Recent clinical trials of cancer immunogene therapy in companion animals

From Conventional to Precision Therapy in Canine Mammary Cancer: A Comprehensive Review

Canine mammary tumors (CMTs) are the most common neoplasm in intact female dogs. Canine mammary cancer (CMC) represents 50% of CMTs, and besides surgery, which is the elective treatment, additional targeted and non-targeted therapies could offer benefits in terms of survival to these patients. Also, CMC is considered a good spontaneous intermediate animal model for the research of human breast cancer (HBC), and therefore, the study of new treatments for CMC is a promising field in comparative oncology. Dogs with CMC have a comparable disease, an intact immune system, and a much shorter life span, which allows the achievement of results in a relatively short time. Besides conventional chemotherapy, innovative therapies have a large niche of opportunities. In this article, a comprehensive review of the current research in adjuvant therapies for CMC is conducted to gather available information and evaluate the perspectives. Firstly, updates are provided on the clinical-pathological approach and the use of conventional therapies, to delve later into precision therapies against therapeutic targets such as hormone receptors, tyrosine kinase receptors, p53 tumor suppressor gene, cyclooxygenases, the signaling pathways involved in epithelial-mesenchymal transition, and immunotherapy in different approaches. A comparison of the different investigations on targeted therapies in HBC is also carried out. In the last years, the increasing number of basic research studies of new promising therapeutic agents on CMC cell lines and CMC mouse xenografts is outstanding. As the main conclusion of this review, the lack of effort to bring the in vitro studies into the field of applied clinical research emerges. There is a great need for well-planned large prospective randomized clinical trials in dogs with CMC to obtain valid results for both species, humans and dogs, on the use of new therapies. Following the One Health concept, human and veterinary oncology will have to join forces to take advantage of both the economic and technological resources that are invested in HBC research, together with the innumerable advantages of dogs with CMC as a spontaneous animal model.

Improving human cancer therapy through the evaluation of pet dogs

Comparative oncology clinical trials play an important and growing role in cancer research and drug development efforts. These trials, typically conducted in companion (pet) dogs, allow assessment of novel anticancer agents and combination therapies in a veterinary clinical setting that supports serial biologic sample collections and exploration of dose, schedule and corresponding pharmacokinetic/pharmacodynamic relationships. Further, an intact immune system and natural co-evolution of tumour and microenvironment support exploration of novel immunotherapeutic strategies. Substantial improvements in our collective understanding of the molecular landscape of canine cancers have occurred in the past 10 years, facilitating translational research and supporting the inclusion of comparative studies in drug development. The value of the approach is demonstrated in various clinical trial settings, including single-agent or combination response rates, inhibition of metastatic progression and randomized comparison of multiple agents in a head-to-head fashion. Such comparative oncology studies have been purposefully included in the developmental plan for several US FDA-approved and up-and-coming anticancer drugs. Challenges for this field include keeping pace with technology and data dissemination/harmonization, improving annotation of the canine genome and immune system, and generation of canine-specific validated reagents to support integration of correlative biology within clinical trial efforts.

Proliferation index and pseudoprogression as predictors of the therapeutic efficacy of suicide gene therapy for canine melanoma

In our veterinary clinical trials, the combination of systemic immunotherapy with local herpes simplex virus thymidine kinase/ganciclovir suicide gene (SG) treatment induced tumor pseudoprogression as part of a strong local antitumor response. This phenomenon could be owing to tumor inflammation, increased vascular permeability and to different tumor growth rates before, during and after SG therapy. The proliferation index (PI: the fraction of viable cells in S, G2/M, and hyperdiploid phases) would reflect the in-vivo and in-vitro proportion of proliferating melanoma cells in the absence of treatment (PIB) or in response to SG (PISG). The extent of in-vivo and in-vitro melanoma cells responses to SG exhibited a reverse correlation with PIB and a direct correlation with PISG. Then, the final SG outcome depended on the balance between PIB-dependent 'regrowth resistance' versus 'regrowth sensitivity' to SG treatment. In all the cell lines derived from canine tumors presenting partial responses to SG treatment, PISG prevailed over PIB. Conversely, as more aggressive was the tumor (greater PIB of the cell line), the more the balance displacement towards 'regrowth resistance' over SG 'regrowth sensitivity'. All these parameters could have a prognostic value for SG treatment response and provide a glimpse at the clinical benefit of this therapy.

