In vivo imaging reveals a tumor-associated macrophage-mediated resistance pathway in anti-PD-1 therapy

Impact of rheumatoid factors on the function of therapeutic monoclonals specific for PD-1/PD-L1

The efficacy of blocking antibodies against programmed death-1 (PD-1) and its ligand (PD-L1) is modulated by signalling through their Fc regions. The Fc region of anti-PD-1/PD-L1 antibodies, when cell-bound, represents a potential target for recognition by circulating rheumatoid factor (RF) autoantibodies. The resultant cell-associated immune complex may then provide different Fc signals to that of the PD-1/PD-L1 antibodies alone. However, little is known regarding the interaction of RF and therapeutic PD-1/PD-L1 antibodies. We report that PD-1 (pembrolizumab, nivolumab) and PD-L1 (avelumab) antibodies, when bound to their cellular targets, are recognised by both IgM-RF and IgA-RF components of RF+ patient serum. We further demonstrate that the presence of RF provides PD-1 antibodies with the ability to induce complement-dependent cytotoxicity (CDC) of a PD-1+ target cell line in the presence of human complement. Although RF provided avelumab with the ability to induce CDC in assays using rabbit complement, no CDC was observed in the presence of human complement. The presence of RF did not modulate the level of Fc receptor-triggered cellular cytotoxicity or neutrophil activation that was induced by PD-1/PD-L1 antibodies alone. This study demonstrates that RF has the potential to modulate the Fc-associated signals generated following binding of PD-1/PD-L1 antibodies. The impact of RF on their efficacy therefore merits further investigation.

Role of tumor microenvironment in ovarian cancer metastasis and clinical advancements

Ovarian cancer (OC) is the most lethal gynecological malignancy worldwide, characterized by heterogeneity at the molecular, cellular and anatomical levels. Most patients are diagnosed at an advanced stage, characterized by widespread peritoneal metastasis. Despite optimal cytoreductive surgery and platinum-based chemotherapy, peritoneal spread and recurrence of OC are common, resulting in poor prognoses. The overall survival of patients with OC has not substantially improved over the past few decades, highlighting the urgent necessity of new treatment options. Unlike the classical lymphatic and hematogenous metastasis observed in other malignancies, OC primarily metastasizes through widespread peritoneal seeding. Tumor cells (the "seeds") exhibit specific affinities for certain organ microenvironments (the "soil"), and metastatic foci can only form when there is compatibility between the "seeds" and "soil." Recent studies have highlighted the tumor microenvironment (TME) as a critical factor influencing the interactions between the "seeds" and "soil," with ascites and the local peritoneal microenvironment playing pivotal roles in the initiation and progression of OC. Prior to metastasis, the interplay among tumor cells, immunosuppressive cells, and stromal cells leads to the formation of an immunosuppressive pre-metastatic niche in specific sites. This includes characteristic alterations in tumor cells, recruitment and functional anomalies of immune cells, and dysregulation of stromal cell distribution and function. TME-mediated crosstalk between cancer and stromal cells drives tumor progression, therapy resistance, and metastasis. In this review, we summarize the current knowledge on the onset and metastatic progression of OC. We provide a comprehensive discussion of the characteristics and functions of TME related to OC metastasis, as well as its association with peritoneal spread. We also outline ongoing relevant clinical trials, aiming to offer new insights for identifying potential effective biomarkers and therapeutic targets in future clinical practice.

Impact of durvalumab re-administration after moderate symptomatic pneumonitis in locally advanced non-small cell lung cancer

BACKGROUND

The standard of care for unresectable locally advanced non-small cell lung cancer (LA-NSCLC) includes post-chemoradiotherapy durvalumab consolidation therapy. However, moderate symptomatic pneumonitis (Grade 2) constitutes a significant adverse event that frequently leads to treatment interruption and warrants careful consideration of re-administration. We evaluated the efficacy and safety of durvalumab re-administration after recovery from grade 2 pneumonitis.

METHODS

This retrospective study included 208 patients with LA-NSCLC who received post-chemoradiotherapy durvalumab consolidation therapy at seven institutions between July 2018 and March 2022. Among them, 62 developed Grade 2 pneumonitis that led to treatment interruption and were stratified into the durvalumab re-administration (n = 33) and durvalumab non-re-administration (n = 29) groups. Survival outcomes were analyzed using the Cox proportional hazards model.

RESULTS

Participants in the durvalumab re-administration group had significantly longer progression-free survival (PFS; 32.0 months [95 % confidence interval (CI): 11.7-Not Available (NA)] vs. 5.3 months [95 % CI: 3.5-17.4], P = 0.003) and overall survival (OS; not reached [95 % CI: 29.0-NA] vs. 27.1 months [95 % CI: 12.1-NA], P = 0.012) than in the durvalumab non-re-administration group. Pneumonitis recurred in 30.3 % of the re-administration group, albeit without Grade ≥ 3 events. Multivariate analysis identified durvalumab re-administration as an independent predictor of improved survival, with hazard ratios of 0.31 (95 % CI: 0.15-0.65, P = 0.002) for PFS and 0.33 (95 % CI: 0.13-0.82, P = 0.017) for OS.

CONCLUSION

Durvalumab re-administration after grade 2 pneumonitis was associated with prolonged survival and a low recurrence rate of mild pneumonitis, which suggests that re-administration is a feasible, effective strategy with adequate monitoring.

Oncogenic Signalling Pathways in Cancer Immunotherapy: Leader or Follower in This Delicate Dance?

Immune checkpoint inhibitors have become a mainstay of treatment in many solid organ malignancies. Alongside this has been the rapid development in the identification and targeting of oncogenic drivers. The presence of alterations in oncogenic drivers not only predicts response to target therapy but can modulate the immune microenvironment and influence response to immunotherapy. Combining immune checkpoint inhibitors with targeted agents is an attractive therapeutic option but overlapping toxicity profiles may limit the clinical use of some combinations. In addition, there is growing evidence of shared resistance mechanisms that alter the response to immunotherapy when it is used after targeted therapy. Understanding this complex interaction between oncogenic drivers, targeted therapy and response to immune checkpoint inhibitors is vital for selecting the right treatment, at the right time for the right patient. In this review, we summarise the preclinical and clinical evidence of the influence of four common oncogenic alterations on immune checkpoint inhibitor response, combination therapies, and the presence of shared resistance mechanisms. We highlight the common resistance mechanisms and the need for more randomised trials investigating both combination and sequential therapy.

Application of extended immunotherapy in advanced clear cell renal cell carcinoma treated with first-line combination of immune-checkpoint inhibitor and tyrosine kinase inhibitor

PURPOSE

To evaluate the efficacy and safety of extended immunotherapy in first-line immune checkpoint inhibitors (ICIs)-tyrosine kinase inhibitors (TKIs) combination treatment for advanced renal cell carcinoma (RCC).

PATIENTS AND METHODS

We retrospectively analyzed data from patients with advanced RCC who received first-line ICIs-TKIs combination treatment at West China Hospital of Sichuan University between October 2018 and July 2024. Patients who are assessed as having a disease control status after 2 years of continuous treatment will continue to receive immune checkpoint inhibitors until the inhibitors are discontinued due to disease progression or death.

