Inhibitors of the CD73-adenosinergic checkpoint as promising combinatory agents for conventional and advanced cancer immunotherapy

Brown B, Chan TA, Chand D, Constanzo J, Demaria S, I. Gabrilovich D, Golden E, Godkin A, Guha C, P. Gupta G, Hasan A, G. Herrera F, Kaufman H, Li D, A. Melcher A, McDonald S, Merghoub T, Monjazeb AM, Paris S, Pitroda S, Sadanandam A, Schaue D, Santambrogio L, Szapary P, Sage J, W. Welsh J, Wilkins A, H. Young K, Wennerberg E, Zitvogel L, Galluzzi L, Deutsch E, C. Formenti S. Updates on radiotherapy-immunotherapy combinations: Proceedings of 8th Annual ImmunoRad Conference

The annual ImmunoRad Conference has established itself as a recurrent occasion to explore the possibility of combining radiation therapy (RT) and immunotherapy (IT) for clinical cancer management. Bringing together a number of preclinical and clinical leaders in the fields of radiation oncology, immuno-oncology and IT, this annual event fosters indeed essential conversations and fruitful exchanges on how to address existing challenges to expand the therapeutic value of RT-IT combinations. The 8th edition of the ImmunoRad Conference, which has been held in October 2024 at the Weill Cornell Medical College of New York City, highlighted exciting preclinical and clinical advances at the interface between RT and IT, setting the stage for extra progress toward extended benefits for patients with an increasing variety of tumor types. Here, we critically summarize the lines of investigation that have been discussed at the occasion of the 8th Annual ImmunoRad Conference.

Tumor-stromal metabolic crosstalk in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy with a dire prognosis. Standard-of-care chemotherapy regimens offer marginal survival benefit and carry risk of severe toxicity, while immunotherapy approaches have uniformly failed in clinical trials. Extensive desmoplasia in the PDAC tumor microenvironment (TME) disrupts blood flow to and from the tumor, thereby creating a nutrient-depleted, hypoxic, and acidic milieu that suppresses the function of antitumor immune cells and imparts chemotherapy resistance. Additionally, recent seminal studies have demonstrated crucial roles for metabolic crosstalk - the exchange of metabolites between PDAC cells and stromal cell populations in the TME - in establishing and maintaining core malignant behaviors of PDAC: tumor growth, metastasis, immune evasion, and therapy resistance. In this review, we provide a conceptual overview of metabolic crosstalk and how it evolves under various selection pressures in the TME, analyze the landscape of proposed tumorigenic metabolic crosstalk pathways, and highlight potentially druggable nodes.

Acyclic purine and pyrimidine nucleotide analogs as ecto-5'-nucleotidase (CD73) inhibitors

Ecto-5'-nucleotidase (CD73) is a novel target in cancer (immuno)therapy. Its blockade prevents the formation of immunosuppressive and cancer-promoting adenosine from AMP. Here, we report on the development of a series of small molecules that mimic adenine nucleotides, in which the ribose moiety was replaced by an alkyl chain. Its length was found to be crucial for potency. A crystal structure of the N6-disubstituted acyclic ADP analog 26 (N6-benzyl,N6-methyladenine-9-yl)pentyloxydiphosphonate) in complex with human CD73 revealed that the flexible pentyl linker adopts to interdomain rotation angles differing by up to 18.5°. The most potent CD73 inhibitor of the present series was analog 27 (N6-benzyl,N6-methyladenine-9-yl)hexyloxydiphosphonate, PSB-24000) which exhibited submicromolar potency at human CD73 (Ki 563 nM at soluble CD73; Ki 481 nM at membrane-bound CD73 of triple-negative breast cancer cells). Acyclic nucleotide analogs may be advantageous compared to the previously reported nucleotidic CD73 inhibitors due to their high chemical stability, and because less off-target effects are to be expected. The structure-activity relationships discovered in this study provide valuable insights which will be useful for the development of CD73 inhibitors as immunotherapeutic drugs.

Unveiling purine metabolism dysregulation orchestrated immunosuppression in advanced pancreatic cancer and concentrating on the central role of NT5E

Background

The dismal efficacy of immunotherapy for Pancreatic cancer (PC) can be predominantly ascribed to its distinctive cold-tumor properties. The by-products of purine metabolic reprogramming are extensively engaged in tumor immune modulation, influencing the functions and recruitment of immune cells and molding an immune microenvironment that is propitious for tumor growth.

