Harnessing immunotherapy for brain metastases: insights into tumor-brain microenvironment interactions and emerging treatment modalities

Challenges and material innovations in drug delivery to central nervous system tumors

Central nervous system (CNS) tumors, encompassing a diverse array of neoplasms in the brain and spinal cord, pose significant therapeutic challenges due to their intricate anatomy and the protective presence of the blood-brain barrier (BBB). The primary treatment obstacle is the effective delivery of therapeutics to the tumor site, which is hindered by multiple physiological, biological, and technical barriers, including the BBB. This comprehensive review highlights recent advancements in material science and nanotechnology aimed at surmounting these delivery challenges, with a focus on the development and application of nanomaterials. Nanomaterials emerge as potent tools in designing innovative drug delivery systems that demonstrate the potential to overcome the limitations posed by CNS tumors. The review delves into various strategies, including the use of lipid nanoparticles, polymeric nanoparticles, and inorganic nanoparticles, all of which are engineered to enhance drug stability, BBB penetration, and targeted tumor delivery. Additionally, this review highlights the burgeoning role of theranostic nanoparticles, integrating therapeutic and diagnostic functionalities to optimize treatment efficacy. The exploration extends to biocompatible materials like biodegradable polymers, liposomes, and advanced material-integrated delivery systems such as implantable drug-eluting devices and microfabricated devices. Despite promising preclinical results, the translation of these material-based strategies into clinical practice necessitates further research and optimization.

Cutting-edge technologies illuminate the neural landscape of cancer: Insights into tumor development

Neurogenesis constitutes a pivotal facet of malignant tumors, wherein cancer and its therapeutic interventions possess the ability to reconfigure the nervous system, establishing a pathologic feedback loop that exacerbates tumor progression. Recent strides in high-resolution imaging, single-cell analysis, multi-omics technologies, and experimental models have opened unprecedented avenues in cancer neuroscience. This comprehensive review summarizes the latest advancements of these emerging technologies in elucidating the biological mechanisms underlying tumor initiation, invasion, metastasis, and the dynamic heterogeneity of the tumor microenvironment(TME), with a specific focus on neuron-glial-tumor interactions in glioblastoma(GBM) and other neurophilic cancers. Moreover, we innovatively propose target screening processes based on sequencing technologies and database frameworks. It rigorously evaluates ongoing clinical trial drugs and efficacy while spotlighting characteristic cells in the central and peripheral TME, consolidating cancer biomarkers pivotal for future targeted therapies and management strategies. By integrating these cutting-edge findings, this review aims to offer fresh insights into tumor-nervous system interactions, establishing a robust foundation for forthcoming clinical advancements.

Microwave ablation for small papillary thyroid carcinomas: clinical outcomes and thyroid function preservation

Purpose

This study explores the impact of microwave ablation (MWA) on thyroid function in patients with small papillary thyroid carcinomas (SPTCs) using a specific energy/volume model to optimize treatment and evaluate clinical efficacy.

Methods

A cohort of 70 patients with confirmed SPTCs underwent MWA tailored to individual nodule characteristics. Pre- and post-ablation assessments included ultrasound imaging for nodule size and thyroid function tests (thyroid-stimulating hormone, free thyroxine and free triiodothyronine levels) were conducted at baseline, 1, 3, 6 and 12 months post-treatment. The main results are the complete ablation rate of nodules and the stability of thyroid function after treatment. Secondary outcomes include the incidence of complications and other clinical parameters.

Results

The complete ablation rate was achieved in 95% of the nodules, with most patients (90%) requiring a single ablation session. Nodule size reduced significantly from an average of 174.0 ± 259.1 to 3.2 ± 11.3 mm3, with a mean volume reduction rate of 98.47 (5.82%) at the 18-month follow-up. Stable thyroid function and minimal fluctuations in hormone levels were observed in 90% of patients, demonstrating the effectiveness of MWA in preserving thyroid function. Notably, lower energy/volume ratios were linked to a reduced risk of complications and preservation of thyroid function. Only 5% of patients reported minor complications, with no major adverse events.