RESULT

A total of 86 patients were screened and 14 patients diagnosed with clear cell RCC (ccRCC) were enrolled. After 65 months of follow-up, three-year progression-free survival (PFS) rate was 71.4% and 4 year PFS rate was 59.5%. The 5 year overall survival (OS) rate was 58.3%. During extended treatment, one patient (7.1%) experienced a transition from stable disease (SD) to partial response (PR) and two patients (14.3%) experienced a transition from PR to complete response (CR). The best tumor shrinkage rates presenting after 24 months had longer PFS and OS compared to those presenting within 24 months (median PFS: not reached vs. 36 months; Hazard Ratio (HR) = 0.10, 95% CI 0.01-0.80, P = 0.03). For safety, extended immunotherapy did not increase treatment-related toxicities compared to safety profile before 24 months.

CONCLUSION

Our analysis of real-world data indicates that patients with extended immunotherapy after 24 months had potential survival benefits and manageable toxicity. Large-scale, prospective studies are still needed to further verify the conclusion.

SDCBP Orchestrated Gastric Cancer Aggression Through Epithelial- Mesenchymal Transition and Macrophages M2 Polarization

Gastric cancer remains a significant global health burden with limited treatment options and high mortality. Syndecan-binding protein (SDCBP), a scaffolding protein involved in tumor differentiation, has attracted attention as a potential therapeutic target in cancers. However, its precise role in gastric cancer progression is not fully understood. In this study, through bioinformatics analysis and gastric cancer samples detection, we discovered that SDCBP was highly expressed in gastric cancer tissues, which was correlated with clinicopathological features such as tumor invasion depth and distant metastasis, and exhibited heterogeneity across histological or molecular subtypes. Elevated SDCBP expression promoted the proliferation, invasion and migration of gastric cancer cells, and modulated epithelial-mesenchymal transition (EMT) via the ERK signaling pathway. Xenograft experiments in mice confirmed that inhibiting SDCBP or ERK signaling could delay cancer progression. We also found that gastric cancer cells with SDCBP knockdown were able to inhibit the M2 polarization of cocultured macrophages, reduce chemotaxis and enhance phagocytosis of macrophages. Therefore, SDCBP plays a crucial role in driving gastric cancer progression. Targeting SDCBP in gastric cancer can partially reverse the malignant phenotype, and SDCBP is expected to be a promising therapeutic target for gastric cancer.

Intravital Imaging of Immune Responses in the Cancer Microenvironment

BACKGROUND

To date, many types of immune cells have been identified, but their precise role in cancer immunity remains unclear. Understanding the immune responses involved in cancer and the cancer microenvironment is becoming increasingly important for elucidating disease mechanisms. In recent years, the application of intravital imaging in cancer research has provided new insights into the mechanisms of cancer-specific immune events, including innate and adaptive immunity.

RESULTS

In this review, we focus on the emerging role of intravital imaging in cancer research and describe how cancer and immune cells can be observed using intravital imaging in vivo. We also discuss new insights gained by this state-of-the-art technique.

CONCLUSIONS

Intravital imaging is a relatively new field of research that offers significant advantages, including the ability to directly capture cell-cell interactions, pathophysiology, and immune cell dynamics in the cancer microenvironment in vivo.

Tumor-Associated Macrophages Write the Script of Cancer Obesity Paradox

Obesity paradoxically advances cancer progression while enhancing certain immunotherapies, like anti-PD-1/PD-L1. Bader et al. discovered that obesity-driven factors increase PD-1 on tumor-associated macrophages (TAMs), suppressing anti-tumor responses. Remarkably, anti-PD-1 therapy reverses this metabolic dysfunction, boosting immune checkpoint blockade (ICB) effectiveness by reactivating PD-1+ TAMs.

CDKN2A Low cancer cells outcompete macrophages for microenvironmental zinc to drive immunotherapy resistance

Approximately 50% of cancers exhibit decreased CDKN2A expression ( CDKN2A Low ), which is linked to immune checkpoint blockade (ICB) resistance. While CDKN2A is traditionally recognized as a tumor suppressor and cell cycle regulator, we have previously put forth a new paradigm demonstrating its role in intracellular metabolic reprogramming. Whether the metabolic derangement due to CDKN2A loss alters metabolites within the tumor microenvironment (TME) and how that affects the immune compartment and ICB response has never been investigated. Here we found that CDKN2A Low cancer cells reorganize zinc compartmentalization by upregulating the zinc importer SLC39A9 in the plasma membrane, leading to intracellular zinc accumulation in cancer cells and concurrent zinc depletion in the TME. This competition for zinc results in zinc-starved tumor-associated macrophages (TAMs), leading to reduced phagocytic activity. Increasing zinc in TAMs through multiple approaches, including a dietary intervention that increases availability of TME zinc, re-educates these TAMs to a pro-phagocytic phenotype. Remarkably, both knockdown of Slc39a9 in cancer cells or providing a high zinc diet sensitizes Cdkn2a Low tumors to ICB. TAMs, not T cells, are indispensable for ICB response. Clinically, TAMs from CDKN2A Low cancer patients have decreased zinc signatures, corresponding to reduced phagocytosis signatures. Moreover, patients with low circulating zinc levels have reduced time-to-event outcomes compared to those with higher zinc levels. Our work reveals a previously unrecognized mechanism through which CDKN2A Low cancer cells outcompete TAMs for zinc, directly disrupting their function and ICB efficacy.

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.

Chrono-immunotherapy as a low-hanging fruit for cancer treatment? A call for pragmatic randomized clinical trials

The share of immune checkpoint inhibitors (ICIs) used in cancer treatment has rapidly increased in recent years. Although ICIs have the potential to provide a durable survival benefit in a subset of patients, many patients do not respond to these costly and often toxic therapies.Recent retrospective clinical data indicate that the time of day of ICI infusion may be a powerful modulator of their efficacy. These observational studies suggest an enhanced efficacy of morning over evening infusion. However, randomized trials have not confirmed in other fields findings obtained by observational studies, possibly because of selection bias and residual confounding factors. Thus, while the data are intriguing, the time dependence of the efficacy of immunotherapy needs to be confirmed in pragmatic randomized clinical trials. Here, we provide an overview of the modulation of ICI efficacy by the timing of immunotherapy infusion and critically discuss the biological rationale for chrono-immunotherapy, the circadian regulation of the immune system, and the need for pragmatic randomized clinical trials to confirm an effect of the timing of immunotherapy infusions on patient outcomes.

The role of tumor-associated macrophages in lung cancer

Lung cancer remains a leading cause of cancer-related deaths worldwide, necessitating innovative treatments. Tumor-associated macrophages (TAMs) are primary immunosuppressive effectors that foster tumor proliferation, angiogenesis, metastasis, and resistance to therapy. They are broadly categorized into proinflammatory M1 and tumor-promoting M2 phenotypes, with elevated M2 infiltration correlating with poor prognosis. Strategies aimed at inhibiting TAM recruitment, depleting TAMs, or reprogramming M2 to M1 are therefore highly promising. Key signaling pathways, such as CSF-1/CSF-1R, IL-4/IL-13-STAT6, TLRs, and CD47-SIRPα, regulate TAM polarization. Additionally, macrophage-based drug delivery systems permit targeted agent transport to hypoxic regions, enhancing therapy. Preclinical studies combining TAM-targeted therapies with chemotherapy or immune checkpoint inhibitors have yielded improved responses and prolonged survival. Several clinical trials have also reported benefits in previously unresponsive patients. Future work should clarify the roles of macrophage-derived exosomes, cytokines, and additional mediators in shaping the immunosuppressive tumor microenvironment. These insights will inform the design of next-generation drug carriers and optimize combination immunotherapies within precision medicine frameworks. Elucidating TAM phenotypes and their regulatory molecules remains central to developing novel strategies that curb tumor progression and ultimately improve outcomes in lung cancer. Importantly, macrophage-based immunomodulation may offer expanded treatment avenues.

