Is there a role for immunotherapy in osteosarcoma?

Current approaches in tissue engineering-based nanotherapeutics for osteosarcoma treatment

Osteosarcoma (OS) is a malignant bone neoplasm plagued by poor prognosis. Major treatment strategies include chemotherapy, radiotherapy, and surgery. Chemotherapy to treat OS has severe adverse effects due to systemic toxicity to healthy cells. A possible way to overcome the limitation is to utilize nanotechnology. Nanotherapeutics is an emerging approach in treating OS using nanoparticulate drug delivery systems. Surgical resection of OS leaves a critical bone defect requiring medical intervention. Recently, tissue engineered scaffolds have been reported to provide physical support to bone defects and aid multimodal treatment of OS. These scaffolds loaded with nanoparticulate delivery systems could also actively repress tumor growth and aid new bone formation. The rapid developments in nanotherapeutics and bone tissue engineering have paved the way for improved treatment efficacy for OS-related bone defects. This review focuses on current bifunctional nanomaterials-based tissue engineered (NTE) scaffolds that use novel approaches such as magnetic hyperthermia, photodynamic therapy, photothermal therapy, bioceramic and polymeric nanotherapeutics against OS. With further optimization and screening, NTE scaffolds could meet clinical applications for treating OS patients.

Autophagy and its role in osteosarcoma

Osteosarcoma (OS) is the most common bone malignancy and preferably occurs in children and adolescents. Despite significant advances in surgery and chemotherapy for OS over the past few years, overall survival rates of OS have reached a bottleneck. Thus, extensive researches aimed at developing new therapeutic targets for OS are urgently needed. Autophagy, a conserved process which allows cells to recycle altered or unused organelles and cellular components, has been proven to play a critical role in multiple biological processes in OS. In this article, we summarized the association between autophagy and proliferation, metastasis, chemotherapy, radiotherapy, and immunotherapy of OS, revealing that autophagy-related genes and pathways could serve as potential targets for OS therapy.

Osteosarcoma: a review of current and future therapeutic approaches

Osteosarcoma (OS) is the most common primary bone malignancy that affects children and young adults. OS is characterized by a high degree of malignancy, strong invasiveness, rapid disease progression, and extremely high mortality rate; it is considered as a serious threat to the human health globally. The incidence of OS is common in the metaphysis of long tubular bones, but rare in the spine, pelvis, and sacrum areas; moreover, majority of the OS patients present with only a single lesion. OS has a bimodal distribution pattern, that is, its incidence peaks in the second decade of life and in late adulthood. We examine historical and current literature to present a succinct review of OS. In this review, we have discussed the types, clinical diagnosis, and modern and future treatment methods of OS. The purpose of this article is to inspire new ideas to develop more effective therapeutic options.

miR-218 suppresses the proliferation of osteosarcoma through downregulation of E2F2

Osteosarcoma is the most common primary malignant bone tumor type in children and adolescents under 20 years of age. Biological characteristics include invasiveness, metastasis, abnormal differentiation and loss of contact inhibition. microRNAs (miRNAs) are involved in the transcriptional and post-transcriptional regulation of target mRNAs. Previous studies have demonstrated that miR-218 inhibits tumor formation and progression in glioma, colon cancer and renal cell carcinoma; however, the mechanism of action of miR-218 in osteosarcoma has not been completely determined. In the present study, it was demonstrated that miR-218 exhibited low expression and targeted E2F2 in osteosarcoma cells. Additionally, overexpression of miR-218 inhibited osteosarcoma cell proliferation, with the opposite result occurring following the knockdown of miR-218. Furthermore, it was determined that miR-218 inhibited tumor formation and reduced the expression of E2F2 and proliferating cell nuclear antigen in nude mice. Collectively, the present data demonstrated that miR-218 serves an important role in suppressing the proliferation of osteosarcoma cells, potentially regulated by E2F2, which may provide a novel protein marker for the treatment of osteosarcoma.

