1. ¹Division of Pediatric Stem Cell Transplantation, Texas Transplant Institute, San Antonio, TX, USA
2. ²Methodist Children's Hospital, San Antonio, TX, USA

Correspondence: Dr KW Chan, Division of Pediatric Blood and Marrow Transplantation, Texas Transplant Institute, 7711 Louis Pasteur Drive, Suite 708, San Antonio, TX 78229, USA. E-mail: Kawah.chan@mhshealth.com

Received 3 October 2007; Revised 16 January 2008; Accepted 20 January 2008; Published online 10 March 2008.

Abstract

Delayed hematologic recovery is common after unrelated donor umbilical cord blood transplants (UCBT). Clinically it is important to quickly differentiate slow engraftment from graft failure (GF). We report the engraftment data on 110 pediatric UCBT recipients. By day 28, 71 patients achieved an ANC >0.5 10⁹ per liter, and 6 others died early without recovery. Of the remaining 33 patients who were still neutropenic, 20 eventually attained donor myeloid recovery, 3 died of transplant-related complications or recurrent leukemia and 10 survived without donor-derived hematopoiesis. These patients received a second UCBT 33–95 days after the first transplant, after additional immunosuppression. One patient died early, the remaining nine patients were engrafted; eight demonstrated complete, and one mixed, donor chimerism (with subsequent graft loss). Acute GVHD developed in three, and chronic GVHD in six of the eight engrafted patients. Two patients developed EBV-lymphoproliferative disorder. Infections, especially viral, were common and protracted. Six of 10 patients are alive, 165–1375 (median 1147) days after second UCBT. Chimerism studies correlated with subsequent engraftment course. Any result showing <5% donor cells was associated with irreversible graft loss. In conclusion, early second UCBT after primary GF is a feasible treatment option. Chronic GVHD and viral reactivation are common post transplant.