The ETS-family transcription factor PU.1 is a critical regulator of the inhibitory Fcγ receptor IIB expression in humans

The inhibitory Fc gamma receptor IIB (FcγRIIB) is a critical determinant of humoral immunity. By providing feedback inhibition, through inhibitory signalling or competition for antibody Fc engagement, it counterbalances and contextualises cellular responses to signals emanating from co-ligated activating receptors, such as the B-cell receptor and activating FcγR. These activities collectively suppress the emergence of B- cell-mediated autoimmune disease and immune complex-mediated pathologies. However, FcγRIIB upregulation within the tumour microenvironment limits the efficacy of monoclonal antibody (mAb)-mediated immunotherapy of cancer. While the functional significance of FcγRIIB is well established in mice, its physiological roles and the regulatory mechanisms governing its expression remain incompletely understood in humans. Here we characterise the molecular determinants of FcγRIIB expression in human immune models and primary cells. Our findings reveal that the ETS-family transcription factor PU.1 plays a crucial role in regulating basal and inducible FcγRIIB expression. Moreover, when co-expressed, PU.1 co-operates with the related ETS-family member SPIB to drive FcγRIIB expression. PU.1 binding to the proximal FcγRIIB promoter elicits transcription, at least in part, through recruitment of the CBP/p300 transcriptional co-activators. Interestingly, similar mechanisms are also observed at the proximal promoters of the activating FcγRI and FcγRIIA, suggesting that additional, potentially lineage specific, factors cooperate with PU.1 to drive the distinct expression patterns of these FcγR. These insights pave the way for future investigations aimed at understanding the molecular mechanisms responsible for cell lineage-specific FcγR expression and subsequently manipulating them for therapeutic purposes.

Spatial interaction mapping of PD-1/PD-L1 in head and neck cancer reveals the role of macrophage-tumour barriers associated with immunotherapy response

BACKGROUND

Mucosal head and neck squamous cell carcinoma (HNSCC) is often diagnosed at an advanced stage, where the prognosis is poor due to the high rates of recurrence and metastasis. With approximately one million new cases projected in 2024, worldwide mortality of HNSCC is estimated to reach 50% of detected cases the same year. Patients with early-stage tumours showed a 50-60% five-year survival rate in the US. Immune checkpoint inhibitors (ICIs) have shown promising results in prolonging survival in a subset of patients with recurrent or metastatic disease. However, challenges remain, particularly the limited efficacy of PD-1/PD-L1 blockade therapies. PD-L1 protein expression has been shown to be limited in its predictive power for ICI therapies. Emerging evidence shows that intricate characterisation of the tumour microenvironment (TME) is fundamental to understand interacting cells. This study aims to bridge the gap in understanding the tumor microenvironment by identifying distinct spatial patterns of PD-1/PD-L1 interactions and their association with immunotherapy responses in head and neck squamous cell carcinoma (HNSCC).

METHODS

In this study, we sought to apply a more nuanced approach to understanding cellular interactions by mapping PD-1/PD-L1 interactions across whole-slide HNSCC tissue samples collected prior to ICI therapy. We used a combination of spatial proteomics (Akoya Biosciences) and an in situ proximity ligation assay (isPLA, Navinci Diagnostics) to visualise PD-1/PD-L1 interactions across cell types and cellular neighbourhoods within the tumour TME.

RESULTS

Our findings indicate the existence of isPLA+ PD-1/PD-L1 interactions between macrophages/CD3 T cell-enriched neighbourhoods and tumour cells at the tumour-stroma boundaries in ICI-resistant tumours. The presence of these dense macrophage-tumour layers, which are either absent or dispersed in responders, indicates a barrier that may restrict immune cell infiltration and promote immune escape mechanisms. In contrast, responders had abundant B and T cell aggregates, predominantly around the tumour edges linked to enhanced immune responses to ICI therapy and better clinical outcomes.

CONCLUSION

This study highlights the utility of isPLA in detecting distinct tumour-immune interactions within the TME, offering new cellular interaction metrics for stratifying and optimising immunotherapy strategies.

Emerging insights into intravital imaging, unraveling its role in cancer immunotherapy

Cancer immunotherapy has attracted great attention as a potential therapeutic approach for advanced malignancies due to its promising survival benefits. Comprehension of intricate interactions between the tumor microenvironment (TME) and immune checkpoint inhibitors (ICIs) is crucial for optimizing and improving immunotherapies. Currently, several experimental strategies are available to monitor this complexity but most of them fail to facilitate real-time monitoring of the immune response such as cellular phagocytosis and cytolysis. Consequently, the application of intravital imaging has been extensively studied in the domain of cancer immunotherapy. Intravital imaging has been proven to be a powerful real-time imaging modality that provides insights into intratumoral immune responses, cellular metabolic signatures, tumor vasculature, and cellular functions. This review aims to provide a comprehensive overview of the latest research on intravital imaging in cancer immunotherapy, especially addressing how intravital imaging sheds light on essential features of tumor immunity, immune infiltrations, tumor angiogenesis, and aids in the clarification of underlying immunotherapeutic mechanisms. Moreover, a variety of labeling tools, imaging windows and models for real-time visualizations of TME are also summarized. We will also investigate the full potential of using intravital imaging to circumvent the limitations of currently available imaging modalities, which hold promise to advent efficient immunotherapy for cancer patients.

Changes in tumor and cardiac metabolism upon immune checkpoint

Cardiovascular disease and cancer are the leading causes of death in the Western world. The associated risk factors are increased by smoking, hypertension, diabetes, sedentary lifestyle, aging, unbalanced diet, and alcohol consumption. Therefore, the study of cellular metabolism has become of increasing importance, with current research focusing on the alterations and adjustments of the metabolism of cancer patients. This may also affect the efficacy and tolerability of anti-cancer therapies such as immune-checkpoint inhibition (ICI). This review will focus on metabolic adaptations and their consequences for various cell types, including cancer cells, cardiac myocytes, and immune cells. Focusing on ICI, we illustrate how anti-cancer therapies interact with metabolism. In addition to the desired tumor response, we highlight that ICI can also lead to a variety of side effects that may impact metabolism or vice versa. With regard to the cardiovascular system, ICI-induced cardiotoxicity is increasingly recognized as one of the most life-threatening adverse events with a mortality of up to 50%. As such, significant efforts are being made to assess the specific interactions and associated metabolic changes associated with ICIs to improve both efficacy and management of side effects.

Linking macrophage metabolism to function in the tumor microenvironment

Macrophages are present at high frequency in most solid tumor types, and their relative abundance negatively correlates with therapy responses and survival outcomes. Tissue-resident macrophages are highly tuned to integrate tissue niche signals, and multiple factors within the idiosyncratic tumor microenvironment (TME) drive macrophages to polarization states that favor immune suppression, tumor growth and metastasis. These diverse functional states are underpinned by extensive and complex rewiring of tumor-associated macrophage (TAM) metabolism. In this Review, we link distinct and specific macrophage functional states within the TME to major, phenotype-sustaining metabolic programs and discuss the metabolic impact of macrophage-modulating therapeutic interventions.

