Osteosarcoma (OS) is the most common primary bone tumor diagnosed in dogs.
Appendicular skeletal OS, the most frequent form of this disease (80%), is typically seen in large to giant breeds of dogs and most commonly presents with bone swelling and lameness.
Our understanding of the underlying causes for OS development in dogs is rapidly expanding through genet-ic studies. Unfortunately, the discovery, development, and availability of newer treatment options remain limited. Current standard of care for dogs with OS remains a two-pronged approach: surgical resection of the affected bone tumor, followed by systemic therapy with carboplatin to delay the spread and development of metastases. New treatment options are needed to improve the long-term outcome for dogs diagnosed with OS.
The vast majority of dogs with OS that present for bone pain and lameness will already have microscopic metastases throughout their body, most commonly within the lungs. These small clusters of OS cells are too small to be detected by conventional imaging methods, including digital radiographs and computed tomography.
Despite their clinically undetectable nature, proactive management of these microscopic metastases is critical for improving long-term survival of dogs with OS. The presence of detectable meta-static lesions at the time of diagnosis is a recognized poor prognostic factor, and dogs that have visible metastases on chest X-rays generally do not respond to standard chemotherapy. For these reasons, early and proactive treatment of dogs with presumed microscopic OS cells through-out their body is essential for achieving best outcomes.
Fighting Microscopic Osteosarcoma Metastases
In the era of precision medicine (i.e., small molecule inhibitors) and immunotherapy, the options for fighting microscopic OS metastases have expanded considerably. Whether these novel adjuvant treatments can actually increase quality and quantity of life for dogs with OS, however, remains to be proven through well-conducted clinical trials.
At the University of Illinois Urbana-Champaign, the clinical trials team at the Veterinary Teaching Hospital has been pioneering newer forms of immunotherapy for combatting OS metastases through collaborations with renowned scientists and human oncologists across the United States. Not only might these cutting-edge treatments improve treatment outcomes in pet dogs, but they are also being used to guide the development of the same technologies for helping children diagnosed with OS.
Some of the ongoing clinical trials with newer immunotherapy approaches to fight microscopic and macroscopic metastatic OS cells within the lungs include:
- Adoptive cellular therapy with intravenous infusion of genetically engineered T cells (CAR T cells) combined with an oral drug to maintain immune activation (for microscopic metastases)
- Radiation therapy combined with intratumoral injection of interleukin-12 to systemically activate T cells to fight developing lung metastases (for microscopic metastases)
- Intravenous infusion of a lipid nanoparticle small molecule (Z-007) that stimulates the immune system to fight existing OS lung metastases (for established macroscopic metastases)
Referring veterinarians and pet owners can view current oncology trials at: go.vetmed.illinois.edu/OncoTrials
For oncology referrals or questions regarding clinical trial eligibility, please contact the oncology clinical trials team at oncology@illinois.edu or call 217-300-6453.
By Timothy M. Fan, DVM, PhD, DACVIM (Oncology, Small Animal Internal Medicine)
