Natural Killer Cell Persistence Research Articles

CD70-specific CAR NK cells expressing IL-15 for the treatment of CD19-negative B-cell malignancy

AbstractChimeric antigen receptor (CAR) natural killer (NK) cells can eliminate tumors not only through the ability of the CAR molecule to recognize antigen-expressed cancer cells but also through NK-cell receptors themselves. This overcomes some of the limitations of CAR T cells, paving the way for CAR NK cells for safer and more effective off-the-shelf cellular therapy. In this study, CD70-specific (a pan-target of lymphoma) fourth-generation CAR with 4-1BB costimulatory domain and interleukin-15 (IL-15) was constructed and transduced into cord blood–derived NK cells by Baboon envelope pseudotyped lentiviral vector. CD70-CAR NK cells displayed superior cytotoxic activity in vitro and in vivo against CD19-negative B-cell lymphoma when compared with nontransduced NK cells and CD19-specific CAR NK cells. Importantly, mice that received 2 doses of CD70-CAR NK cells showed effective eradication of tumors, accompanied by increased concentration of plasma IL-15 and enhanced CAR NK cell proliferation and persistence. Our study suggests that repetitive administration-based CAR NK-cell therapy has clinical advantage compared with a single dose of CAR NK cells for the treatment of B-cell lymphoma.

Abstract 1334: Evaluation of NK cell combination therapies in mouse models of cancer

Abstract Adoptive immunotherapy with natural killer (NK) cells has emerged as a promising innovative approach against hematological malignancies and solid tumors. To enhance the functional aspects of NK cells and to achieve stronger, sustained anti-tumor responses, combination strategies are under development. They are focused on optimization of NK cell potency, persistence and tumor targeting using monoclonal antibodies, multi-specific NK cell engagers and immune modulators like cytokines. SAR445419 is a universal off-the-shelf allogeneic human NK cell (hNK) product made using Sanofi’s proprietary platform with potential broad application across hematologic and solid tumor indications. We evaluated the therapeutic potential of these NK cells in combination with internal assets and standard of care treatments in preclinical mouse models. The studies were performed in immunodeficient NOG mouse strains transgenic for hIL-15, supporting long-term engraftment of functional hNK cells. We demonstrated the therapeutic advantage of NK cell combination with an anti-CD20 monoclonal antibody (mAb) in a disseminated lymphoma model. We also reported prolonged lifespan of leukemia-bearing animals treated with NK cells and pegenzileukin, a PEGylated non-alpha rhIL-2 variant engineered to preferentially bind to the IL-2 βγ receptors and promote NK cell function. The anti-tumor response correlated with pegenzileukin-induced increase in NK cell numbers in the blood. A combination of CD38KO NK cells with an anti-CD38 mAb was also investigated in a model of multiple myeloma (MM). FcγR-KO immunodeficient mice were used in these studies to limit the confounding contribution of residual murine immune cells engaging with the Fc-competent therapeutic antibody and to specifically detect hNK-cell mediated activity. The comparison of CD38KO versus WT NK cell numbers in the blood of animals treated with an anti-CD38 mAb showed a significant decrease in CD38-expressing NK cell count that was mitigated by the genetic deletion of CD38. Obtained results suggest that CD38KO NK cells are resistant to anti-CD38 mAb-mediated fratricide and provide a rationale for the combination of CD38KO NK cells with anti-an CD38 mAb against MM. Overall, these preclinical in vivo studies have a pivotal role in the evaluation of NK cell combination therapies against cancer and reveal their therapeutic potential. Citation Format: Katarzyna Franciszkiewicz, Pauline Rettman, Beatrice Gauthier, Laurence Noblet, Celine Nicolazzi, Andre Kunert, Rob Igarashi, Loreley Calvet, Valeria Fantin, Sukhvinder Sidhu. Evaluation of NK cell combination therapies in mouse models of cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1334.

Abstract 1338: Novel activation domains coupled to chimeric ILT receptors (CIR) enhance NK cell targeting of HLA-G+leukemic and solid tumor cells

Abstract Human leukocyte antigen-G (HLA-G) suppresses lymphoid and myeloid immune systems by binding ILT2 and ILT4 respectively and activating ITIM signaling. HLA-G is abundantly expressed in placental cytotrophoblasts to block fetal rejection. HLA-G is not expressed in most normal cells but is derepressed in in about 50% of malignancies. We engineered ILT2 and ILT4 to produce activating signals as Chimeric ILT Receptors or CIR. Preliminary results indicated robust killing of Acute Myeloid Leukemia (AML) cells by Natural Killer (NK) cells expressing either ILT2 or ILT4 CIRs. Here, we evaluated the effect of alteration of activating domains in the CIR constructs to produce signals that mimic the effect of IL-18 signaling in CIR-NK cells to enhance cytotoxicity, NK cell growth and persistence. Further, HLA-G expression and CIR-NK cell targeting of primary human cell types were rigorously screened. Activated NK cells derived from peripheral blood (2 to 5 donors) were transduced with γ-retroviruses directing expression of CIR proteins (CIR.X.Y or CIR.Y.X) where X stimulates cytotoxicity through CD3ζ, DAP10 or DAP12, and Y directs coactivation through 4-1BB, fusion of the MyD88 death domain or recruitment of endogenous MyD88 with receptor-derived TIR domains and soluble IL-15. CIR-NK cells were cocultured with GFPffluc-expressing AML and solid tumor target cell lines or normal primary human cells. NK cell proliferation and cytotoxicity of CIR-NK cells was monitored by Incucyte microscopy and supernatants were analyzed for cytokine release by ELISA. At low E:T (1:20 - 1:40) in 7-day cocultures, mock-transduced NK cells displayed innate killing activity against HLA-G+ Molm13 and Kasumi1 AML cells that was augmented by CIR constructs containing direct fusions of MyD88 and DAP10 or DAP12 (mock = 2.06E7 ± 4.53E6 vs. CIR-ILT4.MyD88.DAP10 = 1.03E7 ± 5.46E6) with 7-fold elevation of IFN-γ production. CIR constructs that recruited endogenous MyD88 signaling through the TLR2 TIR domain (4-1BB.DAP10.TLR2) also exhibited enhanced anti-HLA-G activity (9.13E6 ± 5.33E6). Against HLA-G+ HT-1376 bladder cancer cells (E:T = 1:10-1:20), CIR-NK cells also displayed enhanced tumor cell killing with enhanced NK cell growth. Conversely, CIR-enhanced killing was not observed against HLA-G− HCT-116 colorectal cancer cells. The persistence of CIR-NK cell potency after 4 weeks of expansion varied markedly with different activation domains employed. When screened against primary human cells (cardiomyocytes, hepatocytes, hepatic endothelial cells, corneal, colon and lung epithelial cells), no CIR-specific targeting was observed at high E:T ratios (1:1 and 1:5). In conclusion, CIR-NK cells exhibit potent and specific anti-tumor activity against HLA-G+ solid and leukemia cells. Alteration of CIR-NK cell intracellular signaling can optimize the potency and persistence of NK cell anti-tumor activity. Citation Format: MyLinh Duong, Jihyun Park, Raphel Ognar, Simon Wain-Hobson, Henri Bayle. Novel activation domains coupled to chimeric ILT receptors (CIR) enhance NK cell targeting of HLA-G+leukemic and solid tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1338.

