Pre-Transplant 5-Azacitidine (Vidaza®) May Improve Outcome of Allogeneic Hematopoietic Cell Transplantation (HCT) in Patients with Myelodysplastic Syndrome (MDS).

Most patients with MDS are older than 60 yrs and, because of age, many have previously been excluded from HCT due to the high risk of transplant related mortality. Reduced intensity conditioning has decreased regimen related mortality in HCT and has increased the age of patients for whom this treatment is offered. There remains substantial risk of relapse after HCT especially in patients with > Int-1 MDS who benefit the most from immediate HCT. One strategy to suppress leukemia burden and potentially decrease the risk of relapse is pre-transplant treatment with 5-azacitidine (Vidaza®). This DNA hypomethylating drug is FDA approved for the treatment of MDS. We analyzed the outcome for 34 MDS patients who received a myeloablative HCT from an HLA compatible sibling or unrelated donor from July 2004 through June of 2006, to investigate the potential impact of pre-transplant 5-azacitidine on response and post-transplant relapse. Fourteen of thirty-four patients received a median of 2 (1–7) cycles of 5-azacitidine prior to HCT. Median age was 59 (49 – 69) yrs. Diagnosis and IPSS category included MDS (8) [Int-1 (1) and Int-2 (7)], MDS-AML (5) and CMML (1). Two patients had induction chemotherapy with residual MDS prior to 5-azacitidine. Subsequent to 5-azacitidine: ten responded [CR (2), PR (1) improvement (7)] three progressed and one was not evaluable. The IPSS category after 5-azacitidine treatment and prior to HCT was Int-2(1), Int-1 (4), and Low (5; 3 in CR) in addition to AML (2) and CMML (1). One was unable to assess. The median follow-up in the survivors is 191 (47 – 524) days. Of the fourteen 5-azacitidine treated patients, none have relapsed post-HCT including patients who progressed on 5-azacitidine. Four have died from non-Hodgkins lymphoma (1), DAH (1), adenovirus pneumonia (1) and chronic GVHD (1). Ten are alive in remission, two for greater than one year. Twenty patients did not receive 5-azacitidine. Diagnosis and IPSS category included MDS (9) [Int-1 (3) and Int-2 (6)], MDS-AML (9) and CMML (1) and one not determined due to lack of cytogenetics. Their median age was 53 (33 – 68) yrs. Treatment included supportive care, induction chemotherapy (9) and SCIO-469 (1). IPSS distribution prior to HCT was Int-2 (7), Int-1 (5) Low (5; 4 in CR); in addition to AML (1) and CMML (1). One was unable to assess. The median follow-up in the survivors is 420 (21 – 742) days. Ten of twenty are alive without relapse and eight have relapsed. Five have died, with relapse (3), fungal pneumonia (1) or multi-organ failure (1). The 1 year K-M estimates of overall and progression free survivals are 64% (SEM 15%) and 64% (SEM 15%), respectively for 5-azacitidine group and 70% (SEM 11%) and 51% (SEM 13%) for non-5-azacytidine group. We conclude from this preliminary analysis that pre-HCT conditioning treatment with 5-azacitidine may reduce the risk for MDS relapse after allogeneic transplant in higher risk patients. In addition to its direct anti-tumor effect, 5-azacitidine may sensitize neoplastic cells to the effects of high dose chemotherapy or promote the expression of antigens critical to effective graft-vs-tumor response. This treatment strategy will be evaluated in a prospective trial to investigate the role of pre-transplant 5-azacitidine on transplant outcomes in patients with higher risk MDS.