A multimodal imaging pipeline to decipher cell-specific metabolic functions and tissue microenvironment dynamics

Tissue microenvironments are extremely complex and heterogeneous. It is challenging to study metabolic interaction between the different cell types in a tissue with the techniques that are currently available. Here we describe a multimodal imaging pipeline that allows cell type identification and nanoscale tracing of stable isotope-labeled compounds. This pipeline extends upon the principles of correlative light, electron and ion microscopy, by combining confocal microscopy reporter or probe-based fluorescence, electron microscopy, stable isotope labeling and nanoscale secondary ion mass spectrometry. We apply this method to murine models of hepatocellular and mammary gland carcinomas to study uptake of glucose derived carbon (13C) and glutamine derived nitrogen (15N) by tumor-associated immune cells. In vivo labeling with fluorescent-tagged antibodies (B220, CD3, CD8a, CD68) in tandem with confocal microscopy allows for the identification of specific cell types (B cells, T cells and macrophages) in the tumor microenvironment. Subsequent image correlation with electron microscopy offers the contrast and resolution to image membranes and organelles. Nanoscale secondary ion mass spectrometry tracks the enrichment of stable isotopes within these intracellular compartments. The whole protocol described here would take ~6 weeks to perform from start to finish. Our pipeline caters to a broad spectrum of applications as it can easily be adapted to trace the uptake and utilization of any stable isotope-labeled nutrient, drug or a probe by defined cellular populations in any tissue in situ.

Noninvasive in vivo imaging of macrophages: understanding tumor microenvironments and delivery of therapeutics

Macrophages are pivotal in the body's defense and response to inflammation. They are present in significant numbers and are widely implicated in various diseases, including cancer. While molecular and histological techniques have advanced our understanding of macrophage biology, their precise function within the cancerous microenvironments remains underexplored. Enhancing our knowledge of macrophages and the dynamics of their extracellular vesicles (EVs) in cancer development can potentially improve therapeutic management. Notably, macrophages have also been harnessed to deliver drugs. Noninvasive in vivo molecular imaging of macrophages is crucial for investigating intricate cellular processes, comprehending the underlying mechanisms of diseases, tracking cells and EVs' migration, and devising macrophage-dependent drug-delivery systems in living organisms. Thus, in vivo imaging of macrophages has become an indispensable tool in biomedical research. The integration of multimodal imaging approaches and the continued development of novel contrast agents hold promise for overcoming current limitations and expanding the applications of macrophage imaging. This study comprehensively reviews several methods for labeling macrophages and various imaging modalities, assessing the merits and drawbacks of each approach. The review concludes by offering insights into the applicability of molecular imaging techniques for real time monitoring of macrophages in preclinical and clinical scenarios.

CD133+PD-L1+ cancer cells confer resistance to adoptively transferred engineered macrophage-based therapy in melanoma

Adoptive transfer of genetically or nanoparticle-engineered macrophages represents a promising cell therapy modality for treatment of solid tumor. However, the therapeutic efficacy is suboptimal without achieving a complete tumor regression, and the underlying mechanism remains elusive. Here, we discover a subpopulation of cancer cells with upregulated CD133 and programmed death-ligand 1 in mouse melanoma, resistant to the phagocytosis by the transferred macrophages. Compared to the CD133-PD-L1- cancer cells, the CD133+PD-L1+ cancer cells express higher transforming growth factor-β signaling molecules to foster a resistant tumor niche, that restricts the trafficking of the transferred macrophages by stiffened extracellular matrix, and inhibits their cell-killing capability by immunosuppressive factors. The CD133+PD-L1+ cancer cells exhibit tumorigenic potential. The CD133+PD-L1+ cells are further identified in the clinically metastatic melanoma. Hyperthermia reverses the resistance of CD133+PD-L1+ cancer cells through upregulating the 'eat me' signal calreticulin, significantly improving the efficacy of adoptive macrophage therapy. Our findings demonstrate the mechanism of resistance to adoptive macrophage therapy, and provide a de novo strategy to counteract the resistance.

Resistance mechanisms to immune checkpoint inhibitors: updated insights

The last decade has witnessed unprecedented succusses with the use of immune checkpoint inhibitors in treating cancer. Nevertheless, the proportion of patients who respond favorably to the treatment remained rather modest, partially due to treatment resistance. This has fueled a wave of research into potential mechanisms of resistance to immune checkpoint inhibitors which can be classified into primary resistance or acquired resistance after an initial response. In the current review, we summarize what is known so far about the mechanisms of resistance in terms of being tumor-intrinsic or tumor-extrinsic taking into account the multimodal crosstalk between the tumor, immune system compartment and other host-related factors.

Harnessing the tumor microenvironment: targeted cancer therapies through modulation of epithelial-mesenchymal transition

The tumor microenvironment (TME) is integral to cancer progression, impacting metastasis and treatment response. It consists of diverse cell types, extracellular matrix components, and signaling molecules that interact to promote tumor growth and therapeutic resistance. Elucidating the intricate interactions between cancer cells and the TME is crucial in understanding cancer progression and therapeutic challenges. A critical process induced by TME signaling is the epithelial-mesenchymal transition (EMT), wherein epithelial cells acquire mesenchymal traits, which enhance their motility and invasiveness and promote metastasis and cancer progression. By targeting various components of the TME, novel investigational strategies aim to disrupt the TME's contribution to the EMT, thereby improving treatment efficacy, addressing therapeutic resistance, and offering a nuanced approach to cancer therapy. This review scrutinizes the key players in the TME and the TME's contribution to the EMT, emphasizing avenues to therapeutically disrupt the interactions between the various TME components. Moreover, the article discusses the TME's implications for resistance mechanisms and highlights the current therapeutic strategies toward TME modulation along with potential caveats.

Targeted SPP1 Inhibition of Tumor-Associated Myeloid Cells Effectively Decreases Tumor Sizes

Secreted phosphosprotein 1 (SPP1)High tumor-associated macrophages (TAM) are abundant tumor myeloid cells that are immunosuppressive, pro-tumorigenic, and have a highly negative prognostic factor. Despite this, there is a lack of efficient TAM-specific therapeutics capable of reducing SPP1 expression. Here, on a phenotypic screen is reported to identify small molecule SPP1 modulators in macrophages. Several hits and incorporated them into a TAM-avid systemic nanoformulation are identified. It is shown that the lead compound (CANDI460) can down-regulate SPP1 in vitro and in vivo and lead to tumor remissions in different murine models. These findings are important as they offer a promising avenue for developing novel therapeutic strategies targeting TAM.

Leveraging insights from cancer to improve tuberculosis therapy

Exploring and exploiting the microenvironmental similarities between pulmonary tuberculosis (TB) granulomas and malignant tumors has revealed new strategies for more efficacious host-directed therapies (HDTs). This opinion article discusses a paradigm shift in TB therapeutic development, drawing on critical insights from oncology. We summarize recent efforts to characterize and overcome key shared features between tumors and granulomas, including excessive fibrosis, abnormal angiogenesis, hypoxia and necrosis, and immunosuppression. We provide specific examples of cancer therapy application to TB to overcome these microenvironmental abnormalities, including matrix-targeting therapies, antiangiogenic agents, and immune-stimulatory drugs. Finally, we propose a new framework for combining HDTs with anti-TB agents to maximize therapeutic delivery and efficacy while reducing treatment dosages, duration, and harmful side effects to benefit TB patients.