Exosomes as Biomarkers of Human and Feline Mammary Tumours; A Comparative Medicine Approach to Unravelling the Aggressiveness of TNBC

Comparative oncology is defined as the discipline that integrates naturally occurring cancers seen in veterinary medicine, into more general studies of cancer biology and therapy in humans, including the study of cancer-pathogenesis and new cancer treatments. While experimental studies in mice and rodents offer several advantages, including a wealth of genetic information, reduced variation and short generation intervals, their relevance in cancer biology is somewhat limited. Toward this end, as the biomedical research community works to make the promise of precision medicine a reality, more efficient animal cohort studies are critical. Like humans, companion animals such as cats and dogs living in family homes, are exposed to environmental factors that may influence the development of disease. Furthermore, it has been shown that the basic biochemical and physiological processes of companion animals more closely resemble humans compared to rodents. Research has demonstrated that female domestic cats (Felis catus) may represent a comparative model for investigation of mammary carcinogenesis, and in particular, Triple Negative Breast Cancer (TNBC). TNBC is a subtype of breast cancer that typically lacks the expression of the oestrogen receptor (ER), progesterone receptor (PR), and does not overexpress the human epidermal growth factor receptor 2 (HER2). An exciting and rapidly expanding area in cancer biology is the study of exosomes. Exosomes are nanoparticles released from cells and have been found in biological fluids of humans, domestic cats and dogs. In addition to their role as biomarkers, exosomes are implicated in the pathogenesis of certain diseases, including cancer. This review explores the current understanding of exosome biology in human TNBC, and of the potential benefits of comparative research in naturally-occurring mammary tumours in companion animals.

Cytokine Expression in Canine Lymphoma, Osteosarcoma, Mammary Gland Tumour and Melanoma: Comparative Aspects

Cytokines released in the tumour microenvironment play a major role in cancer pathogenesis. In human cancers and corresponding animal models, cytokine expression contributes to tumour growth and progression, as well as regulation of the host anti-tumour response. The elucidation of the function and importance of cytokines in canine cancers is still in an early stage, although relevant data have been obtained in classical examples of comparative models of human cancers, such as osteosarcoma, melanoma, mammary tumour and lymphoma. A deeper understanding of the cytokine signature may advance diagnosis, prevention and treatment of canine cancers.

Combination of cytokine-enhanced vaccine and chemo-gene therapy as surgery adjuvant treatments for spontaneous canine melanoma

After 6 years of follow-up treating 364 canine melanoma patients, we present here results about the proof-of-concept, safety, and efficacy of a new surgery adjuvant combined gene therapy. The adjuvant treatment (AT) group was divided in three arms as follows: (i) complete surgery plus vaccine (CS-V), (ii) complete surgery plus combined treatment (CS-CT), and (iii) partial surgery plus combined treatment (PS-CT). Besides the genetic vaccines composed by tumor extracts and lipoplexes carrying human interleukin-2 and granulocyte-macrophage colony-stimulating factor genes, the patients were subjected to combined treatment received in the post-surgical bed injections of lipid-complexed thymidine kinase suicide gene plus ganciclovir and canine interferon-β gene plus bleomycin. As compared with surgery-only treated controls (So), CS-CT and CS-V treatments significantly increased the fraction of local disease-free (from 20 to 89 and 74%) and distant metastases-free patients (M0: from 45 to 87 and 84%). Although less effective than CS arms, PS-CT arm demonstrated a significantly improved control of metastatic disease (M0: 80%) compared with So (M0: 44%). In addition, AT produced a significant 9.3- (CS-CT), 6.5- (CS-V), and 5.4-fold (PS-CT) increase of overall survival as compared with their respective So controls. In general terms, the AT changed a lethal disease into a chronic disease where 70% of CS-CT, 51% of CS-V, and 14% of PS-CT patients died of melanoma unrelated causes. These surgery adjuvant treatments delayed or prevented post-surgical recurrence and distant metastasis, and improved disease-free and overall survival while maintaining quality of life. These successful outcomes encourage assaying a similar scheme for human melanoma.