Interleukin-2 is required for NKp30-dependent NK cell cytotoxicity by preferentially regulating NKp30 expression.

Natural killer (NK) cells are key effectors in cancer immunosurveillance, eliminating a broad spectrum of cancer cells without major histocompatibility complex (MHC) specificity and graft-versus-host diseases (GvHD) risk. The use of allogeneic NK cell therapies from healthy donors has demonstrated favorable clinical efficacies in treating diverse cancers, particularly hematologic malignancies, but it requires cytokines such as IL-2 to primarily support NK cell persistence and expansion. However, the role of IL-2 in the regulation of activating receptors and the function of NK cells expanded for clinical trials is poorly understood and needs clarification for the full engagement of NK cells in cancer immunotherapy. Here, we demonstrated that IL-2 deprivation significantly impaired the cytotoxicity of primary expanded NK cells by preferentially downregulating NKp30 but not NKp46 despite their common adaptor requirement for expression and function. Using NK92 and IL-2-producing NK92MI cells, we observed that NKp30-mediated cytotoxicity against myeloid leukemia cells such as K562 and THP-1 cells expressing B7-H6, a ligand for NKp30, was severely impaired by IL-2 deprivation. Furthermore, IL-2 deficiency-mediated NK cell dysfunction was overcome by the ectopic overexpression of an immunostimulatory NKp30 isoform such as NKp30a or NKp30b. In particular, NKp30a overexpression in NK92 cells improved the clearance of THP-1 cells in vivo without IL-2 supplementation. Collectively, our results highlight the distinct role of IL-2 in the regulation of NKp30 compared to that of NKp46 and suggest NKp30 upregulation, as shown here by ectopic overexpression, as a viable modality to harness NK cells in cancer immunotherapy, possibly in combination with IL-2 immunocytokines.

Trials in Progress: A Phase I/II Clinical Trial of Off the Shelf Universal Donor Natural Killer Cells Combined with Chemotherapy for Treatment of Relapsed/Refractory Acute Myeloid Leukemia (KARMA)

Background and Significance: Natural killer (NK) cells are cytotoxic lymphocytes that play a key role in recognizing malignant cells. In AML, qualitative and quantitative dysfunction of innate NK cells portends a poor prognosis and adoptive NK cell therapy has been shown to be safe and effective with minimal risk for GVHD (Ciurea et al. 2022; Silla et al. 2021). To circumvent cost and logistics restraints of per patient manufacture of NK cells, we developed a universal donor (UD) NK cell bank for “off-the-shelf” NK cells (UD FC21-NK cells). Donors with optimal NK cell characteristics are identified through the National Marrow Donor Program, and peripheral blood NK cells are expanded for two weeks by co-culture with irradiated K562 feeder cells expressing 4-1BB ligand and membrane bound IL-21 as previously described (Denman et al. 2012). We seek to study the safety and efficacy of multiple doses of UD FC21-NK cells combined with fludarabine and cytarabine (FLA) chemotherapy in patients with relapsed or refractory AML. Study Design and Methods: This open label, single-center phase I/II study will include a dose escalation phase to establish safety and determine the recommended phase II dose followed by an expansion phase to estimate efficacy (complete response rate and MRD negative response rate). Up to 20 patients ages 18-25 with relapsed or refractory AML, including isolated extramedullary disease, will be enrolled. Exclusion criteria include active GVHD, uncontrolled infections, hematopoietic stem cell transplant within 3 months of enrollment, and donor lymphocyte infusion within 30 days of enrollment. Patients will undergo FLA chemotherapy followed by six doses of UD FC21-NK cells given thrice weekly for two weeks (Figure 1). Dose levels include 1 x 10 7 UD FC21-NK cells/kg/dose, 3 x 10 7 UD FC21-NK cells/kg/dose, and 1 x 10 8 UD FC21-NK cells/kg/dose. Patients may receive up to 2 cycles if they do not achieve a CR after cycle 1 or if necessary to bridge to transplant. Peripheral blood samples will be drawn weekly for immune correlatives including in vivo NK cell expansion and persistence. The trial is currently open to enrollment to adult patients with the intent to expand to pediatrics after demonstrating preliminary safety. Clinical trial information: NCT05503134

Mitochondrial Fitness and Immune Function of Natural Killer Cells Are Impaired By the Multiple Myeloma (MM) Tumor Cells: The Role of MM Microenvironment Interactions

