The role of tumor metabolism in modulating T-Cell activity and in optimizing immunotherapy

Breaking the immune desert: Strategies for overcoming the immunological challenges of pancreatic cancer

Pancreatic cancer is characterised by its highly aggressive nature and extremely poor prognosis, with a uniquely complex tumour immune microenvironment that manifests as a prototypical "immune desert." This immune-desert phenotype primarily arises from the inherently low immunogenicity of the tumour, the formation of a dense fibrotic stroma, severe deficiency in immune cell infiltration, and profound immunosuppressive effects of the metabolic landscape. Specifically, dysregulated tryptophan metabolism, such as indoleamine 2,3-dioxygenase (IDO)-mediated catabolism, and excessive lactate accumulation contribute to impaired T-cell functionality. Collectively, these factors severely limit the efficacy of current immunotherapy strategies, particularly those based on immune checkpoint inhibitors, which have demonstrated significantly lower clinical response rates in pancreatic cancer than in other malignancies. In response to these therapeutic challenges, this review explores integrated treatment strategies that combine metabolic reprogramming, tumour microenvironment remodelling, and next-generation immune checkpoint blockades, such as LAG-3, TIM-3, and VISTA. These emerging approaches hold substantial promise for clinical application. For example, targeting key metabolic pathways, including glycolysis (Warburg effect) and glutamine metabolism, may help restore T-cell activity by alleviating metabolic stress within the tumour milieu. Additionally, localised administration of immune stimulators such as interleukin-12 (IL-12) and CD40 agonists may enhance immune cell infiltration and promote tumour-specific immune activation. Future research should prioritise large-scale, multicentre clinical trials to validate the therapeutic efficacy of these innovative strategies, aiming to achieve meaningful breakthroughs in pancreatic cancer immunotherapy and significantly improve long-term survival and clinical outcomes in affected patients.

Interaction between redox regulation, immune activation, and response to treatment in HER2+ breast cancer

In HER2+ breast cancer (BC), neoadjuvant therapy represents an ideal scenario for translational research, considering pathological complete response (pCR) as an endpoint. In these patients, achieving pCR after neoadjuvant therapy is associated with a better prognosis. However, biomarkers are needed to tailor optimal treatment for each patient. Evaluating tumour-infiltrating lymphocytes (TILs) has gained attention in predicting pCR. In the context of metastatic disease, TILs also appear to play a role in predicting outcomes. The interaction between the presence of TILs and reactive oxygen species (ROS) remains an area to be explored. ROS are critical for tumour cell homeostasis, and different levels can trigger differential biological responses in cancer cells and their microenvironment. Nevertheless, the influence of ROS on treatment efficacy and prognosis in patients with HER2+ BC remains to be elucidated. In this article, we reviewed the interplay between treatment response, immune system activation, and ROS production in HER2+ BC and suggested novel areas of intervention and research. We also present a bioinformatic analysis demonstrating that the altered expression of several redox-related genes could be associated with the prevalence of immune cell populations in the tumour microenvironment and with patient survival. New biomarkers are thus suggested and should be further explored to tailor the best treatment to each patient.

Advancing Cancer Treatment: A Review of Immune Checkpoint Inhibitors and Combination Strategies

A groundbreaking milestone in oncology has been the recognition and targeted elimination of malignant cells through cancer immunotherapy, which harnesses the body's immune system to attack cancer [...].

Role of metabolic transformation in cancer immunotherapy resistance: molecular mechanisms and therapeutic implications

BACKGROUND

Immunotherapy in the treatment of cancer, with immune inhibitors helps in many cancer types. Many patients still encounter resistance to these treatments, though. This resistance is mediated by metabolic changes in the tumour microenvironment and cancer cells. The development of novel treatments to overcome resistance and boost immunotherapy's effectiveness depends on these metabolic changes.

OBJECTIVE

This review concentrates on the molecular mechanisms through which metabolic transformation contributes to cancer immunotherapy resistance. Additionally, research therapeutic approaches that target metabolic pathways to enhance immunotherapy for resistance.