A Review of Immunotherapeutic Strategies in Canine Malignant Melanoma

In dogs, melanomas are relatively common tumors and the most common form of oral malignancy. Biological behavior is highly variable, usually aggressive, and frequently metastatic, with reported survival times of three months for oral or mucosal melanomas in advanced disease stages. Classical clinical management remains challenging; thus, novel and more efficacious treatment strategies are needed. Evidence-based medicine supports the role of the immune system to treat neoplastic diseases. Besides, immunotherapy offers the possibility of a precise medicinal approach to treat cancer. In recent years, multiple immunotherapeutic strategies have been developed, and are now recognized as a pillar of treatment. In addition, dogs represent a good model for translational medicine purposes. This review will cover the most relevant immunotherapeutic strategies for the treatment of canine malignant melanoma, divided among five different categories, namely, monoclonal antibodies, nonspecific immunotherapy activated by bacteria, vaccines, gene therapy, and lymphokine-activated killer cell therapy.

Concise Review: Canine Diabetes Mellitus as a Translational Model for Innovative Regenerative Medicine Approaches

Diabetes mellitus (DM) is a common spontaneous endocrine disorder in dogs, which is defined by persistent hyperglycemia and insulin deficiency. Like type 1 diabetes (T1D) in people, canine DM is a complex and multifactorial disease in which genomic and epigenomic factors interact with environmental cues to induce pancreatic β‐cell loss and insulin deficiency, although the pathogenesis of canine DM is poorly defined and the role of autoimmunity is further controversial. Both diseases are incurable and require life‐long exogenous insulin therapy to maintain glucose homeostasis. Human pancreatic islet physiology, size, and cellular composition is further mirrored by canine islets. Although pancreatic or isolated islets transplantation are the only clinically validated methods to achieve long‐term normoglycemia and insulin independence, their availability does not meet the clinical need; they target a small portion of patients and have significant potential adverse effects. Therefore, providing a new source for β‐cell replacement is an unmet need. Naturally occurring DM in pet dogs, as a translational platform, is an untapped resource for various regenerative medicine applications that may offer some unique advantages given dogs' large size, longevity, heterogenic genetic background, similarity to human physiology and pathology, and long‐term clinical management. In this review, we outline different strategies for curative approaches, animal models used, and consider the value of canine DM as a translational animal/disease model for T1D in people. stem cells translational medicine2019;8:450–455

Perspectives for cancer immunotherapy mediated by p19Arf plus interferon-beta gene transfer

While cancer immunotherapy has gained much deserved attention in recent years, many areas regarding the optimization of such modalities remain unexplored, including the development of novel approaches and the strategic combination of therapies that target multiple aspects of the cancer-immunity cycle. Our own work involves the use of gene transfer technology to promote cell death and immune stimulation. Such immunogenic cell death, mediated by the combined transfer of the alternate reading frame (p14ARF in humans and p19Arf in mice) and the interferon-β cDNA in our case, was shown to promote an antitumor immune response in mouse models of melanoma and lung carcinoma. With these encouraging results, we are now setting out on the road toward translational and preclinical development of our novel immunotherapeutic approach. Here, we outline the perspectives and challenges that we face, including the use of human tumor and immune cells to verify the response seen in mouse models and the incorporation of clinically relevant models, such as patient-derived xenografts and spontaneous tumors in animals. In addition, we seek to combine our immunotherapeutic approach with other treatments, such as chemotherapy or checkpoint blockade, with the goal of reducing dosage and increasing efficacy. The success of any translational research requires the cooperation of a multidisciplinary team of professionals involved in laboratory and clinical research, a relationship that is fostered at the Cancer Institute of Sao Paulo.

