Inflammation, apoptosis, and necrosis induced by neoadjuvant fas ligand gene therapy improves survival of dogs with spontaneous bone cancer

Distinct mechanisms of PTEN inactivation in dogs and humans highlight convergent molecular events that drive cell division in the pathogenesis of osteosarcoma

A hallmark of osteosarcoma in both human and canine tumors is somatic fragmentation and rearrangement of chromosome structure which leads to recurrent increases and decreases in DNA copy number. The PTEN gene has been implicated as an important tumor suppressor in osteosarcoma via forward genetic screens. Here, we analyzed copy number changes, promoter methylation and transcriptomes to better understand the role of PTEN in canine and human osteosarcoma. Reduction in PTEN copy number was observed in 23 of 95 (25%) of the canine tumors examined leading to corresponding decreases in PTEN transcript levels from RNA-Seq samples. Unexpectedly, canine tumors with an intact PTEN locus had higher levels of PTEN transcripts than human tumors. This variation in transcript abundance was used to evaluate the role of PTEN in osteosarcoma biology. Decreased PTEN copy number and transcript level was observed in - and likely an important driver of - increases in cell cycle transcripts in four independent canine transcriptional datasets. In human osteosarcoma, homozygous copy number loss was not observed, instead increased methylation of the PTEN promoter was associated with increased cell cycle transcripts. Somatic modification of PTEN, either by homozygous deletion in dogs or by promoter methylation in humans, is clinically relevant to osteosarcoma, because the cell cycle related transcripts are associated with patient outcomes. The PTEN gene is part of a syntenic rearrangement unique to the canine genome, making it susceptible to somatic loss of both copies of distal chromosome 26 which also includes the FAS death receptor. SIGNIFICANCE STATEMENT: PTEN function is abrogated by different mechanisms in canine and human osteosarcoma tumors leading to uncontrolled cell cycling. Somatic loss of this canine specific syntenic region may help explain why the canine genome appears to be uniquely susceptible to osteosarcoma. Syntenic arrangement, in the context of copy number change, may lead to synergistic interactions that in turn modify species specific cancer risk. Comparative models of tumorigenesis may utilize different driver mechanisms.

Exploring the association of intratumoral immune cell infiltrates with histopathologic grade in canine mast cell tumors

Cutaneous canine mast cell tumors (ccMCTs) vary in their biological behavior, treatment, and prognosis, based on their grade. Immune cell infiltration has been associated with prognosis and response to treatments in some human cancers, and immune-targeting therapeutics are increasingly being explored in veterinary oncology. However, currently little is known about the tumor microenvironment (TME) in ccMCTs. Therefore, the objective of this study was to determine the prevalence of T lymphocytes, T regulatory lymphocytes, PD-1+ cells and macrophages in low- and high-grade ccMCTs. Thirty low-grade and 20 high-grade formalin-fixed paraffin-embedded ccMCT samples were included. Immunohistochemistry (IHC) was performed to detect CD3, FOXP3, Iba1, and PD-1 on sequential sections. Three 400x fields with the highest numbers of CD3+ cells were identified for each tumor. The percentage of CD3+, FOXP3+, and Iba1+ cells, and the number of PD-1+ cells, was quantified in each of these three "hot-spot" fields using ImageJ software. Iba1 expression was significantly greater in high-grade compared to low-grade ccMCTs (mean = 12.5% vs. 9.6%, p = 0.043). PD-1 expression was low overall, but a significantly higher number of PD-1-expressing cells was observed in high-grade ccMCTs (median 1 vs. 0, p = 0.001). No significant difference was noted in CD3 and FOXP3 expression between ccMCT grades. Macrophages and PD-1+ cells were more frequent in high-grade, compared to low-grade ccMCTs. Further studies are needed to define the role of macrophages and rare PD-1+ cells in high-grade ccMCTs.

Comparative analysis of genome-wide DNA methylation identifies patterns that associate with conserved transcriptional programs in osteosarcoma

Osteosarcoma is an aggressive tumor of the bone that primarily affects young adults and adolescents. Osteosarcoma is characterized by genomic chaos and heterogeneity. While inactivation of tumor protein p53 (TP53) is nearly universal other high frequency mutations or structural variations have not been identified. Despite this genomic heterogeneity, key conserved transcriptional programs associated with survival have been identified across human, canine and induced murine osteosarcoma. The epigenomic landscape, including DNA methylation, plays a key role in establishing transcriptional programs in all cell types. The role of epigenetic dysregulation has been studied in a variety of cancers but has yet to be explored at scale in osteosarcoma. Here we examined genome-wide DNA methylation patterns in 24 human and 44 canine osteosarcoma samples identifying groups of highly correlated DNA methylation marks in human and canine osteosarcoma samples. We also link specific DNA methylation patterns to key transcriptional programs in both human and canine osteosarcoma. Building on previous work, we built a DNA methylation-based measure for the presence and abundance of various immune cell types in osteosarcoma. Finally, we determined that the underlying state of the tumor, and not changes in cell composition, were the main driver of differences in DNA methylation across the human and canine samples. SIGNIFICANCE: Genome wide comparison of DNA methylation patterns in osteosarcoma across two species lays the ground work for the exploration of DNA methylation programs that help establish conserved transcriptional programs in the context of varied mutational landscapes.

