May Daher

BACKGROUND: Anti-CD19 chimeric antigen receptor (CAR) T-cell therapy has shown remarkable clinical efficacy in B-cell cancers. However, CAR T cells can induce substantial toxic effects, and the manufacture of the cells is complex. Natural killer (NK) cells that have been modified to express an anti-CD19 CAR have the potential to overcome these limitations. METHODS: CAR-NK cells per kilogram of body weight) after lymphodepleting chemotherapy. RESULTS: The administration of CAR-NK cells was not associated with the development of cytokine release syndrome, neurotoxicity, or graft-versus-host disease, and there was no increase in the levels of inflammatory cytokines, including interleukin-6, over baseline. The maximum tolerated dose was not reached. Of the 11 patients who were treated, 8 (73%) had a response; of these patients, 7 (4 with lymphoma and 3 with CLL) had a complete remission, and 1 had remission of the Richter's transformation component but had persistent CLL. Responses were rapid and seen within 30 days after infusion at all dose levels. The infused CAR-NK cells expanded and persisted at low levels for at least 12 months. CONCLUSIONS: Among 11 patients with relapsed or refractory CD19-positive cancers, a majority had a response to treatment with CAR-NK cells without the development of major toxic effects. (Funded by the M.D. Anderson Cancer Center CLL and Lymphoma Moonshot and the National Institutes of Health; ClinicalTrials.gov number, NCT03056339.).

Abstract There is a pressing need for allogeneic chimeric antigen receptor (CAR)-immune cell therapies that are safe, effective and affordable. We conducted a phase 1/2 trial of cord blood-derived natural killer (NK) cells expressing anti-CD19 chimeric antigen receptor and interleukin-15 (CAR19/IL-15) in 37 patients with CD19 + B cell malignancies. The primary objectives were safety and efficacy, defined as day 30 overall response (OR). Secondary objectives included day 100 response, progression-free survival, overall survival and CAR19/IL-15 NK cell persistence. No notable toxicities such as cytokine release syndrome, neurotoxicity or graft-versus-host disease were observed. The day 30 and day 100 OR rates were 48.6% for both. The 1-year overall survival and progression-free survival were 68% and 32%, respectively. Patients who achieved OR had higher levels and longer persistence of CAR-NK cells. Receiving CAR-NK cells from a cord blood unit (CBU) with nucleated red blood cells ≤ 8 × 10 7 and a collection-to-cryopreservation time ≤ 24 h was the most significant predictor for superior outcome. NK cells from these optimal CBUs were highly functional and enriched in effector-related genes. In contrast, NK cells from suboptimal CBUs had upregulation of inflammation, hypoxia and cellular stress programs. Finally, using multiple mouse models, we confirmed the superior antitumor activity of CAR/IL-15 NK cells from optimal CBUs in vivo. These findings uncover new features of CAR-NK cell biology and underscore the importance of donor selection for allogeneic cell therapies. ClinicalTrials.gov identifier: NCT03056339 .

Immune checkpoint therapy has resulted in remarkable improvements in the outcome for certain cancers. To broaden the clinical impact of checkpoint targeting, we devised a strategy that couples targeting of the cytokine-inducible Src homology 2-containing (CIS) protein, a key negative regulator of interleukin 15 (IL-15) signaling, with fourth-generation "armored" chimeric antigen receptor (CAR) engineering of cord blood-derived natural killer (NK) cells. This combined strategy boosted NK cell effector function through enhancing the Akt/mTORC1 axis and c-MYC signaling, resulting in increased aerobic glycolysis. When tested in a lymphoma mouse model, this combined approach improved NK cell antitumor activity more than either alteration alone, eradicating lymphoma xenografts without signs of any measurable toxicity. We conclude that targeting a cytokine checkpoint further enhances the antitumor activity of IL-15-secreting armored CAR-NK cells by promoting their metabolic fitness and antitumor activity. This combined approach represents a promising milestone in the development of the next generation of NK cells for cancer immunotherapy.

Glioblastoma multiforme (GBM), the most aggressive brain cancer, recurs because glioblastoma stem cells (GSCs) are resistant to all standard therapies. We showed that GSCs, but not normal astrocytes, are sensitive to lysis by healthy allogeneic natural killer (NK) cells in vitro. Mass cytometry and single-cell RNA sequencing of primary tumor samples revealed that GBM tumor-infiltrating NK cells acquired an altered phenotype associated with impaired lytic function relative to matched peripheral blood NK cells from patients with GBM or healthy donors. We attributed this immune evasion tactic to direct cell-to-cell contact between GSCs and NK cells via αv integrin-mediated TGF-β activation. Treatment of GSC-engrafted mice with allogeneic NK cells in combination with inhibitors of integrin or TGF-β signaling or with TGFBR2 gene-edited allogeneic NK cells prevented GSC-induced NK cell dysfunction and tumor growth. These findings reveal an important mechanism of NK cell immune evasion by GSCs and suggest the αv integrin/TGF-β axis as a potentially useful therapeutic target in GBM.