B7-H3 as a Target for CAR-T Cell Therapy in Skull Base Chordoma

Single-cell sequencing reveals VEGFR as a potential target for CAR-T cell therapy in chordoma

BACKGROUND

Chordomas are rare osseous neoplasms with a dismal prognosis when they recur. Here we identified cell surface proteins that could potentially serve as novel immunotherapeutic targets in patients with chordoma.

METHODS

Fourteen chordoma samples from patients attending Xuanwu Hospital Capital Medical University were subjected to single-cell RNA sequencing. Target molecules were identified on chordoma cells and cancer metastasis-related signalling pathways characterised. VEGFR-targeting CAR-T cells and VEGFR CAR-T cells with an additional TGF-β scFv were synthesised and their in vitro antitumor activities were evaluated, including in a primary chordoma organoid model.

RESULTS

Single-cell transcriptome sequencing identified the chordoma-specific antigen VEGFR and TGF-β as therapeutic targets. VRGFR CAR-T cells and VEGFR/TGF-β scFv CAR-T cells recognised antigen-positive cells and exhibited significant antitumor effects through CAR-T cell activation and cytokine secretion. Furthermore, VEGFR/TGF-β scFv CAR-T cells showed enhanced and sustained cytotoxicity of chordoma cell lines in vitro compared with VRGFR CAR-T cells.

CONCLUSIONS

This study provides a comprehensive single-cell landscape of human chordoma and highlights its heterogeneity and the role played by TGF-β in chordoma progression. Our findings substantiate the potential of VEGFR as a target for CAR-T cell therapies in chordoma which, together with modulated TGF-β signalling, may augment the efficacy of CAR-T cells.

Chordoma Genetic Aberrations and Targeted Therapies Panorama: A Systematic Literature Review

Background: Chordomas pose a challenge in treatment due to their local invasiveness, high recurrence, and potential lethality. Despite being slow-growing and rarely metastasizing, these tumors often resist conventional chemotherapies (CTs) and radiotherapies (RTs), making surgical resection a crucial intervention. However, achieving radical resection for chordomas is seldom possible, presenting therapeutic challenges. The accurate diagnosis of these tumors is vital for their distinct prognoses, yet differentiation is hindered by overlapping radiological and histopathological features. Fortunately, recent molecular and genetic studies, including extracranial location analysis, offer valuable insights for precise diagnosis. This literature review delves into the genetic aberrations and molecular biology of chordomas, aiming to provide an overview of more successful therapeutic strategies. Methods: A systematic search was conducted across major medical databases (PubMed, Embase, and Cochrane Library) up to 28 January 2023. The search strategy utilized relevant Medical Subject Heading (MeSH) terms and keywords related to "chordomas", "molecular biology", "gene aberrations", and "target therapies". The studies included in this review consist of preclinical cell studies, case reports, case series, randomized controlled trials, non-randomized controlled trials, and cohort studies reporting on genetic and biological aberrations in chordomas. Results: Of the initial 297 articles identified, 40 articles were included in the article. Two tables highlighted clinical studies and ongoing clinical trials, encompassing 18 and 22 studies, respectively. The clinical studies involved 185 patients diagnosed with chordomas. The tumor sites were predominantly sacral (n = 8, 44.4%), followed by clivus (n = 7, 38.9%) and lumbar spine (n = 3, 16.7%). Primary treatments preceding targeted therapies included surgery (n = 10, 55.6%), RT (n = 9, 50.0%), and systemic treatments (n = 7, 38.9%). Various agents targeting specific molecular pathways were analyzed in the studies, such as imatinib (a tyrosine kinase inhibitor), erlotinib, and bevacizumab, which target EGFR/VEGFR. Common adverse events included fatigue (47.1%), skin reactions (32.4%), hypertension (23.5%), diarrhea (17.6%), and thyroid abnormalities (5.9%). Clinical outcomes were systematically assessed based on progression-free survival (PFS), overall survival (OS), and tumor response evaluated using RECIST or CHOI criteria. Notably, stable disease (SD) occurred in 58.1% of cases, and partial responses (PRs) were observed in 28.2% of patients, while 13.7% experienced disease progression (PD) despite targeted therapy. Among the 22 clinical trials included in the analysis, Phase II trials were the most prevalent (40.9%), followed by I-II trials (31.8%) and Phase I trials (27.3%). PD-1 inhibitors were the most frequently utilized, appearing in 50% of the trials, followed by PD-L1 inhibitors (36.4%), CTLA-4 inhibitors (22.7%), and mTOR inhibitors (13.6%). Conclusions: This systematic review provides an extensive overview of the state of targeted therapy for chordomas, highlighting their potential to stabilize the illness and enhance clinical outcomes.