Valproic Acid Combined with Zoledronate Enhance γδ T Cell-Mediated Cytotoxicity against Osteosarcoma Cells via the Accumulation of Mevalonate Pathway Intermediates

The long-term survival of osteosarcoma has remained unchanged in the last several decades. Immunotherapy is proved to be a promising therapeutic strategy against osteosarcoma, especially for those with metastasis. Our previous study explored the sensibilization of zoledronate (ZOL) in γδ T cell-mediated cytotoxicity against osteosarcoma, but we have not yet elucidated the specific mechanism. Besides, high concentration is required to achieve these effects, whereas plasma ZOL concentration declines rapidly in the circulation. Valproic acid (VPA), a histone deacetylase inhibitor commonly used as the antiepileptic drug, has attracted much attention due to its synergistic antitumor efficacy with chemotherapy or immunotherapy. Here, we demonstrated that VPA combined with ZOL revealed the synergistic effect in enhancing antitumor efficacy of γδ T cells against osteosarcoma cells. This enhancement was mainly TCR-mediated and largely dependent on granule exocytose pathway. Of note, our findings indicated that ZOL sensitized osteosarcoma cells to γδ T cells by increasing the accumulation of the mevalonate pathway intermediates, which could be facilitated by VPA. We also found that this combination had similar effects on primary osteosarcoma cells. All the results suggested that VPA combined with ZOL could reduce the dose required to achieve a significant antitumor effect of γδ T cells, promoting it to be a novel therapy against osteosarcoma.

Effectiveness of mifamurtide in addition to standard chemotherapy for high-grade osteosarcoma: a systematic review

BACKGROUND

Osteosarcoma mostly occurs during the period of rapid bone growth in children and adolescents as high-grade osteosarcomas. Current treatment recommended for high-grade non-metastatic and metastatic and/or relapsed osteosarcoma involves neoadjuvant multiagent conventional chemotherapy, followed by surgical resection of macroscopically detected tumor and postoperative adjuvant chemotherapy. However, residual micrometastatic deposits that develop following surgery have shown resistance to postoperative/adjuvant chemotherapy. Therefore, there is a critical need for more effective and innovative therapeutic approaches such as immune stimulatory agents. The most extensively studied immune stimulatory agent in the treatment of osteosarcoma is mifamurtide. The aim of this systematic review was to identify and synthesize the evidence on the effectiveness of mifamurtide in addition to standard chemotherapy on survival outcomes.

OBJECTIVES

To present the best available evidence on the treatment of high-grade non-metastatic and metastatic osteosarcoma with mifamurtide in addition to standard chemotherapy.

INCLUSION CRITERIA TYPES OF PARTICIPANTS

All populations of patients regardless of age, gender or ethnicity with high-grade, resectable, non-metastatic and metastatic osteosarcoma based on histological diagnosis.

TYPES OF INTERVENTIONS AND COMPARATORS

This review focused on intravenous infusion of either of the pharmaceutical formulations of mifamurtide (MTP-PE or L-MTP-PE) in addition to standard chemotherapy, and the comparator was chemotherapy alone.

TYPES OF STUDIES

This review considered any experimental study design including randomized controlled trials, non-randomized trials and quasi-experimental studies.

OUTCOMES

The primary outcomes of interest were event-free survival, overall survival and recurrence of osteosarcoma. Secondary outcomes that were considered included health-related quality of life and any mifamurtide-related adverse events.

SEARCH STRATEGY

A search for published and unpublished literature in English was undertaken (seven published literature databases, four unpublished literature databases, and three government agency and organizational websites were searched). Studies published between 1990 to June 2016 were considered. A three-step strategy was developed using MeSH terminology and keywords to ensure that all relevant studies were included related to this review.

METHODOLOGICAL QUALITY

The methodological quality of included studies was assessed by two reviewers, who appraised each study independently, using a standardized Joanna Briggs Institute (JBI) critical appraisal tool.

