Prospective immunotherapies in childhood sarcomas: PD1/PDL1 blockade in combination with tumor vaccines

Advances and challenges in gene therapy strategies for pediatric cancer: a comprehensive update

Pediatric cancers represent a tragic but also promising area for gene therapy. Although conventional treatments have improved survival rates, there is still a need for targeted and less toxic interventions. This article critically analyzes recent advances in gene therapy for pediatric malignancies and discusses the challenges that remain. We explore the innovative vectors and delivery systems that have emerged, such as adeno-associated viruses and non-viral platforms, which show promise in addressing the unique pathophysiology of pediatric tumors. Specifically, we examine the field of chimeric antigen receptor (CAR) T-cell therapies and their adaptation for solid tumors, which historically have been more challenging to treat than hematologic malignancies. We also discuss the genetic and epigenetic complexities inherent to pediatric cancers, such as tumor heterogeneity and the dynamic tumor microenvironment, which pose significant hurdles for gene therapy. Ethical considerations specific to pediatric populations, including consent and long-term follow-up, are also analyzed. Additionally, we scrutinize the translation of research from preclinical models that often fail to mimic pediatric cancer biology to the regulatory landscapes that can either support or hinder innovation. In summary, this article provides an up-to-date overview of gene therapy in pediatric oncology, highlighting both the rapid scientific progress and the substantial obstacles that need to be addressed. Through this lens, we propose a roadmap for future research that prioritizes the safety, efficacy, and complex ethical considerations involved in treating pediatric patients. Our ultimate goal is to move from incremental advancements to transformative therapies.

Liposome Nanomedicine Based on Tumor Cell Lysate Mitigates the Progression of Lynch Syndrome-Associated Colon Cancer

Treatment with immune checkpoint inhibitors (ICIs) has shown efficacy in some patients with Lynch syndrome-associated colon cancer, but some patients still do not benefit from it. In this study, we adopted a combination strategy of tumor vaccines and ICIs to maximize the benefits of immunotherapy. Here, we obtained tumor-antigen-containing cell lysate (TCL) by lysing MC38Mlh1 KD cells and prepared liposome nanoparticles (Lipo-PEG) with a typical spherical morphology by thin-film hydration. Anti-PD-L1 was coupled to the liposome surface by the amidation reaction. As observed, anti-PD-L1/TCL@Lipo-PEG was not significantly toxic to mouse intestinal epithelial cells (MODE-K) in the safe concentration range and did not cause hemolysis of mouse red blood cells. In addition, anti-PD-L1/TCL@Lipo-PEG reduced immune escape from colon cancer cells (MC38Mlh1 KD) by the anti-PD-L1 antibody, restored the killing function of CD8+ T cells, and targeted more tumor antigens to bone marrow-derived dendritic cells (BMDCs), which also expressed PD-L1, to stimulate BMDC antigen presentation. In syngeneic transplanted Lynch syndrome-associated colon cancer mice, the combination of anti-PD-L1 and TCL provided better cancer suppression than monoimmunotherapy, and the cancer suppression effect of anti-PD-L1/TCL@Lipo-PEG treatment was even better than that of the free drug. Meanwhile anti-PD-L1/TCL@Lipo-PEG enhanced the immunosuppressive tumor microenvironment. In vivo fluorescence imaging and H&E staining showed that the nanomedicine was mainly retained in the tumor site and had no significant toxic side effects on other major organs. The anti-PD-L1/TCL@Lipo-PEG prepared in this study has high efficacy and good biosafety in alleviating the progression of Lynch syndrome-associated colon cancer, and it is expected to be a therapeutic candidate for Lynch syndrome-associated colon cancer.

Origin and Therapies of Osteosarcoma

Simple Summary

Osteosarcoma is the most common malignant bone tumor in children, with a 5-year survival rate ranging from 70% to 20% depending on the aggressiveness of the disease. The current treatments have not evolved over the past four decades due in part to the genetic complexity of the disease and its heterogeneity. This review will summarize the current knowledge of OS origin, diagnosis and therapies.