Methods

We harnessed single-cell transcriptomics and spatial transcriptomics to concurrently analyze the purine metabolism (PM) features of the PC microenvironment. We quantitatively appraised the PM traits of diverse cell subsets via scoring algorithms such as AUCell and Ucell. Moreover, cell development and cell-cell interaction analysis elucidated the alterations in TME induced by PM dysregulation. Additionally, we defined the PM disorder characteristics of PC patients and utilized this to assess the immune phenotypes and prognoses of the patient population. Also, we identified the crucial intermediate genes that impact PM reprogramming and the establishment of an immunosuppressive environment within the TME of PC, and validated them through spatial sectioning and cell co-culture experiments.

Results

Multi - dimensional transcriptome data elucidated the unique heterogeneity of PM in the PC microenvironment, which manifested that tumor cells and fibroblasts demonstrating higher PM scores in the TME. Cellchat analysis revealed that malignant cells with elevated PM expression were concomitantly associated with frequent interactions with CAFs as well as high expression of ligand-receptor pairs and transcription factors. Spatial data further corroborated this finding. Furthermore, the newly constructed PM disorder criteria indicated that patients with high PM levels were associated with a lack of response to immunotherapy and an immunosuppressive microenvironment. Finally, this study identified the singular role of NT5E in the immunosuppression resulting from PM reprogramming in PC. CCK8 and invasion experiments following the co-culture model demonstrated that intervention targeting NT5E could reverse the augmented malignancy of PC induced by co-cultured CAFs. NT5E is potentially a key target for reversing the "stiff-cancer" characteristics of PC.

Conclusion

This study demonstrates that PM metabolic disorders could impinge upon tumor immunotherapy and exacerbate the immunosuppression engendered by the progression of PC fibrosis. Therapeutic strategies targeting PM or NT5E may offer a ray of hope for patients with advanced PDAC.

Design of a fragment crystallizable-engineered tetravalent bispecific antibody targeting programmed cell death-1 and vascular endothelial growth factor with cooperative biological effects

Clinical studies have shown that combination therapy of PD-1 and VEGF antibodies significantly improves clinical benefit over PD-1 antibody alone in certain settings. Ivonescimab, an on-market tetravalent anti-PD-1/VEGF bispecific antibody, was designed to improve efficacy and safety over combo therapy. In this study, the mechanism of action is investigated. In the presence of VEGF, ivonescimab forms soluble complexes with VEGF dimers, leading to the enhanced binding avidity of ivonescimab to PD-1 therefore promoting its increased potency on PD-1/PD-L1-signaling blockade. Likewise, PD-1 binding enhanced ivonescimab binding to VEGF, therefore enhancing VEGF-signaling blockade. Furthermore, ivonescimab treatment demonstrated statistically significant anti-tumor response in vivo. Moreover, ivonescimab contains Fc-silencing mutations abrogating FcγRI/IIIa binding and showed significantly reduced effector function in vitro which is consistent with the better safety profile of ivonescimab in monkeys and humans. Briefly, ivonescimab displays unique cooperative binding and promotes the increased in vitro functional bioactivities with a favorable safety profile.

Increased primary breast tumor expression of CD73 is associated with development of bone metastases and is a potential biomarker for adjuvant bisphosphonate use

PURPOSE

Increased CD73 expression has been associated with progression in various cancer types. Results of the AZURE and other trials suggest that, in postmenopausal breast cancer patients, adjuvant bisphosphonates inhibit bone relapses and prolong overall survival. Based on these findings, adjuvant bisphosphonates (typically zoledronic acid) are standard-of-care in postmenopausal patients with high-risk early breast cancer. However, biomarkers are needed for improved patient selection. The aim of this study was to investigate the association of primary tumor CD73 expression with later development of bone metastases.

METHODS

To determine whether CD73 levels correlated with tumor parameters (hormone receptor status, tumor stage and grade), patient outcomes (bone metastases and survival) or other patient characteristics (menopausal status, chemotherapy or statin use), we analyzed primary breast tumor CD73 expression immunohistochemically in tumor microarray samples from the AZURE (BIG01/04) trial.

