Favorable Outcomes with Acceptable Toxicity Using a Reduced Intensity Conditioning Regimen for Patients Otherwise Ineligible for Related Donor Allogeneic Stem Cell Transplantation.

Allogeneic stem cell transplantation represents a potentially curative treatment modality for patients with advanced hematologic malignancies. However, the toxicity associated with fully myeloablative conditioning regimens has historically limited its use to younger, otherwise healthy patients. To investigate the feasibility of allogeneic stem cell transplantation in older (over 55 years) or otherwise higher risk patients (eg, prior transplant) with fully HLA-matched sibling donors, a reduced intensity conditioning regimen consisting of fludarabine (30 mg/M2 IV qd X 6, day −8 to −3), ATGAM 10 mg/kg IV qod X 4, day −7/−5/−3/−1) and melphalan (100 mg/M2 IV X 1, day −2) was employed in a single institution setting. GVHD prophylaxis consisted of cyclosporine (2 mg/kg IV bid, adjusted, beginning day −1) and methotrexate (10 mg/m2 IV, day +1/+3/+6). RESULTS: 21 patients with a variety of hematologic malignancies (AML=4, MDS=5, NHL=5, CML/MPD=3, HD=2, MM=1, CLL=1) were enrolled. Mean age was 54 years (range 28–66). 7 patients had undergone prior autologous transplants. Median followup among surviving patients was 42 months (range 3–58 months). Peripheral blood chimerism at day +100 was >95% donor in 16/18 patients, 80% (with subsequent conversion to 95%) in one patient, and >95% recipient (with documented relapse) in one patient. Acute GVHD grade 1–2 was seen in 52% and grade 3–4 in 10% of patients. Chronic GVHD was observed in 9/20 evaluable patients (45%). Infectious complications included documented bacteremia (6 cases), candida albicans fungemia (1), aspergillus pneumonitis (3), nocardia pneumonitis (2), CMV viremia (6), CMV colitis (1). Veno-occlusive disease (self-limited, grade 1–2) was observed in 4/21 patients (19%). Relapse was observed in 5/21 patients (24%) at a median 249 days post-transplant (range 97–328 days). Event-free survival was 90% (19/21) at 100 days, 58% (11/19) at 1 year and 47% (8/17) at 3 years. Overall survival was 95% (20/21) at 100 days, 68% (13/19) at 1 year and 47% (8/17) at 3 years. Primary causes of death were relapse (4/9), infection (4/9), and idiopathic pneumonitis/multi-organ failure (1/9). Chronic GVHD was a significant contributing factor in 3/4 fatal infections. PTLD was observed in one patient, who subsequently died of CMV infection/sepsis syndrome. CONCLUSIONS. Allogeneic BM/SCT using a reduced intensity conditioning regimen is feasible among older patients, and those who are otherwise poor candidates for myeloablative BM/SCT regimens; however, GVHD, infection, and relapse remain formidable obstacles to achieving successful outcomes.