Fludarabine Phosphate-Based Nonmyeloablative Stem Cell Transplantation in the Elderly Patients: A BHS Study.

Background: Fludarabine phosphate (F)-based nonmyeloablative conditioning regimens are associated with reduced transplant-related toxicity and allow transplantation in patients (pts) above 55 y.o.

Aims: We prospectively studied the role of ATG to control the development of graft-versus-host-disease (GVHD), accelerate donor engraftment and maintain GVT effects in pts not eligible for classical allogeneic transplant. The subgroup of pts with 60 yo or more was analysed and compared with the younger population.

Population: A total of 113 pts were enrolled in the phase II study. Pts with lymphoid malignancies were conditioned with F (30 mg/m²/day for 4 days) plus cyclophosphamide (1g/m²/day for 3 days) or cytarabine (Ara-C, 2g/m²/day) for myeloid malignancies. All pts received cyclosporine (3–5 mg/kg IV, daily) and ATG (10 mg/kg/day for 4 days - [ATG-4, n= 36] or 2 days - [ATG-2, n=67] ). Chimerism analyses were performed on d30, 45, 60 and 90.

Results: 29 pts had 60 y.o. or more.Diagnoses were as follows: 9 MM, 5 NHL, 3 CLL, 5 AML, 4 MDS, 2 CML, 1 WM. The median age was 63 (range 60–74) years. The median follow-up was 24 months. Prior to transplantation, 35% of pts were in complete remission. 65% had poor prognostic disease(PR, RR or PD). Engraftment rate was 100% of the evaluable pts. Treatment-related mortality was 48%,much higher than in the younger population (15%) and due primarily to infectious complications. Grade II-IV acute GVHD (aGVHD) at d90 were similar in both populations (35%). Chronic GVHD rates were similar in both groups (40%). At d90, 23 pts were evaluable for T-cell chimerism analysis. Full (>90%) donor chimerism was achieved in 20/23 pts. Overall survival was higher in patients with good prognostic diseases (60% vs. 48%). No pts developed veno-occlusive disease.

Conclusion: These results confirm the feasibility of F-based nonmyeloablative conditioning in elderly population but infectious complications remain a concern compared to younger population.