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Patients with acute myelogenous leukemia (AML) who undergo killer immunoglobulin-like receptor (KIR)-mismatched haploidentical hematopoietic stem cell transplantation (HSCT) have improved survival. Children's Oncology Group AAML05P1 is a prospective phase 2 trial of unrelated donor (URD) HSCT in which KIR typing of donors was available to the treating physician at donor selection, aiming to determine feasibility (defined as the ability to obtain donor samples from URDs and obtain KIR data before transplantation) of prospective selection of KIR-mismatched donors and effect on outcomes. Patients age ≤30 years with high-risk AML at presentation or relapsed AML were eligible; the study accrued 90 evaluable patients. After enrollment, as many as 5 potential URD samples were KIR-typed (including gene expression) in a central laboratory and results reported to the treating physician, who made the final donor selection. Cases were categorized as KIR-matched or KIR-mismatched using different published strategies. Overall survival (OS), disease-free survival (DFS), and relapse did not differ significantly by KIR mismatch status. Acute graft-versus-host disease (GVHD) was significantly lower in recipients of KIR-mismatched stem cells (35% versus 60%; P = .027). We examined DFS according to time to natural killer (NK) receptor recovery after HSCT. NK p44 recovery was significantly associated with KIR mismatch and with decreased DFS and increased relapse risk in multivariate Cox analysis (P = .006 and .009, respectively). We show that prospective selection of URD according to KIR type was feasible, acute GVHD was reduced, but survival did not differ using any model of KIR mismatch. However, the study enrolled mostly matched transplants, so ligand-ligand mismatch was rare, and thus the sample size was insufficient to determine potential benefit according to this model. Cord blood recipients demonstrated a trend toward improved DFS with KIR mismatch, but the study was not powered to detect a difference in this small subset of patients. Our data suggest that recovery of NK receptor expression might influence DFS after HSCT.

Allogeneic hematopoietic cell transplantation involves consideration of both donor and recipient characteristics to guide the selection of a suitable graft. Sufficient high-resolution donor-recipient HLA match is of primary importance in transplantation with adult unrelated donors, using conventional graft-versus-host disease prophylaxis. In cord blood transplantation, optimal unit selection requires consideration of unit quality, cell dose and HLA-match. In this summary, the National Marrow Donor Program (NMDP) and the Center for International Blood and Marrow Transplant Research, jointly with the NMDP Histocompatibility Advisory Group, provide evidence-based guidelines for optimal selection of unrelated donors and cord blood units.

With advances in supportive care, autologous hematopoietic cell transplant (AHCT) is increasingly being performed for patients older than 60 years. We analyzed patients receiving an AHCT for multiple myeloma or lymphoma in a contemporary cohort (2010-2012), with consistent treatment and supportive care and compared outcomes [CTCAE grade 3-5 toxicities, nonrelapse mortality (NRM) and overall-survival (OS)] of younger (40-59 years, n = 77) versus older (≥60 years, n = 67) recipients. The proportion of patients with neutropenic infections was higher in the older group (64% vs. 44%; P = 0.02). The proportion of patients with any grade 3-5 toxicity was also higher in the older group (84% vs. 67%, P = 0.03). In multivariate analysis, older age was significantly associated with higher odds (OR: 2.57, 95% CI:1.09-6.05) of grade 3-5 toxicity. The NRM was 3% (older) vs. 0% (younger) at 1 year. The probability of OS at 2 years was lower in the older group (76% vs. 90%, P = 0.04). Though AHCT can be performed safely in older recipients, the higher toxicity and slightly higher NRM in this population needs attention. Studies focusing on risk-stratification in older patients would further help predict toxicity. Further studies addressing enhanced supportive care needs for older patients who are most likely to benefit are indicated.

Controversy surrounds the question of whether clinical trial participants have better outcomes than comparable patients who are not treated on a trial. We explored this question using a recent large, randomized, multi-center study comparing peripheral blood (PB) with bone marrow (BM) transplantation from unrelated donors (URD), conducted by the Blood and Marrow Transplant Clinical Trials Network (BMT CTN).