Inhibition of mitochondrial complex I reverses NOTCH1-driven metabolic reprogramming in T-cell acute lymphoblastic leukemia.

T-cell acute lymphoblastic leukemia (T-ALL) is commonly driven by activating mutations in NOTCH1 that facilitate glutamine oxidation. Here we identify oxidative phosphorylation (OxPhos) as a critical pathway for leukemia cell survival and demonstrate a direct relationship between NOTCH1, elevated OxPhos gene expression, and acquired chemoresistance in pre-leukemic and leukemic models. Disrupting OxPhos with IACS-010759, an inhibitor of mitochondrial complex I, causes potent growth inhibition through induction of metabolic shut-down and redox imbalance in NOTCH1-mutated and less so in NOTCH1-wt T-ALL cells. Mechanistically, inhibition of OxPhos induces a metabolic reprogramming into glutaminolysis. We show that pharmacological blockade of OxPhos combined with inducible knock-down of glutaminase, the key glutamine enzyme, confers synthetic lethality in mice harboring NOTCH1-mutated T-ALL. We leverage on this synthetic lethal interaction to demonstrate that IACS-010759 in combination with chemotherapy containing L-asparaginase, an enzyme that uncovers the glutamine dependency of leukemic cells, causes reduced glutaminolysis and profound tumor reduction in pre-clinical models of human T-ALL. In summary, this metabolic dependency of T-ALL on OxPhos provides a rational therapeutic target.

Characteristics of anti-CD19 CAR T cell infusion products associated with efficacy and toxicity in patients with large B cell lymphomas.

Autologous chimeric antigen receptor (CAR) T cell therapies targeting CD19 have high efficacy in large B cell lymphomas (LBCLs), but long-term remissions are observed in less than half of patients, and treatment-associated adverse events, such as immune effector cell-associated neurotoxicity syndrome (ICANS), are a clinical challenge. We performed single-cell RNA sequencing with capture-based cell identification on autologous axicabtagene ciloleucel (axi-cel) anti-CD19 CAR T cell infusion products to identify transcriptomic features associated with efficacy and toxicity in 24 patients with LBCL. Patients who achieved a complete response by positron emission tomography/computed tomography at their 3-month follow-up had three-fold higher frequencies of CD8 T cells expressing memory signatures than patients with partial response or progressive disease. Molecular response measured by cell-free DNA sequencing at day 7 after infusion was significantly associated with clinical response (P = 0.008), and a signature of CD8 T cell exhaustion was associated (q = 2.8 × 10-149) with a poor molecular response. Furthermore, a rare cell population with monocyte-like transcriptional features was associated (P = 0.0002) with high-grade ICANS. Our results suggest that heterogeneity in the cellular and molecular features of CAR T cell infusion products contributes to variation in efficacy and toxicity after axi-cel therapy in LBCL, and that day 7 molecular response might serve as an early predictor of CAR T cell efficacy.

The Role of Fibrinogen-Like Protein 2 on Immunosuppression and Malignant Progression in Glioma.

BACKGROUND: Virtually all low-grade gliomas (LGGs) will progress to high-grade gliomas (HGGs), including glioblastoma, the most common malignant primary brain tumor in adults. A key regulator of immunosuppression, fibrinogen-like protein 2 (FGL2), may play an important role in the malignant transformation of LGG to HGG. We sought to determine the mechanism of FGL2 on tumor progression and to show that inhibiting FGL2 expression had a therapeutic effect. METHODS: We analyzed human gliomas that had progressed from low- to high-grade for FGL2 expression. We modeled FGL2 overexpression in an immunocompetent genetically engineered mouse model to determine its effect on tumor progression. Tumors and their associated microenvironments were analyzed for their immune cell infiltration. Mice were treated with an FGL2 antibody to determine a therapeutic effect. Statistical tests were two-sided. RESULTS: We identified increased expression of FGL2 in surgically resected tumors that progressed from low to high grade (n = 10). The Cancer Genome Atlas data showed that LGG cases with overexpression of FGL2 (n = 195) had statistically significantly shorter survival (median = 62.9 months) compared with cases with low expression (n = 325, median = 94.4 months, P < .001). In a murine glioma model, HGGs induced with FGL2 exhibited a mesenchymal phenotype and increased CD4+ forkhead box P3 (FoxP3)+ Treg cells, implicating immunosuppression as a mechanism for tumor progression. Macrophages in these tumors were skewed toward the immunosuppressive M2 phenotype. Depletion of Treg cells with anti-FGL2 statistically significantly prolonged survival in mice compared with controls (n = 11 per group, median survival = 90 days vs 62 days, P = .004), shifted the phenotype from mesenchymal HGG to proneural LGG, and decreased M2 macrophage skewing. CONCLUSIONS: FGL2 facilitates glioma progression from low to high grade. Suppressing FGL2 expression holds therapeutic promise for halting malignant transformation in glioma.