Immune checkpoint inhibition combined with targeted therapy using a novel virus-like drug conjugate induces complete responses in a murine model of local and distant tumors

Targeting ocular malignancies using a novel light-activated virus-like drug conjugate

Background

Targeted therapy is a promising approach to improve the treatment of tumors, including ocular malignancies. Current therapies, such as radiotherapy and surgery, often lead to serious damage to vision or to loss of the eye. New approaches have examined nanoparticles for use as targeted delivery vehicles for drugs. A newly-developed virus-like drug conjugate is a promising nanoparticle with a defined target: the novel virus-like particle-photosensitizer conjugate Belzupacap sarotalocan (Bel-sar, previous name AU-011).

Main text

In this review, we summarize the application of this novel light-activated virus-like particle conjugate in pre-clinical and clinical studies and discuss its potential to treat ocular malignancies, such as uveal melanoma and conjunctival melanoma. We furthermore discuss the combination with immunotherapy and its application on pigmented and non-pigmented tumors as well as its effect on macrophage polarization, which is important to achieve effective results in immunotherapy.

Conclusions

Belzupacap sarotalocan (Bel-sar) is a promising targeted drug carrier that enhances tumor-specific delivery and minimizes off-target effects. Its photodynamic therapy effectively treats pigmented and non-pigmented tumors while inducing immunogenic cell death through DAMP exposure, triggering local and systemic immune responses. Combining Bel-sar PDT with immunotherapy improves efficacy in preclinical models, warranting further clinical investigation.

NIR-activated multifunctional agents for the combined application in cancer imaging and therapy

Anticancer therapies that combine both diagnostic and therapeutic capabilities hold significant promise for enhancing treatment efficacy and patient outcomes. Among these, agents responsive to near-infrared (NIR) photons are of particular interest due to their negligible toxicity and multifunctionality. These compounds are not only effective in photodynamic therapy (PDT), but also serve as contrast agents in various imaging modalities, including fluorescence and photoacoustic imaging. In this review, we explore the photophysical and photochemical properties of NIR-activated porphyrin, cyanine, and phthalocyanines derivatives as well as aggregation-induced emission compounds, highlighting their application in synergistic detection, diagnosis, and therapy. Special attention is given to the design and optimization of these agents to achieve high photostability, efficient NIR absorption, and significant yields of fluorescence, heat, or reactive oxygen species (ROS) generation depending on the application. Additionally, we discuss the incorporation of these compounds into nanocarriers to enhance their solubility, stability, and target specificity. Such nanoparticle-based systems exhibit improved pharmacokinetics and pharmacodynamics, facilitating more effective tumor targeting and broadening the application range to photoacoustic imaging and photothermal therapy. Furthermore, we summarize the application of these NIR-responsive agents in multimodal imaging techniques, which combine the advantages of fluorescence and photoacoustic imaging to provide comprehensive diagnostic information. Finally, we address the current challenges and limitations of photodiagnosis and phototherapy and highlight some critical barriers to their clinical implementation. These include issues related to their phototoxicity, limited tissue penetration, and potential off-target effects. The review concludes by highlighting future research directions aimed at overcoming these obstacles, with a focus on the development of next-generation agents and platforms that offer enhanced therapeutic efficacy and imaging capabilities in the field of cancer treatment.

Local tumour control and patient survival after ruthenium-106 brachytherapy for small choroidal melanoma

AIM

To report local tumour control, metastasis and survival rates of patients with small choroidal melanoma (CM) after treatment with ruthenium-106 (Ru-106) plaque brachytherapy.

METHODS

Retrospective case series of 353 consecutive eyes with small CM (thickness ≤2.5 mm and largest basal diameter ≤16 mm) treated with Ru-106 brachytherapy at the London Ocular Oncology Service, between October 2004 and May 2019.

RESULTS

The final cohort included 310 eyes and tumour recurrence was observed in 52 (17%) eyes. Ocular retention rate was 96%. Metastatic disease and tumour-related death occurred in 18 (5.8%) and 12 (3.9%) patients, respectively. Metastases were diagnosed after a median of 54 (54±35; range 3.6-118) months from initial treatment. Kaplan-Meier estimates for tumour recurrence, melanoma-related metastases and survival were 17% (95% CI 13.3% to 22.9%), 4.8% (95% CI 2.6% to 8.5%) and 98% (95% CI 94.4% to 99.1%) at 5 years and 26% (95% CI 18.3% to 35.3%), 16% (95% CI 8.7% to 27.7%) and 92% (95% CI 84.5% to 95.7%) at 10 years, respectively. On multivariable analysis, factors predictive for tumour recurrence included juxtapapillary location, larger plaque and final tumour thickness, and for metastasis exudative retinal detachment.

CONCLUSION

Small CMs treated with Ru-106 brachytherapy show recurrence and death rates of 17% and 2% at 5 years and 26% and 8% at 10 years. As small CMs have better prognosis than large tumours, early treatment is the key for better survival outcomes.