RESULTS

In the AZURE control arm, high CD73 score are significantly prognostic for overall survival (p-value = 0.03, HR = 1.87, 95% CI = 1.06-3.29), disease-free survival (p-value = 0.06, HR = 1.66, 95% CI = 0.982-2.8) and time to first metastasis to bone (p-value = 0.04, HR = 2.23, 95% CI = 1.04-4.81), as compared with low CD73 scores. However, high CD73 score did not display an association with time to non-bone metastasis or first recurrence to a non-skeletal site. In the zoledronate arm, high CD73 score did not have association with patient outcomes, first metastasis to bone, nor with bone recurrence at any time (distant recurrence, including skeletal) or first non-skeletal recurrence. In multivariate testing, CD73 had no significant association with age, ER status, tumor stage, histological grade, menopausal status, chemotherapy or statin use in either arm.

CONCLUSIONS

High CD73 expression is associated with development of bone metastases. Zoledronate counteracts this effect. These results suggest that CD73 expression might serve as a biomarker for adjuvant zoledronic acid use.

Oncolytic Virus Therapy in a New Era of Immunotherapy, Enhanced by Combination with Existing Anticancer Therapies: Turn up the Heat!

Oncolytic viral therapy is a promising treatment for cancer, where 'cold' tumour cells can become 'hot' to the host immune system. However, with few FDA approved therapies, development of new strategies for more cancer types has been slow and relatively unsuccessful in recent years, Combination therapy has been successful for other types of cancer treatment, therefore, may be a viable alternative to improve the efficacy of oncolytic viral therapy which may reduce some of the adverse events of currently used monotherapies, oncolytic virus therapy and chemotherapy being mutually complimentary with each other. Combining oncolytic viruses with immune checkpoint inhibitors provides a significant increase in efficacy when viral therapy was combined with the drug ipilimumab. Phase I and II studies concluded that combination with chemotherapies was safe and effective but did not significantly improve on current monotherapies. Recent experiments suggest that a combination of CAR-T and CAR--M cells is a promising therapeutic approach but needs to advance to clinical testing to observe the human response to the therapy. Viral combination with ipilimumab showed the highest potential for a successful treatment and clinical trials should be advanced to phase III to find conclusive supporting evidence. This review aims to identify and evaluate the potential of currently evolving oncolytic viral therapy with recent advances in genetic engineering providing enhanced oncolytic activity in the tumour, and addressing the lack of host immune responses in 'cold' tumours, with an additional role in enhancing conventional treatment efficacy with combination therapies. The potential of oncolytic viruses to 'turn up the heat' of a tumour microenvironment immunogenicity in combination with other anticancer treatments, provides a promising future for new cancer therapies.

Optimising CAR T therapy for the treatment of solid tumors

INTRODUCTION

Adoptive immunotherapy using chimeric antigen receptor (CAR)-engineered T cells has proven transformative in the management of B cell and plasma cel derived malignancies. However, solid tumors have largely proven to be resistant to this therapeutic modality. Challenges include the paucity of safe target antigens, heterogeneity of target expression within the tumor, difficulty in delivery of CAR T cells to the site of disease, poor penetration within solid tumor deposits and inability to circumvent the array of immunosuppressive and biophysical barriers imposed by the solid tumor microenvironment.

AREAS COVERED

Literature was reviewed on the PubMed database, excluding occasional papers which were not available as open access publications or through other means.

EXPERT OPINION

Here, we have surveyed the large body of technological advances that have been made in the quest to bridge the gap toward successful deployment of CAR T cells for the treatment of solid tumors. These encompass the development of more sophisticated targeting strategies to engage solid tumor cells safely and comprehensively, improved drug delivery solutions, design of novel CAR architectures that achieve improved functional persistence and which resist physical, chemical and biological hurdles present in tumor deposits. Prospects for combination therapies that incorporate CAR T cells are also considered.

CD38 symmetric dimethyl site R58 promotes malignant tumor cell immune escape by regulating the cAMP-GSK3β-PD-L1 axis

