Double Cord Blood Transplantation for Patients with High Risk Hematological Diseases: Delayed Immune Recovery and High Incidence of Infections.

The possibility to perform double cord blood transplantation (dCBT) has extended its use in adults with high risk hematological disease; however there is no data on immune recovery and report on infections complications. We have performed a phase II study on 16 dCBT from 2004 to 2006. Ten patients had high risk malignant disorders (ALL=1, AML+MDS=6, CML=3) and 6 high risk of rejection (SAA=4, PNH=1 and Fanconi Anemia=1). Among those patients, 4 (25%) received a dBCT as a rescue of previous non-engrafted transplants (2 SAA, 1 AML and 1 CML). Analyses of T, B and NK cells phenotype were performed once a month during the first 3 months and ever two months until 12 months. The median age was 21 years (11–42), the median weight 63 kg (30–90) and the median follow-up was 6 months (3–18). Conditioning regimen varied according to disease (myeloablative) or second transplant (reduced intensity), all but two patients have received ATG. GVHD prophylaxis consisted in CsA + steroids in 12 patients and associated to MMF in 4.

Results: 2 patients did not engraft (both with SAA), one patient relapsed 8 days after dCBT, and 12 patients engrafted at a median of 23 days (14–42). Chimerism available in 12 patients before day 100 showed both CB units in 7 patients. After day 100, in 8 evaluable patients, 3 patients had evidence of both CB units engraftement. Acute GVHD was observed in 5 patients (grade II in 4 and grade III in 1) and chronic GVHD in 7 out of 12 at risk. During the first 100 days, 9 CMV reactivations were diagnosed; 4 HSV (resistant to acyclovir); 3 HHV6 infections; 3 EBV reactivations; 2 adenovirus diseases, 4 VRS infections, 2 septicaemias, 3 fungal infections, 1 disseminated toxoplasmosis. After day 100, we observed 4 CMV reactivations, 1 CMV disease, 1 HSV, 1 adenovirus disease and 1 EBV-PTLD. Important lymphopenia was observed in all patients (median of 259mm3 at 3 months (n=14); 389 at 6 months (n=13) and 480 at 12 months (n=8). Median numbers of CD3/CD4 at 3, 6 and 12 months were: 8, 15 and 46 mm3 respectively; of NK cells 203, 249 and 115mm3, and of B cells were 0, 0 and 110 mm3, respectively. At 6 months overall survival was 58±14% and event-free survival was 52±14%. Six patients died: 2 of relapse and 4 from infections. Three out of 4 patients have been rescued of previous non-engraftment and are alive and well (4–18 months). In conclusion, despite the short follow-up dBCT seems to be an option to treat patients with high risk diseases and without a suitable compatible HLA donor. High incidence of infections and delayed immune recovery are major problems after dCBT.