Natural Killer and T Cell Infiltration in Canine Osteosarcoma: Clinical Implications and Translational Relevance

Metastatic osteosarcoma has a bleak prognosis in both humans and dogs, and there have been minimal therapeutic advances in recent decades to improve outcomes. Naturally occurring osteosarcoma in dogs is shown to be a highly suitable model for human osteosarcoma, and limited data suggest the similarities between species extend into immune responses to cancer. Studies show that immune infiltrates in canine osteosarcoma resemble those of human osteosarcoma, and the analysis of tumor immune constituents as predictors of therapeutic response is a promising direction for future research. Additionally, clinical studies in dogs have piloted the use of NK transfer to treat osteosarcoma and can serve as valuable precursors to clinical trials in humans. Cytotoxic lymphocytes in dogs and humans with osteosarcoma have increased activation and exhaustion markers within tumors compared with blood. Accordingly, NK and T cells have complex interactions among cancer cells and other immune cells, which can lead to changes in pathways that work both for and against the tumor. Studies focused on NK and T cell interactions within the tumor microenvironment can open the door to targeted therapies, such as checkpoint inhibitors. Specifically, PD-1/PD-L1 checkpoint expression is conserved across tumors in both species, but further characterization of PD-L1 in canine osteosarcoma is needed to assess its prognostic significance compared with humans. Ultimately, a comparative understanding of T and NK cells in the osteosarcoma tumor microenvironment in both dogs and humans can be a platform for translational studies that improve outcomes in both dogs and humans with this frequently aggressive disease.

Non-rodent animal models of osteosarcoma: A review

Osteosarcoma is extremely malignant, and the most common cancer that affects bone. Current treatments involve surgical resection of the affected area and multi-agent chemotherapy, though survival rate is generally poor for those affected by metastases. As treatment for osteosarcoma has remained unchanged for the past few decades, there is a need for further advancements in the understanding of osteosarcoma biology and therapeutics. Thus, reliable animal models that can accurately recapitulate the disease are required. Though rodents represent the most popular animal model of osteosarcoma, they may not model the disease best. This review analyzes emerging alternative non-rodent animal models of osteosarcoma, such as the chick chorioallantoic membrane (CAM) assay, pigs, and canines. Each of these alternatives offer advantages over classic rodent models for pre-clinical research. Research of these cross-species platforms imparts knowledge of metastases biology and potential new treatments for osteosarcoma.

Comparative Immunology and Immunotherapy of Canine Osteosarcoma

Approximately 800 people are diagnosed with osteosarcoma (OSA) per year in the USA. Although 70% of patients with localized OSA are cured with multiagent chemotherapy and surgical resection, the prognosis for patients with metastatic or relapsed disease is guarded. The small number of patients diagnosed annually contributes to an incomplete understanding of disease pathogenesis, and challenges in performing appropriately powered clinical trials and detecting correlative biomarkers of response. While mouse models of OSA are becoming increasingly sophisticated, they generally fail to accurately recapitulate tumor heterogeneity, tumor microenvironment (TME), systemic immune dysfunction, and the clinical features of tumor recurrence, metastases, and chemoresistance, which influence outcome. Pet dogs spontaneously develop OSA with an incidence that is 30-50 times higher than humans. Canine OSA parallels the human disease in its clinical presentation, biological behavior, genetic complexity, and therapeutic management. However, despite therapy, most dogs die from metastatic disease within 1 year of diagnosis. Since OSA occurs in immune-competent dogs, immune factors that sculpt tumor immunogenicity and influence responses to immune modulation are in effect. In both species, immune modulation has shown beneficial effects on patient outcome and work is now underway to identify the most effective immunotherapies, combination of immunotherapies, and correlative biomarkers that will further improve clinical response. In this chapter, the immune landscape of canine OSA and the immunotherapeutic strategies used to modulate antitumor immunity in dogs with the disease will be reviewed. From this immunological viewpoint, the value of employing dogs with spontaneous OSA to accelerate and inform the translation of immunotherapies into the human clinic will be underscored.

Neoadjuvant chemotherapy and radiation therapy in veterinary cancer treatment: a review

Multi-modality treatment strategies are more becoming commonplace in veterinary oncology practice yet the evidence base is far inferior to what has been generated in people. Surgery is unquestionably the cornerstone of most solid tumour treatment plans but certain scenarios dictate combining surgery with systemic chemotherapy and radiation therapy as an adjunct. By using these in the neoadjuvant setting, one can leverage certain effects of the treatment to improve local disease control, improve overall survival, gain insight into drug efficacy, reduce surgical morbidity and reduce long-term complications. An unintended consequence of combining therapies is an increased flow of information between members of the care team upfront that in almost all cases leads to improved patient outcomes albeit a difficult metric to quantify. This review sets out to explore some of the principles of neoadjuvant therapies and discuss potential opportunities to expand the evidence base in veterinary medicine.