Integrated Molecular and Histological Insights for Targeted Therapies in Mesenchymal Sinonasal Tract Tumors

PURPOSE OF REVIEW

This review aims to provide a comprehensive overview of mesenchymal sinonasal tract tumors (STTs), a distinct subset of STTs. Despite their rarity, mesenchymal STTs represent a unique clinical challenge, characterized by their rarity, often slow progression, and frequently subtle or overlooked symptoms. The complex anatomy of the sinonasal area, which includes critical structures such as the orbit, brain, and cranial nerves, further complicates surgical treatment options. This underscores an urgent need for more advanced and specialized therapeutic approaches.

RECENT FINDINGS

Advancements in molecular diagnostics, particularly in next-generation sequencing, have significantly enhanced our understanding of STTs. Consequently, the World Health Organization has updated its tumor classification to better reflect the distinct histological and molecular profiles of these tumors, as well as to categorize mesenchymal STTs with greater accuracy. The growing understanding of the molecular characteristics of mesenchymal STTs opens new possibilities for targeted therapeutic interventions, marking a significant shift in treatment paradigms. This review article concentrates on mesenchymal STTs, specifically addressing sinonasal tract angiofibroma, sinonasal glomangiopericytoma, biphenotypic sinonasal sarcoma, and skull base chordoma. These entities are marked by unique histopathological and molecular features, which challenge conventional treatment approaches and simultaneously open avenues for novel targeted therapies. Our discussion is geared towards delineating the molecular underpinnings of mesenchymal STTs, with the objective of enhancing therapeutic strategies and addressing the existing shortcomings in the management of these intricate tumors.

HER2-low expression in patients with advanced or metastatic solid tumors

BACKGROUND

Human epidermal growth factor receptor 2 (HER2)-low is a newly defined category with HER2 1+ or 2+ expression by immunohistochemistry (IHC) and lack of HER2 gene amplification measured by in situ hybridization (ISH). Much remains unknown about the HER2-low status across tumor types and changes in HER2 status between primary and metastatic samples.

PATIENTS AND METHODS

HER2 expression by IHC was evaluated in 4701 patients with solid tumors. We have evaluated the HER2 expression by IHC and amplification by ISH in paired breast and gastric/gastroesophageal (GEJ) primary and metastatic samples. HER2 expression was correlated with ERBB2 genomic alterations evaluated by next-generation sequencing (NGS) in non-breast, non-gastric/GEJ samples.

RESULTS

HER2 expression (HER2 IHC 1-3+) was found in half (49.8%) of the cancers, with HER2-low (1 or 2+) found in many tumor types: 47.1% in breast, 34.6% in gastric/GEJ, 50.0% in salivary gland, 46.9% in lung, 46.5% in endometrial, 46% in urothelial, and 45.5% of gallbladder cancers. The concordance evaluation of HER2 expression between primary and metastatic breast cancer samples showed that HER2 3+ remained unchanged in 87.1% with a strong agreement between primary and metastatic samples, with a weighted kappa (Κ) of 0.85 (95% confidence interval 0.79-0.91). ERBB2 alterations were identified in 117 (7.5%) patients with non-breast, non-gastric/GEJ solid tumors who had NGS testing. Of 1436 patients without ERBB2 alterations, 512 (35.7%) showed any level HER2 expression by IHC.

CONCLUSION

Our results show that HER2-low expression is frequently found across tumor types. These findings suggest that many patients with HER2-low solid tumors might benefit from HER2-targeted therapies.

The role of tumor immune microenvironment in chordoma: promising immunotherapy strategies

Chordoma is a rare malignant bone tumor with limited therapeutic options, which is resistant to conventional chemotherapy and radiotherapy, and targeted therapy is also shown with little efficacy. The long-standing delay in researching its mechanisms of occurrence and development has resulted in the dilemma of no effective treatment targets and no available drugs in clinical practice. In recent years, the role of the tumor immune microenvironment in driving tumor growth has become a hot and challenging topic in the field of cancer research. Immunotherapy has shown promising results in the treatment of various tumors. However, the study of the immune microenvironment of chordoma is still in its infancy. In this review, we aim to present a comprehensive reveal of previous exploration on the chordoma immune microenvironment and propose promising immunotherapy strategies for chordoma based on these characteristics.

