Natural killer cell-enriched donor lymphocyte infusions from A 3-6/6 HLA matched family member following nonmyeloablative allogeneic stem cell transplantation

Abstract

Infusing natural killer (NK) cells following transplantation may allow less infections and relapse with little risk of acute graft-versus-host disease (aGVHD). We delivered 51 total NK cell-enriched donor lymphocyte infusions (DLIs) to 30 patients following a 3-6/6 HLA matched T cell-depleted nonmyeloablative allogeneic transplant. The primary endpoint of this study was feasibility and safety. Eight weeks following transplantation, donor NK cell-enriched DLIs were processed using a CD56(+) selecting column with up to 3 fresh infusions allowed. Toxicity, relapse, and survival were monitored. T cell phenotype, NK cell functional recovery, and KIR typing were assessed for association with outcomes. Fourteen matched and 16 mismatched transplanted patients received a total of 51 NK cell-enriched DLIs. Selection resulted in 96% (standard deviation [SD] 8%) purity and 83% (SD 21%) yield in the matched setting and 97% (SD 3%) purity and 77% (SD 24%) yield in the mismatched setting. The median number of CD3(-) CD56(+) NK cells infused was 10.6 (SD 7.91) x 10(6) cells/kg and 9.21 (SD 5.6) x 10(6) cells/kg, respectively. The median number of contaminating CD3(+)CD56(-) T cells infused was .53 (1.1) x 10(6) and .27 (.78) x 10(6) in the matched and mismatched setting, respectively. Only 1 patient each in the matched (n = 14) or mismatched (n = 16) setting experienced severe aGVHD with little other toxicity attributable to the infusions. Long-term responders with multiple NK cell-enriched infusions and improved T cell phenotypic recovery had improved duration of responses (p = .0045) and overall survival (OS) (P = .0058). A 1-step, high-yield process is feasible, and results in high doses of NK cells infused with little toxicity. NK cell-enriched DLIs result in improved immune recovery and outcomes for some. Future studies must assess whether the improved outcomes are the direct result of the high doses and improved NK cell function or other aspects of immune recovery.

Trial registration: ClinicalTrials.gov NCT00586690.

Figure 1

NK cell function was measured by their capacity to lyse K562 target cells, which is dependent upon the content of CD56⁺ effector cells within a sample. Improved NK cell ability to lyse the target cells is denoted by a steeper line as effector-to-target cell ratios increase. Typical results following T cell depleted nonmyeloablative therapy are noted here. At 2 months following transplant in this patient there were still not enough lymphocytes to quantify a meaningful response (indicated with a stippled line). There was marginal recovery at approximately 4 months (black squares) and still only modest recovery at 6 months (shown with black triangles). Error bars represent the standard deviation derived from triplicate samples.

Figure 2. Impact of NK Cell Enriched DLI

Panel A. NK cell function was measured at 6 to 8 weeks post-transplant, immediately prior to receiving NK infusions. At that time, NK cell function had returned fully in only a few patients (Full), while 2 additional patients demonstrated at least some NK cell function (Mid). However, the majority of patients demonstrated low NK cell function (Low) or did not recover sufficient lymphocytes to assay NK function (No, indicated with a stippled line). Panel B. The total recovery of lymphocytes to the peripheral blood was examined within each patient group. At 6 to 8 weeks post-transplant, lymphocyte recovery was only consistently strong among patients that recovered full NK cell function (Full). Panel C. The impact of NK cell donor lymphocyte infusion (DLI) was monitored in patients that had not previously responded (‘Low’ or ‘No’ NK cell function patients in panel A). Of those patients, 4 responded within 6 to 8 weeks after a single NK cell-DLI. Panel D. In one patient, NK cell function returned gradually following a 2^nd and 3^rd DLI. In all panels, the error bars represent the standard deviation derived from triplicate samples. * the ‘0’ measure for percent lysis refers to patients with functional ability below the level of detection in this assay due to either poor function and/or too few cells recovered to have measurable with this assay.