Safety evaluation of the canine osteosarcoma vaccine, live Listeria vector

Canine osteosarcoma (OSA) is an aggressive bone tumour in dogs. Standard‐of‐care treatment typically results in relatively short survival times; thus, alternative treatments are needed to confer a survival advantage. It has been shown that OSA is an immunogenic tumour, suggesting that immune modulation may result in superior outcomes. A cryopreserved, Listeria‐based OSA vaccine was recently developed and an initial study in dogs reported prolonged survival for patients receiving the vaccine in conjunction with standard‐of‐care. The goal of the current observational study was to report on the safety of the lyophilized formulation of this vaccine (the canine OSA vaccine, live Listeria vector [COV‐LLV]) in a group of dogs previously diagnosed with OSA. Forty‐nine (49) dogs received the COV‐LLV and were included for analysis. Adverse events (AEs) noted during and after vaccinations were recorded. The AEs observed were typically mild and self‐limiting, with nausea, lethargy and fever being most common. Four dogs (8%) cultured positive for Listeria (three infections including an amputation site abscess, septic stifle joint and bacterial cystitis; and one dog whose lungs cultured Listeria‐positive on necropsy within 24 hours of COV‐LLV administration). These cases join the previously reported Listeria‐positive thoracic abscess that developed in a canine following use of COV‐LLV. Although uncommon, it is important to realize this clinically significant AE is possible in patients treated with live therapeutic Listeria vaccines. As Listeria is zoonotic, caution is required not only for the patient receiving the vaccine, but also for the health care workers and family caring for the patient.

Sarcomas-A barren immunological wasteland or field of opportunity for immunotherapy?

Key advances in our understanding of immunobiology and the immunosuppressive mechanisms of the tumour microenvironment have led to significant breakthroughs in manipulating the immune system to successfully treat cancer. Remarkable therapeutic responses have occurred with tumours that carry a high mutational burden. In these cases, pre-existing tumour-specific T cells can be rejuvenated via checkpoint inhibition to eliminate tumours. Furthermore, durable remissions have been achieved in haematological malignancies following adoptive transfer of T cells that specifically target cell surface proteins where expression is restricted to the malignancy's cell of origin. Soft tissue sarcomas and bone sarcomas have a paucity of non-synonymous somatic mutations and do not commonly express known, targetable, tumour-specific antigens. Historically, soft tissue sarcomas have been considered immunologically 'cold' and as such, unlikely candidates for immune therapy. Here, we review the immune landscape of canine and feline sarcomas and the immunotherapeutic strategies that have been employed in veterinary clinical trials to improve patient outcome. We also provide insight into immunotherapeutic approaches being used to treat human sarcomas. Together, current data indicates that, rather than a barren immunological wasteland, sarcomas represent a field of opportunities for immunotherapies. Furthermore, we and others would suggest that strategic combinations of immunotherapeutic approaches may hold promise for more effective treatments for high grade soft tissue sarcomas and bone sarcomas.

Recent and current clinical trials in canine appendicular osteosarcoma

Osteosarcoma (OSA) is an aggressive primary bone tumor in the domestic dog that most often occurs within the appendicular skeleton. Despite the use of adjuvant chemotherapy, most dogs succumb to metastatic disease within 1 year of diagnosis. To improve this outcome, substantial research is currently focused on investigating novel therapies. Herein, we review emerging treatments and clinical trials that, if proven efficacious, could revolutionize the standard of care for canine appendicular OSA. This article includes a critical perspective on the safety, efficacy, and limitations of select immunotherapy, virotherapy, radiotherapy, targeted therapy, and personalized medicine trials, all of which reflect similar investigations taking place in human oncology. These clinical trials represent a major evolution in the overall approach to therapy for dogs with appendicular OSA that could have significant implications for improving survival.

Interleukin-8 in the Tumor Immune Niche: Lessons from Comparative Oncology

Interleukin (IL)-8 is a chemokine that is essential for inflammation and angiogenesis. IL-8 expression is elevated in tumor cell lines and tissues, as well as in peripheral blood obtained from cancer patients. Primary works have attempted to determine the biological effect of IL-8 on tumor cells, including cell proliferation, survival, and migration. More recently, IL-8 has acquired considerable attention as an immune modulator in the context of certain tumor microenvironments (TME); specifically, it can support a niche that favors tumor progression and metastasis. Tumor-derived IL-8 stimulates inflammation by interacting with the microenvironmental constituents, including fibroblasts, endothelial cells, and immune cells. However, the tumor immune system is complex, and mechanisms that construct the immune phenotype remain incompletely characterized. Herein, we will (1) address a potential role of IL-8 in regulating gene expression to establish immune landscape in tumor. Then, we will (2) review IL-8 signaling in the maintenance of stem cells and regulation of hematopoietic progenitors. Finally, (3) IL-8 functions will be discussed in naturally occurring animal cancers that offer a clinically realistic model for translational research. This chapter will provide a new insight into the tumor immune niche and help us develop immunotherapies for cancers.

