Safety and efficacy of quavonlimab, a novel anti-CTLA-4 antibody (MK-1308), in combination with pembrolizumab in first-line advanced non-small-cell lung cancer

BACKGROUND

Quavonlimab (MK-1308), a novel anti-CTLA-4 antibody, in combination with pembrolizumab was investigated in a phase I study.

PATIENTS AND METHODS

Dose-escalation (DE) phase: patients with advanced/metastatic solid tumors received an initial flat dose of quavonlimab as monotherapy [25 mg (cohort 1), 75 mg (cohort 2), or 200 mg (cohort 3)] followed by four treatments of the same quavonlimab dose plus pembrolizumab every 3 weeks (Q3W). Dose-confirmation phase (DC): patients with stage IIIB/IV non-small-cell lung cancer (NSCLC) received first-line quavonlimab [25 mg Q3W (arm A), 25 mg Q6W (arm B), 75 mg Q6W (arm C), or 75 mg Q3W (arm E)] plus pembrolizumab. Primary objectives were safety and tolerability and establishment of the recommended phase II dose (RP2D) of quavonlimab when used with pembrolizumab. Objective response rate (ORR) was a secondary endpoint. Efficacy based on PD-L1 expression, tumor mutational burden (TMB), and changes in circulating CD4+/CD8+ cells were exploratory endpoints.

RESULTS

Thirty-nine patients were enrolled in DE [n = 14 (cohort 1); n = 17 (cohort 2); n = 8 (cohort 3)] and 134 in DC [n = 40 (arm A); n = 40 (arm B); n = 40 (arm C); n = 14 (arm E)]. Maximum-tolerated dose was not reached. Grade 3-5 treatment-related adverse events (AEs; graded according to NCI CTCAE v4.03) occurred in 0%, 23.5%, and 75.0% of patients in DE cohorts 1, 2, and 3, respectively, and 35.0%, 30.0%, 35.0%, and 57.1% of patients in DC arms A, B, C, and E, respectively. Efficacy was observed at all dose levels/schedules in patients with NSCLC. ORRs were 40.0% [95% confidence interval (CI), 24.9-56.7; arm A], 37.5% (95% CI, 22.7-54.2; arm B), 27.5% (95% CI, 14.6-43.9; arm C), and 35.7% (95% CI, 12.8-64.9; arm E). PD-L1 expression and total number of circulating CD4+ cells correlated with ORR.

CONCLUSIONS

Quavonlimab 25 mg Q6W plus pembrolizumab demonstrated similar efficacy and a better safety profile among all quavonlimab doses/schedules evaluated; this regimen was the chosen RP2D.

Differentiation of IL-17-Producing Invariant Natural Killer T Cells Requires Expression of the Transcription Factor c-Maf

c-Maf belongs to the large Maf family of transcription factors and plays a key role in the regulation of cytokine production and differentiation of T_H2, T_H17, T_FH, and Tr1 cells. Invariant natural killer T (iNKT) cells can rapidly produce large quantity of T_H-related cytokines such as IFN-γ, IL-4, and IL-17A upon stimulation by glycolipid antigens, such as α-galactosylceramide (α-GalCer). However, the role of c-Maf in iNKT cells and iNKT cells-mediated diseases remains poorly understood. In this study, we demonstrate that α-GalCer-stimulated iNKT cells express c-Maf transcript and protein. By using c-Maf-deficient fetal liver cell-reconstituted mice, we further show that c-Maf-deficient iNKT cells produce less IL-17A than their wild-type counterparts after α-GalCer stimulation. While c-Maf deficiency does not affect the development and activation of iNKT cells, c-Maf is essential for the induction of IL-17-producing iNKT (iNKT17) cells by IL-6, TGF-β, and IL-1β, and the optimal expression of RORγt. Accordingly, c-Maf-deficient iNKT17 cells lose the ability to recruit neutrophils into the lungs. Taken together, c-Maf is a positive regulator for the expression of IL-17A and RORγt in iNKT17 cells. It is a potential therapeutic target in iNKT17 cell-mediated inflammatory disease.

Transcription factor MafB may play an important role in secondary hyperparathyroidism

The transcription factor MafB is essential for development of the parathyroid glands, the expression of which persists after morphogenesis and in adult parathyroid glands. However, the function of MafB in adult parathyroid tissue is unclear. To investigate this, we induced chronic kidney disease (CKD) in wild-type and MafB heterozygote (MafB+/-) mice by feeding them an adenine-supplemented diet, leading to secondary hyperparathyroidism. The elevated serum creatinine and blood urea nitrogen levels in heterozygous and wild-type mice fed the adenine-supplemented diet were similar. Interestingly, secondary hyperparathyroidism, characterized by serum parathyroid hormone elevation and enlargement of parathyroid glands, was suppressed in MafB+/- mice fed the adenine-supplemented diet compared to similarly fed wild-type littermates. Quantitative RT-PCR and immunohistochemical analyses showed that the increased expression of parathyroid hormone and cyclin D2 in mice with CKD was suppressed in the parathyroid glands of heterozygous CKD mice. A reporter assay indicated that MafB directly regulated parathyroid hormone and cyclin D2 expression. To exclude an effect of a developmental anomaly in MafB+/- mice, we analyzed MafB tamoxifen-induced global knockout mice. Hypocalcemia-stimulated parathyroid hormone secretion was significantly impaired in MafB knockout mice. RNA-sequencing analysis indicated PTH, Gata3 and Gcm2 depletion in the parathyroid glands of MafB knockout mice. Thus, MafB appears to play an important role in secondary hyperparathyroidism by regulation of parathyroid hormone and cyclin D2 expression. Hence, MafB may represent a new therapeutic target in secondary hyperparathyroidism.