Conclusions

The study's results validate the clinical utility of MWA in energy/volume setting as an effective, minimally invasive treatment for SPTCs.

Immune response recalibration using immune therapy and biomimetic nano-therapy against high-grade gliomas and brain metastases

Although with aggressive standards of care like surgical resection, chemotherapy, and radiation, high-grade gliomas (HGGs) and brain metastases (BM) treatment has remained challenging for more than two decades. However, technological advances in this field and immunotherapeutic strategies have revolutionized the treatment of HGGs and BM. Immunotherapies like immune checkpoint inhibitors, CAR-T targeting, oncolytic virus-based therapy, bispecific antibody treatment, and vaccination approaches, etc., are emerging as promising avenues offering new hope in refining patient's survival benefits. However, selective trafficking across the blood-brain barrier (BBB), immunosuppressive tumor microenvironment (TME), metabolic alteration, and tumor heterogeneity limit the therapeutic efficacy of immunotherapy for HGGs and BM. Furthermore, to address this concern, the NanoBioTechnology-based bioinspired delivery system has been gaining tremendous attention in recent years. With technological advances such as Trojan horse targeting and infusing/camouflaging nanoparticles surface with biological molecules/cells like immunocytes, erythrocytes, platelets, glioma cell lysate and/or integrating these strategies to get hybrid membrane for homotypic recognition. These biomimetic nanotherapy offers advantages over conventional nanoparticles, focusing on greater target specificity, increased circulation stability, higher active loading capacity, BBB permeability (inherent inflammatory chemotaxis of neutrophils), decreased immunogenicity, efficient metabolism-based combinatorial effects, and prevention of tumor recurrence by induction of immunological memory, etc. provide new age of improved immunotherapies outcomes against HGGs and BM. In this review, we emphasize on neuro-immunotherapy and the versatility of these biomimetic nano-delivery strategies for precise targeting of hard-to-treat and most lethal HGGs and BM. Moreover, the challenges impeding the clinical translatability of these approaches were addressed to unmet medical needs of brain cancers.

Density and entropy of immune cells within the tumor microenvironment of primary tumors and matched brain metastases

BACKGROUND

Tumor-infiltrating lymphocytes (TILs) and tumor-associated macrophages (TAMs) have increasingly been reported to impact the brain metastatic process of solid tumors. However, data on intra-individual differences between primary tumor and brain metastasis (BM), as well as their correlation with clinical outcome parameters, is scarce.

METHODS

We retrospectively identified patients who received resection of the primary tumor and BM between 01/1990 and 10/2022. Density quantification of TAMs (CD68+, CD163+) and TILs (CD3+, CD8+, CD45RO+, FOXP3+) was performed by immunohistochemical staining of matched tumor tissue samples. Images were processed with QuPath software and heterogeneity of generated heatmaps was measured by Shannon Entropy. Time-to-BM (TTBM) was defined as the time from diagnosis of the primary tumor until the first diagnosis of BM.

RESULTS

In total, 104 patients (46.2% female; median age 57.3 years at BM diagnosis) were included: 78/104 (75%) non-small cell lung cancer, 18/104 (17%) breast cancer, 8/104 (8%) renal cell carcinomas. Densities of CD3+ (p < 0.001) and CD8+-TILs (p < 0.001) were higher in primary tumor samples, while CD68+ (p = 0.035) and CD163+-TAM densities (p < 0.001) were higher in the matched BM. Higher CD3+, CD8+-TILs and CD163+-TAMs densities in primary tumors were associated with shorter TTBM (p = 0.005, p = 0.015 and p = 0.006, respectively). Higher entropies of CD3+ (p < 0.001) and FOXP3+ (p = 0.011) TILs were observed in primary tumors compared to BM. Longer TTBM was associated with higher entropy of FOXP3+ TILs (p = 0.024) and lower entropy in CD163+ TAMs (p = 0.039). No significant associations of immune cell densities or entropies with OS after BM diagnosis were found.