Shedding light on emerging therapeutic targets for chordoma

INTRODUCTION

Despite encouraging advances in radiation and surgical treatment, chordomas remain resistant to chemotherapy and local recurrence is common. Although the primary mechanism of recurrence is local, metastatic disease occurs in a small subset of patients. Recurrence may also occur along the surgical trajectory if care is not taken to fully excise the open biopsy pathway. There is increasing morbidity with reoperation upon disease recurrence, and radiation is an option for cytoreduction in primary disease or for recurrent disease, although toxicity may be observed with high-dose therapies. Given these challenges, targeted chemotherapeutic agents for postoperative adjuvant treatment are needed.

AREAS COVERED

In this review, we summarize the genetic drivers of chordoma and the state of the current research in chordoma immunotherapy and epigenetics.

EXPERT OPINION

Chordoma is a heterogenous tumor that should be targeted from different angles and the study of its characteristics, from molecular to immunological to epigenetic, is necessary. Combining different approaches, such as studying noninvasive patient methylation patterns with tissue-based molecular and drug screening, can transform patient care by guiding treatment decisions based on prognostic mechanisms from different sources, while helping individualize surgical planning and treatment.

New frontiers in immune checkpoint B7-H3 (CD276) research and drug development

B7-H3 (CD276), a member of the B7 family of proteins, is a key player in cancer progression. This immune checkpoint molecule is selectively expressed in both tumor cells and immune cells within the tumor microenvironment. In addition to its immune checkpoint function, B7-H3 has been linked to tumor cell proliferation, metastasis, and therapeutic resistance. Furthermore, its drastic difference in protein expression levels between normal and tumor tissues suggests that targeting B7-H3 with drugs would lead to cancer-specific toxicity, minimizing harm to healthy cells. These properties make B7-H3 a promising target for cancer therapy.Recently, important advances in B7-H3 research and drug development have been reported, and these new findings, including its involvement in cellular metabolic reprograming, cancer stem cell enrichment, senescence and obesity, have expanded our knowledge and understanding of this molecule, which is important in guiding future strategies for targeting B7-H3. In this review, we briefly discuss the biology and function of B7-H3 in cancer development. We emphasize more on the latest findings and their underlying mechanisms to reflect the new advances in B7-H3 research. In addition, we discuss the new improvements of B-H3 inhibitors in cancer drug development.

Immunotherapy approaches for rare pediatric solid tumors: advances and future directions

PURPOSE OF REVIEW

Immunotherapy for pediatric tumors is rapidly evolving. From major successes in pediatric hematologic malignancies, immunotherapy utility increased in the pediatric solid tumor landscape. Numerous pediatric solid tumors are defined as rare with limitations in diagnosis and treatment. This review will describe four major immunotherapies used in pediatrics and discuss results seen in rare pediatric tumors. We will also briefly review the challenges of immunotherapy in solid tumors and opportunities to drive this therapy forward.

RECENT FINDINGS

Despite rare success employing immunotherapy for pediatric solid tumors, recently there have been several successes in pediatric rare solid tumors. After describing the evolving landscape of rare pediatric tumors, we will demonstrate the successes or disappointments of immunotherapy. We will describe the mechanism of four immunotherapies used in the pediatrics, followed by the published results. Finally, we will discuss the challenges and opportunities for immunotherapies in pediatric rare tumors.

SUMMARY

Pediatric rare tumors are lacking in treatment options. Despite numerous disappointments utilizing immunotherapies in the more common pediatric solid tumors, there have been several successes within the pediatric rare tumor landscape. Much work is still needed to enhance our understanding and knowledge on utilizing these immunotherapies for pediatric rare solid tumors.

Current advances and challenges in CAR T-Cell therapy for solid tumors: tumor-associated antigens and the tumor microenvironment

The past decade has witnessed ongoing progress in immune therapy to ameliorate human health. As an emerging technique, chimeric antigen receptor (CAR) T-cell therapy has the advantages of specific killing of cancer cells, a high remission rate of cancer-induced symptoms, rapid tumor eradication, and long-lasting tumor immunity, opening a new window for tumor treatment. However, challenges remain in CAR T-cell therapy for solid tumors due to target diversity, tumor heterogeneity, and the complex microenvironment. In this review, we have outlined the development of the CAR T-cell technique, summarized the current advances in tumor-associated antigens (TAAs), and highlighted the importance of tumor-specific antigens (TSAs) or neoantigens for solid tumors. We also addressed the challenge of the TAA binding domain in CARs to overcome off-tumor toxicity. Moreover, we illustrated the dominant tumor microenvironment (TME)-induced challenges and new strategies based on TME-associated antigens (TMAs) for solid tumor CAR T-cell therapy.

