HOUSTON – Acute lymphoblastic leukemia patients with measurable residual disease (MRD) negativity prior to hematopoietic cell transplantation achieve better outcomes than do those who are MRD positive, particularly when total body irradiation (TBI)–based conditioning is used, a large retrospective study suggests.
Dr. Arnon Nagler
Of 2,780 ALL patients who underwent hematopoietic cell transplantation (HCT) in first or second complete remission (CR), and who were included in the study, 1,816 were MRD negative before transplantation and 964 were MRD positive.
Overall, with follow-up of 40-44 months, MRD positivity was a significant independent predictor of lower overall survival (OS; hazard ratio, 1.19), leukemia-free survival (LFS; HR, 1.26), and higher relapse incidence (RI; 1.51), Arnon Nagler, MD, reported at the Transplantation & Cellular Therapy Meetings.
Conditioning was TBI-based in 76% of the patients; when these patients were compared with those who received chemotherapy-based conditioning, they were found to have better OS, LFS, and RI (HRs, 0.75, 0.70, and 0.60, respectively), said Dr. Nagler, director of both the division of hematology and the bone marrow transplantation and cord blood bank at the Chaim Sheba Medical Center, Tel-Hashomer, and professor of medicine at Tel Aviv University, both in Israel.
“There was no significant interaction between the MRD status and the conditioning,” he said.
On multivariate analysis, MRD positivity was found to be associated with lower OS and LFS (HRs, 1.26 and 1.3), and higher RI (HR, 1.53) in the TBI group, and with higher RI (HR 1.58) in the chemotherapy group, he said. There was no significant association between MRD and other outcomes in this last cohort, he added, noting that TBI-based conditioning was associated with improved OS, LFS, and RI in both MRD-negative and MRD-positive patients.
“MRD is an extremely important prognostic factor for ALL,” he said, noting that its prognostic value in this setting has been established in multiple studies, and that MRD measured at the end of induction is increasingly used to guide further therapy.
However, although MRD detectable immediately before HCT is known to be associated with poor outcomes, it has been unclear if – or to what extent – this differs with different types of conditioning, he added.
“So the aim of this study was to explore if MRD detectable before allogeneic HCT for ALL is associated with different outcomes in adult patients receiving myeloablative conditioning, either TBI or chemotherapy based,” he said at the meeting held by the American Society for Blood and Marrow Transplantation and the Center for International Blood and Marrow Transplant Research.
At its meeting, the American Society for Blood and Marrow Transplantation announced a new name for the society: American Society for Transplantation and Cellular Therapy (ASTCT).
Patients included in the analysis had a median age of 38 years and underwent HCT between 2000 and 2017 using sibling or unrelated 9/10 or 10/10 matched donors. None received blinatumomab or inotuzumab, Dr. Nagler said, adding that more patients are likely to achieve MRD negativity with these agents.
It will be interesting to see if the prognostic value of MRD will remain as strong with the new agents, and if TBI will be “a strong factor in overall survival and disease-free survival” with modern immunotherapy, he concluded.
The study was conducted on behalf of the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation (EBMT).
Dr. Nagler reported having no relevant financial disclosures.
SOURCE: Nagler A et al. TCT 2019, Abstract 7.