In recent years, immunotherapy has emerged as an effective approach for treating tumors, with programmed cell death ligand 1 (PD-L1)/programmed cell death protein-1 (PD-1) immune checkpoint blockade (ICB) being a promising strategy. However, suboptimal therapeutic efficacy limits its clinical benefit. Understanding the regulation mechanism of PD-L1 expression is crucial for improving anti-PD-L1/PD-1 therapy and developing more effective tumor immunotherapy. Previous studies have revealed that resistance to PD-L1/PD-1 blockade therapy arises from the upregulation of CD38 on tumor cells induced by ATRA and IFN-β, which mediates the inhibition of CD8+ T cell function through adenosine receptor signaling, thereby promoting immune evasion.Yet, the precise role of CD38 in regulating PD-L1 on malignant tumor cells and its impact on CD8+ T cells through PD-L1 remain unclear. Here, we demonstrate that CD38 is highly expressed in malignant tumors (lung cancer, nasopharyngeal carcinoma, cervical cancer) and upregulates PD-L1 protein expression, impairing CD8+ T cell function. Mechanistically, CD38 phosphorylates GSK3β via the adenosine-activated cAMP-PKA signaling pathway, leading to GSK3β inactivation and enhanced PD-L1 stability and expression, facilitating tumor immune escape. Furthermore, we identify PRMT5 as a novel CD38-interacting molecule that symmetrically dimethylates CD38 arginine position 58, augmenting PD-L1 stability and expression through the ADO-cAMP-GSK3β signaling axis. This inhibits CD8+ T cell-mediated tumor cell killing, enabling tumor cells to evade immune surveillance. Our findings suggest that targeting the CD38 R58 site offers a new avenue for enhancing anti-PD-L1/PD-1 therapy efficacy in tumor treatment.

PET imaging of colon cancer CD73 expression using cysteine site-specific 89Zr-labeled anti-CD73 antibody

CD73 is a cell-surface ectoenzyme that hydrolyzes the conversion of extracellular adenosine monophosphate to adenosine, which in turn can promote resistance to immune checkpoint blockade therapy. Immune response may therefore be improved by targeting tumor CD73, and this possibility underlines the need to non-invasively assess tumor CD73 level. In this study, we developed a cysteine site-specific 89Zr-labeled anti-CD73 (89Zr-CD73) IgG immuno-PET technique that can image tumor CD73 expression in living bodies. Anti-CD73 IgG was reduced with tris(2-carboxyethyl)phosphine, underwent sulfohydryl moiety-specific conjugation with deferoxamine-maleimide, and was radiolabeled with 89Zr. CT26 mouse colon cancer cells, CT26/CD73 cells engineered to constitutively overexpress CD73, and 4T1.2 mouse breast cancer cells underwent cell binding assays and western blotting. Balb/c nude mice bearing tumors underwent 89Zr-CD73 IgG PET imaging and biodistribution studies. 89Zr-CD73 IgG showed 20-fold higher binding to overexpressing CT26/CD73 cells compared to low-expressing CT26 cells, and moderate expressing 4T1.2 cells showed uptake that was 38.9 ± 1.51% of CT26/CD73 cells. Uptake was dramatically suppressed by excess unlabeled antibody. CD73 content proportionately increased in CT26 and CT26/CD73 cell mixtures was associated with linear increases in 89Zr-CD73 IgG uptake. 89Zr-CD73 IgG PET/CT displayed clear accumulation in CT26/CD73 tumors with greater uptake compared to CT26 tumors (3.13 ± 1.70%ID/g vs. 1.27 ± 0.31%ID/g at 8 days; P = 0.04). Specificity was further supported by low CT26/CD73 tumor-to-blood ratio of 89Zr-isotype-IgG compared to 89Zr-CD73 IgG (0.48 ± 0.08 vs. 2.68 ± 0.52 at 4 days and 0.53 ± 0.07 vs. 4.81 ± 1.02 at 8 days; both P < 0.001). Immunoblotting and immunohistochemistry confirmed strong CD73 expression in CT26/CD73 tumors and low expression in CT26 tumors. 4T1.2 tumor mice also showed clear 89Zr-CD73 IgG accumulation at 8 days (3.75 ± 0.70%ID/g) with high tumor-to-blood ratio compared to 89Zr-isotype-IgG (4.91 ± 1.74 vs. 1.20 ± 0.28; P < 0.005). 89Zr-CD73 IgG specifically targeted CD73 on high expressing cancer cells in vitro and tumors in vivo. Thus, 89Zr-CD73 IgG immuno-PET may be useful for the non-invasive monitoring of CD73 expression in tumors of living subjects.