The immune system including Natural Killer (NK) activity was shown to be impaired in active MM. We and others have previously demonstrated the important role of the bone marrow (BM) microenvironment in MM pathophysiology, however, data on its effects on NK activity in MM is limited. We first assessed the phenotype of the BM-derived NK cells. BM-NK from MM pts (n=10) showed an exhausted phenotypic signature with significantly reduced expression of CD16 (p<0.01), and increased expression of exhaustion markers CD39 (p<0.001) and CD57 (p<0.001) compared to BM-NK cells from healthy controls (n=8). Furthermore, MM-BM NK cells demonstrated reduced mitochondrial membrane potential, suggesting impaired mitochondrial fitness. The dysfunction of the mitochondria led to deficiency of ATP synthesis; mitochondrial ATP levels were reduced in NK cells from MM BM samples in comparison to the normal BMs (p<0.001). Next, the functional response of BM NK cells to the stimulation with IL-2 (2000 IU/ml for 7 and 14 days) was evaluated in vitro. NK cells from MM BM demonstrated reduced proliferation capacity, increased CD39, reduced expression of activating receptors NKp44 and NKp30, and reduced mitochondrial membrane potential upon the activation with IL-2. The impaired mitochondrial fitness correlated with reduced levels of NKp44, indicating a potential link between the decreased mitochondrial activity and the reduced functionality of NK cells. Indeed, in vitro, the cytotoxic activity of IL-2-stimulated MM-BM NK cells against MM cell lines was significantly diminished compared to healthy IL-2-activated BM-NK cells. Glucose and fatty acids (FA) are key substrates of the mitochondrial bioenergetic pathways and essential for NK cell activation. Of note, glucose uptake was increased comparably upon IL-2 stimulation in NK cells from both MM patients and healthy donors. In contrast, MM-BM NK cells demonstrated reduced FA uptake in response to IL-2 stimulation compared to BM NK cells from healthy donors. These data indicate impaired mitochondrial and NK cell properties in the BM MM niche. Next, we established an in vitro model to interrogate the relationship between NK cell mitochondrial and immune dysfunction within the MM BM microenvironment. Specifically, we cultured MM cell lines (n=5) with the NK92 cell line or primary IL-2-activated or not activated blood-derived NK cells, and assessed NK cell mitochondrial fitness, metabolic activity, and immune functional properties. Co-culture with MM cells significantly impaired mitochondrial mass and mitochondrial membrane potential in NK cells, decreased mitochondrial ATP levels, while upregulating MM mitochondrial ROS in NK cells, indicating that MM cells induce mitochondrial damage and impair ATP synthesis in NK cells. Mitochondrial fitness and energy production are pivotal for NK cell persistence and cytotoxicity. In accordance, direct interaction with MM cells suppressed NK cell proliferation in vitro, inducing G0/G1 cell cycle arrest. Moreover, MM-induced mitochondrial impairment in NK cells correlated with reduced responsiveness of MM cells to NK-induced killing, while short-term exposure to MM cells significantly diminished the anti-myeloma cytotoxic activity of NK cells. Accordingly, CD39 expression was upregulated, while NKp44 levels significantly decreased in NK cells upon interaction with MM cells. To further characterize the molecular mechanisms associated with MM-mediated NK cell mitochondrial impairment, we assessed the gene expression profile of MM-exposed sorted NK92 cells versus unexposed cells. A distinct metabolic signature characterized by reduced expression of genes involved in the mitochondrial activity was detected in MM-exposed NK cells. Thus, genes involved in respiratory activity and mitochondrial dynamics were downregulated post-MM exposure. Furthermore, a profound increase in fructose-1,6-biphosphatase 1 (FBP1) expression was detected in MM-exposed NK cells. FBP1 is the rate-limiting enzyme for gluconeogenesis that simultaneously inhibits glycolysis, possibly interfering with NK cell metabolic activity and immune function. Altogether, our data suggest that MM BM microenvironment and direct interactions with malignant plasma cells impair NK mitochondrial fitness, diminishing energy production, increasing oxidative stress, and driving exhaustion with reduced anti-tumor capacity in NK cells.

Innate Cell Engager (ICE®) AFM13 Combined with Preactivated and Expanded (P+E) Cord Blood (CB)-Derived Natural Killer (NK) Cells for Patients with Refractory CD30-Positive Lymphomas: Final Results

CONCLUSIONS Pts with refractory Hodgkin (HL) and other CD30+ lymphomas have few effective therapies available and targeted NK cell immunotherapy is an active area of research. Transfer of non-targeted NK cells has shown limited clinical benefit as target recognition of cancer cells by NK cells constitutes a barrier. The innate cell engager AFM13 is a first-in-class CD30/CD16A bispecific antibody construct that induces selective killing of CD30+ tumor cells by engaging and activating NK cells. As a single agent, AFM13 has limited clinical activity against HL, likely due to the reduced effector function of autologous NK cells in these pts, which provides the rationale for combining AFM13 with allogeneic NK cells. Our prior preclinical work identified a promising combination of CB-derived NK cells that were first IL-12/IL-15/IL-18-preactivated followed by ex vivo expansion (P+E) with engineered K562 feeder cells expressing membrane-bound IL-21, 4-1BBL and CD48 and exogenous IL-2, and subsequently complexed with AFM13 just before infusion; these cytokine-induced memory-like NK cells presented chimeric antigen receptor (CAR)-NK-like features and increased in vitro and in vivo antitumor activity compared to either non-AFM13-precomplexed P+E NK cells or to AFM13 alone (Kerbauy et al, Clin Cancer Res 2021). Building on this work we wished to study this CB NK-cell therapy in pts with refractory CD30+ lymphomas. This investigator-initiated single-center phase I-II trial (NCT04074746) evaluated the safety and activity of P+E AFM13-precomplexed CB NK cells followed by systemic AFM13. Pts ages 15-75 with CD30+ lymphomas refractory to brentuximab vedotin were enrolled. The goals were to identify the recommended phase 2 dose (RP2D) of NK cells, estimate the overall (ORR) and complete response (CR), event-free (EFS) and overall survival (OS) rates, and study NK cell activation and persistence. Each treatment cycle consisted of fludarabine/cyclophosphamide (days −5 to −3) followed by infusion (day 0) of the AFM13-precomplexed CB NK cells, cultured for 14 days as described above, and three weekly IV infusions of AFM13 (200 mg, days 7, 14 and 21). Two cycles were planned for pts 1-19 and up to 4 cycles from patient 20 on. Response was evaluated on day 28 of each cycle. Enrollment proceeded at 3 dose levels (DL) of 10 6, 10 7 and 10 8 NK/Kg, respectively. Each patient received the same NK dose in all cycles. Between 09/20-12/22 we enrolled 42 pts (37 HL, 5 NHL), pretreated with a median 7 lines, at DL1 (N=3), DL2 (N=3) and DL3 (N=36), with 1 (N=2), 2 (N=21), 3 (N=3) or 4 cycles (N=16). All had active progressive disease at enrollment and no bridging therapy was given. The cords used for each of the 117 cycles were selected without consideration for HLA match, which was 0/6 (N=53), 1/6 (N=46), 2/6 (N=14), 3/6 (N=3) and 4/6 (N=1). The product infused consisted of >94% NK cells (expanded >2,700 fold), with only 0.02% T cells. The NK cells were 96% viable, 91% bound to AFM13, and 97.6% CD16+. The products were infused fresh. There was 1 grade 2 infusion-related reaction (IRR) in 115 infusions of AFM13-NK (0.8%) and 27 IRR infusion related reactions in 350 infusions of AFM13 (7.7%) (1 G3, 26 G2). We saw no cases of CRS, ICANS or GVHD of any grade. DL3 (10 8 NK/Kg) was established as the RP2D. The ORR and CR were 92.8% and 66.7%, respectively (94.4% and 72.2%, respectively, in 36 pts treated at the RP2D). Nine pts had a response consolidated with SCT (5 allo, 4 auto). At median follow-up of 14 (6-34) months, the EFS/OS rates are 31%/76%; median EFS/OS are 8 months/not reached. No relapses were associated with antigen loss. In the subset of pts planned for 4 cycles at RP2D, 15 of 23 pts remained event free at 6 mo (4 pts with and 11 without SCT consolidation), for 6-month EFS/OS rates of 65%/83%. Overall, 8 of the 9 pts (89%) receiving a consolidation SCT are event free at 10 to 34 months. AFM-bound CB NK cells were detected in blood from day 1 post infusion for up to 3 weeks. Donor NK levels followed similar patterns after each cycle, which argues against a sensitization after the first NK infusion. CyTOF studies showed increased expression of AFM13 and activation markers in donor NK cells. We confirmed trafficking of AFM13-bound donor NK cells to tumor sites shortly after infusion. CB-derived cytokine-induced memory-like NK cells precomplexed with AFM13 have excellent tolerability and activity for pts with heavily pretreated and refractory CD30+ lymphoma.