The Tumor Immune Microenvironment in Primary CNS Neoplasms: A Review of Current Knowledge and Therapeutic Approaches

Primary CNS neoplasms are responsible for considerable mortality and morbidity, and many therapies directed at primary brain tumors have proven unsuccessful despite their success in preclinical studies. Recently, the tumor immune microenvironment has emerged as a critical aspect of primary CNS neoplasms that may affect their malignancy, prognosis, and response to therapy across patients and tumor grades. This review covers the tumor microenvironment of various primary CNS neoplasms, with a focus on glioblastoma and meningioma. Additionally, current therapeutic strategies based on elements of the tumor microenvironment, including checkpoint inhibitor therapy and immunotherapeutic vaccines, are discussed.

Immunotherapy as a Promising Option for the Treatment of Advanced Chordoma: A Systemic Review

OBJECTIVE

To summarize the function and efficacy of immunotherapy as an adjunctive therapy in the treatment of advanced chordoma.

METHODS

Literature search was conducted by two reviewers independently. Case reports, case series and clinical trials of immunotherapy for chordoma were retrieved systematically from Pubmed, Web of Science, Scoupus and Cochrane Library. Clinical outcome data extracted from the literature included median progression-free survival (PFS), median overall survival (OS), clinical responses and adverse events (AEs).

RESULTS

All studies were published between 2015 and 2022. Twenty-two eligible studies were selected for systemic review. PD-1/PD-L1 immune checkpoint inhibitors (ICIs) were the most common used immunotherapy agents in chordoma, among which Pembrolizumab was the most frequently prescribed. CTLA-4 antibody was only used as combination therapy in chordoma. Dose Limiting Toxicity (DLT) was not observed in any vaccine targeting brachyury, and injection site response was the most frequent AV. The response evaluation criteria in solid tumors (RECIST) were the most generally used evaluation standard in chordoma immunotherapy, and none of the included studies employed the Choi criteria.

CONCLUSIONS

No clinical data have demonstrated that CTLA-4 ICIs combined with PD-1/PD-L1 ICIs is more effective than ICIs monotherapy in treating chordoma, and ICIs in combination with other therapies exhibit more toxicity than monotherapy. PD-1/PD-L1 ICIs monotherapy is recommended as an immunotherapy in patients with advanced chordoma, which may even benefit PD-L1-negative patients. The brachyury vaccine has shown good safety in chordoma patients, and future clinical trials should focus on how to improve its therapeutic efficacy. The use of immunomodulatory agents is a promising therapeutic option, though additional clinical trials are required to evaluate their safety and effectiveness. RECIST does not seem to be an appropriate standard for assessing medications of intratumoral immunotherapy.

Identification of glioblastoma-specific antigens expressed in patient-derived tumor cells as candidate targets for chimeric antigen receptor T cell therapy

Background

New therapies for glioblastoma (GBM) are urgently needed because the disease prognosis is poor. Chimeric antigen receptor (CAR)-T cell therapy that targets GBM-specific cell surface antigens is a promising therapeutic strategy. However, extensive transcriptome analyses have uncovered few GBM-specific target antigens.

Methods

We established a library of monoclonal antibodies (mAbs) against a tumor cell line derived from a patient with GBM. We identified mAbs that reacted with tumor cell lines from patients with GBM but not with nonmalignant human brain cells. We then detected the antigens they recognized using expression cloning. CAR-T cells derived from a candidate mAb were generated and tested in vitro and in vivo.

Results

We detected 507 mAbs that bound to tumor cell lines from patients with GBM. Among them, E61 and A13 reacted with tumor cell lines from most patients with GBM, but not with nonmalignant human brain cells. We found that B7-H3 was the antigen recognized but E61. CAR-T cells were established using the antigen-recognition domain of E61-secreted cytokines and exerted cytotoxicity in co-culture with tumor cells from patients with GBM.

Conclusions

Cancer-specific targets for CAR-T cells were identified using a mAb library raised against primary GBM tumor cells from a patient. We identified a GBM-specific mAb and its antigen. More mAbs against various GBM samples and novel target antigens are expected to be identified using this strategy.

