ORLANDO – Posttransplant cyclophosphamide may be superior to conventional immunosuppression as graft-versus-host disease prophylaxis, according to findings presented at the annual meeting of the American Society of Hematology.
A phase 3 trial showed that posttransplant cyclophosphamide (PT-Cy) reduced graft-versus-host disease (GVHD) without affecting relapse. Rates of acute and chronic GVHD were significantly lower among patients who received PT-Cy than among those who received conventional immunosuppression (CIS). Rates of progression/relapse, progression-free survival, and overall survival were similar between the PT-Cy and CIS arms.
These results suggest PT-Cy provides a “long-term benefit and positive impact on quality of life” for patients undergoing allogeneic hematopoietic stem cell transplant, according to Annoek E.C. Broers, MD, PhD, of Erasmus Medical Center Cancer Institute in Rotterdam, the Netherlands. Dr. Broers presented the results during the plenary session at ASH 2019.
The trial enrolled 160 patients with leukemias, lymphomas, myelomas, and other hematologic malignancies. All patients had a matched, related donor or an 8/8 or greater matched, unrelated donor.
The patients were randomized to receive CIS (n = 55) or PT-Cy (n = 105) as GVHD prophylaxis. The CIS regimen consisted of cyclosporine A (from day –3 to 180) and mycophenolic acid (from day 0 to 84). Patients in the PT-Cy arm received cyclophosphamide at 50 mg/kg (days 3 and 4) and cyclosporine A (from day 5 to 70).
Baseline characteristics were similar between the treatment arms. The median age was 58 years in the CIS arm and 57 years in the PT-Cy arm. A majority of patients were men – 63% and 67%, respectively.
Two patients in the CIS arm received myeloablative conditioning, but all other patients received reduced-intensity conditioning. Most patients in the CIS arm (67%) and the PT-Cy arm (70%) had a matched, unrelated donor. All patients in the CIS arm and 96% in the PT-Cy arm received peripheral blood cell grafts.
PT-Cy significantly reduced the cumulative incidence of acute and chronic GVHD. The incidence of grade 2-4 acute GVHD at 6 months was 48% in the CIS arm and 32% in the PT-Cy arm (P = .014). The incidence of chronic extensive GVHD at 24 months was 50% and 19%, respectively (P = .001).
There were no significant between-arm differences for any other individual endpoint assessed.
“With a median follow-up of 3.2 years, so far, there’s no difference in the cumulative incidence of progression or relapse, nor is there a difference in progression-free or overall survival,” Dr. Broers said.
At 60 months, the rate of relapse/progression was 32% in the PT-Cy arm and 26% in the CIS arm (P = .36). The rate of nonrelapse mortality was 11% and 14%, respectively (P = .53).
At 60 months, the progression-free survival was 60% in the CIS arm and 58% in the PT-Cy arm (P = .67). The overall survival was 69% and 63%, respectively (P = .63).
In addition to assessing endpoints that “determine the success of our transplant strategy,” Dr. Broers said she and her colleagues also looked at a combined endpoint to account for “the effect GVHD has on morbidity and quality of life.” That endpoint is GVHD- and relapse-free survival.
The researchers found that PT-Cy improved GVHD- and relapse-free survival at 12 months. It was 22% in the CIS arm and 45% in the PT-Cy arm (P = .001). PT-Cy conferred this benefit irrespective of donor type, Dr. Broers noted.
Overall, the incidence of adverse events was somewhat higher in the PT-Cy arm (60%) than in the CIS arm (42%). The incidence of infections also was higher in the PT-Cy arm (41%) than in the CIS arm (21%), and this was largely caused by a greater incidence of neutropenic fever with PT-Cy (25% vs. 15%).
The study was funded by the Dutch Cancer Society, and Novartis provided the mycophenolic acid used in the study. Dr. Broers reported having no conflicts of interest.
SOURCE: Broers AEC et al. ASH 2019, .