Abstract

Osteosarcoma (OS) is the most frequent primary bone tumor, mainly affecting children and young adults. Despite therapeutic advances, the 5-year survival rate is 70% but drastically decreases to 20–30% for poor responders to therapies or for patients with metastasis. No real evolution of the survival rates has been observed for four decades, explained by poor knowledge of the origin, difficulties related to diagnosis and the lack of targeted therapies for this pediatric tumor. This review will describe a non-exhaustive overview of osteosarcoma disease from a clinical and biological point of view, describing the origin, diagnosis and therapies.

Silencing Signal Transducer and Activator of Transcription 3 (STAT3) and Use of Anti-Programmed Cell Death-Ligand 1 (PD-L1) Antibody Induces Immune Response and Anti-Tumor Activity

BACKGROUND The treatment of cancer is still unable to meet the needs of patients and remains a huge challenge. This study investigated the immune response and anti-cancer effect of silencing STAT3 combined with the use of anti-PD-L1 antibody. MATERIAL AND METHODS Transfected CT26.WT cells were used to subcutaneously inoculate C57B/L6 mice, which were subsequently injected with anti-PD-L1 antibody. Treated mice were examined for tumor formation and inflammation using HE staining. Tumors were investigated for apoptosis using the TUNEL assay. The expression of STAT3, PD-L1, and C-met was studied immunohistochemistrially and by using PCR and Western blot analysis. RESULTS Four weeks after inoculation, tumors were observed in the inoculated mice. HE staining showed obvious inflammation in mice injected with cells that were silenced for STAT3 and injected with PD-L1 antibody. TUNEL assay showed low level of apoptosis in mice injected with cells silenced for STAT3 or injected with PD-L1 antibody, and higher level of apoptosis following combined treatment of STAT3 silencing and PD-L1 antibody injection. Immunohistochemistry, PCR, and Western blot analyses revealed that the expression of C-met, PD-L1, and STAT3 was significantly reduced in tumors following the combined treatment. Compared with treatment of STAT3 silencing or PD-L1 antibody injection, the combined treatment enhanced apoptosis. CONCLUSIONS Silencing STAT3 and PD-L1 antibody injection in combination increased apoptosis in tumor cells and thus offers better anti-cancer activity.

Characterization of Postinfusion Phenotypic Differences in Fresh Versus Cryopreserved TCR Engineered Adoptive Cell Therapy Products

Adoptive cell therapy (ACT) consisting of genetically engineered T cells expressing tumor antigen-specific T-cell receptors displays robust initial antitumor activity, followed by loss of T-cell activity/persistence and frequent disease relapse. We characterized baseline and longitudinal T-cell phenotype variations resulting from different manufacturing and administration protocols in patients who received ACT. Patients with melanoma who enrolled in the F5-MART-1 clinical trial (NCT00910650) received infusions of MART-1 T-cell receptors transgenic T cells with MART-1 peptide-pulsed dendritic cell vaccination. Patients were divided into cohorts based on several manufacturing changes in the generation and administration of the transgenic T cells: decreasing ex vivo stimulation/expansion time, increased cell dose, and receiving fresh instead of cryopreserved cells. T-cell phenotypes were analyzed by flow cytometry at baseline and longitudinally in peripheral blood. Transgenic T cells with shorter ex vivo culture/expansion periods displayed significantly increased expression of markers associated with less differentiated naive/memory populations, as well as significantly decreased expression of the inhibitory receptor programmed death 1 (PD1). Patients receiving fresh infusions of transgenic cells demonstrated expansion of central memory T cells and delayed acquisition of PD1 expression compared with patients who received cryopreserved products. Freshly infused transgenic T cells showed persistence and expansion of naive and memory T-cell populations and delayed acquisition of PD1 expression, which correlated with this cohort’s superior persistence of transgenic cells and response to dendritic cell vaccines. These results may be useful in designing future ACT protocols.

Immunotherapy for osteosarcoma: Where do we go from here?