Blood and tissue biomarker analysis in dogs with osteosarcoma treated with palliative radiation and intra-tumoral autologous natural killer cell transfer

We have previously reported radiation-induced sensitization of canine osteosarcoma (OSA) to natural killer (NK) therapy, including results from a first-in-dog clinical trial. Here, we report correlative analyses of blood and tissue specimens for signals of immune activation in trial subjects. Among 10 dogs treated with palliative radiotherapy (RT) and intra-tumoral adoptive NK transfer, we performed ELISA on serum cytokines, flow cytometry for immune phenotype of PBMCs, and PCR on tumor tissue for immune-related gene expression. We then queried The Cancer Genome Atlas (TCGA) to evaluate the association of cytotoxic/immune-related gene expression with human sarcoma survival. Updated survival analysis revealed five 6-month survivors, including one dog who lived 17.9 months. Using feeder line co-culture for NK expansion, we observed maximal activation of dog NK cells on day 17-19 post isolation with near 100% expression of granzyme B and NKp46 and high cytotoxic function in the injected NK product. Among dogs on trial, we observed a trend for higher baseline serum IL-6 to predict worse lung metastasis-free and overall survival (P = 0.08). PCR analysis revealed low absolute gene expression of CD3, CD8, and NKG2D in untreated OSA. Among treated dogs, there was marked heterogeneity in the expression of immune-related genes pre- and post-treatment, but increases in CD3 and CD8 gene expression were higher among dogs that lived > 6 months compared to those who did not. Analysis of the TCGA confirmed significant differences in survival among human sarcoma patients with high and low expression of genes associated with greater immune activation and cytotoxicity (CD3e, CD8a, IFN-γ, perforin, and CD122/IL-2 receptor beta). Updated results from a first-in-dog clinical trial of palliative RT and autologous NK cell immunotherapy for OSA illustrate the translational relevance of companion dogs for novel cancer therapies. Similar to human studies, analyses of immune markers from canine serum, PBMCs, and tumor tissue are feasible and provide insight into potential biomarkers of response and resistance.

Comparative Approach to the Temporo-Spatial Organization of the Tumor Microenvironment

The complex ecosystem in which tumor cells reside and interact, termed the tumor microenvironment (TME), encompasses all cells and components associated with a neoplasm that are not transformed cells. Interactions between tumor cells and the TME are complex and fluid, with each facet coercing the other, largely, into promoting tumor progression. While the TME in humans is relatively well-described, a compilation and comparison of the TME in our canine counterparts has not yet been described. As is the case in humans, dog tumors exhibit greater heterogeneity than what is appreciated in laboratory animal models, although the current level of knowledge on similarities and differences in the TME between dogs and humans, and the practical implications of that information, require further investigation. This review summarizes some of the complexities of the human and mouse TME and interjects with what is known in the dog, relaying the information in the context of the temporo-spatial organization of the TME. To the authors' knowledge, the development of the TME over space and time has not been widely discussed, and a comprehensive review of the canine TME has not been done. The specific topics covered in this review include cellular invasion and interactions within the TME, metabolic derangements in the TME and vascular invasion, and the involvement of the TME in tumor spread and metastasis.

Osteosarcoma in the Post Genome Era: Preclinical Models and Approaches to Identify Tractable Therapeutic Targets

PURPOSE OF REVIEW

Osteosarcoma (OS) is the most common cancer of bone, yet is classified as a rare cancer. Treatment and outcomes for OS have not substantively changed in several decades. While the decoding of the OS genome greatly advanced the understanding of the mutational landscape of OS, immediately actionable therapeutic targets were not apparent. Here we describe recent preclinical models that can be leveraged to identify, test, and prioritize therapeutic candidates.

RECENT FINDINGS

The generation of multiple high fidelity murine models of OS, the spontaneous disease that arises in pet dogs, and the establishment of a diverse collection of patient-derived OS xenografts provide a robust preclinical platform for OS. These models enable evidence to be accumulated across multiple stages of preclinical evaluation. Chemical and genetic screening has identified therapeutic targets, often demonstrating cross species activity. Clinical trials in both PDX models and in canine OS have effectively tested new therapies for prioritization. Improving clinical outcomes in OS has proven elusive. The integrated target discovery and testing possible through a cross species platform provides validation of a putative target and may enable the rigorous evaluation of new therapies in models where endpoints can be rapidly assessed.

Metastatic immune infiltrates correlate with those of the primary tumour in canine osteosarcoma

Our lack of understanding of the immune microenvironment in canine osteosarcoma (cOSA) has limited the identification of potential immunotherapeutic targets. In particular, our ability to utilize readily available tissue from a dog's primary tumour to predict the type and extent of immune response in their pulmonary metastatic lesions is unknown. We, therefore, collected 21 matched pairs of primary tumours and pulmonary metastatic lesions from dogs with OSA and performed immunohistochemistry to quantify T-lymphocyte (CD3), FOXP3+ cell, B-lymphocyte (Pax-5), and CD204+ macrophage infiltration. We found that T-lymphocytes and FOXP3+ infiltrates in primary tumours positively correlated with that of metastatic lesions (ρ = 0.512, P = 0.038 and ρ = 0.698, P = 0.007, respectively), while a strong trend existed for CD204+ infiltrates (ρ = 0.404, P = 0.087). We also observed T- and B-lymphocytes, and CD204+ macrophages to be significantly higher in a dog's pulmonary metastasis compared to their primary tumour (P = 0.018, P = 0.018, P = 0.016, respectively), while FOXP3+ cells were only significantly higher in metastases when all primary tumour and metastasis lesions were compared without pairing (P = 0.036). Together, these findings suggest that the metastatic immune microenvironment may be influenced by that of the primary cOSA, and that primary tumour immune biomarkers could potentially be applied to predict immunotherapeutic responses in gross metastatic disease. We, therefore, provide a rationale for the treatment of cOSA pulmonary metastases with immunotherapeutics that enhance the anti-tumour activity of these immune cells, particularly in dogs with moderate to high immune cell infiltration in their primary tumours.

