Reduced Intensity Conditioning Regimen in Single Unrelated Cord Blood Transplantation in Adults with Hematological Malignant Disorders. An Eurocord-Netcord and SFGM-TC Survey.

Results of reduced intensity conditioning regimen (RIC) in unrelated cord blood transplantation (UCBT) have been reported, however more frequently RIC was performed using double cord blood transplants. In order to study risk factors in single RIC-UCBT we have analyzed 65 patients with hematological malignancies (ALL=10, AML=37, Hodking and NHL=10, MDS=4, CML=3, Myeloma =1) transplanted from 1999–2005 and reported to Eurocord and SFGM-TC. The median follow-up was 8 months (3–26) and the median age was 47 years (16–76). At transplant, 49% of the patients had advanced phase of disease and 39% had received a previous autologous transplants. The conditioning regimen varied according diasease and centers: Fludarabine(FLU)+Endoxan (EDX) +TBI (2Gy) was given to 33 patients, FLU+(EDX or Melphalan) in 11, FLU+BU (<8mg/kg) associated or not to other drugs in 13, FLU+TBI(2GY) in 3 and other regimens in 5 patients. ATG/ALG was added in 26% of the cases. GVHD prophylaxis most commonly (55%) consisted of CsA and MMF; 87% received hematopoietic growth factors (<day 8). The median nucleated cell dose infused was 2.4 x10⁷/kg and the graft was HLA identical (6/6) ( HLA A and B low resolution and DRB1 allelic typing) in 3 cases, 5/6 in 15, 4/6 in 37 and 3/6 in 10.

Results: Median time to neutrophil recovery (>500/mm3) was 20 days (0–56) and 35 dyas for platelets recovery (>20.000/mm3). At day 60 probability of neutrophil recovery was 87± 7% of the 33 patients who received the Flu+End+TBI conditioning regimen and was 65±10% for patients receiving other regimens (p<0.01). Chimerism analysis was available in 71% of the patients at 3 months and was full donor in 67%, mixed chimerism in 9% and autologous reconstitution in 24%. Grade II aGVHD was observed in 13%, grade III in 7% and grade IV in 7%; the TRM was 45±7% overall, 50±15% in acute leukemia, 30±15% in lymphomas and 27±16% for other diagnoses. The TRM at one year for those receiving <2.4 x 10⁷ TNC/kg was 53±9% and for those receiving >2.4 x10⁷TNC/kg was 39±10% (p=0.07). For patients receiving Flu+End+TBI the TRM at one year was 24±10% and for those receiving other conditioning regimens was 60±9% (p=0.001). DFS at one year for lymphomas was 50±9%, for leukemias was 27±7% and for other diagnoses was zero. When the HLA compatibility was 6/6 or 5/6, DFS at one year was 42±12%, for 4/6 disparities DFS was 27±9% and for 3/6 disparities DFS was zero. DFS was 43±11% for those receiving Flu+End+TBI, and was 16±7% for patients receiving other conditioning regimens (p=0.005). For patients receiving >2.4 x 10⁷TNC/kg the DFS was 31±12% and for patients receiving <2.4 x 10⁷TNC/kg the DFS was 14±8% (p=0.05). In collusion, results of single RIC-UCBT are encouraging; cell dose and HLA remain important factors in this setting. The type of conditioning (Flu+End+TBI) seems to be associated with decreased TRM and better DFS, but a multivariate analysis with a higher number of patients is needed.