Posttranslational protein modifications as gatekeepers of cancer immunogenicity

Triple-negative breast cancer (TNBC) presents a formidable challenge in oncology due to its aggressive phenotype and the immunosuppressive nature of its tumor microenvironment (TME). In this issue of the JCI, Zhu, Banerjee, and colleagues investigated the potential of targeting the OTU domain-containing protein 4 (OTUD4)/CD73 axis to mitigate immunosuppression in TNBC. They identified elevated CD73 expression as a hallmark of immunosuppression in TNBC. Notably, the CD73 expression was regulated by OTUD4-mediated posttranslational modifications. Using ST80, a pharmacologic inhibitor of OTUD4, the authors demonstrated the restoration of cytotoxic T cell function and enhanced efficacy of anti-PD-L1 therapy in preclinical models. These findings underscore the therapeutic potential of targeting the OTUD4/CD73 axis in TNBC.

Metabolic adaptations determine whether natural killer cells fail or thrive within the tumor microenvironment

Natural Killer (NK) cells are a top contender in the development of adoptive cell therapies for cancer due to their diverse antitumor functions and ability to restrict their activation against nonmalignant cells. Despite their success in hematologic malignancies, NK cell-based therapies have been limited in the context of solid tumors. Tumor cells undergo various metabolic adaptations to sustain the immense energy demands that are needed to support their rapid and uncontrolled proliferation. As a result, the tumor microenvironment (TME) is depleted of nutrients needed to fuel immune cell activity and contains several immunosuppressive metabolites that hinder NK cell antitumor functions. Further, we now know that NK cell metabolic status is a main determining factor of their effector functions. Hence, the ability of NK cells to withstand and adapt to these metabolically hostile conditions is imperative for effective and sustained antitumor activity in the TME. With this in mind, we review the consequences of metabolic hostility in the TME on NK cell metabolism and function. We also discuss tumor-like metabolic programs in NK cell induced by STAT3-mediated expansion that adapt NK cells to thrive in the TME. Finally, we examine how other approaches can be applied to enhance NK cell metabolism in tumors.

Targeting the adenosine signaling pathway in macrophages for cancer immunotherapy

One of the ways in which macrophages support tumorigenic growth is by producing adenosine, which acts to dampen antitumor immune responses and is generated by both tumor and immune cells in the tumor microenvironment (TME). Two cell surface expressed molecules, CD73 and CD39, boost catalytic adenosine triphosphate, leading to further increased adenosine synthesis, under hypoxic circumstances in the TME. There are four receptors (A1, A2A, A2B, and A3) expressed on macrophages that allow adenosine to perform its immunomodulatory effect. Researchers have shown that adenosine signaling is a key factor in tumor progression and an attractive therapeutic target for treating cancer. Several antagonistic adenosine-targeting biological therapies that decrease the suppressive action of tumor-associated macrophages have been produced and explored to transform this result from basic research into a therapeutic advantage. Here, we'll review the newest findings from studies of pharmacological compounds that target adenosine receptors, and their potential therapeutic value based on blocking the suppressive action of macrophages in tumors.

CD73 contributes to the pathogenesis of fusion-negative rhabdomyosarcoma through the purinergic signaling pathway

Rhabdomyosarcoma (RMS) is the most common type of soft tissue sarcoma in children and adolescents. Fusion-negative RMS (FN-RMS) accounts for more than 80% of all RMS cases. The long-term event-free survival rate for patients with high-grade FN-RMS is below 30%, highlighting the need for improved therapeutic strategies. CD73 is a 5' ectonucleotidase that hydrolyzes AMP to adenosine and regulates the purinergic signaling pathway. We found that CD73 is elevated in FN-RMS tumors that express high levels of TWIST2. While high expression of CD73 contributes to the pathogenesis of multiple cancers, its role in FN-RMS has not been investigated. We found that CD73 knockdown decreased FN-RMS cell growth while up-regulating the myogenic differentiation program. Moreover, mutation of the catalytic residues of CD73 rendered the protein enzymatically inactive and abolished its ability to stimulate FN-RMS growth. Overexpression of wildtype CD73, but not the catalytically inactive mutant, in CD73 knockdown FN-RMS cells restored their growth capacity. Likewise, treatment with an adenosine receptor A2A-B agonist partially rescued FN-RMS cell proliferation and bypassed the CD73 knockdown defective growth phenotype. These results demonstrate that the catalytic activity of CD73 contributes to the pathogenic growth of FN-RMS through the activation of the purinergic signaling pathway. Therefore, targeting CD73 and the purinergic signaling pathway represents a potential therapeutic approach for FN-RMS patients.

