A new kind of targeted therapy to treat head and neck cancer in cats could hold the key to developing similar treatments in humans, according to a new study.
Head and neck squamous cell carcinoma (HNSCC) is a notoriously deadly and difficult-to-treat cancer in cats and humans.
Now, a small trial including 20 cats with this cancer suggests companion animals could be better models than mice to test drugs for the condition in humans.
Researchers found in the trial that over a third of the cats who received treatment had their disease controlled with minimal side effects, with results indicating the drug could be effective for humans with HNSCC as well.
In the study, scientists tested a first-of-its-kind drug initially conceptualised to treat human head and neck cancers.
It is the first to target the molecule STAT3, which controls the expression of some genes and is present in a range of both solid and liquid tumours, including HNSCC cases.
Cancers like HNSCC are known to be extremely difficult to treat in pet cats and most animals with the condition die within 2 to 3 months of diagnosis.
One cat from the trial was a 9-year-old black domestic shorthair named Jak, who was initially given only 6 to 8 weeks to live after diagnosis.
After weekly treatments for one month, researchers found that his symptoms – mainly, a watery eye – greatly improved, and he ultimately lived more than 8 months after diagnosis.
“During that time, my son finished college and my daughter finished her master’s programme. Jak got to spend one more Christmas with us, and he loved our Christmas tree. He was worth every bit of the effort,” said Tina Thomas, the cat’s human companion.
Of the 20 cats that were enrolled, researchers observed that seven of them showed either a partial response or stable disease during the study period.
The seven that responded to treatment had an average survival post-treatment of 161 days, according to the study.
“There are two major findings from this study,” explains study co-author Daniel Johnson of the University of California, San Francisco.
Firstly, it shows that it’s possible to target molecules behind gene expression called transcription factors that are behind the rise of cancer.
“This is something that has been notoriously difficult in the past,” Dr Johnson says.
“Also, it demonstrated that pets with cancer can be a good representation of human disease and that clinical trials in pets may yield more reliable results than tests in mouse models,” he adds.
Scientists found that the drug molecule worked by blocking the activity of STAT3 and increasing the levels of PD-1, a protein associated with an immune response to cancer.
“This study is a great example of how we can think more carefully about spending our very limited resources on studies in lab mice that are not even the best models of human cancers,” said Jennifer Grandis, another author of the study.
“By partnering with veterinary oncologists and doing clinical trials in companion animals, we can learn an enormous amount about how these drugs work while also helping people’s pets. None of the cats in these trials were harmed, and many of them benefited,” Dr Grandis said.
