Spontaneous regression of osteosarcoma in four dogs

A Target Animal Effectiveness Study on Adjuvant Peptide-Based Vaccination in Dogs with Non-Metastatic Appendicular Osteosarcoma Undergoing Amputation and Chemotherapy

Simple Summary

Despite efforts to develop novel treatment strategies, human and canine osteosarcomas continue to have limited overall survival. Spontaneous canine osteosarcoma shares many molecular similarities with humans, and shows the same aggressive disease course, thereby rendering the dog an effective model for the human disease equivalent. In both species, surgery followed by chemotherapy represents the gold standard treatment. Immunotherapy represents a promising treatment modality. A peptide-based anticancer vaccine was administered to 20 dogs with non-metastatic osteosarcoma as an add-on therapy to standard treatment consisting of limb amputation and adjuvant chemotherapy. Endpoints were to evaluate the efficacy and safety of this combined therapeutic approach. By using a bacterial-based strategy for vaccine development, we report an efficacious induction of an immune response, ultimately translating in improved outcome compared with historical controls receiving standard-of-care treatment. The results of this clinical trial provide promising potential for future management in both humans and dogs with osteosarcoma.

Abstract

Despite efforts to develop novel treatment strategies, human and canine osteosarcomas continue to have poor prognosis and limited overall survival. The aim of this clinical trial was to test the antitumor effect and safety of multiple dermal administrations of a peptide-based anticancer vaccine in dogs with non-metastatic appendicular osteosarcoma undergoing standard of care (SOC), consisting of limb amputation and adjuvant chemotherapy. Salmonella-infected canine osteosarcoma cells were induced to release immunogenic peptides in the extracellular space via Cx43 hemichannels opening; the secretome was collected and constituted the vaccine. Dogs with non-metastatic appendicular osteosarcoma were eligible for recruitment. Following limb amputation and adjuvant carboplatin, dogs were vaccinated on a monthly basis for six times and followed up with serial thoracic radiographs. A population of dogs undergoing SOC treatment (amputation and adjuvant carboplatin) before the vaccine was available served as controls. Primary endpoints were time to metastasis (TTM) and tumor-specific survival (TSS). Secondary endpoints were feasibility, toxicity, T-cell and humoral immune responses. A total of 20 dogs were vaccinated along with SOC and 34 received SOC only. Vaccine-specific humoral and T-cell responses were observed; their amplitude correlated with TSS. Vaccine-associated toxicity was not recorded. TTM and TSS were significantly longer in vaccinated versus unvaccinated dogs (TTM: 308 vs. 240 days, respectively; p = 0.010; TSS: 621 vs. 278 days, respectively; p = 0.002). In dogs with non-metastatic osteosarcoma undergoing SOC, the addition of a bacteria-based vaccination strategy increased TTM, thereby prolonging survival, while maintaining a safe profile. Additionally, vaccinated dogs developed a long-term tumor-specific response, as documented by the immunomonitoring of these patients over time. These results hold promise for future management of canine 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.

Adverse events and outcomes in dogs with appendicular osteosarcoma treated with limb amputation and a single subcutaneous infusion of carboplatin

OBJECTIVE

To evaluate adverse events and outcomes in dogs with appendicular osteosarcoma treated with limb amputation followed by a single SC infusion of carboplatin.

ANIMALS

45 client-owned dogs with appendicular osteosarcoma treated with limb amputation and SC infusion of carboplatin between January 1, 2006, and January 15, 2017.

PROCEDURES

Medical records were reviewed, and data collected included signalment, tumor location, treatment, results of clinicopathologic analyses and diagnostic imaging, adverse effects of chemotherapy, metastasis-free interval, survival time, and communications with owners and referring veterinarians. Findings were evaluated with the Kaplan-Meier survival analysis and Mantel-Haenszel log-rank test.

RESULTS

45 dogs were identified that met the inclusion criteria (12 of the 45 dogs had been reported in a previous case series). No dogs had pulmonary metastases detectable by CT or radiography before treatment. All dogs completed the protocol as planned. Median survival time (MST) was 196 days; metastasis-free interval was 197 days. Three of the 45 (7%) dogs required hospitalization for gastrointestinal signs related to chemotherapy. There were no chemotherapy-related deaths.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that although treatment with SC infusion of carboplatin was well tolerated, the MST for dogs in the present study was similar to reported MSTs in dogs with appendicular osteosarcoma treated with limb amputation alone and was in the lower range of historically reported survival times for dogs receiving IV adjunctive chemotherapy. Therefore, we could not recommend this protocol of SC infusion of carboplatin but recommended that protocols with IV administration of carboplatin be used instead.

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.

