Evaluation of hypoxia in a feline model of head and neck cancer using ⁶⁴Cu-ATSM positron emission tomography/computed tomography

Preclinical models in head and neck squamous cell carcinoma

Head and neck cancer is the sixth most frequent cancer type. Drug resistance and toxicity are common challenges of the existing therapies, making the development of reliable preclinical models essential for the study of the involved molecular mechanisms as well as for eventual intervention approaches that improve the clinical outcome. Preclinical models of head and neck squamous cell carcinoma have been traditionally based on cell lines and murine models. In this review, we will go over the most frequently used preclinical models, from immortalised-cell and primary tumour cultures in monolayer or 3D, to the currently available animal models. We will scrutinise their efficiency in mimicking the molecular and cellular complexity of head and neck squamous cell carcinoma. Finally, the challenges and the opportunities of other envisaged putative approaches, as well as the potential of the preclinical models to further develop personalised therapies will be discussed.

Mouse Models for Immune Checkpoint Blockade Therapeutic Research in Oral Cancer

The most prevalent oral cancer globally is oral squamous cell carcinoma (OSCC). The invasion of adjacent bones and the metastasis to regional lymph nodes often lead to poor prognoses and shortened survival times in patients with OSCC. Encouraging immunotherapeutic responses have been seen with immune checkpoint inhibitors (ICIs); however, these positive responses to monotherapy have been limited to a small subset of patients. Therefore, it is urgent that further investigations into optimizing immunotherapies are conducted. Areas of research include identifying novel immune checkpoints and targets and tailoring treatment programs to meet the needs of individual patients. Furthermore, the advancement of combination therapies against OSCC is also critical. Thus, additional studies are needed to ensure clinical trials are successful. Mice models are advantageous in immunotherapy research with several advantages, such as relatively low costs and high tumor growth success rate. This review paper divided methods for establishing OSCC mouse models into four categories: syngeneic tumor models, chemical carcinogen induction, genetically engineered mouse, and humanized mouse. Each method has advantages and disadvantages that influence its application in OSCC research. This review comprehensively surveys the literature and summarizes the current mouse models used in immunotherapy, their advantages and disadvantages, and details relating to the cell lines for oral cancer growth. This review aims to present evidence and considerations for choosing a suitable model establishment method to investigate the early diagnosis, clinical treatment, and related pathogenesis of OSCC.

Title: Advances of Gold Nanoclusters for Bioimaging

Gold nanoclusters (AuNCs) have become a promising material for bioimaging detection because of their tunable photoluminescence, large Stokes shift, low photobleaching, and good biocompatibility. Last decade, great efforts have been made to develop AuNCs for enhanced imaging contrast and multimodal imaging. Herein, an updated overview of recent advances in AuNCs was present for visible fluorescence (FL) imaging, near-infrared fluorescence (NIR-FL) imaging, two-photon near-infrared fluorescence (TP-NIR-FL) imaging, computed tomography (CT) imaging, positron emission tomography (PET) imaging, magnetic resonance imaging (MRI), and photoacoustic (PA) imaging. The justification of AuNCs applied in bioimaging mentioned above applications was discussed, the performance location of different AuNCs were summarized and highlighted in an unified parameter coordinate system of corresponding bioimaging, and the current challenges, research frontiers, and prospects of AuNCs in bioimaging were discussed. This review will bring new insights into the future development of AuNCs in bio-diagnostic imaging.

Paired 18F-Fluorodeoxyglucose (18F-FDG), and 64Cu-Copper(II)-diacetyl-bis(N(4)-methylthiosemicarbazone) (64Cu-ATSM) PET Scans in Dogs with Spontaneous Tumors and Evaluation for Hypoxia-Directed Therapy