Osteosarcoma is the most common bone tumor in children and young adults, with few advances in survival and treatment, especially for metastatic disease, in the last 30 years. Recently, immunotherapy has begun to show promise in various adult cancers, but the utility of this approach for osteosarcoma remains relatively unexplored. In this review, we outline the mechanisms and status of immunotherapies currently in clinical trials as well as future therapies on the horizon, and discuss their potential application for osteosarcoma.

Characterization of Pattern Recognition Receptor Expression and Functionality in Liver Primary Cells and Derived Cell Lines

Different liver cell types are endowed with immunological properties, including cell-intrinsic innate immune functions that are important to initially control pathogen infections. However, a full landscape of expression and functionality of the innate immune signaling pathways in the major human liver cells is still missing. In order to comparatively characterize these pathways, we purified primary human hepatocytes, hepatic stellate cells, liver sinusoidal endothelial cells (LSEC), and Kupffer cells (KC) from human liver resections. We assessed mRNA and protein expression level of the major innate immune sensors, as well as checkpoint-inhibitor ligands in the purified cells, and found Toll-like receptors (TLR), RIG-I-like receptors, as well as several DNA cytosolic sensors to be expressed in the liver microenvironment. Amongst the cells tested, KC were shown to be most broadly active upon stimulation with PRR ligands emphasizing their predominant role in innate immune sensing the liver microenvironment. By KC immortalization, we generated a cell line that retained higher innate immune functionality as compared to THP1 cells, which are routinely used to study monocyte/macrophages functions. Our findings and the establishment of the KC line will help to understand immune mechanisms behind antiviral effects of TLR agonists or checkpoint inhibitors, which are in current preclinical or clinical development.

Irradiation enhanced the effects of PD-1 blockade in brain metastatic osteosarcoma

Brain metastasis of osteosarcoma are rare but carry a dismal prognosis. Despite the advances in both systemic immunotherapy and localized radiation, it is still difficult to treat brain metastasis, with less than 12 months of survival from the time of diagnosis for most patients. Currently, there is interest in combining strategies to take advantage of the potential synergy. In this study, the mouse model of metastatic osteosarcoma to brain was used to explore the ability of local radiation and anti-PD-1 blockade to induce beneficial anti-tumor immune responses against distant, unirradiated brain metastatic tumors. Immune markers from the peripheral blood and tumor tissue were analyzed by flow cytometry, real-time PCR and western blot. The combination treatment produced a stronger systemic anti-tumor response than either treatment alone, shown by the reduced tumor burden and larger numbers of cytotoxic CD8⁺ T cells in the unirradiated tumors, indicating an abscopal effect. These data suggested that combination treatment of irradiation with anti-PD-1 immunotherapy can induce abscopal anti-tumor responses and improve both local and distant control.

Enhanced expression of Programmed cell death 1 (PD-1) protein in benign vascular anomalies

Programmed cell death 1 (PD-1) and its ligands have been shown to play a significant role in evasion of malignant tumour cells from the immune system. Last year, the United States Food and Drug Administration (FDA) approved anti-PD-1 inhibitors for treatment of non-small cell lung carcinoma and recently has approved anti-PD-L1 blocker for treatment of metastatic urothelial cell carcinoma. However, the role that the immune system might have on benign tumours including vascular anomalies has received less attention. In this study, we evaluated PD-1 and PD-L1 expression on two benign vascular anomalies: infantile haemangiomas and venous malformations. Tissue microarrays (TMAs) from these two entities were stained for PD-1 and PD-L1 antibodies. Blood vessels from normal tissue were used as control. The endothelial cells in both infantile haemangioma and venous malformation showed high expression of PD-1 but were negative for PD-L1. Endothelial cells within the blood vessels in normal tissues were negative for both PD-1 and PD-L1. Our results showed over-expression of PD-1 in subsets of vascular anomalies, while PD-L1 was negative. This would raise the possibility of immunotherapy in benign vascular tumour when other options are exhausted.