ASH 2025 | Predicting donor engraftment success post-haploidentical transplantation in patients with SCD

Robert Nickel:

Our particular study used research samples from the BMT CTN 1507 clinical trial, which was a multi-center study looking at a reduced intensity, haploidentical transplant regimen for sickle cell disease. And what we were particularly interested in looking at was to see if we could use a novel assay to evaluate engraftment in this cohort of patients. And we do have a way of monitoring chimerism or engraftment in patients clinically, but we were using this novel assay to see if it could tell us something different and new and potentially be used to complement existing clinical donor chimerism testing. 

Joshree Shrestha:

So yeah, in our lab, we did correlative studies. Apart from clinical studies going in parallel, we did chimerism based on molecular level. We used something called HFA assay, that is molecular-based assay where we’re using HLA antigens to detect pre and post transplant to see if the donor-based lymphocyte chimerism is there post transplant in patient. And with this method with the HFA assay that we did in our lab, it’s a novel method, we optimized it and we translated it. We saw out of 33 patients 31 engrafted, which also we saw that clinically, and in two patients we saw one secondary graft failure, which was confirmed to be secondary graft failure clinically and one problematic engraftment where we saw depletion in T-cells and NK-cell chimerism, which also we saw that clinically as well. So our assay, on a molecular level, seems to be a little bit more precise for early detection is what our conclusion was. 

Robert Nickel:

Yeah, so importantly, our assay correlated, you know, very well with the expected clinical results, but it potentially allows us to identify patients who may be evolving to have graft failure or at risk for graft failure earlier than conventional testing, which could allow for interventions to be done to save those patients who they don’t have graft failure. Because we only had two patients in the entire cohort that had problematic engraftment, the study is a little bit limited, you know, given that low number, so it needs to be kind of further studied in larger populations. This was just the adult cohort. We also are looking at it in the pediatric stratum of the trial, which did unfortunately have a slightly higher rate of graft failure.

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