Importance of high early NK cell recovery after allogeneic HSCT

Recent developments in the knowledge of Natural Killer (NK) cell immunobiology have led to novel anti-cancer therapies. More specifically, NK cell recovery may be of benefit in preventing rejection after Allogeneic Hematopoietic Stem Cell Transplantation (HSCT), yet the potential clinical outcomes are still to be determined. Since patients with high-risk leukemia generally require transplantation, data and strategies on the improvement of post-transplant recovery, the reduction of infection, the prevention of relapse and improvement in overall survival are always required.

 Minculescu L. et al., of the National University Hospital Rigshospitalet, Denmark, analyzed the immune reconstitution of 298 adult Acute Myeloid Leukemia (AML), Acute Lymphoblastic Leukemia (ALL) and Myelodysplastic Syndrome (MDS) HSCT recipients. The study aimed to determine whether there were any clinical benefits of early NK cell recovery in T-cell replete transplant patients.

The key results from this study provided useful insights into the relationship between high early NK cell reconstitution and overall survival. Their data were published in September 2016 in Biology of Blood Marrow Transplant.

 Please see their published abstract with their results below:

 Abstract

 Early immune reconstitution plays a critical role in clinical outcome after allogeneic hematopoietic stem cell transplantation (HSCT). Natural killer (NK) cells are the first lymphocytes to recover after transplantation and are considered powerful effector cells in HSCT. We aimed to evaluate the clinical impact of early NK cell recovery in T-cell replete transplant recipients. Immune reconstitution was studied in 298 adult patients undergoing HSCT for acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL) and myelodysplastic syndrome (MDS) from 2005 to 2013. In multivariate analysis NK cell numbers day 30 (NK30) >150cells/µL were independently associated with superior overall survival (hazard ratio 0.79, 95% confidence interval 0.66-0.95, p=0.01). Cumulative incidence analyses showed that patients with NK30 >150cells/µL had significantly less transplant related mortality (TRM), p=0.01. Patients with NK30 >150cells/µL experienced significantly lower numbers of life threatening bacterial infections as well as viral infections, including CMV. No association was observed in relation to relapse. These results suggest an independent protective effect of high early NK cell reconstitution on TRM which translates into improved overall survival after T-cell replete HSCT.