Spontaneous Regression of a Mandibular Plasmacytoma in a Juvenile Dog: A Case Report

A 4 mo old female Finnish lapphund presented for further investigation of a swelling of the right rostral mandible. A computed tomography scan showed the swelling to be an expansile and osteolytic mandibular lesion. Histopathology revealed a poorly differentiated, moderately well-demarcated, unencapsulated, highly infiltrative round cell neoplasm, and immunohistochemistry was supportive of a plasmacytoma. Performance of a rostral partial mandibulectomy was initially discussed with the owners, but the lesion improved spontaneously both clinically and on repeated computed tomography scanning before surgery could be performed. It subsequently almost completely resolved 6 mo after diagnosis. Hypotheses for spontaneous regression of the lesion are discussed and the human literature is briefly reviewed.

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.

What do we know about canine osteosarcoma treatment? Review

Osteosarcoma (OSA) is the most common type of bone tumors in dogs, which has high metastasis ability. 80 % of dogs with OSA die due to lung metastasis. As a result its treatment is a challenge for veterinary practitioners. The authors discuss the etiology, pathogenesis and the possible risk factors of OSA. The article focuses on literature review and the study of recent advances in OSA treatment. The authors describe therapies which have significantly prolonged the lives of dogs, as well as those that have proven to be ineffective. Advantages and disadvantages of limb amputation and limb-sparing surgery have been described. Authors present also the results of both single agent’s therapies with the most commonly used drugs as cisplatin, carboplatin and doxorubicin and compare them to the results obtained using combined chemotherapy. The use of nanotechnology as a new approach in OSA treatment in order to avoid multidrug resistance and reduce negative side effects of cytostatic drugs is presented. The main reasons of the therapies failure are also provided in this article.

Vitamin d receptor, retinoid x receptor, ki-67, survivin, and ezrin expression in canine osteosarcoma

Canine osteosarcoma (OS) is an aggressive malignant bone tumor. Prognosis is primarily determined by clinical parameters. Vitamin D has been postulated as a novel therapeutic option for many malignancies. Upon activation, vitamin D receptors (VDRs) combine with retinoid receptor (RXR) forming a heterodimer initiating a cascade of events. Vitamin D's antineoplastic activity and its mechanism of action in OS remain to be clearly established. Expression of VDR, RXR, Ki-67, survivin, and ezrin was studied in 33 archived, canine OS specimens. VDR, RXR, survivin, and ezrin were expressed in the majority of cases. There was no statistically significant difference in VDR expression in relationship with tumor grade, type, or locations or animal breed, age, and/or sex. No significant association (p = 0.316) between tumor grade and Ki-67 expression was found; in particular, no difference in Ki-67 expression between grades 2 and 3 OSs was found, while a negative correlation was noted between Ki-67 and VDR expression (ρ = -0.466), a positive correlation between survivin and RXR expression was found (p = 0.374). A significant relationship exists between VDR and RXR expression in OSs and proliferative/apoptosis markers. These results establish a foundation for elucidating mechanisms by which vitamin D induces antineoplastic activity in OS.

Characterization of the biological behaviour of appendicular osteosarcoma in Rottweilers and a comparison with other breeds: a review of 258 dogs

The purpose of this retrospective study was to compare Rottweilers diagnosed with osteosarcoma (OSA) with other breeds to determine whether Rottweilers experienced a more aggressive form of the disease. Two hundred and fifty-eight dogs were evaluated (102 clinical and 156 necropsy cases). In the necropsy population, Rottweilers had a younger mean age at death (7.3 versus 9 years, P = 0.006). There were no significant differences between Rottweilers and other breeds in age at diagnosis, median disease-free interval or survival time. However, Rottweilers were more likely to have metastasis to the brain (7 versus 0%, P = 0.03). These results suggest that OSA in Rottweilers may have a different biological behaviour, but this study did not confirm that these differences were associated with a worse outcome.

Percutaneous arterial embolization and chemoembolization for treatment of benign and malignant tumors in three dogs and a goat

The term bland arterial embolization refers to catheter-directed delivery of particulate material for the purpose of embolizing selected arteries. This technique is used in humans to treat a number of conditions, including arteriovenous malformations, uterine fibroids, and epistaxis. The term chemoembolization refers to selective intra-arterial delivery of chemotherapeutic agents in conjunction with particulate material for the purpose of embolizing arteries supplying blood to a tumor. Compared with traditional modes of drug delivery, chemoembolization increases local concentration and dwell time of the chemotherapeutic agent, augments tumor ischemia, and minimizes systemic toxic effects. In humans, the technique has shown encouraging results in the treatment of a variety of nonresectable tumors. The present report describes techniques for percutaneous bland arterial embolization and chemoembolization in dogs and goats and results of these techniques in 3 dogs and a goat. Bland arterial embolization was performed in 2 dogs and the goat. The goals of treatment included pain palliation, reduction of tumor growth, and control of hemorrhage, and each animal was considered to have benefited from the procedure on the basis of the preprocedural goals. Chemoembolization was performed in 1 dog for treatment of a nonresectable hepatocellular carcinoma. Unfortunately, this dog did not live long enough to identify any response to treatment. Results for animals studied illustrate the feasibility of bland arterial embolization and chemoembolization in veterinary patients and suggest that embolization may provide an alternative method of treatment for animals with inoperable lesions.