DATA EXTRACTION

Data was extracted from the studies that were identified as meeting the criteria for methodological quality using the standard JBI data extraction tool.

DATA SYNTHESIS

Due to the heterogeneity of populations and interventions in available studies, meta-analysis was not possible and results are presented in narrative form.

RESULTS

Three papers outlining two studies involving 802 patients evaluated the effectiveness of mifamurtide in addition of chemotherapy. Results indicated no significant difference in event-free survival between the addition of mifamurtide to standard chemotherapy regimen and chemotherapy alone, both in non-metastatic and metastatic osteosarcoma patients. There was a significant difference in progression-free survival favoring the addition of mifamurtide in pulmonary metastatic and/or relapsed osteosarcoma. There was no significant difference in overall survival between the addition of mifamurtide and chemotherapy alone in metastatic osteosarcoma; however there was a significant difference favoring the addition of mifamurtide in non-metastatic osteosarcoma patients. The addition of mifamurtide resulted in a significant difference in survival after relapse in pulmonary metastatic and/or relapsed osteosarcoma patients. Both studies reported on mifamurtide-related adverse events - the first was reported as toxicity which included haematological, hepatic, renal, gastrointestinal disorders, cardiac, rhythm and nervous system disorders, ear disorders and others (infection, fever; and performance status) in metastatic osteosarcoma patients. Results were similar across all combined treatment regimens. Although no statistical analysis was undertaken, the figures suggest there were no significant differences between the treatment regimens. In the other study, mifamurtide-related adverse events were reported as clinical toxic effects of mifamurtide in relapsed osteosarcoma, which included chills, fever and headache for the initial dose of mifamurtide, while for the subsequent doses of mifamurtide all patients reported toxicity as delayed fatigue.

CONCLUSIONS

The available evidence on the effectiveness of mifamurtide in addition to a standard chemotherapy regimen for the treatment of high-grade osteosarcoma is limited and therefore no definitive conclusions can be made.

Early Lymphocyte Recovery and Outcome in Osteosarcoma

BACKGROUND

Early lymphocyte recovery following chemotherapy has been associated with improved outcome in many cancers, including in one small study of osteosarcoma patients.

MATERIALS AND METHODS

To confirm this finding, we retrospectively reviewed data from 53 patients with newly diagnosed osteosarcoma who had blood counts on day 14 (±1 d) following the first cycle of cisplatin and doxorubicin.

RESULTS

The median absolute lymphocyte count (ALC) 14 days after starting the first cycle of chemotherapy (ALC-14) was 1990 cells/μL (range: 600 to 6470). For 32 patients with an ALC-14≥1800 cells/μL, the 5-year progression-free survival (PFS) was 69%, compared with 33% for patients with an ALC-14 of <1800 cell/μL (P=0.036). In multivariable analysis of factors including age, sex, metastatic disease, and favorable histologic response to induction chemotherapy, ALC-14 was significantly associated with PFS (P=0.0081) and overall survival (P=0.0131). The use of ALC-14 appears to further stratify PFS and overall survival among patients when grouped by histologic response.

CONCLUSIONS

We confirmed that early lymphocyte recovery was associated with outcome in pediatric osteosarcoma. Although presumably reflecting immune-mediated tumor control, the precise mechanism for this is unclear. Further study of peripheral blood lymphocyte subpopulations in prospectively treated patients is underway.

Strategies and developments of immunotherapies in osteosarcoma

Osteosarcoma (OS) is a frequently observed primary malignant tumor. Current therapy for osteosarcoma consists of comprehensive treatment. The long-term survival rate of patients exhibiting nonmetastatic OS varies between 65-70%. However, a number of OS cases have been observed to be resistant to currently used therapies, leading to disease recurrence and lung metastases, which are the primary reasons leading to patient mortality. In the present review, a number of pieces of evidence provide support for the potential uses of immunotherapy, including immunomodulation and vaccine therapy, for the eradication of tumors via upregulation of the immune response. Adoptive T-cell therapy and oncolytic virotherapy have been used to treat OS and resulted in objective responses. Immunologic checkpoint blockade and targeted therapy are also potentially promising therapeutic tools. Immunotherapy demonstrates significant promise with regard to improving the outcomes for patients exhibiting OS.

