Opinion Recommendations for Donor Human Leukocyte Antigen Assessment and Matching for Allogeneic Stem Cell Transplantation: Consensus Opinion of the Blood and Marrow Transplant Clinical Trials Network (BMT CTN) C. Alan Howard 1 , Marcelo A. Fernandez-Vina 2 , Frederick R. Appelbaum 3 , Dennis L. Confer 1 , 4 , Steven M. Devine 5 , Mary M. Horowitz 6 , Adam Mendizabal 7 , Ginna G. Laport 8 , Marcelo C. Pasquini 6 , Stephen R. Spellman 1 , * 1 Immunobiology Research, Center for International Blood and Marrow Transplant Research, Minneapolis, Minnesota 2 Department of Pathology, Stanford Medical School Blood Center, Stanford, California 3 Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 4 National Marrow Donor Program, Minneapolis, Minnesota 5 Blood and Marrow Transplant Program, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio 6 Center for International Blood and Marrow Transplant Research, Medical College of Wisconsin, Milwaukee, Wisconsin 7 The EMMES Corporation, Rockville, Maryland 8 Division of Blood and Marrow Transplantation, Stanford University Medical Center, Stanford, California Article history: Received 16 September 2014 Accepted 24 September 2014 Key words: Allogeneic transplantations Cord blood donor Unrelated donor Related donor Recipient abstract The Blood and Marrow Transplant Clinical Trials Network (BMT CTN) conducts large, multi-institutional clinical trials with the goal of improving the outcomes of hematopoietic cell transplantation (HCT) for pa- tients with life-threatening disorders. Well-designed HCT trials benefit from standardized criteria for defining diagnoses, treatment plans, and graft source selection. In this perspective, we summarize evidence sup- porting criteria for the selection of related and unrelated adult volunteer progenitor cell donors or umbilical cord blood units. These standardized criteria for graft source selection have been adopted by the BMT CTN to enhance the interpretation of clinical findings within and among future clinical protocols. Ó 2015 American Society for Blood and Marrow Transplantation. INTRODUCTION The Blood and Marrow Transplant Clinical Trials Network (BMT CTN) was established in 2001 to conduct large, multi- institutional clinical trials with the goal of improving the outcomes of hematopoietic cell transplantation (HCT) for patients facing life-threatening disorders. The BMT CTN al- lows the HCT community to conduct prospective, collabo- rative, clinical research within an infrastructure designed to offer participation in HCT clinical trials to patients in all re- gions of the United States. Nearly 18,000 HCTs are performed in the United States annually and this increases by approxi- mately 5% per year [1]. This growth reflects the utility of HCT in treating both malignant and nonmalignant disease, a higher donor availability, and treatment advances that allow HCT to be performed in older and sicker patients. Although HCT is a rapidly evolving field, HCT clinical trials face unique challenges, including the relatively small number of HCTs performed at any single center, the diverse indications for HCT, the complexities of the procedure and risks for multiple post-transplantation complications. The BMT CTN was established to address these challenges and execute multi- center HCT trials with broad national participation. Well- designed HCT trials benefit from standardized criteria for defining diagnoses, treatment plans, and graft source selection. The development of clinical guidelines and standards founded on evidence-based research is an important aspect of directing and implementing clinical patient care. Over the past decade, there have been significant developments in HLA-typing technologies and in the availability of outcome data from large multicenter studies evaluating a growing Financial disclosure: See Acknowledgments on page 6. * Correspondence and reprint requests: Stephen R. Spellman, Immu- nobiology and Observational Research, Center for International Blood and Marrow Transplant Research, 3001 Broadway Street NE, Suite 100, Min- neapolis, MN 55413. E-mail address: sspellma@nmdp.org (S.R. Spellman). http://dx.doi.org/10.1016/j.bbmt.2014.09.017 1083-8791/Ó 2015 American Society for Blood and Marrow Transplantation. Biol Blood Marrow Transplant 21 (2015) 4e7 Biology of Blood and Marrow Transplantation journal homepage: www.bbmt.org