Identifying candidate allogeneic NK-cell donors for hematopoietic stem-cell transplantation based on functional phenotype

Regulatory Considerations for NK Cells Used in Human Immunotherapy Applications

Translating cellular therapy from the laboratory to the clinic is a complicated process that involves scale-up of procedures to generate clinically relevant cell numbers, adaptation to reagents and equipment that are qualified for human use, establishing parameters of safety for reagents and equipment that are not already qualified for human use, codifying these processes into standards of practice and rules of conduct, and obtaining approval from regulatory bodies based on those codified standards and rules. As the laws and regulations that apply to cellular therapy will vary by time and geography, this chapter reviews some common key principles for the manufacturing of NK cells for human use that will need to be considered within the constraints of local policies and regulations.

Haploidentical Natural Killer Cells Infused before Allogeneic Stem Cell Transplantation for Myeloid Malignancies: A Phase I Trial

Allogeneic stem cell transplantation is an effective treatment for high-risk myeloid malignancies, but relapse remains the major post-transplantation cause of treatment failure. Alloreactive natural killer (NK) cells mediate a potent antileukemic effect and may also enhance engraftment and reduce graft-versus-host disease (GVHD). Haploidentical transplantations provide a setting in which NK cell alloreactivity can be manipulated, but they are associated with high rates of GVHD. We performed a phase I study infusing escalating doses of NK cells from an HLA haploidentical-related donor-selected for alloreactivity when possible-as a component of the preparative regimen for allotransplantation from a separate HLA-identical donor. The goal of infusing third-party alloreactive NK cells was to augment the antileukemic effect of the transplantation without worsening GVHD and, thus, improve the overall outcome of hematopoietic transplantation. Twenty-one patients with high-risk acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), or chronic myelogenous leukemia refractory or beyond first remission received a preparative regimen with busulfan and fludarabine followed by infusion of apheresis-derived, antibody-selected, and IL-2-activated NK cells. Doses were initially based on total nucleated cell (TNC) content and later based on CD56(+) cells to reduce variability. CD56(+) content ranged from .02 to 8.32 × 10(6)/kg. IL-2, .5 × 10(6) units/m(2) subcutaneously was administered daily for 5 days in the final cohort (n = 10). CD3(+) cells in the NK cell product were required to be < 10(5)/kg. Median relapse-free, overall, and GVHD-free/relapse-free survival for all patients enrolled was 102, 233, and 89 days, respectively. Five patients are alive, 5 patients died of transplantation-related causes, and 11 patients died of relapse. Despite the small sample size, survival was highly associated with CD56(+) cells delivered (P = .022) and development of ≥ grade 3 GVHD (P = .006). There were nonsignificant trends toward higher survival rates in those receiving NK cells from KIR ligand-mismatched donors and KIR-B haplotype donors. There was no association with disease type, remission at time of transplantation, or KIR content. GVHD was not associated with TNC, CD56(+), or CD3(+) cells infused in the NK cell product or the stem cell product. This trial demonstrates a lack of major toxicity attributable to third-party NK cell infusions delivered in combination with an HLA-compatible allogeneic transplantation. The infusion of haploidentical alloreactive NK cells was well tolerated and did not interfere with engraftment or increase the rate of GVHD after allogeneic hematopoietic transplantation. Durable complete remissions occurred in 5 patients at high risk for disease recurrence. This approach is being further developed in a phase I/II trial with ex vivo-expanded NK cells to increase the NK cell dose with the objective of reducing relapse and improving the outcome of allogeneic hematopoietic transplantation for AML/MDS.

Membrane-bound IL-21 promotes sustained ex vivo proliferation of human natural killer cells

