First-in-human phase 1 study of the arginase inhibitor INCB001158 alone or combined with pembrolizumab in patients with advanced or metastatic solid tumours

Tumor microenvironment-driven resistance to immunotherapy in non-small cell lung cancer: strategies for Cold-to-Hot tumor transformation

Non-small cell lung cancer (NSCLC) represents a formidable challenge in oncology due to its molecular heterogeneity and the dynamic suppressive nature of its tumor microenvironment (TME). Despite the transformative impact of immune checkpoint inhibitors (ICIs) on cancer therapy, the majority of NSCLC patients experience resistance, necessitating novel approaches to overcome immune evasion. This review highlights shared and subtype-specific mechanisms of immune resistance within the TME, including metabolic reprogramming, immune cell dysfunction, and physical barriers. Beyond well-characterized components such as regulatory T cells, tumor-associated macrophages, and myeloid-derived suppressor cells, emerging players - neutrophil extracellular traps, tertiary lymphoid structures, and exosomal signaling networks - underscore the TME's complexity and adaptability. A multi-dimensional framework is proposed to transform cold, immune-excluded tumors into hot, immune-reactive ones. Key strategies include enhancing immune infiltration, modulating immunosuppressive networks, and activating dormant immune pathways. Cutting-edge technologies, such as single-cell sequencing, spatial transcriptomics, and nanomedicine, are identified as pivotal tools for decoding TME heterogeneity and personalizing therapeutic interventions. By bridging mechanistic insights with translational innovations, this review advocates for integrative approaches that combine ICIs with metabolic modulators, vascular normalizers, and emerging therapies such as STING agonists and tumor vaccines. The synergistic potential of these strategies is poised to overcome resistance and achieve durable antitumor immunity. Ultimately, this vision underscores the importance of interdisciplinary collaboration and real-time TME profiling in refining precision oncology for NSCLC, offering a blueprint for extending these advances to other malignancies.

Arginase Activity Inhibition With Thymoquinone Induces a Hybrid Type of Cell-Death in MDA-MB-231 Cell Line

Arginase plays a crucial role in the urea cycle; it also has immunosuppressive and pro-tumor effects. The present study aimed to assess the effects of arginase inhibition by thymoquinone (2-Isopropyl-5-methyl-1,4-benzoquinone), an active compound of Nigella sativa, on cell death in the MDA-MB-231 triple-negative breast tumor cell line. Cell viability assays, Western blot analysis, and flow cytometry analysis were used to characterize oxidative stress and cell death. Our results showed that inhibition of arginase activity with thymoquinone significantly increased intracellular nitric oxide levels and resulted in overproduction of cellular and mitochondrial reactive oxygen species. Reductions in cell viability, cycle arrest, and increased cell death were also observed. Loss of transmembrane mitochondrial potential, activation of caspase-3, -7, and -9, cleavage of PARP, condensation and/or fragmentation of the nuclei, suggest that this cell death involved apoptosis. Furthermore, a cytoplasm vacuole formation and an increase in the ratio of [LC3-II/LC3-I] suggests a concomitant activation of autophagy with apoptosis. Altogether, the present study highlighted that arginase inhibition with thymoquinone induces a hybrid type of cell death defined as oxiapoptophagy. Thus, arginase inhibition with thymoquinone in the MDA-MB-231 cell line could be, in part, involved in the anticancer effect of thymoquinone.

Promotion of nitric oxide production: mechanisms, strategies, and possibilities

The discovery of nitric oxide (NO) and the role of endothelial cells (ECs) in its production has revolutionized medicine. NO can be produced by isoforms of NO synthases (NOS), including the neuronal (nNOS), inducible (iNOS), and endothelial isoforms (eNOS), and via the non-classical nitrate-nitrite-NO pathway. In particular, endothelium-derived NO, produced by eNOS, is essential for cardiovascular health. Endothelium-derived NO activates soluble guanylate cyclase (sGC) in vascular smooth muscle cells (VSMCs), elevating cyclic GMP (cGMP), causing vasodilation. Over the past four decades, the importance of this pathway in cardiovascular health has fueled the search for strategies to enhance NO bioavailability and/or preserve the outcomes of NO's actions. Currently approved approaches operate in three directions: 1) providing exogenous NO, 2) promoting sGC activity, and 3) preventing degradation of cGMP by inhibiting phosphodiesterase 5 activity. Despite clear benefits, these approaches face challenges such as the development of nitrate tolerance and endothelial dysfunction. This highlights the need for sustainable options that promote endogenous NO production. This review will focus on strategies to promote endogenous NO production. A detailed review of the mechanisms regulating eNOS activity will be first provided, followed by a review of strategies to promote endogenous NO production based on the levels of available preclinical and clinical evidence, and perspectives on future possibilities.

Synthesis of Arginase Inhibitors: An Overview

Arginase (ARG) is a binuclear manganese-containing metalloenzyme that can convert L-arginine to L-ornithine and urea and plays a key role in the urea cycle. It also mediates different cellular functions and processes such as proliferation, senescence, apoptosis, autophagy, and inflammatory responses in various cell types. In mammals, there are two isoenzymes, ARG-1 and ARG-2; they are functionally similar, but their coding genes, tissue distribution, subcellular localization, and molecular regulation are distinct. In recent decades, the abnormal expression of ARG-1 or ARG-2 has been reported to be increasingly linked to a variety of diseases, including cardiovascular disease, inflammatory bowel disease, Alzheimer's disease, and cancer. Therefore, considering the current relevance of this topic and the need to address the growing demand for new and more potent ARG inhibitors in the context of various diseases, this review was conceived. We will provide an overview of all classes of ARG inhibitors developed so far including compounds of synthetic, natural, and semisynthetic origin. For the first time, the synthesis protocol and optimized reaction conditions of each molecule, including those reported in patent applications, will be described. For each molecule, its inhibitory activity in terms of IC50 towards ARG-1 and ARG-2 will be reported specifying the type of assay conducted.

Opportunities and Challenges of Arginase Inhibitors in Cancer: A Medicinal Chemistry Perspective

The overexpression of two arginase (ARG) isoforms, ARG1 and ARG2, contributes to the onset of numerous disorders, including cardiovascular and immune-mediated diseases, as well as tumors. To elucidate the specific roles of ARG1 and ARG2 without interfering with their physiological functions, it is crucial to develop effective ARG inhibitors that target only one isoform, while maintaining low toxicity and an adequate pharmacokinetic profile. In this context, we present a comprehensive overview of the different generations of ARG inhibitors. Given the general lack of selectivity in most existing inhibitors, we analyzed the structural features and plasticity of the ARG1 and ARG2 binding sites to explore the potential for designing inhibitors with novel binding patterns. We also review ongoing preclinical and clinical studies on selected inhibitors, highlighting both progress and challenges in developing potent, selective ARG inhibitors. Furthermore, we discuss medicinal chemistry strategies that may accelerate the discovery of selective ARG inhibitors.