Cryo-thermal therapy inducing MI macrophage polarization created CXCL10 and IL-6-rich pro-inflammatory environment for CD4+ T cell-mediated anti-tumor immunity

PURPOSE

We previously developed a novel cryo-thermal therapy to treat malignant mammary carcinoma and melanoma in a mouse model; long-term survival and CD4⁺ T cell orchestrating anti-tumor immune memory response were achieved. Moreover, cryo-thermal-induced CD4⁺ T cell differentiation into Th1 and CD4⁺CTL sub-lineages, in which M1 macrophage polarization played a direct, important role. In particular, cryo-thermal therapy triggered M1 macrophage polarization with up-regulated expression of C-X-C motif ligand 10 (CXCL10) and Interleukin 6 (IL-6). But whether CXCL10 and IL-6 contribute to CD4⁺ T cell-mediated anti-tumor immunity remains unclear. In this study, the role of cryo-thermal-induced CXCL10 and IL-6 in anti-tumor immunity was determined.

METHODS

The level of CXCL10 and IL-6 in spleen and serum was determined by RT-PCR and ELISA on day 14 after cryo-thermal therapy. Splenic dendritic cells (DCs) and macrophages were isolated from cryo-thermal-treated mice on day 5 and 14, and the level of CXCL10 and IL-6 in macrophages and DCs was determined by ELISA. The transwell migration assay was performed to study immune cell migration. In vivo neutralization of CXCL10 or IL-6 was performed to investigate the phenotypic changes of immune cells.

RESULTS

Cryo-thermal therapy induced M1 macrophage polarization with up-regulation of CXCL10 and IL-6 expression in spleen. CXCL10 and IL-6 promoted DCs migration and maturation, and subsequently promoted CD4⁺ T cell migration and differentiation into Th1 and CD4⁺ CTL, moreover, reduced myeloid-derived suppressor cells (MDSCs) accumulation.

CONCLUSIONS

Cryo-thermal-induced CXCL10 and IL-6 created acute inflammatory environment to initiate a systemically cascading innate and adaptive anti-tumor immunity, which was more permissive for tumor eradication.

Association of macrophage and lymphocyte infiltration with outcome in canine osteosarcoma

Immunotherapeutic strategies have shown promise for the treatment of canine osteosarcoma (cOSA). Very little is known about the immune microenvironment within cOSA, however, limiting our ability to identify potential immune targets and biomarkers of therapeutic response. We therefore prospectively assessed the disease-free interval (DFI) and overall survival time (ST) of 30 dogs with cOSA treated with amputation and six doses of adjuvant carboplatin. We then quantified lymphocytic (CD3+, FOXP3+) and macrophage (CD204+) infiltrates within the primary tumours of this cohort using immunohistochemistry, and evaluated their association with outcome. Overall, the median DFI and ST were 392 and 455 days, respectively. The median number of CD3+ and FOXP3+ infiltrates were 45.8 cells/mm² (4.6-607.6 cells/mm² ) and 8.5 mm² (0-163.1 cells/mm² ), respectively. The median area of CD204+ macrophages was 4.7% (1.3%-23.3%), and dogs with tumours containing greater than 4.7% CD204+ macrophages experienced a significantly longer DFI (P = 0.016). Interestingly, a significantly lower percentage of CD204+ macrophages was detected in cOSA arising from the proximal humerus compared to other appendicular bone locations (P = 0.016). Lymphocytic infiltrates did not appear to correlate with outcome in cOSA. Overall, our findings suggest that macrophages may play a role in inhibiting cOSA progression, as has been suggested in human osteosarcoma.

Clonal cooperativity in heterogenous cancers

Tumor heterogeneity is a major obstacle to the development of effective therapies and is thus an important focus of cancer research. Genetic and epigenetic alterations, as well as altered tumor microenvironments, result in tumors made up of diverse subclones with different genetic and phenotypic characteristics. Intratumor heterogeneity enables competition, but also supports clonal cooperation via cell-cell contact or secretion of factors, resulting in enhanced tumor progression. Here, we summarize recent findings related to interclonal interactions within a tumor and the therapeutic implications of such interactions, with an emphasis on how different subclones collaborate with each other to promote proliferation, metastasis and therapy-resistance. Furthermore, we propose that disruption of clonal cooperation by targeting key factors (such as Wnt and Hedgehog, amongst others) can be an alternative approach to improving clinical outcomes.