CD45 limits early Natural Killer cell development.

The clinical development of Natural Killer (NK) cell-mediated immunotherapy marks a milestone in the development of new cancer therapies and has gained traction due to the intrinsic ability of the NK cell to target and kill tumor cells. To fully harness the tumor killing ability of NK cells, we need to improve NK cell persistence and to overcome suppression of NK cell activation in the tumor microenvironment. The trans-membrane, protein tyrosine phosphatase CD45, regulates NK cell homeostasis, with the genetic loss of CD45 in mice resulting in increased numbers of mature NK cells. This suggests that CD45-deficient NK cells might display enhanced persistence following adoptive transfer. However, we demonstrate here that adoptive transfer of CD45-deficiency did not enhance NK cell persistence in mice, and instead, the homeostatic disturbance of NK cells in CD45-deficient mice stemmed from a developmental defect in the progenitor population. The enhanced maturation within the CD45-deficient NK cell compartment was intrinsic to the NK cell lineage, and independent of the developmental defect. CD45 is not a conventional immune checkpoint candidate, as systemic loss is detrimental to T and B cell development, compromising the adaptive immune system. Nonetheless, this study suggests that inhibition of CD45 in progenitor or stem cell populations may improve the yield of in vitro generated NK cells for adoptive therapy.

Polymer Micropatches as Natural Killer Cell Engagers for Tumor Therapy.

Natural killer (NK) cell therapies have emerged as a potential therapeutic approach to various cancers. Their efficacy, however, is limited by their low persistence and anergy. Current approaches to sustain NK cell persistence in vivo include genetic modification, activation via pretreatment, or coadministration of supporting cytokines or antibodies. Such supporting therapies exhibit limited efficacy in vivo, in part due to the reversal of their effect within the immunosuppressive tumor microenvironment and off-target toxicity. Here, we report a material-based approach to address this challenge. Specifically, we describe the use of polymeric micropatches as a platform for sustained, targeted activation of NK cells, an approach referred to as microparticles as cell engagers (MACE). Poly(lactide-co-glycolic) acid (PLGA) micropatches, 4-8 μm in diameter and surface-modified with NK cell receptor targeting antibodies, exhibited strong adhesion to NK cells and induced their activation without the need of coadministered cytokines. The activation induced by MACE was greater than that induced by nanoparticles, attesting to the crucial role of MACE geometry in the activation of NK cells. MACE-bound NK cells remained viable and exhibited trans-endothelial migration and antitumor activity in vitro. MACE-bound NK cells activated T cells, macrophages, and dendritic cells in vitro. Adoptive transfer of NK-MACE also demonstrated superior antitumor efficacy in a mouse melanoma lung metastasis model compared to unmodified NK cells. Overall, MACE offers a simple, scalable, and effective way of activating NK cells and represents an attractive platform to improve the efficacy of NK cell therapy.

Off-the-shelf CAR–engineered natural killer cells targeting FLT3 enhance killing of acute myeloid leukemia

AbstractThe majority of patients with acute myeloid leukemia (AML) succumb to the disease or its complications, especially among older patients. Natural killer (NK) cells have been shown to have antileukemic activity in patients with AML; however, to our knowledge, primary NK cells armed with a chimeric antigen receptor (CAR) targeting antigens associated with AML as an “off-the-shelf” product for disease control have not been explored. We developed frozen, off-the-shelf allogeneic human NK cells engineered with a CAR recognizing FLT3 and secreting soluble interleukin-15 (IL-15) (FLT3 CAR_sIL-15 NK) to improve in vivo NK cell persistence and T-cell activation. FLT3 CAR_sIL-15 NK cells had higher cytotoxicity and interferon gamma secretion against FLT3+ AML cell lines when compared with activated NK cells lacking an FLT3 CAR or soluble IL-15. Frozen and thawed allogeneic FLT3 CAR_sIL-15 NK cells prolonged survival of both the MOLM-13 AML model as well as an orthotopic patient-derived xenograft AML model when compared with control NK cells. FLT3 CAR_sIL-15 NK cells showed no cytotoxicity against healthy blood mononuclear cells or hematopoietic stem cells. Collectively, our data suggest that FLT3 is an AML-associated antigen that can be targeted by frozen, allogeneic, off-the-shelf FLT3 CAR_sIL-15 NK cells that may provide a novel approach for the treatment of AML.

IMMU-22. ALLOGENEIC NK CELLS SECRETING IL15 AND RESISTANT TO TGF-β Show Antitumor Activity Against Gliobastoma

Abstract INTRODUCTION High grade brain cancers, like most solid tumors, often relapse and are resistant to current therapies. Limited efficacy to cell therapy may be related to intratumoral heterogeneity and the suppressive tumor microenvironment. Hence, we aimed to modify allogeneic natural killer (NK) cells, which can recognize expressed tumor stress ligands, to resist TGF-β and secrete IL15. METHODS Cord blood-derived NK cells were expanded and modified to express IL15 and a dominant negative receptor (DNR) against TGF-β. NK cell product activity against the GBM cell line U87MG were evaluated in vitro and in vivo. The behavior of these cells were also analyzed ex vivo, to evaluate the impact (including potential toxicity) of increasing the potency of this allogeneic NK cell product. RESULTS While animals injected with NK cells secreting IL15 and expressing DNR successfully cleared tumors 6 days after T cell infusion, we did not observe significant differences in survival between the groups (no treatment control mice vs treated with mock-transduced NK cell vs DNR-transduced NK cells vs IL-15/DNR-transduced NK cells). Therefore, we sought to determine whether cytokine-related toxicity was responsible for death in the setting of tumor clearance. We compared no treatment control mice vs mice treated with mock-transduced or IL-15/DNR-transduced NK cell products. Elevated levels of IL-15 were detected in the plasma of mice treated with IL-15/DNR-transduced NK cells. These elevated IL-15 levels corresponded with NK cell persistence in the brain measured by ddPCR. However, no other cytokines were upregulated. CONCLUSIONS We observed improved tumor clearance when NK cells were both protected against immune suppressive TGF-β and were capable of secreting the stimulatory cytokine IL15. We are currently performing additional experiments to determine whether toxicity from IL15 secretion occurs. To potentially mitigate this toxicity we plan to engineer a suicide gene into these constructs.