Method for Non-covalent Functionalization of DNA Nanostructures with DNA Aptamers

DNA nanostructures generated through rolling circle amplification (RCA) technology have found widespread application in drug delivery systems due to their simple fabrication, modification, and unique structures for loading various types of drugs. In this chapter, we describe methods for generating DNA nanostructures using RCA technology and providing functionality with DNA aptamers. These methods involve non-covalent functionalization of DNA nanostructures with DNA aptamers. Methods for constructing DNA nanostructures, such as DNA nanoballs and DNA nanogels, are described with a focus on using RCA technology, as well as characterization of the nanostructures. Methods for the functionalization of DNA nanostructures include complementary hybridization of base pairs and the decoration of DNA nanostructures with a polyadenine-tailed DNA aptamer based on hydrophobic interactions. Methods for testing the modification of nanostructures with aptamers are described, with examples of experimental data provided. Consideration points for constructing the nanostructures and modifying them with DNA aptamers are noted. Methods for designing and characterizing DNA nanostructures modified with DNA aptamers will be useful for diverse biomedical applications such as targeted drug delivery and imaging for the treatment and diagnosis of diseases.

Reprogrammed Lung Metastasis Immunodeficiency via Targeted Penetrated Delivery of M1 Macrophage-Wrapped NanoCubes-Mediated T Cell Infiltration

The infiltration of cytotoxic T lymphocytes holds promise for suppressing even the most resilient metastatic tumors in immunotherapy. Polarizing tumor-associated macrophages (TAMs) and remodeling the immune-deficient tumor microenvironment (TME) can enhance T lymphocyte recruitment and infiltration. However, the immune privilege and low immunogenic responses of these aggressive tumor clusters often limit lymphocyte recruitment. Here, an M1 macrophage membrane-coated iron oxide nanoparticle (IO@MM) double as a tumor-penetrated agent and naïve M0 macrophage to M1 polarizer is developed for lung metastatic colorectal cancer (CRC) immunotherapy. At the tumor site, IO@MM combined with resiquimod (R848) increased the immune cell infiltration, turning the "Cold" TME into an immune-activating "Hot" one. Together with self-cascade immunotherapy, IO@MM with R848 promotes tumor release of damage-associated molecular patterns (DAMPs). At the same time, IO@MM uses the membrane as an antigen reservoir and provides autologous DAMPs to retain dendritic cells. This IO@MM effectively inhibits tumors and improves survival rate as an immunomodulator in lung metastasis.

Artificial intelligence for chimeric antigen receptor-based therapies: a comprehensive review of current applications and future perspectives

Using artificial intelligence (AI) to enhance chimeric antigen receptor (CAR)-based therapies' design, production, and delivery is a novel and promising approach. This review provides an overview of the current applications and challenges of AI for CAR-based therapies and suggests some directions for future research and development. This paper examines some of the recent advances of AI for CAR-based therapies, for example, using deep learning (DL) to design CARs that target multiple antigens and avoid antigen escape; using natural language processing to extract relevant information from clinical reports and literature; using computer vision to analyze the morphology and phenotype of CAR cells; using reinforcement learning to optimize the dose and schedule of CAR infusion; and using AI to predict the efficacy and toxicity of CAR-based therapies. These applications demonstrate the potential of AI to improve the quality and efficiency of CAR-based therapies and to provide personalized and precise treatments for cancer patients. However, there are also some challenges and limitations of using AI for CAR-based therapies, for example, the lack of high-quality and standardized data; the need for validation and verification of AI models; the risk of bias and error in AI outputs; the ethical, legal, and social issues of using AI for health care; and the possible impact of AI on the human role and responsibility in cancer immunotherapy. It is important to establish a multidisciplinary collaboration among researchers, clinicians, regulators, and patients to address these challenges and to ensure the safe and responsible use of AI for CAR-based therapies.

PD-1 antibody interactions with Fc gamma receptors enable PD-1 agonism to inhibit T cell activation - therapeutic implications for autoimmunity

PD-1 has emerged as a central inhibitory checkpoint receptor in maintaining immune homeostasis and as a target in cancer immunotherapies. However, targeting PD-1 for the treatment of autoimmune diseases has been more challenging. We recently showed in a phase 2a trial that PD-1 could be stimulated with the PD-1 agonist antibody peresolimab to treat rheumatoid arthritis. Here, we demonstrate that PD-1 antibodies can elicit agonism and inhibit T cell activation by co-localization of PD-1 with the T cell receptor via Fcγ receptor (FcγR) engagement. Three PD-1 agonist antibodies with different antigen binding domains, including the clinically validated PD-1 blocking antibody pembrolizumab, suppressed T cell activation to a similar degree; this finding suggests that a specific PD-1-binding epitope is not required for PD-1 agonism. We next explored whether antibody-mediated clustering was an important driver of inhibition of T cell activation; however, we found that a monovalent PD-1 antibody was not inferior to a conventional bivalent antibody in its ability to suppress T cell activation. Importantly, we found that affinity to PD-1 correlated positively with inhibition of T cell activation, with higher affinity antibodies exhibiting higher levels of inhibition. Using a series of human Fc mutants with altered affinities to various FcγRs, we dissected the contributions of FcγRs and found that multiple FcγRs rather than a single receptor contribute to agonist activity. Our work reveals an important role for FcγR binding in the activity of PD-1 antibodies, which has implications for optimizing both PD-1 agonist and antagonist antibodies.

LAG-3-An incompletely understood target in cancer therapy

LAG-3 is a member of the immunoglobulin superfamily expressed on activated T cells, but also on other immune cells. It has significant homology to CD4. Both molecules have four extracellular Ig-like domains with similar structural motifs but the sequence identity between LAG-3 and CD4 is low. Furthermore, unlike CD4 LAG-3 restrains T cell responses and antibodies targeting this receptor are emerging drugs in cancer immunotherapy. A combination of LAG-3 and PD-1 antibodies has already been approved for the treatment of metastatic melanoma. Despite this success, its biology is still not well understood. Here we summarize the current knowledge on expression, ligands, and function of LAG-3. We point to the differences between LAG-3 and other inhibitory immune checkpoints and describe obstacles to study the role of this receptor in T cell activation processes. Finally, we discuss future directions for scientific efforts to come to a more complete understanding of the biology of this eminent immune checkpoint.

Periodontitis promotes tumor growth and immune evasion via PD-1/PD-L1

BACKGROUND

Our study investigated the role of experimental periodontitis on tumor growth, local and systemic immunosuppressive status, and programmed death receptor 1 (PD-1) / programmed death ligand 1 (PD-L1) expression in oral squamous cell carcinoma (OSCC) and prostate cancer.

METHODS

Mouse oral or prostate cancer xenograft models were divided into control, periodontitis and periodontitis + anti-PD-1 groups. Tumor volume and weight were recorded and the levels of relevant immune-suppressive cells and T cells were detected by flow cytometry or immunofluorescence. THP-1 cells were stimulated using conditioned media of LPS-stimulated Cal-27 cells and PD-L1 expression was measured by quantitative real-time PCR, western blotting and immunofluorescence. Tumor specimens from OSCC patients with or without periodontitis were also collected for immunofluorescence.

RESULTS

Periodontitis significantly promoted tumor volume and weight. Compared to the control, the proportions of tumor-associated macrophages (TAMs), regulatory T cells (Tregs), PD-L1+TAMs and PD-1+CD8+T cells increased, while CD8+T cells decreased in the periodontitis group. Immunofluorescence demonstrated that there was an increase in PD-L1+TAMs and PD-1+CD8+T cells, but a decrease in IFN-γ+CD8+T cells in both xenografts and clinical OSCC samples with periodontitis. In vitro, LPS-stimulated Cal-27 cells had a stronger potential to induce PD-L1 expression in macrophages compared with unstimulated Cal-27 cells. And the promoting effect of periodontitis on tumor growth and immune evasion was significantly attenuated after anti-PD-1 therapy.