A phase I clinical study to evaluate safety of orally administered, genetically engineered Salmonella enterica serovar Typhimurium for canine osteosarcoma

We conducted a prospective phase I study to evaluate safety of an orally administered Salmonella encoding IL‐2 (SalpIL2) in combination with amputation and adjuvant doxorubicin for canine appendicular osteosarcoma. Efficacy was assessed as a secondary measure. The first dose of SalpIL2 was administered to 19 dogs on Day 0; amputation was done after 10 days with chemotherapy following 2 weeks later. SalpIL2 was administered concurrent with chemotherapy, for a total of five doses of doxorubicin and six doses of SalpIL2. There were six reportable events prior to chemotherapy, but none appeared due to SalpIL2. Dogs receiving SalpIL2 had significantly longer disease‐free interval (DFI) than a comparison group of dogs treated with doxorubicin alone. Dogs treated using lower doses of SalpIL2 also had longer DFI than dogs treated using the highest SalpIL2 dose. The data indicate that SalpIL2 is safe and well tolerated, which supports additional testing to establish the potential for SalpIL2 as a novel form of adjuvant therapy for dogs with osteosarcoma.

Understanding the Osteosarcoma Pathobiology: A Comparative Oncology Approach

Osteosarcoma is an aggressive primary bone tumor in humans and is among the most common cancer afflicting dogs. Despite surgical advancements and intensification of chemo- and targeted therapies, the survival outcome for osteosarcoma patients is, as of yet, suboptimal. The presence of metastatic disease at diagnosis or its recurrence after initial therapy is a major factor for the poor outcomes. It is thought that most human and canine patients have at least microscopic metastatic lesions at diagnosis. Osteosarcoma in dogs occurs naturally with greater frequency and shares many biological and clinical similarities with osteosarcoma in humans. From a genetic perspective, osteosarcoma in both humans and dogs is characterized by complex karyotypes with highly variable structural and numerical chromosomal aberrations. Similar molecular abnormalities have been observed in human and canine osteosarcoma. For instance, loss of TP53 and RB regulated pathways are common. While there are several oncogenes that are commonly amplified in both humans and dogs, such as MYC and RAS, no commonly activated proto-oncogene has been identified that could form the basis for targeted therapies. It remains possible that recurrent aberrant gene expression changes due to gene amplification or epigenetic alterations could be uncovered and these could be used for developing new, targeted therapies. However, the remarkably high genomic complexity of osteosarcoma has precluded their definitive identification. Several advantageous murine models of osteosarcoma have been generated. These include spontaneous and genetically engineered mouse models, including a model based on forward genetics and transposon mutagenesis allowing new genes and genetic pathways to be implicated in osteosarcoma development. The proposition of this review is that careful comparative genomic studies between human, canine and mouse models of osteosarcoma may help identify commonly affected and targetable pathways for alternative therapies for osteosarcoma patients. Translational research may be found through a path that begins in mouse models, and then moves through canine patients, and then human patients.

Defining the Value of a Comparative Approach to Cancer Drug Development

Comparative oncology as a tool in drug development requires a deeper examination of the value of the approach and examples of where this approach can satisfy unmet needs. This review seeks to demonstrate types of drug development questions that are best answered by the comparative oncology approach. We believe common perceived risks of the comparative approach relate to uncertainty of how regulatory bodies will prioritize or react to data generated from these unique studies conducted in diseased animals, and how these new data will affect ongoing human clinical trials. We contend that it is reasonable to consider these data as potentially informative and valuable to cancer drug development, but as supplementary to conventional preclinical studies and human clinical trials particularly as they relate to the identification of drug-associated adverse events. Clin Cancer Res; 22(9); 2133-8. ©2015 AACR.

Progress in Adaptive Immunotherapy for Cancer in Companion Animals: Success on the Path to a Cure

Harnessing the ability of the immune system to eradicate cancer has been a long-held goal of oncology. Work from the last two decades has finally brought immunotherapy into the forefront for cancer treatment, with demonstrable clinical success for aggressive tumors where other therapies had failed. In this review, we will discuss a range of therapies that are in different stages of clinical or preclinical development for companion animals with cancer, and which share the common objective of eliciting adaptive, anti-tumor immune responses. Even though challenges remain, manipulating the immune system holds significant promise to create durable responses and improve outcomes in companion animals with cancer. Furthermore, what we learn from this process will inform and accelerate development of comparable therapies for human cancer patients.

Aberrant Retinoblastoma (RB)-E2F Transcriptional Regulation Defines Molecular Phenotypes of Osteosarcoma

We previously identified two distinct molecular subtypes of osteosarcoma through gene expression profiling. These subtypes are associated with distinct tumor behavior and clinical outcomes. Here, we describe mechanisms that give rise to these molecular subtypes. Using bioinformatic analyses, we identified a significant association between deregulation of the retinoblastoma (RB)-E2F pathway and the molecular subtype with worse clinical outcomes. Xenotransplantation models recapitulated the corresponding behavior for each osteosarcoma subtype; thus, we used cell lines to validate the role of the RB-E2F pathway in regulating the prognostic gene signature. Ectopic RB resets the patterns of E2F regulated gene expression in cells derived from tumors with worse clinical outcomes (molecular phenotype 2) to those comparable with those observed in cells derived from tumors with less aggressive outcomes (molecular phenotype 1), providing a functional association between RB-E2F dysfunction and altered gene expression in osteosarcoma. DNA methyltransferase and histone deacetylase inhibitors similarly reset the transcriptional state of the molecular phenotype 2 cells from a state associated with RB deficiency to one seen with RB sufficiency. Our data indicate that deregulation of RB-E2F pathway alters the epigenetic landscape and biological behavior of osteosarcoma.

