Abstract
Allogeneic marrow or peripheral blood stem cell transplantation (PBSCT) is the only curative treatment for myelodysplastic syndrome (MDS). Historically, transplantation for MDS has produced long-term disease-free survival rates of 30–40%, partially due to high procedural mortality (~40%) in this patient population. Although transplant outcomes in younger patients with low-risk disease have been favorable, inferior results are seen in older patients and those with more advanced disease. Evidence suggests that the lower transplant-related mortality (TRM) and improved graft-versus-leukemia seen with PBSCT may translate into improved clinical outcomes for MDS patients. Forty-four patients, aged 12–73 years (median 50) received a PBSCT from a matched related sibling donor (MRD). Patients aged <55 years, without prohibitive comorbidity, received myeloablative conditioning consisting of total body irradiation and cyclophosphamide, followed by a T cell depleted allograft and scheduled post-transplant donor lymphocyte infusions (MST, n=23). Patients ineligible for an ablative transplant due to age or poor health received reduced intensity conditioning (fludarabine and cyclophosphamide, melphalan, or busulfan) followed by a T cell replete allograft (n=21). Six patients had low-risk MDS (RA/RARS), while the majority of patients (86%) had advanced disease (RAEB [9], RAEBT [6], AML [13], therapy-related MDS [10]). Median follow-up is 15.3 (range 2–82) months. Patients with therapy-related MDS had a significantly lower survival rate due to a very high risk of relapse (figure). The actuarial probabilities of overall survival (OS), disease-free survival (DFS), relapse, and TRM were 64%, 59%, 26%, and 23% for primary MDS patients, and 51%, 47%, 40%, and 25% for the whole cohort. Transplant-related mortality in patients under 50 years of age was 11% vs. 45% in patients ≥50 years (p=0.03). OS and DFS were significantly better in recipients of MST (64%, 57%) than in patients receiving reduced-intensity PBSCT (33%, 34%), due to a higher risk of relapse in the latter group (55% vs. 29%, p=0.10). In nineteen patients <50 years receiving MST, actuarial probability of OS, DFS, relapse, and TRM were 81%, 72%, 23%, and 7%, respectively. In summary, PBSCT yields superior outcomes for patients with primary MDS, even in patients in transformation to AML. The inferior outcomes seen in therapy-related MDS suggest alternative therapies are required for this patient population. Reduced intensity transplantation permits curative therapy for MDS patients not amenable to MST, but at the price of increased TRM and relapse in this older cohort.
Figure Figure
20: Higher CD34+ Cell Doses are Associated with Decreased Relapse Rates Following Unrelated Donor Allogeneic Peripheral Blood Stem Cell Transplantation with Trends to Improved Disease-Free Survival
