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Research Highlight | June 03, 2022

New clinical trial in dogs seeks to test innovative “seek and destroy” treatment that could bring new hope to pets and people with cancer

A nanoparticle developed by TFRI-funded researchers is being used for the first time as part of an innovative clinical trial in dogs that could pave the way for a new “seek and destroy” cancer treatment for pets and people. 

The clinical trials, which are taking place at the University of Guelph’s Ontario Veterinary College (OVC), combine these nanoparticles, also known as porphysomes, with laser light therapy. While the trial focuses on dogs with thyroid cancer, if successful, it would help demonstrate the ability to use this new combination as a targeted, non-surgical way to diagnose and treat tumours in humans and other animals.

“This is such an exciting opportunity to have an impact on how cancer is treated in both humans and pets, and to be involved in such an incredibly innovative idea and invention,” said Dr. Michelle Oblak, a veterinary surgeon oncologist and professor at University of Guelph’s  Department of Clinical Studies, who is leading the trial. “It’s motivating for us to continue the work we’re doing. This could change the way we treat and diagnose cancer in the future.”

Dr. Oblak’s team plans to recruit 10 canine patients for this year’s clinical trial. The first trial occurred in late February with a 10-year-old beagle named Shiloh.

Porphysomes pinpoint tumour location, make tissue vulnerable to laser

Porphysomes are a type of light-sensitive nanoparticle created by a Terry Fox New Frontiers Program Project Grant team led by Dr. Gang Zheng at the Princess Margaret Cancer Centre in Toronto.

As part of this clinical trial, the OVC team injects the porphysomes into the bloodstream. The nanoparticles then collect in the tumour or any spot where the cancer may have spread. The light-activated molecule’s fluorescent glow allows the team to track its location using a special light source.

Besides pinpointing the tumour’s whereabouts, the porphysomes make the tissue more vulnerable to damage from laser light. A beam of near-infrared laser light directed through a nano-fibre activates the porphysome, which then destroys cancerous tissue. The use of light to kill cancer cells is known as photodynamic therapy (PDT).

For the clinical trial, the team is using PDT to destroy only a portion of the tumour, then taking samples of the tumour and lymph nodes to assess results of the therapy. Patients in the trial still undergo standard-of-care surgery to remove the entire tumour.

Oblak said photodynamic therapy is less invasive than surgery and targets the tumour cleanly without harming normal tissue. The technology also avoids harmful side effects, including neck scarring and nerve damage that may affect the voice. Although these concerns are more prevalent in human patients, pet owners seeking minimally invasive treatment options may view this technology as beneficial for their pets.

“There’s a lot of interest in this as a non-surgical option,” said Oblak. “This could really revolutionize many different aspects of cancer treatment and diagnosis.”

Dr. Gang Zheng and his team have already tested the technology in rodent and rabbit cancer models during preclinical trials. Pending Health Canada approval and OVC’s results, the team hopes to begin a human clinical trial with the technology later this year or in early 2023.

This story is based on a press release provided by the University of Guelph. Read the original release here. Photo: Miya wears doggles following a porphysome infusion (Credit: University of Guelph)