Hypoxia is associated with neoplastic tissue, protecting cancer cells from death by irradiation and chemotherapy. Identification of hypoxic volume of tumors could optimize patient selection for hypoxia-directed medical, immunological, and radiation therapies. Clostridium novyi-NT (CNV-NT) is an oncolytic bacterium derived from attenuated wild-type Clostridium novyi spores, which germinates exclusively in the anaerobic core of tumors with low-oxygen content. The hypothesis was that 64Cu-ATSM would localize to regions of hypoxia, and that greater hypoxic volume would result in greater germination of Clostridium novyi-NT (CNV-NT). Tumor-bearing companion dogs were recruited to a veterinary clinical trial. Dogs received a CT scan, 18F-FDG PET scan (74 MBq) and 64Cu-ATSM PET scan (74 MBq). Scan regions of interest were defined as the highest 20% of counts/voxel for each PET scan, and regions with voxels overlapping between the two scans. Maximum standardized uptake value (MaxSUV) and threshold volume were calculated. Direct oximetry was performed in select tumors. Tumor types evaluated included nerve sheath tumor (10), apocrine carcinoma (1), melanoma (3) and oral sarcoma (6). MaxSUVATSM ranged from 0.3-6.6. Measured oxygen tension ranged from 0.05-89.9 mmHg. Inverse of MaxSUVATSM had a linear relationship with oxygen tension (R2 = 0.53, P = 0.0048). Hypoxia <8 mmHg was associated with an SUVATSM > 1.0. Hypoxic volume ranged from 0 to 100% of gross tumor volume (GTV) and MaxSUVATSM was positively correlated with hypoxic volume (R = 0.674; P = 0.0001), but not GTV (P = 0.182). Tumor hypoxic volume was heterogeneous in location and distribution. 64Cu-ATSM-avid regions were associated with differential CT attenuation. Hypoxic volume did not predict CNV-NT germination. 64Cu-ATSM PET scanning predicts hypoxia patterns within spontaneously occurring tumors of dogs as measured by direct oxymetry. Total tumor volume does not accurately predict degree or proportion of tumor hypoxia.

Beyond tradition and convention: benefits of non-traditional model organisms in cancer research

Traditional laboratory model organisms are indispensable for cancer research and have provided insight into numerous mechanisms that contribute to cancer development and progression in humans. However, these models do have some limitations, most notably related to successful drug translation, because traditional model organisms are often short-lived, small-bodied, genetically homogeneous, often immunocompromised, are not exposed to natural environments shared with humans, and usually do not develop cancer spontaneously. We propose that assimilating information from a variety of long-lived, large, genetically diverse, and immunocompetent species that live in natural environments and do develop cancer spontaneously (or do not develop cancer at all) will lead to a more comprehensive understanding of human cancers. These non-traditional model organisms can also serve as sentinels for environmental risk factors that contribute to human cancers. Ultimately, expanding the range of animal models that can be used to study cancer will lead to improved insights into cancer development, progression and metastasis, tumor microenvironment, as well as improved therapies and diagnostics, and will consequently reduce the negative impacts of the wide variety of cancers afflicting humans overall.

Mouse Tumor-Bearing Models as Preclinical Study Platforms for Oral Squamous Cell Carcinoma

Preclinical animal models of oral squamous cell carcinoma (OSCC) have been extensively studied in recent years. Investigating the pathogenesis and potential therapeutic strategies of OSCC is required to further progress in this field, and a suitable research animal model that reflects the intricacies of cancer biology is crucial. Of the animal models established for the study of cancers, mouse tumor-bearing models are among the most popular and widely deployed for their high fertility, low cost, and molecular and physiological similarity to humans, as well as the ease of rearing experimental mice. Currently, the different methods of establishing OSCC mouse models can be divided into three categories: chemical carcinogen-induced, transplanted and genetically engineered mouse models. Each of these methods has unique advantages and limitations, and the appropriate application of these techniques in OSCC research deserves our attention. Therefore, this review comprehensively investigates and summarizes the tumorigenesis mechanisms, characteristics, establishment methods, and current applications of OSCC mouse models in published papers. The objective of this review is to provide foundations and considerations for choosing suitable model establishment methods to study the relevant pathogenesis, early diagnosis, and clinical treatment of OSCC.

Emerging Translational Opportunities in Comparative Oncology With Companion Canine Cancers: Radiation Oncology

It is estimated that more than 6 million pet dogs are diagnosed with cancer annually in the USA. Both primary care and specialist veterinarians are frequently called upon to provide clinical care that improves the quality and/or quantity of life for affected animals. Because these cancers develop spontaneously in animals that often share the same environment as their owners, have intact immune systems and are of similar size to humans, and because the diagnostic tests and treatments for these cancers are similar to those used for management of human cancers, canine cancer provides an opportunity for research that simultaneously helps improve both canine and human health care. This is especially true in the field of radiation oncology, for which there is a rich and continually evolving history of learning from the careful study of pet dogs undergoing various forms of radiotherapy. The purpose of this review article is to inform readers of the potential utility and limitations of using dogs in that manner; the peer-reviewed literature will be critically reviewed, and current research efforts will be discussed. The article concludes with a look toward promising future directions and applications of this pet dog “model.”