METHODS

We used databases available on PubMed, Scopus, and Web of Science to perform a thorough review of peer-reviewed literature. focusing on the tumor microenvironment, immunotherapy resistance mechanisms, and cancer metabolism. The study of metabolic pathways covers oxidative phosphorylation, glycolysis, lipid metabolism, and amino acid metabolism.

RESULTS

An immunosuppressive tumour microenvironment is produced by metabolic changes in cancer cells, such as dysregulated lipid metabolism, enhanced glutaminolysis, and increased glycolysis (Warburg effect). Myeloid-derived suppressor cells and regulatory T cells are promoted, immune responses are suppressed, and T cell activity is impaired when lactate and other metabolites build up. changes in the metabolism of amino acids in the pathways for arginine and tryptophan, which are nutrients crucial for immune function. By enhancing their function in the tumour microenvironment, these metabolic alterations aid in resistance to immune checkpoint inhibitors.

CONCLUSION

Metabolic change plays a key role in cancer immunotherapy resistance. Gaining knowledge of metabolic processes can help develop efficient treatments that improve immunotherapy's effectiveness. In order to determine the best targets for therapeutic intervention, future studies should concentrate on patient-specific metabolic profiling.

Impact of lactate on immune cell function in the tumor microenvironment: mechanisms and therapeutic perspectives

Lactate has emerged as a key regulator in the tumor microenvironment (TME), influencing both tumor progression and immune dynamics. As a byproduct of aerobic glycolysis, lactate satisfies the metabolic needs of proliferating tumor cells while reshaping the TME to facilitate immune evasion. Elevated lactate levels inhibit effector immune cells such as CD8+ T and natural killer cells, while supporting immunosuppressive cells, such as regulatory T cells and myeloid-derived suppressor cells, thus fostering an immunosuppressive environment. Lactate promotes epigenetic reprogramming, stabilizes hypoxia-inducible factor-1α, and activates nuclear factor kappa B, leading to further immunological dysfunction. In this review, we examined the role of lactate in metabolic reprogramming, immune suppression, and treatment resistance. We also discuss promising therapeutic strategies targeting lactate metabolism, including lactate dehydrogenase inhibitors, monocarboxylate transporter inhibitors, and TME neutralization methods, all of which can restore immune function and enhance immunotherapy outcomes. By highlighting recent advances, this review provides a theoretical foundation for integrating lactate-targeted therapies into clinical practice. We also highlight the potential synergy between these therapies and current immunotherapeutic strategies, providing new avenues for addressing TME-related challenges and improving outcomes for patients with cancer.

Metabolic crossroads: unravelling immune cell dynamics in gastrointestinal cancer drug resistance

Metabolic reprogramming within the tumor microenvironment (TME) plays a critical role in driving drug resistance in gastrointestinal cancers (GI), particularly through the pathways of fatty acid oxidation and glycolysis. Cancer cells often rewire their metabolism to sustain growth and reshape the TME, creating conditions such as nutrient depletion, hypoxia, and acidity that impair antitumor immune responses. Immune cells within the TME also undergo metabolic alterations, frequently adopting immunosuppressive phenotypes that promote tumor progression and reduce the efficacy of therapies. The competition for essential nutrients, particularly glucose, between cancer and immune cells compromises the antitumor functions of effector immune cells, such as T cells. Additionally, metabolic by-products like lactate and kynurenine further suppress immune activity and promote immunosuppressive populations, including regulatory T cells and M2 macrophages. Targeting metabolic pathways such as fatty acid oxidation and glycolysis presents new opportunities to overcome drug resistance and improve therapeutic outcomes in GI cancers. Modulating these key pathways has the potential to reinvigorate exhausted immune cells, shift immunosuppressive cells toward antitumor phenotypes, and enhance the effectiveness of immunotherapies and other treatments. Future strategies will require continued research into TME metabolism, the development of novel metabolic inhibitors, and clinical trials evaluating combination therapies. Identifying and validating metabolic biomarkers will also be crucial for patient stratification and treatment monitoring. Insights into metabolic reprogramming in GI cancers may have broader implications across multiple cancer types, offering new avenues for improving cancer treatment.