Mesenchymal stromal cells inhibit murine syngeneic anti-tumor immune responses by attenuating inflammation and reorganizing the tumor microenvironment

The potential of mesenchymal stromal cells (MSCs) to inhibit anti-tumor immunity is becoming increasingly well recognized, but the precise steps affected by these cells during the development of an anti-tumor immune response remain incompletely understood. Here, we examined how MSCs affect the steps required to mount an effective anti-tumor immune response following administration of adenovirus Fas ligand (Ad-FasL) in the Lewis lung carcinoma (LL3) model. Administration of bone marrow-derived MSCs with LL3 cells accelerated tumor growth significantly. MSCs inhibited the inflammation induced by Ad-FasL in the primary tumors, precluding their rejection; MSCs also reduced the consequent expansion of tumor-specific T cells in the treated hosts. When immune T cells were transferred to adoptive recipients, MSCs impaired, but did not completely abrogate the ability of these T cells to promote elimination of secondary tumors. This impairment was associated with a modest reduction in tumor-infiltrating T cells, with a significant reduction in tumor-infiltrating macrophages, and with a reorganization of the stromal environment. Our data indicate that MSCs in the tumor environment reduce the efficacy of immunotherapy by creating a functional and anatomic barrier that impairs inflammation, T cell priming and expansion, and T cell function-including recruitment of effector cells.

The immunotherapy of canine osteosarcoma: a historical and systematic review

Osteosarcoma is a malignant mesenchymal neoplasm that accounts for the majority of primary bone tumors in dogs and shares biological and clinical similarities with osteosarcoma in humans. Despite dose intensification with conventional cytotoxic therapies, survival times for dogs and humans diagnosed with high‐grade osteosarcoma have not changed in the past 20 years, with the principal cause of mortality being the development of pulmonary metastases. Given the therapeutic plateau reached for delaying metastatic progression with cytotoxic agents, exploration of alterative adjuvant therapies for improving management of osteosarcoma micrometastases is clinically justified. Evidence suggests that osteosarcoma is an immunogenic tumor, and development of immunotherapies for the treatment of microscopic lung metastases might improve long‐term outcomes. In this review, the history and foundational knowledge of immune interactions to canine osteosarcoma are highlighted. In parallel, immunotherapeutic strategies that have been explored for the treatment of canine osteosarcoma are summarized. With a greater understanding and awareness for how the immune system might be redirected toward combating osteosarcoma metastases, the rational development of diverse immune strategies for managing osteosarcoma holds substantial promise for transforming the therapeutic landscape and improving disease management in both dogs and human beings.

Inflammation and cancer: till death tears them apart

Advances in biotechnology have enabled the collection of an immeasurable amount of information from genomic, transcriptomic, metabolomic and proteomic studies of tumours within their microenvironments. The dissection of cytokine and chemokine networks has provided new clues to the interactions between cancer cells and their surrounding inflammatory landscape. To bridge the gap between chronic inflammation and cancer, dynamic participants in the tumour microenvironment have been identified, including tumour-associated macrophages (TAMs) and regulatory T cells (Tregs). Both of these cell types are notable for their ability to cause immunosuppressive conditions and support the evasion of tumour immune surveillance. It is clear now that the tumour-promoting inflammatory environment has to be included as one of the major cancer hallmarks. This review explores the recent advances in the understanding of cancer-related inflammation and how this is being applied to comparative oncology studies in humans and domestic species, such as the dog.

Canine osteosarcoma: a naturally occurring disease to inform pediatric oncology

Osteosarcoma (OSA) is the most common form of malignant bone cancer in children and dogs, although the disease occurs in dogs approximately 10 times more frequently than in people. Multidrug chemotherapy and aggressive surgical techniques have improved survival; however, new therapies for OSA are critical, as little improvement in survival times has been achieved in either dogs or people over the past 15 years, even with significant efforts directed at the incorporation of novel therapeutic approaches. Both clinical and molecular evidence suggests that human and canine OSA share many key features, including tumor location, presence of microscopic metastatic disease at diagnosis, development of chemotherapy-resistant metastases, and altered expression/activation of several proteins (e.g. Met, ezrin, phosphatase and tensin homolog, signal transducer and activator of transcription 3), and p53 mutations, among others. Additionally, canine and pediatric OSA exhibit overlapping transcriptional profiles and shared DNA copy number aberrations, supporting the notion that these diseases are similar at the molecular level. This review will discuss the similarities between pediatric and canine OSA with regard to histology, biologic behavior, and molecular genetic alterations that indicate canine OSA is a relevant, spontaneous, large animal model of the pediatric disease and outline how the study of naturally occurring OSA in dogs will offer additional insights into the biology and future treatment of this disease in both children and dogs.

Ethics of Cancer Gene Transfer Clinical Research

Translation of cancer gene transfer confronts many familiar-and some distinctive-ethical challenges. In what follows, I survey three major ethical dimensions of cancer gene transfer development. Subheading 1 centers on the ethics of planning, designing, and reporting animal studies. Subheading 2 describes basic elements of human subjects protection as pertaining to cancer gene transfer. In Subheading 3, I describe how cancer gene transfer researchers have obligations to downstream consumers of the evidence they produce.