Treatment of Conjunctival Melanoma Cell Lines With a Light-Activated Virus-Like Drug Conjugate Induces Immunogenic Cell Death

Purpose

Conjunctival melanoma (CJM) is a rare malignant ocular surface tumor, which often leads to local recurrences and metastases. In murine models of subcutaneous tumors, treatment with a novel virus-like drug conjugate (VDC; Bel-sar) showed a dual mechanism of action with direct tumor cell killing as well as stimulation of an antitumoral immune response. Bel-sar is currently being evaluated for the treatment of primary uveal melanoma and indeterminate nevi in a phase III clinical trial. We determined whether Bel-sar also has direct antitumor efficiency and a potential immunostimulatory capacity in CJM cells.

Methods

Three human tumor-derived CJM lines were used. Bel-sar's subcellular and intracellular locations were determined with tracers. Following light activation of Bel-sar, cytotoxicity and exposure of damage-associated molecular patterns (DAMPs) were assessed. Treated tumor cells were co-cultured with THP-1 derived macrophages to assess tumor-cell phagocytosis.

Results

Bel-sar was bound and internalized by CJM cells and subsequently found in the cell membrane, lysosome, Golgi apparatus, and mitochondria. Bel-sar activation induced near complete cell death with half-maximal inhibitory concentration (IC50) values between 30 pM and 60 pM. Finally, light-activated Bel-sar enhanced exposure of DAMPs, including calreticulin, heat shock protein 90, and stimulated phagocytosis by macrophages.

Conclusions

Treatment with a novel VDC (Bel-sar) induced pro-immunogenic cell death in all three CJM cell lines. The in vitro cytotoxicity was accompanied by exposure of DAMPs, suggesting Bel-sar is a potential treatment for CJM by a dual mechanism of action. This dual mechanism may provide a targeted and direct killing of tumor cells and induce an immune response which might decrease local recurrences and metastasis.

Natural-source payloads used in the conjugated drugs architecture for cancer therapy: Recent advances and future directions

Drug conjugates are obtained from tumor-located vectors connected to cytotoxic agents via linkers, which are designed to deliver hyper-toxic payloads directly to targeted cancer cells. These drug conjugates include antibody-drug conjugates (ADCs), peptide-drug conjugates (PDCs), small molecule-drug conjugates (SMDCs), nucleic acid aptamer-drug conjugates (ApDCs), and virus-like drug conjugate (VDCs), which show great therapeutic value in the clinic. Drug conjugates consist of a targeting carrier, a linker, and a payload. Payloads are key therapy components. Cytotoxic molecules and their derivatives derived from natural products are commonly used in the payload portion of conjugates. The ideal payload should have sufficient toxicity, stability, coupling sites, and the ability to be released under specific conditions to kill tumor cells. Microtubule protein inhibitors, DNA damage agents, and RNA inhibitors are common cytotoxic molecules. Among these conjugates, cytotoxic molecules of natural origin are summarized based on their mechanism of action, conformational relationships, and the discovery of new derivatives. This paper also mentions some cytotoxic molecules that have the potential to be payloads. It also summarizes the latest technologies and novel conjugates developed in recent years to overcome the shortcomings of ADCs, PDCs, SMDCs, ApDCs, and VDCs. In addition, this paper summarizes the clinical trials conducted on conjugates of these cytotoxic molecules over the last five years. It provides a reference for designing and developing safer and more efficient conjugates.

LAG-3 : recent developments in combinational therapies in cancer

The study of anticancer immune responses and in particular the action of immune checkpoint inhibitors that overcome T cell inhibition has revolutionized metastatic patients' care. Unfortunately, many patients are resistant to these innovative immunotherapies. Over the last decade, several immune checkpoint inhibitors, currently available in the clinic, have been developed, such as anti-PD-1/PD-L1 or anti-CTLA-4. More recently, other immune checkpoints have been characterized, among them lymphocyte activation gene 3 (LAG-3). LAG-3 has been the subject of numerous therapeutic studies and may be involved in cancer-associated immune resistance phenomena. This review summarizes the latest knowledge on LAG-3 as an immunotherapeutic target, particularly in combination with standard or innovative therapies. Indeed, many studies are looking at combining LAG-3 inhibitors with chemotherapeutic, immunotherapeutic, radiotherapeutic treatments, or adoptive cell therapies to potentiate their antitumor effects and/or to overcome patients' resistance. We will particularly focus on the association therapies that are currently in phase III clinical trials and innovative combinations in preclinical phase. These new discoveries highlight the possibility of developing other types of therapeutic combinations currently unavailable in the clinic, which could broaden the therapeutic spectrum of personalized medicine.