Fatty acid synthase as a potential therapeutic target in feline oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is an aggressive and treatment-resistant malignancy in both feline and human patients. Recent work has demonstrated aberrant expression of fatty acid synthase (FASN) and an increased capacity for lipogenesis in human OSCC and other cancers. In human OSCC, inhibition of FASN decreased cell viability and growth in vitro, and diminished tumour growth and metastasis in murine preclinical models. This study aimed to characterize FASN as a therapeutic target in feline OSCC. Immunohistochemistry revealed high FASN expression in primary feline OSCC tumours, and FASN expression was detected in OSCC cell lines (3 feline and 3 human) by immunoblotting and quantitative real-time-polymerase chain reaction (qRT-PCR). Orlistat, a FASN inhibitor, substantially reduced cell viability in both feline and human OSCC lines, although feline cell lines consistently displayed higher sensitivity to the drug. FASN mRNA expression among cell lines mirrored sensitivity to orlistat, with feline cell lines expressing higher levels of FASN. Consistent with this observation, diminished sensitivity to orlistat treatment and decreased FASN mRNA expression were observed in feline OSCC cells following incubation under hypoxic conditions. Treatment with orlistat did not potentiate sensitivity to carboplatin in the cell lines investigated; instead, combinations of the 2 drugs resulted in additive to antagonistic effects. Our results suggest that FASN inhibition is a viable therapeutic target for feline OSCC. Furthermore, cats may serve as a spontaneous large animal model for human oral cancer, although differences in the regulation of lipogenesis between these 2 species require further investigation.

p16, pRb, and p53 in Feline Oral Squamous Cell Carcinoma

Feline oral squamous cell carcinoma (FOSCC) is a highly aggressive head and neck cancer in cats, but the molecular pathogenesis of this cancer is still uncertain. In this study, p16, p53, and pRb proteins were detected and quantified by immunohistochemistry in forty-three FOSCC primary tumors and three FOSCC xenografts. p16 mRNA levels were also measured in three FOSCC cell lines (SCCF1, F2, and F3), which were consistent with their p16 immunoreactivity. Feline SCCF1 cells had very high levels of p16 protein and mRNA (55-fold greater) compared to SCCF2 and F3. A partial feline p16 cDNA sequence was amplified and sequenced. The average age of cats with FOSCC with high p16 immunoreactivity was significantly lower than the average age in the low p16 group. Eighteen of 43 (42%) FOSCCs had low p16 intensity, while 6/43 (14%) had high p16 immunoreactivity. Feline papillomavirus L1 (major capsid) DNA was not detected in the SCC cell lines or the FOSCCs with high p16 immunostaining. Five of 6 (83%) of the high p16 FOSCC had low p53, but only 1/6 (17%) had low pRb immunoreactivity. In summary, the staining pattern of p16, p53, and pRb in FOSCC was different from human head and neck squamous cell carcinoma and feline cutaneous squamous cell carcinoma. The majority of FOSCCs have low p16 immunostaining intensity, therefore, inactivation of CDKN2A is suspected to play a role in the pathogenesis of FOSCC. A subset of FOSCCs had increased p16 protein, which supports an alternate pathogenesis of cancer in these cats.

Animal models of head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the most common oral cancer worldwide. Local bone invasion into the maxilla or mandible and metastasis to regional lymph nodes often result in a poor prognosis, decreased quality of life and shortened survival time for HNSCC patients. Poor response to treatment and clinical outcomes are the major concerns in this aggressive cancer. Multiple animal models have been developed to replicate spontaneous HNSCC and investigate genetic alterations and novel therapeutic targets. This review provides an overview of HNSCC as well as the traditional animal models used in HNSCC preclinical research. The value and challenges of each in vivo model are discussed. Similarity between HNSCC in humans and cats and the possibility of using spontaneous feline oral squamous cell carcinoma (FOSCC) as a model for HNSCC in translational research are highlighted.