CONCLUSION

Periodontitis may facilitate tumor growth and immune escape evidenced by the increased immune-suppressive cells and the decreased functional T cells, via enhancing PD-1/PD-L1 expression in the tumor microenvironment.

Fc-optimized checkpoint antibodies for cancer immunotherapy

The development of checkpoint antibodies for cancer therapy has been guided by the principle of blocking T cell inhibitory signals. Recognition of the role of the Fc domain in therapeutic activities, through the depletion of immunosuppressive populations and myeloid cell activation, prompts a shift toward the development of optimized Fc-engineered checkpoint antibodies.

TAM-tastic: from resistance to resilience in cancer

Overcoming resistance to immunotherapy in cancer is challenging due, in part, to tumor-associated macrophages (TAMs) co-expressing T cell immunoglobulin and mucin domain-containing 3 (TIM3) and V-domain immunoglobulin suppressor of T cell activation (VISTA) in tumor microenvironments (TME) with sparse T cell infiltration. In a recent article, Vanmeerbeek et al. found that blocking TIM3 or VISTA on IL-4-supported TAMs, in combination with paclitaxel (PTX), reprogrammed TAMs to attack cancer cells, highlighting a potential new therapeutic strategy.

Dissecting the roles of prosaposin as an emerging therapeutic target for tumors and its underlying mechanisms

As a dual-function protein, prosaposin (PSAP) is a lysosome-associated protein that participates in a variety of cellular processes. In the lysosome, PSAP is processed to activate enzymes that degrade lipids. In addition, PSAP proteins located extracellularly are involved in cancer progression, such as proliferation and tumor death suppression signaling. Moreover, under different situations, PSAP exhibits distinct metastasis potentials in tumors. However, comprehensive insight into PSAP in cancer progression has been lacking. Here, we provide a framework of the role of PSAP in cancer and its clinical application in cancer patients, providing a novel perspective on the clinical translation of PSAP.

Cadonilimab (PD-1/CTLA-4) in combination with lenvatinib in unresectable hepatocellular carcinoma (uHCC): A retrospective real-world study

Background

Previous research has shown that combining tyrosine kinase inhibitors (TKIs) with immunotherapy results in synergistic clinical efficacy. Cadonilimab, the first approved bi-specific antibody targeting PD-1 and CTLA-4, was studied to evaluate its efficacy and safety in combination with Lenvatinib as a first-line treatment for patients with unresectable hepatocellular carcinoma (uHCC).

Methods

A retrospective study was conducted on 29 uHCC patients diagnosed at Nanfang Hospital, Southern Medical University, between July 7, 2022, and March 3, 2023. Patients received Cadonilimab (10 mg/kg, IV, every 3 weeks) combined with Lenvatinib (8 mg, orally, daily). The primary endpoint was the objective response rate (ORR), with secondary endpoints including disease control rate (DCR), median progression-free survival (mPFS), median overall survival (mOS), median time to progression (mTTP), and safety.

Results

By April 2023, 29 patients had been enrolled in the study. The ORR was 37.9 %, DCR was 82.8 %, mPFS was 8.1 months, mTTP was 8.2 months, and mOS was not reached. A total of 93.1 % of patients experienced at least one treatment-related adverse event (TRAE). The most common adverse events were weight loss (51.7 %), increased aspartate aminotransferase (48.3 %), leukocytopenia (48.3 %), and neutropenia (48.3 %). TRAEs of grade 3 or higher occurred in 51.7 % of patients, with no grade 4 TRAEs observed.

Conclusion

This study demonstrated the efficacy and safety of this combination, potentially improving outcomes as a first-line therapy, and offering a novel therapeutic approach for advanced HCC.

An iron-rich subset of macrophages promotes tumor growth through a Bach1-Ednrb axis

We define a subset of macrophages in the tumor microenvironment characterized by high intracellular iron and enrichment of heme and iron metabolism genes. These iron-rich tumor-associated macrophages (iTAMs) supported angiogenesis and immunosuppression in the tumor microenvironment and were conserved between mice and humans. iTAMs comprise two additional subsets based on gene expression profile and location-perivascular (pviTAM) and stromal (stiTAM). We identified the endothelin receptor type B (Ednrb) as a specific marker of iTAMs and found myeloid-specific deletion of Ednrb to reduce tumor growth and vascular density. Further studies identified the transcription factor Bach1 as a repressor of the iTAM transcriptional program, including Ednrb expression. Heme is a known inhibitor of Bach1, and, correspondingly, heme exposure induced Ednrb and iTAM signature genes in macrophages. Thus, iTAMs are a distinct macrophage subset regulated by the transcription factor Bach1 and characterized by Ednrb-mediated immunosuppressive and angiogenic functions.

Preclinical comparison of prolgolimab, pembrolizumab and nivolumab

Prolgolimab is a recombinant IgG1-based anti-PD-1 antibody, whose properties were improved by the introduction of the LALA mutation, and which has demonstrated high efficacy in patients with metastatic melanoma. This paper presents the results of comparative preclinical studies of antigen-binding and effector functions involving prolgolimab and conventional IgG4 antibodies, nivolumab and pembrolizumab. None of the studied antibodies had undesirable antibody-dependent cellular cytotoxicity activity. Prolgolimab has shown higher PD-1 receptor occupancy and T-cell activation, but lower propensity to activate antibody-dependent cellular phagocytosis as compared to nivolumab and pembrolizumab. An in vivo study in mice inoculated with CT26.wt cancer cells showed that tumor growth inhibition was 16% for pembrolizumab and 56% for prolgolimab. This study warrants clinical comparison of IgG1- and IgG4-based anti-PD-1 antibodies.

In vivo self-assembled albumin nanoparticle elicit antitumor immunity of PD-1 inhibitor by imaging and clearing tumor-associated macrophages

Eliciting anti-tumor immune responses and improving the tumor microenvironment crucial for boosting the effectiveness of anti-PD-1 immunotherapy. Tumor-associated macrophages (TAMs), the primary types of immune cells infiltrating tumors, play a critical role in the formation of an immunosuppressive microenvironment. In this study, we constructed a novel Evans Blue (EB)-based in vivo self-assembled nanocarrier system, mUNO-EB-ICG-Fc@Alb nanoparticles (designated as MA NPs), for targeted imaging and clearance of M2-TAMs to elicit antitumor immunotherapy of PD-1 inhibitor. In vitro experiments demonstrated the specific fluorescence imaging and killing effect of MA NPs on M2-TAMs. In vivo experiments shown that MA NPs-induced chemodynamic therapy (CDT) successfully reversed the tumor immunosuppressive microenvironment (ITM), promoted intratumoral infiltration of T lymphocytes, and ultimately enhancing the anti-tumor immunotherapy effect of PD-1 inhibitors. This study might provide good inspiration for improving the therapeutic efficacy of cancer immunotherapy.