Expanded clinical-grade NK cells exhibit stronger effects than primary NK cells against HCMV infection.

Cytomegalovirus (CMV) reactivation remains a common complication and leads to high mortality in patients who undergo allogeneic hematopoietic stem cell transplantation (allo-HSCT). Early natural killer (NK) cell reconstitution may protect against the development of human CMV (HCMV) infection post-HSCT. Our previous data showed that ex vivo mbIL21/4-1BBL-expanded NK cells exhibited high cytotoxicity against leukemia cells. Nevertheless, whether expanded NK cells have stronger anti-HCMV function is unknown. Herein, we compared the anti-HCMV functions of ex vivo expanded NK cells and primary NK cells. Expanded NK cells showed higher expression of activating receptors, chemokine receptors and adhesion molecules; stronger cytotoxicity against HCMV-infected fibroblasts; and better inhibition of HCMV propagation in vitro than primary NK cells. In HCMV-infected humanized mice, expanded NK cell infusion resulted in higher NK cell persistence and more effective tissue HCMV elimination than primary NK cell infusion. A clinical cohort of 20 post-HSCT patients who underwent adoptive NK cell infusion had a significantly lower cumulative incidence of HCMV infection (HR = 0.54, 95% CI = 0.32-0.93, p = 0.042) and refractory HCMV infection (HR = 0.34, 95% CI = 0.18-0.65, p = 0.009) than controls and better NK cell reconstitution on day 30 post NK cell infusion. In conclusion, expanded NK cells exhibit stronger effects than primary NK cells against HCMV infection both in vivo and in vitro.

Abstract 2904: CAT-179, an allogeneic NK cell product expressing HER2-CAR, IL-15 and TGFβ dominant negative receptor, durably regresses HER2-expressing xenograft tumors in mice

Abstract While chimeric antigen receptor (CAR)-engineered immune cell therapies have been at the forefront of cancer immunotherapy for hematological malignancies, patients with solid tumors have yet to benefit from such therapies. Engineered, off-the-shelf, allogeneic natural killer (NK) cells are particularly attractive as cell therapies for solid tumors given their clinical safety, efficacy, and multimodal recognition of tumor cells. We describe here the pre-clinical pharmacokinetics, efficacy, biodistribution and safety of CAT-179, a novel allogeneic, cryopreserved CAR-NK cell therapy, in naïve animals as well as multiple xenograft models of HER2-amplified ovarian and gastric cancer. CAT-179 cells are engineered to express an optimized HER2-directed CAR to effectively target tumor cells, a transforming growth factor b (TGFβ) dominant negative receptor (DNR) to protect against TGFβ-mediated immunosuppression, and interleukin-15 (IL-15) to enhance NK cell persistence. A single intravenous (IV) dose of CAT-179 resulted in IL-15-dependent (p<0.0001) expansion and persistence of CAT-179 cells for at least 140 days in NOD-scid IL2Rgnull (NSG) mice, peaking at approximately 15,000 cells/µL of blood (by day 60). Persisting CAT-179 NK cell levels at day 60 were functionally active and significantly reduced tumor burden when challenged intraperitoneally (IP) with HER2+ SKOV3-luc tumor cells. No significant changes in body weight or condition were observed during this study. The therapeutic anti-tumor activity of CAT-179 against established tumors was assayed using two different xenograft models. In the first model, NSG mice were given an IP dose of 1 million SKOV3-luc tumor cells (derived from ovarian cancer) followed by either 4 million CAT-179 or control NK cells on days 4, 11 and 18. CAT-179 dosed animals showed a rapid and sustained 95% decline in tumor burden (p<0.0001) and a significant extension in survival relative to animals dosed with control NK cells (p<0.0001). In the second model, 1 million HER2+ N87 cancer cells (derived from gastric cancer) were implanted subcutaneously into the right flank of NSG mice. When tumors reached 70mm3, a single IV dose of 2M CAT-179 or control NK cells was administered. CAT-179 dosed animals showed a 96% durable tumor regression and significant survival benefit relative to animals dosed with control NK cells (p<0.0001). Efficacy strongly correlated with the circulating levels of CAT-179, which significantly infiltrated the tumor xenograft. Our pre-clinical results demonstrate the potential of CAT-179 as a novel, durable, and off-the-shelf cell therapy to overcome the challenges associated with solid tumors and provide quantitative insights into pharmacokinetics, pharmacodynamics and anti-tumor activity of engineered NK cells expressing CAR, TGFb DNR and IL-15. Citation Format: Bashar Hamza, Angela Nunez, Marilyn Marques, Alexia Barandiaran, Henry Moreno, Finola Moore, Meghan Walsh, Eugene Choi, Kisha Pradhan, Krista Daniel, Jennifer Johnson, Charlotte Franco, Andres Alvarez, Karl Malakian, Keith H. Wong, Joseph Gold, Vipin Suri, Dominic Picarella. CAT-179, an allogeneic NK cell product expressing HER2-CAR, IL-15 and TGFβ dominant negative receptor, durably regresses HER2-expressing xenograft tumors in mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2904.

Abstract 2902: Off-the-Shelf CAR-NK cells engineered to express calibrated release IL-15 exhibit enhanced persistence and anti-tumor activities

