Combined IL-15 and IL-12 drives the generation of CD34⁺-derived natural killer cells with superior maturation and alloreactivity potential following adoptive transfer

Abstract

Adoptive transfer of allogeneic natural killer (NK) cells represents a promising treatment approach against cancer, including acute myeloid leukemia (AML). Previously, we reported a cytokine-based culture method for the generation of NK cell products with high cell number and purity. In this system, CD34C hematopoietic progenitor cells (HPC) were expanded and differentiated into NK cells under stroma-free conditions in the presence of IL-15 and IL-2. We show that combining IL-15 with IL-12 drives the generation of more mature and highly functional NK cells. In particular, replacement of IL-2 by IL-12 enhanced the cytolytic activity and IFNg production of HPC-NK cells toward cultured and primary AML cells in vitro, and improved antileukemic responses in NOD/SCID-IL2Rgnull (NSG) mice bearing human AML cells. Phenotypically, IL-12 increased the frequency of HPC-NK cells expressing NKG2A and killer immunoglobulinlike receptor (KIR), which were more responsive to target cell stimulation. In addition, NK15/12 cell products demonstrated superior maturation potential, resulting in >70% positivity for CD16 and/or KIR within 2 weeks after infusion into NSG mice. We predict that higher functionality and faster in vivo maturation will favor HPC-NK cell alloreactivity toward malignant cells in patients, making this cytokine combination an attractive strategy to generate clinical HPC-NK cell products for cancer adoptive immunotherapy.

Successful Transfer of Umbilical Cord Blood CD34+ Hematopoietic Stem and Progenitor-derived NK Cells in Older Acute Myeloid Leukemia Patients

“…S3A). As reported previously (29), IL15/IL2 expanded HSPC-NK cell products express low levels of KIRs (<5%; Fig. 2B).…”

“…Addition of IL12 to the culture protocol resulted in superior IFNg production and cytolytic activity of HSPC-NK cells towards AML cells in vitro. Importantly, these NK cells demonstrated improved antileukemic responses in mice bearing human AML cells (29). Furthermore, we showed both in mice (28,29), and now also in patients that HSPC-NK cells rapidly gain CD16 expression in vivo.…”

“…Importantly, these NK cells demonstrated improved antileukemic responses in mice bearing human AML cells (29). Furthermore, we showed both in mice (28,29), and now also in patients that HSPC-NK cells rapidly gain CD16 expression in vivo. This facilitates the combination with mAbs directed against antigens expressed on leukemic blasts such as CD33, CD123, and CLEC12A to exploit antibody-dependent cellular cytotoxicity as well as with TriKEs composed of single-chain scFv against CD16 and CD33 in combination with a modified IL15 cross-linker (41).…”

“…Next to boosting in vivo expansion, the killing potential of HSPC-NK cell products could be further improved to maximize clinical efficacy. Recently, we published an improved HSPC-NK cell generation protocol (29). In this protocol, IL2 is replaced by IL12 during ex vivo NK-cell generation.…”

Directed Differentiation of Mobilized Hematopoietic Stem and Progenitor Cells into Functional NK Cells with Enhanced Antitumor Activity

“…Among these, cord blood HSCs have emerged as a preferred source of CD34 + cells due to their primitive stem cell characteristics and high proliferative capacity. Several groups have reported efficient generation of CB-CD34 + -derived NK cell products that display enhanced effector functions and cytolytic activity against tumor cells in vitro and in vivo [20,[22][23][24]. In a phase I clinical trial, infusions of CB-CD34 + -derived NK cells in acute myeloid leukemia (AML) patients were well tolerated, encouraging further development of this approach [25].…”