NK cells have therapeutic potential for a wide variety of human malignancies. However, because NK cells expand poorly in vitro, have limited life spans in vivo, and represent a small fraction of peripheral white blood cells, obtaining sufficient cell numbers is the major obstacle for NK-cell immunotherapy. Genetically-engineered artificial antigen-presenting cells (aAPCs) expressing membrane-bound IL-15 (mbIL15) have been used to propagate clinical-grade NK cells for human trials of adoptive immunotherapy, but ex vivo proliferation has been limited by telomere shortening. We developed K562-based aAPCs with membrane-bound IL-21 (mbIL21) and assessed their ability to support human NK-cell proliferation. In contrast to mbIL15, mbIL21-expressing aAPCs promoted log-phase NK cell expansion without evidence of senescence for up to 6 weeks of culture. By day 21, parallel expansion of NK cells from 22 donors demonstrated a mean 47,967-fold expansion (median 31,747) when co-cultured with aAPCs expressing mbIL21 compared to 825-fold expansion (median 325) with mbIL15. Despite the significant increase in proliferation, mbIL21-expanded NK cells also showed a significant increase in telomere length compared to freshly obtained NK cells, suggesting a possible mechanism for their sustained proliferation. NK cells expanded with mbIL21 were similar in phenotype and cytotoxicity to those expanded with mbIL15, with retained donor KIR repertoires and high expression of NCRs, CD16, and NKG2D, but had superior cytokine secretion. The mbIL21-expanded NK cells showed increased transcription of the activating receptor CD160, but otherwise had remarkably similar mRNA expression profiles of the 96 genes assessed. mbIL21-expanded NK cells had significant cytotoxicity against all tumor cell lines tested, retained responsiveness to inhibitory KIR ligands, and demonstrated enhanced killing via antibody-dependent cell cytotoxicity. Thus, aAPCs expressing mbIL21 promote improved proliferation of human NK cells with longer telomeres and less senescence, supporting their clinical use in propagating NK cells for adoptive immunotherapy.

Cell docking, movement and cell-cell interactions of heterogeneous cell suspensions in a cell manipulation microdevice

This study demonstrates a novel cell manipulation microdevice for cell docking, culturing, cell-cell contact and interaction by microfluidic manipulation of heterogeneous cell suspensions. Heterogeneous cell suspensions include disparate blood cells of natural killer cells and leukemia cancer cells for immune cell transplantation therapy. However, NK cell alloreactivity from different healthy donors present various recovery response levels. Little is still known about the interactions and cytotoxicity effects between donor NK cells and recipient cancer cells. The cell-based micro device first showed the capability of cell docking, movement, contact and cell-cell interaction with respect to cell cytotoxicity of NK cells against cancer cells. With various flow tests for live cell loading, flow rates of 10 μL/h were chosen for injection in the central and side flows such that both types of suspension cells could be gently docked at the gap structure in a reaction zone. The trapping number of particles and cells was linearly proportional to the gap length. Finally, the cytotoxicity of around 40% was found to be similar in the case of dilute cells and a large cell population. As a result, the cell manipulation microdevice has been validated for live suspensions of natural killer and cancer cells, and exhibited the capability to measure the cytotoxicity of dilute cell suspensions.

HLA-C antigen mismatch is associated with worse outcome in unrelated donor peripheral blood stem cell transplantation

The association between HLA matching and outcome in unrelated-donor peripheral blood stem cell (PBSC) transplantation has not yet been established. In the present study, a total of 1933 unrelated donor-recipient pairs who underwent PBSC transplantation between 1999 and 2006 for acute myelogenous leukemia, acute lymphoblastic leukemia, myelodysplastic syndrome, or chronic myelogenous leukemia and received high-resolution HLA typing for HLA-A, -B, -C, -DRB1, -DQA1, and -DQB1 were included in the analysis. Outcomes were compared between HLA-matched and HLA-mismatched pairs, adjusting for patient and transplant characteristics. Matching for HLA-A, -B, -C, and -DRB1 alleles (8/8 match) was associated with better survival at 1 year compared with 7/8 HLA-matched pairs (56% vs 47%). Using 8/8 HLA-matched patients as the baseline (n = 1243), HLA-C antigen mismatches (n = 189) were statistically significantly associated with lower leukemia-free survival (relative risk [RR], 1.36; 95% confidence interval [CI], 1.13-1.64; P = .0010), and increased risk for mortality (RR, 1.41; 95% CI, 1.16-1.70; P = .0005), treatment-related mortality (RR, 1.61; 95% CI, 1.25-2.08; P = .0002), and grade III-IV graft-versus-host disease (RR, 1.98; 95% CI, 1.50-2.62; P < .0001). HLA-B antigen or allele mismatching was associated with an increased risk for acute GVHD grade III-IV. No statistically significant differences in outcome were observed for HLA-C allele (n = 61), HLA-A antigen/allele (n = 136), HLA-DRB1 allele (n = 39), or HLA-DQ antigen/allele (n = 114) mismatches compared with 8/8 HLA-matched pairs. HLA mismatch was not associated with relapse or chronic GVHD. HLA-C antigen-mismatched unrelated PBSC donors were associated with worse outcomes compared with 8/8 HLA-matched donors. The study's limited power due to small sample size precludes conclusions about other mismatches.