The 2022 Tandem Meetings | Myeloablative conditioning regimen with PTCy in elderly patients with AML and MDS
Uday Popat, MD, The University of Texas MD Anderson Cancer Center, Houston, TX, comments on the results of a study exploring the possibility of delivering a myeloablative conditioning regimen in elderly patients with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) (NCT02250937). In this study, patients were given smaller doses of busulfan over the course of a few weeks, and then received either tacrolimus and methotrexate or post-transplant cyclophosphamide (PTCy) as graft-versus-host disease (GvHD) prophylaxis. The study showed that patients treated with PTCy experienced lower non-relapse mortality (NRM) and significantly reduced the incidence of severe acute GvHD. This interview took place at the Transplantation & Cellular Therapy (TCT) Meetings of ASTCT™ and CIBMTR® 2022 in Salt Lake City, Utah.
Transcript (edited for clarity)
So, let me give the background of the study. Transplant is really done to prevent relapse or recurrence of the disease. And what has been well known is you can reduce recurrence by giving higher intensity conditioning or myeloablative conditioning. I think the challenge is this is not suitable for older patients, so we took on the challenge of developing a regimen, a myeloablative regimen, that can be given to older patients with the idea that the myeloablative regimen will reduce relapse rate and will improve their overall outcomes...
So, let me give the background of the study. Transplant is really done to prevent relapse or recurrence of the disease. And what has been well known is you can reduce recurrence by giving higher intensity conditioning or myeloablative conditioning. I think the challenge is this is not suitable for older patients, so we took on the challenge of developing a regimen, a myeloablative regimen, that can be given to older patients with the idea that the myeloablative regimen will reduce relapse rate and will improve their overall outcomes.
Traditionally the conditioning regimen is given over a four-day period. We said, “Why do it a four-day period? Why not split it over two-week or a three-week period?” And so, we started giving outpatient doses of busulfan, about a third of it, say one week and two weeks prior. And what we saw was, with this, we were able to deliver Myeloablative doses of chemotherapy.
Now, our initial studies were done with tacrolimus and methotrexate as graft-versus-host disease prophylaxis. What we found in early studies was that our day 100 mortality was 4% to 6% in older patients, as old as 75. However, one-year mortality was 20%. And the reason for this difference was we saw a lot of data in one way or the other related to graft-versus-host disease. So, seeing very encouraging data on post-transplant cyclophosphamide in preventing graft-versus-host disease and reducing severe acute graft-versus-host disease in the haploidentical transplant setting, we said if the same thing could apply to matched donor transplant.
So, we amended our ongoing trial of a fractionated busulfan regimen. The first 29 patients got traditional tacrolimus methotrexate, but the subsequent patients received post-transplant cyclophosphamide. And so, this abstract compares these two particular sequential cohorts. And what we find is that we reduce severe acute graft-versus-host disease, which results in lower non-relapse mortality. In fact, the one-year non-relapse mortality in PTCy group is 6%, almost unheard of, and patients are as old as 70 included in this trial. So, we think with our fractionated busulfan regimen, addition of post-transplant cyclophosphamide reduces relapse further, and this translates into better overall survival.
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