Abstract Chimeric antigen receptor (CAR) natural killer (NK) cell therapy is an attractive immunotherapy strategy due to potential for increased anti-tumor activity and favorable safety. Allogeneic donor derived NK cells have shown promising clinical outcomes in both hematological and solid tumor malignancies but have a short lifespan in the absence of cytokine support. Interleukin (IL)-15 is a pleiotropic cytokine that promotes the survival, proliferation, and cytotoxicity of NK cells. In this study, we engineered human peripheral blood-derived NK cells to co-express a CAR and calibrated release (cr) IL-15 and studied how crIL-15 affected CAR-NK cell functions. Senti Bio has designed the calibrated release technology to simultaneously produce membrane bound and secreted cytokines, such as IL-15 and IL-12, to provide autocrine and paracrine activity. We further validated crIL-15 activity in vitro and demonstrated enhanced NK cell persistence, tumor killing and autocrine activity in CAR NK cells as well as paracrine stimulation of neighboring T cells and NK cells via pSTAT5 activation. Additionally, we examined in vivo persistence and biodistribution of NK cells engineered with crIL-15 and a nanoluc reporter. crIL-15 NK cells were intravenously (i.v.) injected into NSG mice. These NK cells were detected in the lung, femur, spleen, liver and stomach 1 day post injection by bioluminescence imaging and polymerase chain reaction (PCR) and lasted up to 20 days in the lung. In addition, crIL-15 increased CAR-NK cells persistence in a dose-dependent manner compared to unengineered NK cells. Injection of higher CAR-NK cell numbers (15× 106 vs 7.5× 106 CAR+ cells per mouse) or multiple NK dosages (1 vs 3 doses) both contributed to prolonged persistence. Finally, we studied how crIL-15 affected CAR-NK cell anti-tumor function in acute myeloid leukemia (AML) xenograft models. MV4-11-Fluc AML tumor cells were co-injected with engineered NK cells expressing a FLT3 and/or CD33 bivalent activating CAR, a EMCN inhibitory CAR and crIL-15 into NSG-Tg (Hu-IL15) mice via i.v. injection. Our data showed that these CAR-NK cells significantly reduced MV4-11 tumor burden and prolonged mouse survival compared to unengineered NK cells. The improved anti-tumor functions correlated with IL-15 levels produced by the CAR-NK cells. In conclusion, our results demonstrated that crIL-15 can improve persistence and anti-tumor activity of CAR-NK cells. Citation Format: Chen-Ting Lee, Michelle Hung, Andrew Banicki, Wenqi Song, Niran Almudhfar, Deepika Kaveri, Priscilla Wong, Lawrence Naitmazi, Marcela Guzman, Alice Lam, Gozde Yucel, Timothy Lu, Alba G. Junca, Brian Garrison, Philip Lee. Off-the-Shelf CAR-NK cells engineered to express calibrated release IL-15 exhibit enhanced persistence and anti-tumor activities [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2902.

The natural killer cell immunotherapy platform: An overview of the landscape of clinical trials in liquid and solid tumors

The translation of natural killer (NK) cells to the treatment of malignant disease has made significant progress in the last few decades. With a variety of available sources and improvements in both in vitro and in vivo NK cell expansion, the NK cell immunotherapy platform has come into its own. The enormous effort continues to further optimize this platform, including ways to enhance NK cell persistence, trafficking to the tumor microenvironment, and cytotoxicity. As this effort bears fruit, it is translated into a plethora of clinical trials in patients with advanced malignancies. The adoptive transfer of NK cells, either as a standalone therapy or in combination with other immunotherapies, has been applied for the treatment of both liquid and solid tumors, with numerous early-phase trials showing promising results. This review aims to summarize the key advantages of NK cell immunotherapy, highlight several of the current approaches being taken for its optimization, and give an overview of the landscape of clinical trials translating this platform into clinic.

Innate Cell Engager AFM13 Combined with Preactivated and Expanded Cord Blood-Derived NK Cells for Patients with Double Refractory CD30+ Lymphoma

Patients with multiple relapsed or refractory (R/R) Hodgkin lymphoma (HL) and other CD30+ lymphoma have few effective therapies available and targeted adoptive natural killer (NK) cell immunotherapy is an active area of investigation. Transfer of non-targeted NK cells has shown limited clinical benefit as target recognition of cancers by NK cells remains a substantial barrier. The innate cell engager (ICE®) construct, AFM13, is a first-in-class CD30/CD16A bispecific antibody construct that induces specific and selective killing of CD30+ tumor cells by engaging and activating NK cells. As a single agent, AFM13 has limited clinical activity against HL, likely due to the reduced effector function of autologous NK cells in these patients, which provides the rationale for the combination of AFM13 with allogeneic NK cells. Our prior preclinical work identified a promising combination of cord blood (CB)-derived NK cells that were first IL-12/IL-15/IL-18-preactivated followed by expansion (P+E) with engineered K562 feeder cells expressing membrane-bound IL-21, 4-1BB ligand and CD48 ex vivo, and subsequently complexed with AFM13 just prior to infusion (Kerbauy et al, Clin Cancer Res 2021; 27:3744-56). These cytokine-induced memory-like CB-derived NK cells precomplexed with AFM13 (AFM13-NK) presented chimeric antigen receptor (CAR)-NK cell-like features and showed an increased in vitro and in vivo antitumor activity compared to either P+E NK or AFM13 alone. Building on this work we wished to clinically study adoptive AFM13-NK cell therapy in pts with R/R CD30+ lymphomas. METHODS: This single-center phase I-II trial (NCT04074746) evaluates the safety and activity of AFM13-NK, followed by AFM13 monotherapy. Patients aged 15-75 years with R/R CD30+ lymphomas refractory to brentuximab vedotin are enrolled. The trial goals are to identify the recommended phase 2 dose (RP2D) of AFM13-NK cells, estimate the overall (ORR) and complete response (CR) rates, event-free (EFS) and overall survival (OS) rates, and studies of NK cell activation and persistence. Each treatment cycle consisted of fludarabine/cyclophosphamide (days −5 to −3), followed by infusion of the AFM13-NK cells, cultured for 14 days as described above (day 0), and three weekly IV infusions of AFM13 (200 mg, days 7, 14 and 21). Two cycles were administered to patients 1-19 and 4 cycles were given starting with patient 20. Response was evaluated on day 28 of each cycle. Patients were enrolled at 3 dose levels: DL1 (106 NK/Kg), DL2 (107NK/Kg) and DL3 (108 NK/Kg). Each patient received the same NK dose in all cycles. RESULTS: As of 7/31/22, 30 pts have been enrolled and treated (Table) at DL1 (N=3), DL2 (N=3) and DL3 (N=24), with 1 (N=1), 2 (N=24), 3 (N=3) or 4 cycles (N=3). All patients had active progressive disease at enrollment and no bridging therapy was given. The cords used for each of the 69 cycles were selected with no consideration for HLA match, which was 0/6 (N=31), 1/6 (N=31), 2/6 (N=5), 3/6 (N=1) and 4/6 (N=1). The product infused consisted of >99% NK cells (expanded >2,700 fold), with only 0.02% T cells. The NK cells were >98% viable and 92% of them were bound to AFM13. The products were infused fresh. There were no infusion-related reactions (IRR) after infusing AFM13-NK and 11 IRR in 182 infusions of AFM13 alone (6%) (1 grade 3, 10 grade 2). We saw no cases of CRS, ICANS or GVHD of any grade. DL3 (108 NK/Kg) was established as the RP2D. The ORR in the entire study is 97% with 63% CRs. All 24 patients treated at the RP2D responded (100% ORR) with 70.8% (17/24) CRs. Five patients had a response consolidated with a SCT. At median follow-up of 8 (range 1-23) months, the EFS and OS rates of all 30 patients are 57% and 83%, respectively. AFM-NK cells were detected in serum from day 1 post infusion and persisted for 3-4 weeks. Donor NK levels followed similar patterns after each cycle, which argues against a sensitization effect in the patient after the first NK infusion. Donor NK cells showed by CyTOF increased binding to AFM13 and expression of activation markers. CONCLUSIONS: This is the first clinical trial to date using an ICE® construct precomplexed with cytokine-induced memory-like CB-NK cells to treat patients with CD30+ R/R HL and NHL. Our preliminary results indicate that this ICE® precomplexed CB-NK cell therapy has an excellent tolerability profile and is highly active in patients with heavily pretreated R/R CD30+ lymphomas and warrants further investigation. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Trial in Progress: AB-101, an Allogeneic, Non-Engineered, Cord Blood-Derived Natural Killer (NK) Cell Therapy, As Monotherapy or in Combination with Rituximab in Patients with Relapsed or Refractory Non-Hodgkin Lymphoma