Occupational Exposure to Veterinary Workers from the Positron Emission Tomography Imaging Agent 64Cu-ATSM

Cu-ATSM is an emerging radiopharmaceutical for diagnostic use in positron emission tomography (PET), but to date there are no studies that assess the potential occupational doses to workers in either human or veterinary medicine. This study was aimed at determining the external radiation dose to veterinary workers from clinical PET/CT (PET combined with computed tomography) procedures using Cu-ATSM. To determine the dose to the workers, each worker was assigned two Electronic Personal Dosimeters (EPDs) to be worn on the chest and waist during the entirety of each procedure. The workers monitored during this study included a radiobiologist, a nuclear medicine technologist, an anesthesiologist, and a veterinary surgeon. Seven canine patients were imaged with an average mass of 33.7 kg (a range of 20.0-55.1 kg) with an average injected activity of 5 MBq kg. The dose range for the radiobiologist was 2-17 μSv (mean of 7.1 μSv), for the nuclear medicine technologist 0-14 μSv (mean of 5.6 μSv), for the anesthesiologist 0-12 μSv (mean of 4.0 μSv), and for the surgeon 0-10 μSv (mean of 3.6 μSv). In a comparison between the results of this study and published literature on occupational exposures from veterinary FDG PET/CT procedures, Cu-ATSM veterinary PET/CT procedures, on a per patient bias, exposed workers to less radiation.

Longitudinal tumor hypoxia imaging with [(18)F]FAZA-PET provides early prediction of nanoliposomal irinotecan (nal-IRI) treatment activity

Background

Non-invasive measurement of tumor hypoxia has demonstrated potential for the evaluation of disease progression, as well as prediction and assessment of treatment outcome. [¹⁸F]fluoroazomycin arabinoside (FAZA) positron emission tomography (PET) has been identified as a robust method for quantification of hypoxia both preclinically and clinically. The goal of this investigation was to evaluate the feasibility and value of repeated FAZA-PET imaging to quantify hypoxia in tumors that received multi-dose chemotherapy.

Methods

FAZA-PET imaging was conducted over a 21-day period in a mouse xenograft model of HT-29 human colorectal carcinoma, following multi-dose chemotherapy treatment with irinotecan (CPT-11) or nanoliposomal irinotecan (nal-IRI, MM-398).

Results

Tumors treated with 10 mg/kg nal-IRI maintained significantly lower levels of hypoxia and smaller hypoxic fractions compared to tumors that received 50 mg/kg CPT-11. Specifically, differences in FAZA uptake were detectable 9 days before any significant differences in tumor volume were observed between the treatment groups.

Conclusions

These findings highlight the potential use of FAZA-PET as an early marker of treatment response following multi-dose chemotherapy.

Electronic supplementary material

The online version of this article (doi:10.1186/s13550-015-0135-x) contains supplementary material, which is available to authorized users.

Cats, Cancer and Comparative Oncology

Naturally occurring tumors in dogs are well-established models for several human cancers. Domestic cats share many of the benefits of dogs as a model (spontaneous cancers developing in an immunocompetent animal sharing the same environment as humans, shorter lifespan allowing more rapid trial completion and data collection, lack of standard of care for many cancers allowing evaluation of therapies in treatment-naïve populations), but have not been utilized to the same degree in the One Medicine approach to cancer. There are both challenges and opportunities in feline compared to canine models. This review will discuss three specific tumor types where cats may offer insights into human cancers. Feline oral squamous cell carcinoma is common, shares both clinical and molecular features with human head and neck cancer and is an attractive model for evaluating new therapies. Feline mammary tumors are usually malignant and aggressive, with the ‘triple-negative’ phenotype being more common than in humans, offering an enriched population in which to examine potential targets and treatments. Finally, although there is not an exact corollary in humans, feline injection site sarcoma may be a model for inflammation-driven tumorigenesis, offering opportunities for studying variations in individual susceptibility as well as preventative and therapeutic strategies.

Animal Models of Bone Metastasis

Bone is one of the most common sites of cancer metastasis in humans and is a significant source of morbidity and mortality. Bone metastases are considered incurable and result in pain, pathologic fracture, and decreased quality of life. Animal models of skeletal metastases are essential to improve the understanding of the molecular pathways of cancer metastasis and growth in bone and to develop new therapies to inhibit and prevent bone metastases. The ideal animal model should be clinically relevant, reproducible, and representative of human disease. Currently, an ideal model does not exist; however, understanding the strengths and weaknesses of the available models will lead to proper study design and successful cancer research. This review provides an overview of the current in vivo animal models used in the study of skeletal metastases or local tumor invasion into bone and focuses on mammary and prostate cancer, lymphoma, multiple myeloma, head and neck squamous cell carcinoma, and miscellaneous tumors that metastasize to bone.

Radiometals: towards a new success story in nuclear imaging?

The use of radiometal isotopes in positron emission tomography: a new success story in nuclear imaging?