DISCUSSION

By utilizing a unique cohort of matched primary tumor and BM tissue samples, we could demonstrate higher TIL densities in primary tumors and higher TAM densities in BM, respectively. Higher cell densities of CD3+, CD8+-TILs and CD163+-TAMs in primary tumors were associated with shorter TTBM, while a larger difference between CD3+ and CD8+ densities between primary tumor and BM was associated with longer TTBM. These findings highlight the potential of targeting TAMs as a therapeutic strategy to mitigate the development of brain metastases.

Metastatic brain tumors: from development to cutting-edge treatment

Metastatic brain tumors, also called brain metastasis (BM), represent a challenging complication of advanced tumors. Tumors that commonly metastasize to the brain include lung cancer and breast cancer. In recent years, the prognosis for BM patients has improved, and significant advancements have been made in both clinical and preclinical research. This review focuses on BM originating from lung cancer and breast cancer. We briefly overview the history and epidemiology of BM, as well as the current diagnostic and treatment paradigms. Additionally, we summarize multiomics evidence on the mechanisms of tumor occurrence and development in the era of artificial intelligence and discuss the role of the tumor microenvironment. Preclinically, we introduce the establishment of BM models, detailed molecular mechanisms, and cutting-edge treatment methods. BM is primarily treated with a comprehensive approach, including local treatments such as surgery and radiotherapy. For lung cancer, targeted therapy and immunotherapy have shown efficacy, while in breast cancer, monoclonal antibodies, tyrosine kinase inhibitors, and antibody-drug conjugates are effective in BM. Multiomics approaches assist in clinical diagnosis and treatment, revealing the complex mechanisms of BM. Moreover, preclinical agents often need to cross the blood-brain barrier to achieve high intracranial concentrations, including small-molecule inhibitors, nanoparticles, and peptide drugs. Addressing BM is imperative.

PD-1 blockade does not improve efficacy of EpCAM-directed CAR T-cell in lung cancer brain metastasis

BACKGROUND

Lung cancer brain metastasis has a devastating prognosis, necessitating innovative treatment strategies. While chimeric antigen receptor (CAR) T-cell show promise in hematologic malignancies, their efficacy in solid tumors, including brain metastasis, is limited by the immunosuppressive tumor environment. The PD-L1/PD-1 pathway inhibits CAR T-cell activity in the tumor microenvironment, presenting a potential target to enhance therapeutic efficacy. This study aims to evaluate the impact of anti-PD-1 antibodies on CAR T-cell in treating lung cancer brain metastasis.

METHODS

We utilized a murine immunocompetent, syngeneic orthotopic cerebral metastasis model for repetitive intracerebral two-photon laser scanning microscopy, enabling in vivo characterization of red fluorescent tumor cells and CAR T-cell at a single-cell level over time. Red fluorescent EpCAM-transduced Lewis lung carcinoma cells (EpCAM/tdtLL/2 cells) were implanted intracranially. Following the formation of brain metastasis, EpCAM-directed CAR T-cell were injected into adjacent brain tissue, and animals received either anti-PD-1 or an isotype control.

RESULTS

Compared to controls receiving T-cell lacking a CAR, mice receiving EpCAM-directed CAR T-cell showed higher intratumoral CAR T-cell densities in the beginning after intraparenchymal injection. This finding was accompanied with reduced tumor growth and translated into a survival benefit. Additional anti-PD-1 treatment, however, did not affect intratumoral CAR T-cell persistence nor tumor growth and thereby did not provide an additional therapeutic effect.

CONCLUSION

CAR T-cell therapy for brain malignancies appears promising. However, additional anti-PD-1 treatment did not enhance intratumoral CAR T-cell persistence or effector function, highlighting the need for novel strategies to improve CAR T-cell therapy in solid tumors.