Background: Natural Killer (NK) cells are known to eliminate tumors directly or via antibody-dependent cellular cytotoxicity (ADCC) which is dependent on the maturation, activation and FcγRIIIA (CD16) phenotype of NK cells. Many cancer patients have low NK cell number and dysfunctional innate immunity, which has been correlated with outcomes to monoclonal antibody (mAb) therapy. AB-101 is an allogeneic, non-genetically modified cord blood-derived NK cell therapy, developed to potentially enhance patients' innate anti-tumor activity in combination with approved oncology products with known ADCC mechanism of action. AB-101 has been optimized for combination with mAbs through the novel AlloNK™ proprietary large scale manufacturing process utilizing donor cord blood units. The cord blood unit is selected for key attributes, including an immunoglobulin-like receptor B (KIR-B) haplotype and the natural high-affinity variant of CD16 (158V/V polymorphism). The AlloNK™ process results in an activated and mature NK cell product with increased cell surface expression of CD16, NKG2D, NKp30/44/46, and DNAM-1, without any requirement for genetic engineering. Additionally, the process generates sufficient NK cells to treat hundreds to thousands of patients from a single cord blood unit and produces a consistently active NK cell product, with little donor-to-donor variability. The combination of AB-101 and rituximab has demonstrated strong cytotoxic activity in preclinical studies; the combination led to improved survival over rituximab or NK cells alone in xenograft mouse models. As a cryopreserved, "off-the-shelf", and infusion-ready product, AB-101 is being evaluated for the treatment of hematologic malignancies in combination with standard of care antibody therapies. Study Design, Treatment and Methods: AB-101-01 is a first in human, Phase 1/2, multi-center, open-label study to evaluate the safety and anti-tumor activity of AB-101 as monotherapy and in combination with rituximab in patients with relapsed or refractory (R/R) non-Hodgkin lymphoma (NHL) of B-cell origin or CLL. This study has 3 parts: Phase 1, 1b, and 2. Phase 1 will evaluate 2 dose levels as monotherapy or in combination with rituximab using the 3+3 dose escalation method. Phase 1b will enroll up to 45 patients in combination with rituximab to determine the recommended phase 2 dose (RP2D). Phase 2 will enroll an additional 15 patients at the RP2D. AB-101 will be given at 1 or 4 billion cells per dose. All enrolled patients will receive at least 1 treatment cycle of 4 doses of AB-101, administered once weekly. Prior to receiving the first dose of AB-101, patients will receive 3 consecutive days of lymphodepleting chemotherapy consisting of fludarabine (30 mg/m2/day) and cyclophosphamide (250 or 500 mg/m2/day). After each AB-101 infusion, patients will receive interleukin-2 (IL-2) at 1×106 IU/m2/dose or 6×106 IU/dose to potentiate NK cell activation and persistence. If given, 375 mg/m2 of rituximab is dosed on the second day of lymphodepletion and with the second and fourth dose of AB-101. Patients who have a complete or partial response or maintain stable disease with the first cycle of the combination may receive 3 additional cycles such that cycle 2 is given with lymphodepletion and cycles 3 and 4 do not include lymphodepletion. Eligible patients must have a diagnosis of B-cell NHL or CLL and must have received at least 2 prior lines of therapy, including an anti-CD20 antibody therapy. Treatment with prior CD19 CAR T-cell therapy is permitted. Patients must be at least 18 years of age, have ECOG PS of 0 or 1, and have measurable disease per Lugano 2014 at the time of enrollment. The primary objectives of each phase are as follows: in Phase 1, the evaluation of the safety of 1 and 4 billion cells/dose of AB-101 as monotherapy or in combination with rituximab through the incidence of AEs and DLTs; in Phase 1b, determination of the RP2D based on safety and antitumor response to AB-101 with rituximab; and in Phase 2, further characterization of the efficacy profile. The study is currently enrolling at 10 U.S. centers. (ClinicalTrials.gov Identifier: NCT04673617)

A Phase II Clinical Trial of "Off-the-Shelf" NK Cells with Allogeneic Stem Cell Transplantation to Decrease Disease Relapse in Patients with High-Risk Myeloid Malignancies

Background Acute myeloid leukemia, myelodysplastic syndrome, and TKI resistant CML continue to be among the most aggressive forms of blood cancer. Allogeneic hematopoietic stem cell transplantation (alloSCT) remains one of the most effective treatments available. Much of the benefit of AlloSCT is due to the immune-mediated graft-versus-leukemia effect to prevent relapse. Nevertheless, disease relapse remains the most important cause of treatment failure after alloSCT. A potential solution to reduce the risk of relapse may be found in Natural Killer (NK) cells, which have a demonstrable ability to eliminate leukemic and virally infected cells. However, naturally produced NK cells seen in patients early post-transplant are functionally impaired. A potential solution would be to provide donor-derived, expanded and activated NK cells in the peri-transplant setting. Natural killer cells are a unique class of lymphocytes, with cytotoxic, and immunoregulatory function which can mediate potent anti-leukemia effects. NK cells are regulated by Killer-cell Immunoglobulin-like Receptors (KIR) receptor-ligand interactions and mediate cytotoxicity. Alloreactive NK cells have been reported to enhance engraftment, reduce GVHD and prevent relapse of leukemia post transplant. This study will utilize NK cells from third party donors as adjuvant treatment to eradicate leukemia and prevent disease relapse after transplantation. Study Design and Methods Our clinical trial is registered as NCT05115630. Inclusion criteria includes age 18 to 65 years old, weighing at least 42 kg, with High risk AML, MDS, or TKI-resistant/intolerant CML who have either an HLA matched related donor, HLA matched unrelated donor, a haploidentical related donor, or a one antigen mismatched unrelated donor. HLA matching includes HLA A, B, C, and DR-B1. Exclusion criteria include patients who are HIV positive or has active hepatitis B or C, uncontrolled infections, liver cirrhosis, CNS involvement within 3 months prior to the transplant, or positive pregnancy test in a woman with child bearing potential. We will also exclude any patient with inability to comply with medical therapy or follow-up, patient with a known history of allergic reactions to any constituents of the product, including a known history of allergic reactions to cellular products or DMSO, other malignancy/cancer diagnosis <2 years ago. We will also exclude any patient requiring systemic corticosteroids with prednisone dose >10 mg or equivalent or who has KDS-1001 Donor specific antibodies (dsa) >5000 MFI units, or has KDS-1001 Donor anti-C1q positive. Statistical considerations and exploratory endpoints This is a single-arm Phase II trial of 3rd party natural killer (NK) cells at a fixed dose added to an allogeneic stem cell transplant for AML/MDS/CML. The goal is to reduce the risk of relapse of the malignancy post transplant, and to improve relapse free survival. The primary endpoint is the adverse event Failure = [graft failure, grade 3-4 GVHD, relapse or non-relapse death within 100 days post-transplant]. The stopping rule for time-to-failure (defined as graft failure, gr 3-4 GHVD, or non-relapse death) will be implemented to avoid waiting 100 days (3 months) to evaluate each patient to perform safety monitoring. The design will be based on T with 3 months follow-up, applying the design of Thall et al. Possibly right-censored values of T for patients treated in the trial will be monitored continuously throughout the trial. The accrual rate is expected to be approximately 2 patients per month, with each patient's follow-up continued until all patients have been followed for 3 months from their date of first NK cell administration. The distributions of time to failure and RFS time will be estimated using the method of Kaplan and Meier. Exploratory analyses with immunophenotyping for NK cell chimerism and persistence will be done as feasible. Immune reconstitution studies or additional future research may be performed.