B7-H3 targeted CAR-T cells show highly efficient anti-tumor function against osteosarcoma both in vitro and in vivo

BACKGROUND

Osteosarcoma (OS) mainly happens in children and youths. Surgery, radiotherapy and chemotherapy are the common therapies for osteosarcoma treatment but all their anti-tumor effects are limited. In recent years, a new cellular therapy, CAR-T, a cellular immunotherapy with genetically engineered T cells bearing chimeric antigen receptor targeting specific tumor-associated antigen, has been proved to be an effective therapy against acute lymphoblastic leukemia. Thus, CAR-T is a potentially effective therapy for osteosarcoma treatment.

METHODS

A CAR gene targeting B7-H3 antigen was constructed into lentiviral vector through molecular biology techniques. Then, the CAR gene was transferred to T cells through lentiviral delivery system, and the CAR-T cells were largely expanded using in vitro culture technology. The in vitro anti-tumor effect of CAR-T cells was evaluated through Real Time Cell Analysis system (RTCA) and ELISA assay. The in vivo anti-tumor capabilities of CAR-T cells were evaluated using the patient-derived xenografts (PDX) model of osteosarcoma.

RESULTS

The third-generation CAR-T cells we constructed could target the B7-H3 antigen, and the phenotype of CAR-T cells was consistent with normal T cells; The CAR-T cells showed superior antitumor effects both in vitro and in vivo.

CONCLUSION

Our study showed that B7-H3 targeted CAR-T cells had high anti-tumor efficacy against osteosarcoma both in vitro and in vivo, which proved that B7-H3 targeted CAR-T therapy is potentially effective for osteosarcoma treatment.

Emerging target discovery and drug repurposing opportunities in chordoma

The development of effective and personalized treatment options for patients with rare cancers like chordoma is hampered by numerous challenges. Biomarker-guided repurposing of therapies approved in other indications remains the fastest path to redefining the treatment paradigm, but chordoma's low mutation burden limits the impact of genomics in target discovery and precision oncology efforts. As our knowledge of oncogenic mechanisms across various malignancies has matured, it's become increasingly clear that numerous properties of tumors transcend their genomes - leading to new and uncharted frontiers of therapeutic opportunity. In this review, we discuss how the implementation of cutting-edge tools and approaches is opening new windows into chordoma's vulnerabilities. We also note how a convergence of emerging observations in chordoma and other cancers is leading to the identification and evaluation of new therapeutic hypotheses for this rare cancer.

Immune checkpoint of B7-H3 in cancer: from immunology to clinical immunotherapy

Immunotherapy for cancer is a rapidly developing treatment that modifies the immune system and enhances the antitumor immune response. B7-H3 (CD276), a member of the B7 family that plays an immunoregulatory role in the T cell response, has been highlighted as a novel potential target for cancer immunotherapy. B7-H3 has been shown to play an inhibitory role in T cell activation and proliferation, participate in tumor immune evasion and influence both the immune response and tumor behavior through different signaling pathways. B7-H3 expression has been found to be aberrantly upregulated in many different cancer types, and an association between B7-H3 expression and poor prognosis has been established. Immunotherapy targeting B7-H3 through different approaches has been developing rapidly, and many ongoing clinical trials are exploring the safety and efficacy profiles of these therapies in cancer. In this review, we summarize the emerging research on the function and underlying pathways of B7-H3, the expression and roles of B7-H3 in different cancer types, and the advances in B7-H3-targeted therapy. Considering different tumor microenvironment characteristics and results from preclinical models to clinical practice, the research indicates that B7-H3 is a promising target for future immunotherapy, which might eventually contribute to an improvement in cancer immunotherapy that will benefit patients.

B7-H3-targeted CAR-T cell therapy for solid tumors

Since B7-H3 is overexpressed or amplified in many types of solid tumors with a restricted expression in the normal tissues, it has been an emerging immunotherapeutic target for solid tumors. This review will focus on the structural designs of developing chimeric antigen receptors (CARs) targeting B7-H3. The expression, receptor, and function of the B7-H3, as well as a short overview of B7-H3-targeted monoclonal antibody therapy, are discussed. Finally, a detailed summary of B7-H3 redirected CAR-T and CAR-NK cell approaches utilized in preclinical models and currently ongoing or completed clinical trials are presented. It has been demonstrated that B7-H3-targeted CAR-based cell therapies were safe in initial trials, but their efficacy was limited. Employing the local delivery routes, the introduction of novel modifications promoting CAR-T persistence, and combined treatment with other standard therapies could improve the efficacy of B7-H3-targeted CAR-T cell therapy against solid tumors.