Case report: Immunotherapy guided by molecular profiling of tumors: illustrative cases and literature review

Predictive biomarkers are necessary for the identification of immunotherapy-responsive patients. Tumor mutation burden (TMB), as determined by next-generation sequencing (NGS), and PD-L1 expression, as evaluated by Immunohistochemistry (IHC), are the biomarkers most frequently employed in clinical practice. In addition, microsatellite instability (MSI) was the first biomarker to demonstrate immunotherapy efficacy irrespective of the type of tumor and possesses a high predictive value. However, its limited use across most tumor types limits its therapeutic potential. This report describes two cancer patients with positive TMB and PD-L1 expression. The molecular profile of the tumor indicated that the first patient was responsive to Immune checkpoint inhibitors (ICI), while the second patient was resistant. These case studies demonstrate that tumor molecular analysis in combination with immunotherapy predictive biomarkers, such as PD-L1 expression and TMB, can enhance the prediction of response to ICI for specific patients. This methodology enables an individualized and improved approach to the treatment and management of the disease.

Environment-responsive dendrobium polysaccharide hydrogel embedding manganese microsphere as a post-operative adjuvant to boost cascaded immune cycle against melanoma

Rationale: Surgical resection is a primary treatment for solid tumors, but high rates of tumor recurrence and metastasis post-surgery present significant challenges. Manganese (Mn2+), known to enhance dendritic cell-mediated cancer immunotherapy by activating the cGAS-STING pathway, has potential in post-operative cancer management. However, achieving prolonged and localized delivery of Mn2+ to stimulate immune responses without systemic toxicity remains a challenge. Methods: We developed a post-operative microenvironment-responsive dendrobium polysaccharide hydrogel embedded with Mn2+-pectin microspheres (MnP@DOP-Gel). This hydrogel system releases Mn2+-pectin microspheres (MnP) in response to ROS, and MnP shows a dual effect in vitro: promoting immunogenic cell death and activating immune cells (dendritic cells and macrophages). The efficacy of MnP@DOP-Gel as a post-surgical treatment and its potential for immune activation were assessed in both subcutaneous and metastatic melanoma models in mice, exploring its synergistic effect with anti-PD1 antibody. Result: MnP@DOP-Gel exhibited ROS-responsive release of MnP, which could exert dual effects by inducing immunogenic cell death of tumor cells and activating dendritic cells and macrophages to initiate a cascade of anti-tumor immune responses. In vivo experiments showed that the implanted MnP@DOP-Gel significantly inhibited residual tumor growth and metastasis. Moreover, the combination of MnP@DOP-Gel and anti-PD1 antibody displayed superior therapeutic potency in preventing either metastasis or abscopal brain tumor growth. Conclusions: MnP@DOP-Gel represents a promising drug-free strategy for cancer post-operative management. Utilizing this Mn2+-embedding and ROS-responsive delivery system, it regulates surgery-induced immune responses and promotes sustained anti-tumor responses, potentially increasing the effectiveness of surgical cancer treatments.

Exploring the Molecular Tumor Microenvironment and Translational Biomarkers in Brain Metastases of Non-Small-Cell Lung Cancer

Brain metastases represent a significant clinical challenge in the treatment of non-small-cell lung cancer (NSCLC), often leading to a severe decline in patient prognosis and survival. Recent advances in imaging and systemic treatments have increased the detection rates of brain metastases, yet clinical outcomes remain dismal due to the complexity of the metastatic tumor microenvironment (TME) and the lack of specific biomarkers for early detection and targeted therapy. The intricate interplay between NSCLC tumor cells and the surrounding TME in brain metastases is pivotal, influencing tumor progression, immune evasion, and response to therapy. This underscores the necessity for a deeper understanding of the molecular underpinnings of brain metastases, tumor microenvironment, and the identification of actionable biomarkers that can inform multimodal treatment approaches. The goal of this review is to synthesize current insights into the TME and elucidate molecular mechanisms in NSCLC brain metastases. Furthermore, we will explore the promising horizon of emerging biomarkers, both tissue- and liquid-based, that hold the potential to radically transform the treatment strategies and the enhancement of patient outcomes.