also look out for Jsb as quite a few Jsb- people live here.

Um, sorry Jason, but I think you mean Dithiothreitol (DTT), rather than Dichlorodiphenyltrichloroethane (DDT)!!!!!!!

What? All this time I have been using the wrong stuff! Ha! SPELL CHECK IS NOT YOUR FRIEND! 🤣🤣🤣🤣