Interim Phase I Clinical Data of FT576 As Monotherapy and in Combination with Daratumumab in Subjects with Relapsed/Refractory Multiple Myeloma

Introduction: Despite the recent FDA approval of autologous chimeric antigen receptor (CAR) T-cell therapies targeting B-cell maturation antigen (BCMA), multiple myeloma (MM) remains incurable and relapsed/refractory (R/R) disease remains an area of high unmet medical need. Additionally, patient access to autologous CAR T-cell therapies is currently limited due to manufacturing constraints, the need for bridging therapy, and potentially life-threatening toxicities including cytokine release syndrome and neurologic toxicities (Munshi et al. 2021). Off-the-shelf natural killer (NK) cell therapies may offer an improved therapeutic profile and broader patient access than autologous CAR T-cell therapies. FT576 is a first-of-kind, multiplexed-engineered BCMA CAR NK cell therapy generated from a clonal master engineered induced pluripotent stem cell line, which can be used as a renewable source for the mass production of off-the-shelf NK cells of uniform composition. FT576 is engineered with 4 modalities to combine multifaceted innate immunity with multi-antigen-targeting capability: (1) high-affinity 158V, non-cleavable CD16 (hnCD16) Fc receptor for augmented antibody-dependent cellular cytotoxicity; (2) IL-15/IL-15 receptor fusion that promotes NK cell persistence; (3) CD38 knockout to mitigate NK cell fratricide by CD38-directed monoclonal antibodies (mAbs) and that provides improved metabolic fitness and resistance to oxidative stress within the tumor microenvironment; and (4) a BCMA-directed CAR to target plasma cells. These modalities are designed to enhance the potency and persistence of FT576 and to enable multi-antigen targeting when combined with tumor-targeting mAbs. In preclinical studies, FT576 combined with the anti-CD38 mAb daratumumab demonstrated highly effective tumor control compared to either treatment alone or to primary CAR T cells in a disseminated MM xenograft model (Goodridge et al. 2021), suggestive that limitations in MM treatment confounded by clonal heterogeneity and antigen loss can be overcome with a dual antigen-targeting approach. Methods: This is a Phase I trial of FT576 in patients with R/R MM. The primary objectives are to assess safety and tolerability and to determine the recommended Phase II dose of FT576, given as single or multiple doses, as monotherapy and in combination with daratumumab in R/R MM. Key secondary objectives include anti-tumor activity and pharmacokinetics. The dose-escalation stage of the trial has the following 4 arms: single-dose FT576 monotherapy on Day 1 (Regimen A); multi-dose FT576 monotherapy on Days 1 and 15 (Regimen A1); single-dose FT576 + daratumumab on Day 1 (Regimen B); and multi-dose FT576 + daratumumab on Days 1 and 15 (Regimen B1). Dose levels of FT576 starting from 100 million cells/dose are being evaluated using a modified toxicity probability interval dose-escalation design. Daratumumab is administered per approved dose and schedule. Outpatient conditioning chemotherapy consists of 3 consecutive days of fludarabine and cyclophosphamide administered prior to the first dose of FT576. Results: As of a data cutoff date of 18 Jul 2022, 9 patients with R/R MM were treated and evaluable for safety and efficacy, in the first 2 dose levels of Regimen A (n = 6) and in the first dose level of Regimen B (n = 3). No dose-limiting toxicities, and no events of any grade of cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome, or graft-versus-host disease (GvHD), were observed. Conclusions: Administration of a single dose of FT576 at 100 or 300 million cells/dose alone or in combination with daratumumab is safe and well tolerated thus far without CRS, neurotoxicity, or GvHD. Interim clinical data, including safety and tolerability and initial anti-tumor activity, from the ongoing Phase I dose-escalation study of FT576 will be presented at the conference.

Natural killer cells in antitumour adoptive cell immunotherapy.

Natural killer (NK) cells comprise a unique population of innate lymphoid cells endowed with intrinsic abilities to identify and eliminate virally infected cells and tumour cells. Possessing multiple cytotoxicity mechanisms and the ability to modulate the immune response through cytokine production, NK cells play a pivotal role in anticancer immunity. This role was elucidated nearly two decades ago, when NK cells, used as immunotherapeutic agents, showed safety and efficacy in the treatment of patients with advanced-stage leukaemia. In recent years, following the paradigm-shifting successes of chimeric antigen receptor (CAR)-engineered adoptive T cell therapy and the advancement in technologies that can turn cells into powerful antitumour weapons, the interest in NK cells as a candidate for immunotherapy has grown exponentially. Strategies for the development of NK cell-based therapies focus on enhancing NK cell potency and persistence through co-stimulatory signalling, checkpoint inhibition and cytokine armouring, and aim to redirect NK cell specificity to the tumour through expression of CAR or the use of engager molecules. In the clinic, the first generation of NK cell therapies have delivered promising results, showing encouraging efficacy and remarkable safety, thus driving great enthusiasm for continued innovation. In this Review, we describe the various approaches to augment NK cell cytotoxicity and longevity, evaluate challenges and opportunities, and reflect on how lessons learned from the clinic will guide the design of next-generation NK cell products that will address the unique complexities of each cancer.