Recent Advances in Molecular and Genetic Research on Uveal Melanoma

Uveal melanoma (UM), a distinct subtype of melanoma, presents unique challenges in its clinical management due to its complex molecular landscape and tendency for liver metastasis. This review highlights recent advancements in understanding the molecular pathogenesis, genetic alterations, and immune microenvironment of UM, with a focus on pivotal genes, such as GNAQ/11, BAP1, and CYSLTR2, and delves into the distinctive genetic and chromosomal classifications of UM, emphasizing the role of mutations and chromosomal rearrangements in disease progression and metastatic risk. Novel diagnostic biomarkers, including circulating tumor cells, DNA and extracellular vesicles, are discussed, offering potential non-invasive approaches for early detection and monitoring. It also explores emerging prognostic markers and their implications for patient stratification and personalized treatment strategies. Therapeutic approaches, including histone deacetylase inhibitors, MAPK pathway inhibitors, and emerging trends and concepts like CAR T-cell therapy, are evaluated for their efficacy in UM treatment. This review identifies challenges in UM research, such as the limited treatment options for metastatic UM and the need for improved prognostic tools, and suggests future directions, including the discovery of novel therapeutic targets, immunotherapeutic strategies, and advanced drug delivery systems. The review concludes by emphasizing the importance of continued research and innovation in addressing the unique challenges of UM to improve patient outcomes and develop more effective treatment strategies.

The Future of Checkpoint Inhibitors in Uveal Melanoma: A Narrative Review

INTRODUCTION

Immune checkpoint inhibitors have made tremendous progress over the last decade in the treatment of cutaneous melanoma, but their application in uveal melanoma treatment is less successful, owing in part to the immunological privilege of the eye and the liver, the most frequent site of metastasis. Nevertheless, the therapeutic outcomes reported currently are less pessimistic.

METHODS

In this review, we provide an overview of recent studies of immune checkpoint inhibitors in uveal melanoma and its metastasis and classify studies in this field into three groups: monotherapy of immune checkpoint inhibitors, dual-agent immune checkpoint inhibitors, and immune checkpoint inhibitors combined with other systemic or regional therapies.

RESULTS

Briefly, monotherapy with immune checkpoint inhibitors performed poorly. Dual-agent immune checkpoint inhibitors had slightly better outcomes than traditional treatments, especially in specific patient populations. As for the combination therapy, the combination with other systemic therapies did not show superiority over dual-agent immune checkpoint inhibitors, but combination with hepatic regional therapies was quite promising. Moreover, research on emerging checkpoints is currently limited to the stage of mechanistic studies.

CONCLUSION

We propose that immune checkpoint inhibitors remain alternative treatments for patients with uveal melanoma, but factors such as cost-effectiveness should also be taken into account. The combination therapy with immune checkpoint inhibitors deserves to be further explored.

Tissue biomarkers of immune checkpoint inhibitor therapy

Cancer immunotherapy has been rejuvenated by the growing understanding of the immune system's role in tumor activity over the past two decades. During cancer initiation and progression, tumor cells employ various mechanisms that resemble peripheral immune tolerance to evade the antitumor responses of the immune system. Immune checkpoint molecules are the major mechanism of immune resistance that are exploited by tumor cells to inhibit T-cell activation and suppress immune responses. The targeting of immune checkpoint pathways has led to substantial improvements in survival rates in a number of solid cancers. However, a lack of understanding of the heterogeneity of the tumor microenvironment (TME) has resulted in inefficient therapy responses. A greater understanding of the TME is needed to identify patients likely to respond, and those that will have resistance to immune checkpoint inhibitors (ICIs). Advancement in spatial single-cell technologies has allowed deeper insight into the phenotypic and functional diversities of cells in the TME. In this review, we provide an overview of ICI biomarkers and highlight how high-dimensional spatially resolved, single-cell approaches provide deep molecular insights into the TME and allow for the discovery of biomarkers of clinical benefit.

Tumor Pigmentation Does Not Affect Light-Activated Belzupacap Sarotalocan Treatment but Influences Macrophage Polarization in a Murine Melanoma Model

Purpose

Pigmentation in uveal melanoma is associated with increased malignancy and is known as a barrier for photodynamic therapy. We investigated the role of pigmentation in tumor behavior and the response to light-activated Belzupacap sarotalocan (Bel-sar) treatment in a pigmented (wild type) and nonpigmented (tyrosinase knock-out [TYR knock-out]) cell line in vitro and in a murine model.

Methods

The B16F10 (TYR knock-out) was developed using CRISPR/Cas9. After the treatment with light-activated Bel-sar, cytotoxicity and exposure of damage-associated molecular patterns (DAMPs) were measured by flow cytometry. Treated tumor cells were co-cultured with bone marrow-derived macrophages (BMDMs) and dendritic cells (DCs) to assess phagocytosis and activation. Both cell lines were injected subcutaneously in syngeneic C57BL/6 mice.

Results

Knock-out of the tyrosinase gene in B16F10 led to loss of pigmentation and immature melanosomes. Pigmented tumors contained more M1 and fewer M2 macrophages compared with amelanotic tumors. Bel-sar treatment induced near complete cell death, accompanied with enhanced exposure of DAMPs in both cell lines, resulting in enhanced phagocytosis of BMDMs and maturation of DCs. Bel-sar treatment induced a shift to M1 macrophages and delayed tumor growth in both in vivo tumor models. Following treatment, especially the pigmented tumors and their draining lymph nodes contained IFN-gamma positive CD8+T cells.

Conclusions

Pigmentation influenced the type of infiltrating macrophages in the tumor, with more M1 macrophages in pigmented tumors. Belzupacap sarotalocan treatment induced immunogenic cell death and tumor growth delay in pigmented as well as in nonpigmented models and stimulated M1 macrophage influx in both models.