Combination of Suicide and Cytokine Gene Therapies as Surgery Adjuvant for Canine Mammary Carcinoma

The incidence of canine mammary carcinoma varies with age, breed, and spay status, being among the main tumors appearing in intact female dogs. Thirty-six canine mammary carcinoma patients received injections of canine interferon-β (cIFN-β) and HSV-thymidine kinase/ganciclovir (HSV-tk/GCV) carrying lipoplexes, into the tumor bed, immediately after surgery. Next, they started periodic subcutaneous injections of lipoplexes carrying a human granulocyte-macrophage colony stimulating factor and interleukin-2 mixed with allogeneic mammary carcinoma extracts. This combined strategy was safe and well tolerated. In addition, only two out of 26 patients treated with complete surgery developed a local relapse, and 0 out of 29 stage II and III patients displayed distant metastases, suggesting both local and systemic antitumor activities. The most encouraging result was the long survival times: 22 > 1 year (where 13 > 2 and 4 > 3 years), while maintaining a good quality of life. The preliminary results in five patients presenting with local disease, an additional HSV-tk/GCV plus cIFN-β gene treatment induced local antitumor activity, evidenced by four objective responses (one complete, three partial) and one stable disease. This successful outcome supports further studies to validate this approach not only for canine veterinary patients, but also for translation to human patients.

Metazoan Parasite Vaccines: Present Status and Future Prospects

Eukaryotic parasites and pathogens continue to cause some of the most detrimental and difficult to treat diseases (or disease states) in both humans and animals, while also continuously expanding into non-endemic countries. Combined with the ever growing number of reports on drug-resistance and the lack of effective treatment programs for many metazoan diseases, the impact that these organisms will have on quality of life remain a global challenge. Vaccination as an effective prophylactic treatment has been demonstrated for well over 200 years for bacterial and viral diseases. From the earliest variolation procedures to the cutting edge technologies employed today, many protective preparations have been successfully developed for use in both medical and veterinary applications. In spite of the successes of these applications in the discovery of subunit vaccines against prokaryotic pathogens, not many targets have been successfully developed into vaccines directed against metazoan parasites. With the current increase in -omics technologies and metadata for eukaryotic parasites, target discovery for vaccine development can be expedited. However, a good understanding of the host/vector/pathogen interface is needed to understand the underlying biological, biochemical and immunological components that will confer a protective response in the host animal. Therefore, systems biology is rapidly coming of age in the pursuit of effective parasite vaccines. Despite the difficulties, a number of approaches have been developed and applied to parasitic helminths and arthropods. This review will focus on key aspects of vaccine development that require attention in the battle against these metazoan parasites, as well as successes in the field of vaccine development for helminthiases and ectoparasites. Lastly, we propose future direction of applying successes in pursuit of next generation vaccines.

Craniomaxillofacial Disorders and Solutions in Humans and Animals

Cross-disciplinary collaborations have initiated translational studies in an effort to harness naturally occurring diseases in companion animals to accelerate the development of new treatment modalities, drugs, and device inventions. These synergistic collaborations can identify clinically relevant models that offer the opportunity to conduct rigorous translational investigations. However, the relationship between craniomaxillofacial diseases in companion animals and humans has been widely overlooked. We report here an innovative and visionary 2-d symposium that was organized to gather professionals working on craniomaxillofacial disorders and solutions in humans and/or animals from multiple disciplines, including veterinary physicians, basic scientists, biomedical engineers, physicians, and dentists. The symposium provided a platform for junior and senior investigators and basic science and clinical researchers to network, collaborate, and develop a new clinical and translational framework for accelerated therapy development.

Therapeutic potential of bleomycin plus suicide or interferon-β gene transfer combination for spontaneous feline and canine melanoma

We originated and characterized melanoma cell lines derived from tumors of two feline and two canine veterinary patients. These lines reestablished the morphology, physiology and cell heterogeneity of their respective parental tumors. We evaluated the cytotoxicity of bleomycin (BLM) alone, or combined with interferon-β (IFN-β) or HSVtk/GCV suicide gene (SG) lipofection on these cells. Although the four animals presented stage III disease (WHO system), SG treated feline tumors displayed stable disease in vivo, while the canine ones exhibited partial response. Their derived cell lines reflected this behavior. Feline were significantly more sensitive than canine cells to IFN-β gene transfer. BLM improved the antitumor effects of both genes. The higher levels of reactive oxygen species (ROS) significantly correlated with membrane and DNA damages, emphasizing ROS intervention in apoptotic and necrotic cell death. After 3 days of BLM alone or combined with gene treatments, the colony forming capacity of two canine and one feline treatments survivor cells almost disappeared. Taken together, these results suggest that the treatments eradicated tumor initiating cells and support the clinical potential of the tested combinations.