Induction of a specific CD8+ T-cell response to cancer/testis antigens by demethylating pre-treatment against osteosarcoma

Conventional non-surgical therapeutic regimens against osteosarcoma are subject to chemoresistance and tumor relapse, and immunotherapy may be promising for this tumor. However, it's hard to find satisfactory epitopes for immunotherapy against osteosarcoma. Cancer/testis antigens (CTAs), such as MAGE-A family and NY-ESO-1, the potential antigens that almost exclusively express in tumor cells and immune-privileged sites, have been found expressed in osteosarcoma also. Nevertheless, the expression of CTAs is downregulated in many tumors, constraining the application of immunotherapy. In this article, we demonstrate that the expression of MAGE-A family and NY-ESO-1 in osteosarcoma cells can be upregulated following treatment with demethylating agent 5-aza-2'-deoxycytidine and consequently induces a CTA specific CD8+ T-cell response against osteosarcoma in vitro and in vivo. The in vivo imaging was realized by using luciferase-transfected HOS cells and DiR labeled T-cells in severely combined immunodeficiency mouse models. Cytotoxic T cells specifically recognizing MAGE-A family and NY-ESO-1 clustered at the tumor site in mice pre-treated with DAC and resulted in tumor growth suppression, while it was not observed in mice without DAC pre-treatment. This study is important for more targeted therapeutic approaches and suggests that adoptive immunotherapy, combined with demethylating treatment, has the potential for non-surgical therapeutic strategy against osteosarcoma.

Cytokine-induced killer cells eradicate bone and soft-tissue sarcomas

Unresectable metastatic bone sarcoma and soft-tissue sarcomas (STS) are incurable due to the inability to eradicate chemoresistant cancer stem-like cells (sCSC) that are likely responsible for relapses and drug resistance. In this study, we investigated the preclinical activity of patient-derived cytokine-induced killer (CIK) cells against autologous bone sarcoma and STS, including against putative sCSCs. Tumor killing was evaluated both in vitro and within an immunodeficient mouse model of autologous sarcoma. To identify putative sCSCs, autologous bone sarcoma and STS cells were engineered with a CSC detector vector encoding eGFP under the control of the human promoter for OCT4, a stem cell gene activated in putative sCSCs. Using CIK cells expanded from 21 patients, we found that CIK cells efficiently killed allogeneic and autologous sarcoma cells in vitro. Intravenous infusion of CIK cells delayed autologous tumor growth in immunodeficient mice. Further in vivo analyses established that CIK cells could infiltrate tumors and that tumor growth inhibition occurred without an enrichment of sCSCs relative to control-treated animals. These results provide preclinical proof-of-concept for an effective strategy to attack autologous sarcomas, including putative sCSCs, supporting the clinical development of CIK cells as a novel class of immunotherapy for use in settings of untreatable metastatic disease.

Interferon-α suppresses invasion and enhances cisplatin-mediated apoptosis and autophagy in human osteosarcoma cells

Interferon (IFN)-α is generated in response to viral infections and is used clinically in the therapy of a variety of viral infections and cancers. The present study investigated whether IFN-α could inhibit the invasive ability of osteosarcoma cells using a Matrigel invasion assay. In addition, the osteosarcoma cells were treated with cisplatin and/or IFN-α. Apoptosis and autophagy were assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, Hoechst 33258 staining, flow cytometry assay, acridine orange staining, green fluorescent protein-LC3 dot assay and transmission electron microscopy. Further analysis revealed that the efficacy of cisplatin was enhanced by the addition of the cytokine, IFN-α. These results indicate that the combination therapy of chemotherapeutics and IFN-α is a new approach for osteosarcoma, which requires validation by experiments in vivo.