Tumor cells impair immunological synapse formation via central nervous system-enriched metabolite

Tumors employ various strategies to evade immune surveillance. Central nervous system (CNS) has multiple features to restrain immune response. Whether tumors and CNS share similar programs of immunosuppression is elusive. Here, we analyze multi-omics data of tumors from HER2+ breast cancer patients receiving trastuzumab and anti-PD-L1 antibody and find that CNS-enriched N-acetyltransferase 8-like (NAT8L) and its metabolite N-acetylaspartate (NAA) are overexpressed in resistant tumors. In CNS, NAA is released during brain inflammation. NAT8L attenuates brain inflammation and impairs anti-tumor immunity by inhibiting cytotoxicity of natural killer (NK) cells and CD8+ T cells via NAA. NAA disrupts the formation of immunological synapse by promoting PCAF-induced acetylation of lamin A-K542, which inhibits the integration between lamin A and SUN2 and impairs polarization of lytic granules. We uncover that tumor cells mimic the anti-inflammatory mechanism of CNS to evade anti-tumor immunity and NAT8L is a potential target to enhance efficacy of anti-cancer agents.

Apoptosis, a Metabolic "Head-to-Head" between Tumor and T Cells: Implications for Immunotherapy

Induction of apoptosis represents a promising therapeutic approach to drive tumor cells to death. However, this poses challenges due to the intricate nature of cancer biology and the mechanisms employed by cancer cells to survive and escape immune surveillance. Furthermore, molecules released from apoptotic cells and phagocytes in the tumor microenvironment (TME) can facilitate cancer progression and immune evasion. Apoptosis is also a pivotal mechanism in modulating the strength and duration of anti-tumor T-cell responses. Combined strategies including molecular targeting of apoptosis, promoting immunogenic cell death, modulating immunosuppressive cells, and affecting energy pathways can potentially overcome resistance and enhance therapeutic outcomes. Thus, an effective approach for targeting apoptosis within the TME should delicately balance the selective induction of apoptosis in tumor cells, while safeguarding survival, metabolic changes, and functionality of T cells targeting crucial molecular pathways involved in T-cell apoptosis regulation. Enhancing the persistence and effectiveness of T cells may bolster a more resilient and enduring anti-tumor immune response, ultimately advancing therapeutic outcomes in cancer treatment. This review delves into the pivotal topics of this multifaceted issue and suggests drugs and druggable targets for possible combined therapies.

Arginine deprivation enriches lung cancer proteomes with cysteine by inducing arginine-to-cysteine substitutants

Many types of human cancers suppress the expression of argininosuccinate synthase 1 (ASS1), a rate-limiting enzyme for arginine production. Although dependency on exogenous arginine can be harnessed by arginine-deprivation therapies, the impact of ASS1 suppression on the quality of the tumor proteome is unknown. We therefore interrogated proteomes of cancer patients for arginine codon reassignments (substitutants) and surprisingly identified a strong enrichment for cysteine (R>C) in lung tumors specifically. Most R>C events did not coincide with genetically encoded R>C mutations but were likely products of tRNA misalignments. The expression of R>C substitutants was highly associated with oncogenic kelch-like epichlorohydrin (ECH)-associated protein 1 (KEAP1)-pathway mutations and suppressed by intact-KEAP1 in KEAP1-mutated cancer cells. Finally, functional interrogation indicated a key role for R>C substitutants in cell survival to cisplatin, suggesting that regulatory codon reassignments endow cancer cells with more resilience to stress. Thus, we present a mechanism for enriching lung cancer proteomes with cysteines that may affect therapeutic decisions.