Clinical trials of immunogene therapy for spontaneous tumors in companion animals

Despite the important progress obtained in the treatment of some pets' malignancies, new treatments need to be developed. Being critical in cancer control and progression, the immune system's appropriate modulation may provide effective therapeutic options. In this review we summarize the outcomes of published immunogene therapy veterinary clinical trials reported by many research centers. A variety of tumors such as canine melanoma, soft tissue sarcomas, osteosarcoma and lymphoma, feline fibrosarcoma, and equine melanoma were subjected to different treatment approaches. Both viral and mainly nonviral vectors were used to deliver gene products as cytokines, xenogeneic tumor associated antigens, specific ligands, and proapoptotic regulatory factors. In some cases autologous, allogenic, or xenogeneic transgenic cytokine producing cells were assayed. In general terms, minor or no adverse collateral effects appeared during this kind of therapies and treated patients usually displayed a better course of the disease (longer survival, delayed or suppressed recurrence or metastatic spread, and improvement of the quality of life). This suggests the utility of these methodologies as standard adjuvant treatments. The encouraging outcomes obtained in companion animals support their ready application in veterinary clinical oncology and serve as preclinical proof of concept and safety assay for future human gene therapy trials.

Interleukin-8 promotes canine hemangiosarcoma growth by regulating the tumor microenvironment

Interleukin-8 (IL-8) gene expression is highly up-regulated in canine hemangiosarcoma (HSA); however, its role in the pathogenesis of this disease is unknown. We investigated the expression of IL-8 in canine HSA tissues and cell lines, as well and the effects of IL-8 on canine HSA in vitro, and in vivo using a mouse xenograft model for the latter. Constitutive expression of IL-8 mRNA, IL-8 protein, and IL-8 receptor were variable among different tumor samples and cell lines, but they showed stable steady states in each cell line. Upon the addition of IL-8, HSA cells showed transient intracellular calcium fluxes, suggesting that their IL-8 receptors are functional and that IL-8 binding activates relevant signaling pathways. Yet, neither addition of exogenous IL-8 nor blockade of endogenous IL-8 by neutralizing anti-IL-8 antibody (α-IL-8 Ab) affected HSA cell proliferation or survival in vitro. To assess potential effects of IL-8 in other tumor constituents, we stratified HSA cell lines and whole tumor samples into "IL-8 high" and "IL-8 low" groups. Genome-wide gene expression profiling showed that samples in the "IL-8 high" tumor group were enriched for genes associated with a "reactive microenvironment," including activation of coagulation, inflammation, and fibrosis networks. Based on these findings, we hypothesized that the effects of IL-8 on these tumors were mostly indirect, regulating interactions with the microenvironment. This hypothesis was supported by in vivo xenograft experiments where survival and engraftment of tumor cells was inhibited by administration of neutralizing α-IL-8 Ab. Together, our results suggest that IL-8 contributes to establishing a permissive microenvironment during the early stages of tumorigenesis in HSA.

Recent advances in osteosarcoma

Although osteosarcoma (OS) is a rare malignancy, it is ranked among the leading causes of cancer-related death in the pediatric age group. The cancer's low prevalence and its large tumor heterogeneity make it difficult to obtain meaningful progress in patient survival. In this review we present an overview of current clinical trials which largely focus on stimulation of the immune system or rely on the inhibition of kinases such as Src and mTOR. The potential efficacy of tumor-targeted TNFalpha is discussed, as well as the importance of preclinical validation of new targets. To improve the success of future clinical trials, clinicians and basic researchers need to intensify their exchange. Finally, a case is made for individualized treatment of OS patients, based on interdisciplinary cooperation in dedicated Sarcoma Centers.

MicroRNAs at the human 14q32 locus have prognostic significance in osteosarcoma

Background

Deregulation of microRNA (miRNA) transcript levels has been observed in many types of tumors including osteosarcoma. Molecular pathways regulated by differentially expressed miRNAs may contribute to the heterogeneous tumor behaviors observed in naturally occurring cancers. Thus, tumor-associated miRNA expression may provide informative biomarkers for disease outcome and metastatic potential in osteosarcoma patients. We showed previously that clusters of miRNAs at the 14q32 locus are downregulated in human osteosarcoma.

Methods

Human and canine osteosarcoma patient’s samples with clinical follow-up data were used in this study. We used bioinformatics and comparative genomics approaches to identify miRNA based prognostic biomarkers in osteosarcoma. Kaplan-Meier survival curves and Whitney Mann U tests were conducted for validating the statistical significance.

Results

Here we show that an inverse correlation exists between aggressive tumor behavior (increased metastatic potential and accelerated time to death) and the residual expression of 14q32 miRNAs (using miR-382 as a representative of 14q32 miRNAs) in a series of clinically annotated samples from human osteosarcoma patients. We also show a comparable decrease in expression of orthologous 14q32 miRNAs in canine osteosarcoma samples, with conservation of the inverse correlation between aggressive behavior and expression of orthologous miRNA miR-134 and miR-544.

Conclusions

We conclude that downregulation of 14q32 miRNA expression is an evolutionarily conserved mechanism that contributes to the biological behavior of osteosarcoma, and that quantification of representative transcripts from this family, such as miR-382, miR-134, and miR-544, provide prognostic and predictive markers that can assist in the management of patients with this disease.