Checkpoint inhibition enhances cell contacts between CD4+ T cells and Hodgkin-Reed-Sternberg cells of classic Hodgkin lymphoma

Although checkpoint molecules like CTLA-4 and PD1 have been described several years ago, checkpoint inhibitors such as nivolumab (an anti-PD-1 antibody) have only recently been used to treat classic Hodgkin lymphoma (cHL). Several studies have shown convincing therapeutic effects of nivolumab in cHL. However, the mechanism of action of nivolumab in cHL is not fully understood. The aim of this study was to monitor changes in cell motility and cell contacts after administration of nivolumab to an in vitro model of cHL as well as to native hyperplastic lymphoid tissue and native human tissue from cHL. In both tissue and in vitro, CD4+, CD8+, CD30+ and CD20+ cell velocities were unchanged after nivolumab incubation. In contrast, in primary cHL tissue, the duration of cell contacts between CD4+ T cells and Hodgkin-Reed-Sternberg cells was significantly increased after 5 hours of nivolumab treatment, and the number of contacts with HRS cells was also slightly increased for CD4+ T cells (not significant), suggesting that CD4+ T cells in particular contribute to the cytotoxicity observed as a result of nivolumab therapy. There was no change in the duration of cell contacts in the hyperplastic lymphoid tissue after nivolumab incubation. In conclusion, we show here for the first time by imaging of native lymphoma tissue an enhanced interaction of CD4+ T cells and Hodgkin-Reed-Sternberg cells in cHL after nivolumab administration.

Challenges in validation of combination treatment strategies for CRC using patient-derived organoids

Patient-derived organoids (PDOs) established from tissues from various tumor types gave the foundation of ex vivo models to screen and/or validate the activity of many cancer drug candidates. Due to their phenotypic and genotypic similarity to the tumor of which they were derived, PDOs offer results that effectively complement those obtained from more complex models. Yet, their potential for predicting sensitivity to combination therapy remains underexplored. In this review, we discuss the use of PDOs in both validation and optimization of multi-drug combinations for personalized treatment strategies in CRC. Moreover, we present recent advancements in enriching PDOs with diverse cell types, enhancing their ability to mimic the complexity of in vivo environments. Finally, we debate how such sophisticated models are narrowing the gap in personalized medicine, particularly through immunotherapy strategies and discuss the challenges and future direction in this promising field.

Mechanistic Insights into the Successful Development of Combination Therapy of Enfortumab Vedotin and Pembrolizumab for the Treatment of Locally Advanced or Metastatic Urothelial Cancer

Antibody-drug conjugates (ADCs) consist of an antibody backbone that recognizes and binds to a target antigen expressed on tumor cells and a small molecule chemotherapy payload that is conjugated to the antibody via a linker. ADCs are one of the most promising therapeutic modalities for the treatment of various cancers. However, many patients have developed resistance to this form of therapy. Extensive efforts have been dedicated to identifying an effective combination of ADCs with other types of anticancer therapies to potentially overcome this resistance. A recent clinical study demonstrated that a combination of the ADC enfortumab vedotin (EV) with the immune checkpoint inhibitor (ICI) pembrolizumab can achieve remarkable clinical efficacy as the first-line therapy for the treatment of locally advanced or metastatic urothelial carcinoma (la/mUC)-leading to the first approval of a combination therapy of an ADC with an ICI for the treatment of cancer patients. In this review, we highlight knowledge and understanding gained from the successful development of EV and the combination therapy of EV with ICI for the treatment of la/mUC. Using urothelial carcinoma as an example, we will focus on dissecting the underlying mechanisms necessary for the development of this type of combination therapy for a variety of cancers.

Definitive chemoradiotherapy induces T-cell-inflamed tumor microenvironment in unresectable locally advanced esophageal squamous cell carcinoma

BACKGROUND

Chemoradiotherapy (CRT) modulates the tumor immune microenvironment of multiple cancer types, including esophageal cancer, which potentially induces both immunogenicity and immunosuppression by upregulating the presentation of tumor-specific antigens and immune checkpoint molecules in tumors, respectively. The prognostic effects of immune modification by CRT in esophageal squamous cell carcinoma (ESCC) remain controversial because of the lack of detailed immunological analyses using paired clinical specimens before and after CRT. We aimed to clarify the immunological changes in the tumor microenvironment caused by CRT and elucidate the predictive importance of clinical response and prognosis and the rationale for the necessity of subsequent programmed cell death protein 1 (PD-1) inhibitor treatment.

METHODS

In this study, we performed a comprehensive immunological analysis of paired biopsy specimens using multiplex immunohistochemistry before and after CRT in patients with unresectable locally advanced ESCC.

RESULTS

CRT significantly increased the intra-tumoral infiltration and PD-1 expression of CD8+ T cells and conventional CD4+ T cells but decreased those of regulatory T cells and the accumulation of tumor-associated macrophages. Multivariate analysis of tumor-infiltrating T-cell phenotypes revealed that the density of PD-1+CD8+ T cells in the tumor after CRT could predict a confirmed complete response and favorable survival.

CONCLUSIONS

This study showed that CRT improved the immunological characteristics of unresectable locally advanced ESCC and identified the density of PD-1+CD8+ T cells as a predictive factor for prognosis. This finding supports the rationale for the necessity of subsequent PD-1 inhibitor treatment.

Validation of the C-X-C chemokine receptor 3 (CXCR3) as a target for PET imaging of T cell activation

PURPOSE

CXCR3 is expressed on activated T cells and plays a crucial role in T-cell recruitment to the tumor microenvironment (TME) during cell-based and immune checkpoint inhibitor (ICI) immunotherapy. This study utilized a 64Cu-labeled NOTA-α-CXCR3 antibody to assess CXCR3 expression in the TME and validate it as a potential T cell activation biomarker in vivo.

PROCEDURES

CXCR3+ cells infiltrating MC38 tumors (B57BL/6 mice, untreated and treated with αPD-1/αCTLA-4 ICI) were quantified using fluorescence microscopy and flow cytometry. A commercial anti-mouse CXCR3 antibody (α-CXCR3) was site-specifically conjugated with 2,2,2-(1,4,7-triazacyclononane-1,4,7-triyl)triacetic acid (NOTA) and radiolabeled with 64Cu. Saturation binding of [64Cu]Cu-NOTA-α-CXCR3 was investigated using CHO cells stably transfected with murine CXCR3. Biodistribution and PET imaging studies both at baseline and after 1 to 3 cycles of ICI, respectively, were carried out using different molar activities (10 GBq/µmol to 300 GBq/µmol) of [64Cu]Cu-NOTA-α-CXCR3.

RESULTS

Flow cytometry analysis at baseline confirmed the presence of CXCR3 + T-cells in MC38 tumors, which was significantly increased at day five after ICI (treated 33.8 ± 17.4 vs. control 8.8 ± 6.2 CD3+CXCR3+ cells/mg). These results were qualitatively and quantitatively confirmed by immunofluorescence of tumor cryoslices. In vivo PET imaging of MC38 tumor bearing mice before, during and after ICI using [64Cu]Cu-NOTA-α-CXCR3 (Kd = 3.3 nM) revealed a strong dependence of CXCR3-specificity of tracer accumulation in secondary lymphoid organs on molar activity. At 300 GBq/µmol (1.5 µg of antibody/mouse), a specific signal was observed in lymph nodes (6.33 ± 1.25 control vs. 3.95 ± 1.23%IA/g blocking) and the spleen (6.04 ± 1.02 control vs. 3.84 ± 0.79%IA/g blocking) at 48 h p.i. Spleen-to-liver ratios indicated a time dependent systemic immune response showing a steady increase from 1.08 ± 0.19 (untreated control) to 1.54 ± 0.14 (three ICI cycles).

CONCLUSIONS

This study demonstrates the feasibility of in vivo imaging of CXCR3 upregulation under immunotherapy using antibodies. However, high molar activities and low antibody doses are essential for sensitive detection in lymph nodes and spleen. Detecting therapy-induced changes in CXCR3+ T cell numbers in tumors was challenging due to secondary antibody-related effects. Nonetheless, CXCR3 remains a promising target for imaging T cell activation, with anticipated improvements in sensitivity using alternative tracers with high affinities and favorable pharmacokinetics.