T-bet, but not Gata3, overexpression is detrimental in a neurotropic viral infection

Intracerebral Theiler's murine encephalomyelitis virus (TMEV) infection in mice induces inflammatory demyelination in the central nervous system. Although C57BL/6 mice normally resistant to TMEV infection with viral clearance, we have previously demonstrated that RORγt-transgenic (tg) C57BL/6 mice, which have Th17-biased responses due to RORγt overexpression in T cells, became susceptible to TMEV infection with viral persistence. Here, using T-bet-tg C57BL/6 mice and Gata3-tg C57BL/6 mice, we demonstrated that overexpression of T-bet, but not Gata3, in T cells was detrimental in TMEV infection. Unexpectedly, T-bet-tg mice died 2 to 3 weeks after infection due to failure of viral clearance. Here, TMEV infection induced splenic T cell depletion, which was associated with lower anti-viral antibody and T cell responses. In contrast, Gata3-tg mice remained resistant, while Gata3-tg mice had lower IFN-γ and higher IL-4 production with increased anti-viral IgG1 responses. Thus, our data identify how overexpression of T-bet and Gata3 in T cells alters anti-viral immunity and confers susceptibility to TMEV infection.

c-Maf positively regulates IL-17-producing iNKT cell-mediated airway neutrophilia

c-Maf belongs to the large Maf family transcription factors and plays a key role in regulation of cytokine production and differentiation in TH2, TH17, TFH and Tr1 cells. Invariant natural killer T (iNKT) cells can rapidly produce large quantity of TH-related cytokines such as IFN-γ, IL-4 and IL-17A upon stimulation by its glycolipid antigen α-galactosylceramide (α-GalCer). However, the role of c-Maf in iNKT cells and iNKT cell-mediated diseases remains poorly understood. In this study, we demonstrate that α-GalCer-stimulated iNKT cells express c-Maf transcript and protein. By using c-Maf-deficient fetal liver cell-reconstituted mice, we further show that c-Maf-deficient iNKT cells produce less IL-17A than their WT counterparts after α-GalCer stimulation, but IFN-γ and IL-4 productions were not affected. c-Maf deficiency does not affect the development and activation state of iNKT cells. c-Maf also positively regulates induction of IL-17-producing iNKT (iNKT17) cells by IL-6, TGF-β and IL-1β. c-Maf-deficient iNKT cells express lower RORγt transcripts compared with WT iNKT cells under IL-17-induction condition. Interestingly, c-Maf-deficient iNKT17 cells lose the ability to recruit neutrophils into the lungs. Taken together, c-Maf is a positive regulator for IL-17A production through transactivating RORγt expression in iNKT17 cells. It is a potential therapeutic target in iNKT17 cells-mediated inflammatory disease.

T-bet over-expression regulates aryl hydrocarbon receptor-mediated T helper type 17 differentiation through an interferon (IFN)γ-independent pathway

Various transcription factors are also known to enhance or suppress T helper type 17 (Th17) differentiation. We have shown previously that the development of collagen-induced arthritis was suppressed in T-bet transgenic (T-bet Tg) mice, and T-bet seemed to suppress Th17 differentiation through an interferon (IFN)-γ-independent pathway, although the precise mechanism remains to be clarified. The present study was designed to investigate further the mechanisms involved in the regulation of Th17 differentiation by T-bet over-expression, and we found the new relationship between T-bet and aryl hydrocarbon receptor (AHR). Both T-bet Tg mice and IFN-γ^-/- -over-expressing T-bet (T-bet Tg/IFN-γ^-/- ) mice showed inhibition of retinoic acid-related orphan receptor (ROR)γt expression and IL-17 production by CD4⁺ T cells cultured under conditions that promote Th-17 differentiation, and decreased IL-6 receptor (IL-6R) expression and signal transducer and activator of transcription-3 (STAT-3) phosphorylation in CD4⁺ T cells. The mRNA expression of ahr and rorc were suppressed in CD4⁺ T cells cultured under Th-17 conditions from T-bet Tg mice and T-bet Tg/IFN-γ^-/- mice. CD4⁺ T cells of wild-type (WT) and IFN-γ^-/- mice transduced with T-bet-expressing retrovirus also showed inhibition of IL-17 production, whereas T-bet transduction had no effect on IL-6R expression and STAT-3 phosphorylation. Interestingly, the mRNA expression of ahr and rorc were suppressed in CD4⁺ T cells with T-bet transduction cultured under Th17 conditions. The enhancement of interleukin (IL)-17 production from CD4⁺ T cells by the addition of AHR ligand with Th17 conditions was cancelled by T-bet over-expression. Our findings suggest that T-bet over-expression-induced suppression of Th17 differentiation is mediated through IFN-γ-independent AHR suppression.