Lattice Radiation Therapy Delays Progression and Extends Survival for Dogs with Macroscopic Soft Tissue Sarcoma

Area of Science:

• Veterinary Oncology
• Radiation Oncology
• Immunotherapy

Background:

• Soft tissue sarcomas are common in dogs, sharing similarities with human tumors.
• Spatially fractionated radiotherapy, like Lattice radiation therapy, allows for dose-escalated treatment of large tumors.
• Lattice radiation therapy has shown potential for increased response rates and immune induction.

Purpose of the Study:

• To evaluate the safety and efficacy of Lattice radiation therapy versus palliative radiotherapy in dogs with soft tissue sarcomas.
• To assess the impact of Lattice radiation therapy on local tumor control, overall survival, and immune response.

Main Methods:

• Prospective randomized trial involving seven dogs with soft tissue sarcomas.
• Dogs were assigned to either palliative radiotherapy (20 Gy in 5 fractions) or Lattice radiation therapy (20 Gy to 95% PTV with simultaneous integrated boost).
• Tumor biopsies and peripheral blood mononuclear cell collections were performed pre-treatment and post-treatment for immune analysis using the Nanostring Canine IO panel.

Main Results:

• Lattice radiation therapy achieved a 50% overall response rate with no local tumor progression observed.
• In contrast, 100% of dogs in the palliative group experienced local tumor progression.
• Median overall survival was significantly longer in the Lattice group (436 days) compared to the palliative group (194 days).

Conclusions:

• Lattice radiation therapy is safe and effective for dogs with large sarcomas, offering improved local control and survival over palliative radiotherapy.
• This canine model demonstrates the potential of Lattice radiation therapy to enhance anti-tumor immunity.
• Findings support the use of dogs with naturally occurring tumors as translational models for spatial fractionation approaches in oncology.