Exploring the role of the immune microenvironment in hepatocellular carcinoma: Implications for immunotherapy and drug resistance

Hepatocellular carcinoma (HCC), the most common type of liver tumor, is a leading cause of cancer-related deaths, and the incidence of liver cancer is still increasing worldwide. Curative hepatectomy or liver transplantation is only indicated for a small population of patients with early-stage HCC. However, most patients with HCC are not candidates for radical resection due to disease progression, leading to the choice of the conventional tyrosine kinase inhibitor drug sorafenib as first-line treatment. In the past few years, immunotherapy, mainly immune checkpoint inhibitors (ICIs), has revolutionized the clinical strategy for HCC. Combination therapy with ICIs has proven more effective than sorafenib, and clinical trials have been conducted to apply these therapies to patients. Despite significant progress in immunotherapy, the molecular mechanisms behind it remain unclear, and immune resistance is often challenging to overcome. Several studies have pointed out that the complex intercellular communication network in the immune microenvironment of HCC regulates tumor escape and drug resistance to immune response. This underscores the urgent need to analyze the immune microenvironment of HCC. This review describes the immunosuppressive cell populations in the immune microenvironment of HCC, as well as the related clinical trials, aiming to provide insights for the next generation of precision immunotherapy.

Recent advances in sialic acid-based active targeting chemoimmunotherapy promoting tumor shedding: a systematic review

Tumors have always been a major public health concern worldwide, and attempts to look for effective treatments have never ceased. Sialic acid is known to be a crucial element for tumor development and its receptors are highly expressed on tumor-associated immune cells, which perform significant roles in establishing the immunosuppressive tumor microenvironment and further boosting tumorigenesis, progression, and metastasis. Obviously, it is essential to consider sophisticated crosstalk between tumors, the immune system, and preparations, and understand the links between pharmaceutics and immunology. Sialic acid-based chemoimmunotherapy enables active targeting drug delivery via mediating the recognition between the sialic acid-modified nano-drug delivery system represented by liposomes and sialic acid-binding receptors on tumor-associated immune cells, which inhibit their activity and utilize their homing ability to deliver drugs. Such a "Trojan horse" strategy has remarkably improved the shortcomings of traditional passive targeting treatments, unexpectedly promoted tumor shedding, and persistently induced robust immunological memory, thus highlighting its prospective application potential for targeting various tumors. Herein, we review recent advances in sialic acid-based active targeting chemoimmunotherapy to promote tumor shedding, summarize the current viewpoints on the tumor shedding mechanism, especially the formation of durable immunological memory, and analyze the challenges and opportunities of this attractive approach.

Tumor associated macrophages as key contributors and targets in current and future therapies for melanoma

INTRODUCTION

Despite the success of immunotherapies for melanoma in recent years, there remains a significant proportion of patients who do not yet derive benefit from available treatments. Immunotherapies currently licensed for clinical use target the adaptive immune system, focussing on Tcell interactions and functions. However, the most prevalent immune cells within the tumor microenvironment (TME) of melanoma are macrophages, a diverse immune cell subset displaying high plasticity, to which no current therapies are yet directly targeted. Macrophages have been shown not only to activate the adaptive immune response, and enhance cancer cell killing, but, when influenced by factors within the TME of melanoma, these cells also promote melanoma tumorigenesis and metastasis.

AREAS COVERED

We present a review of the most up-to-date literatureavailable on PubMed, focussing on studies from within the last 10 years. We also include data from ongoing and recent clinical trials targeting macrophages in melanoma listed on clinicaltrials.gov.

EXPERT OPINION

Understanding the multifaceted role of macrophages in melanoma, including their interactions with immune and cancer cells, the influence of current therapies on macrophage phenotype and functions and how macrophages could be targeted with novel treatment approaches, are all critical for improving outcomes for patients with melanoma.

Strategies for overcoming tumour resistance to immunotherapy: harnessing the power of radiation therapy

Immune checkpoint inhibitors (ICI) have revolutionized cancer treatment; yet their efficacy remains variable across patients. This review delves into the intricate interplay of tumour characteristics contributing to resistance against ICI therapy and suggests that combining with radiotherapy holds promise. Radiation, known for its ability to trigger immunogenic cell death and foster an in situ vaccination effect, may counteract these resistance mechanisms, enhancing ICI response and patient outcomes. However, particularly when delivered at high-dose, it may trigger immunosuppressive mechanism and consequent side-effects. Notably, low-dose radiotherapy (LDRT), with its capacity for tumour reprogramming and reduced side effects, offers the potential for widespread application. Preclinical and clinical studies have shown encouraging results in this regard.

Efficacy of IFN-γ, sCD40L, and Poly(I:C) Treated Bone Marrow-Derived Macrophages in Murine Mammary Carcinoma

INTRODUCTION

Here, we explored methods to generate anti-tumor bone marrow-derived macrophages (BMDM) and how delivery of the BMDM at early tumor sites could impact disease progression.

METHODS

BMDM treated with IFN-γ, sCD40L, poly(I:C), and a combination of the three were assessed.

RESULTS

Treatment with sCD40L had no significant impact on the BMDM. Treating BMDM with IFN-γ impacted IL-1β, MHC Class II, and CD80 expression. While poly(I:C) treatment had a greater impact on the BMDM than IFN-γ when assessed by the in vitro assays, the BMDM treated with poly (I:C) had mixed results in vivo where they decreased growth of the EMT6 tumor, did not impact growth of the 168 tumor, and enhanced growth of the 4T1 tumor. The combination of poly(I:C), IFN-γ, and sCD40L had the greatest impact on the BMDM in vitro and in vivo. Treatment with all three agonists resulted in increased IL-1β, TNF-α, and IL-12 expression, decreased expression of arginase and mrc, increased phagocytic activity, nitrite production, and MHC Class II and CD80 expression, and significantly impacted growth of the EMT6 and 168 murine mammary carcinoma models.

DISCUSSION

Collectively, these data show that treating BMDM with poly(I:C), IFN-γ, and sCD40L generates BMDM with more consistent anti-tumor activity than BMDM generated with the individual agonists.

The Interplay between Metabolic Adaptations and Diet in Cancer Immunotherapy

Over the past decade, cancer immunotherapy has significantly advanced through the introduction of immune checkpoint inhibitors and the augmentation of adoptive cell transfer to enhance the innate cancer defense mechanisms. Despite these remarkable achievements, some cancers exhibit resistance to immunotherapy, with limited patient responsiveness and development of therapy resistance. Metabolic adaptations in both immune cells and cancer cells have emerged as central contributors to immunotherapy resistance. In the last few years, new insights emphasized the critical role of cancer and immune cell metabolism in animal models and patients. During therapy, immune cells undergo important metabolic shifts crucial for their acquired effector function against cancer cells. However, cancer cell metabolic rewiring and nutrient competition within tumor microenvironment (TME) alters many immune functions, affecting their fitness, polarization, recruitment, and survival. These interactions have initiated the development of novel therapies targeting tumor cell metabolism and favoring antitumor immunity within the TME. Furthermore, there has been increasing interest in comprehending how diet impacts the response to immunotherapy, given the demonstrated immunomodulatory and antitumor activity of various nutrients. In conclusion, recent advances in preclinical and clinical studies have highlighted the capacity of immune-based cancer therapies. Therefore, further exploration into the metabolic requirements of immune cells within the TME holds significant promise for the development of innovative therapeutic approaches that can effectively combat cancer in patients.