Metabolic Interplay in the Tumor Microenvironment: Implications for Immune Function and Anticancer Response

Malignant tumors exhibit rapid growth and high metabolic rates, similar to embryonic stem cells, and depend on aerobic glycolysis, known as the "Warburg effect". This understanding has enabled the use of radiolabeled glucose analogs in tumor staging and therapeutic response assessment via PET scans. Traditional treatments like chemotherapy and radiotherapy target rapidly dividing cells, causing significant toxicity. Despite immunotherapy's impact on solid tumor treatment, gaps remain, leading to research on cancer cell evasion of immune response and immune tolerance induction via interactions with the tumor microenvironment (TME). The TME, consisting of immune cells, fibroblasts, vessels, and the extracellular matrix, regulates tumor progression and therapy responses. TME-targeted therapies aim to transform this environment from supporting tumor growth to impeding it and fostering an effective immune response. This review examines the metabolic disparities between immune cells and cancer cells, their impact on immune function and therapeutic targeting, the TME components, and the complex interplay between cancer cells and nontumoral cells. The success of TME-targeted therapies highlights their potential to achieve better cancer control or even a cure.

CD276-CAR T cells and Dual-CAR T cells targeting CD276/FGFR4 promote rhabdomyosarcoma clearance in orthotopic mouse models

BACKGROUND

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in childhood, whose prognosis is still poor especially for metastatic, high-grade, and relapsed RMS. New treatments are urgently needed, especially systemic therapies. Chimeric Antigen Receptor T cells (CAR Ts) are very effective against hematological malignancies, but their efficacy against solid tumors needs to be improved. CD276 (B7-H3) is a target upregulated in RMS and detected at low levels in normal tissues. FGFR4 is a very specific target for RMS. Here, we optimized CAR Ts for these two targets, alone or in combination, and tested their anti-tumor activity in vitro and in vivo.

METHODS

Four different single-domain antibodies were used to select the most specific FGFR4-CAR construct. RMS cell killing and cytokine production by CD276- and FGFR4-CAR Ts expressing CD8α or CD28 HD/TM domains in combination with 4-1BB and/or CD28 co-stimulatory domains were tested in vitro. The most effective CD276- and FGFR4-CAR Ts were used to generate Dual-CAR Ts. Tumor killing was evaluated in vivo in three orthotopic RMS mouse models.

RESULTS

CD276.V-CAR Ts (276.MG.CD28HD/TM.CD28CSD.3ζ) showed the strongest killing of RMS cells, and the highest release of IFN-γ and Granzyme B in vitro. FGFR4.V-CAR Ts (F8-FR4.CD28HD/TM.CD28CSD.3ζ) showed the most specific killing. CD276-CAR Ts successfully eradicated RD- and Rh4-derived RMS tumors in vivo, achieving complete remission in 3/5 and 5/5 mice, respectively. In CD276low JR-tumors, however, they achieved complete remission in only 1/5 mice. FGFR4 CAR Ts instead delayed Rh4 tumor growth. Dual-CAR Ts promoted Rh4-tumors clearance in 5/5 mice.

CONCLUSIONS

CD276- and CD276/FGFR4-directed CAR Ts showed effective RMS cell killing in vitro and eradication of CD276high RMS tumors in vivo. CD276low tumors escaped the therapy highlighting a correlation between antigen density and effectiveness. FGFR4-CAR Ts showed specific killing in vitro but could only delay RMS growth in vivo. Our results demonstrate that combined expression of CD276-CAR with other CAR does not reduce its benefit. Introducing immunotherapy with CD276-CAR Ts in RMS seems to be feasible and promising, although CAR constructs design and target combinations have to be further improved to eradicate tumors with low target expression.

Metabolic adaptation of NK cell activity and behavior in tumors: challenges and therapeutic opportunities

The adaptation of natural killer (NK) cells to conditions in the microenvironment of tumors is deeply affected by their metabolic activity, itself a result of nutrient availability and the metabolism of the cancer cells themselves. Elevated rates of glycolysis and lipid metabolism in cancers not only lead to the accumulation of immunosuppressive byproducts but also contribute to an environment of elevated concentrations of extracellular metabolites. This results in altered NK cell bioenergetics through changes in transcriptional and translational profiles, ultimately affecting their pharmacology and impairing NK cell responses. However, understanding the metabolic processes that drive alterations in immunological signaling on NK cells remains both difficult and vastly underexplored. We discuss the varied and complex drivers of NK cell metabolism in homeostasis and the tumor microenvironment (TME), challenges associated with their targetability, and unexplored therapeutic opportunities.