B7-H3 is overexpressed in patients suffering osteosarcoma and associated with tumor aggressiveness and metastasis

B7-H3 is a member of the B7-family of co-stimulatory molecules, which has been shown to be broadly expressed in various tumor tissues, and which plays an important role in adaptive immune responses. The role of B7-H3 in osteosarcoma, however, remains unknown. In this study we used immunohistochemistry to analyze B7-H3 expression in 61 primary osteosarcoma tissues with case-matched adjacent normal tissues, and 37 osteochondroma and 20 bone fibrous dysplasia tissues. B7-H3 expression was expressed in 91.8% (56/61) of the osteosarcoma lesions, and the intensity of B7-H3 expression in osteosarcoma was significantly increased compared with adjacent normal tissues, osteochondroma and bone fibrous dysplasia tissues (p<0.001). Patients with high tumor B7-H3 levels had a significantly shorter survival time and recurrence time than patients with low tumor B7-H3 levels (p<0.001). Moreover, tumor B7-H3 expression inversely correlated with the number of tumor-infiltrating CD8⁺ T cells (p<0.05). In vitro, increasing expression of B7-H3 promotes osteosarcoma cell invasion, at least in part by upregulating matrix metalloproteinase-2 (MMP-2). In conclusion, our study provides the first evidence of B7-H3 expression in osteosarcoma cells as a potential mechanism controlling tumor immunity and invasive malignancy, and which is correlated with patients’ survival and metastasis.

Potential of human γδ T cells for immunotherapy of osteosarcoma

Recurrent or metastatic osteosarcomas remain a challenging malignancy to treat. Therefore, development and testing of novel therapeutic strategies to target these patients are needed. Adoptive cellular therapy strategies are being evaluated intensively as a novel therapeutic strategy for cancer. Unlike αβ T cells requiring antigen processing and MHC-restricted peptide displayed by antigen-presenting cells, γδ T cells exhibit the potent MHC-unrestricted lytic activity against various tumors in vitro and in vivo. The recent considerable success of γδ T cell-based immunotherapy in lung metastasis of renal cell carcinoma warrants further efforts to apply this treatment to other cancers including osteosarcoma, especially recurrent and metastatic osteosarcomas. In this review, we summarize the available evidence on γδ T cell-based immunotherapy for osteosarcoma that has been achieved to date. More importantly, we discuss potential strategies of the combination of expanded γδ T cells and bisphosphonates, and modification and expansion of αβ TCR modified γδ T cells for improving its efficacy for the treatment of osteosarcoma.

Application of a novel inhibitor of human CD59 for the enhancement of complement-dependent cytolysis on cancer cells

Many monoclonal antibodies (mAbs) have been extensively used in the clinic, such as rituximab to treat lymphoma. However, resistance and non-responsiveness to mAb treatment have been challenging for this line of therapy. Complement is one of the main mediators of antibody-based cancer therapy via the complement-dependent cytolysis (CDC) effect. CD59 plays a critical role in resistance to mAbs through the CDC effect. In this paper, we attempted to investigate whether the novel CD59 inhibitor, recombinant ILYd4, was effective in enhancing the rituximab-mediated CDC effect on rituximab-sensitive RL-7 lymphoma cells and rituximab-induced resistant RR51.2 cells. Meanwhile, the CDC effects, which were mediated by rituximab and anti-CD24 mAb, on the refractory multiple myeloma (MM) cell line ARH-77 and the solid tumor osteosarcoma cell line Saos-2, were respectively investigated. We found that rILYd4 rendered the refractory cells sensitive to the mAb-mediated CDC effect and that rILYd4 exhibited a synergistic effect with the mAb that resulted in tumor cells lysis. This effect on tumor cell lysis was apparent on both hematological tumors and solid tumors. Therefore, rILYd4 may serve as an adjuvant for mAb mediated-tumor immunotherapy.