Biotechnology firm PharmAust (ASX: PAA) is looking to recruit more canines with B-cell lymphoma to a new phase IIb trial evaluating a re-formulation of its lead anti-cancer drug monepantel, which has been shown to be effective in dogs that have not yet undergone cancer treatment.
The company has previously completed a phase I monepantel trial in humans and a phase II and phase IIa trial in canines with lymphoma, which is currently considered incurable.
The canine trials used a liquid version of monepantel and though there were no safety issues reported, the formula was found to be unpalatable so PharmAust re-designed the drug as a convenient and easy-to-swallow tablet.
Chief scientific officer Dr Richard Mollard said the new formulation resolved the taste issues and allowed for a significant increase in dosage during the phase IIa trial.
“[The tablet allowed us] to identify an optimal dose where anti-cancer activity was maximised,” he said.
“At this dose, one dog’s total tumour burden reduced by over 60% and some of the individual tumours disappeared, all within 14 days [so we will take] this dose into the new Phase IIb trial.”
Safe and effective
Dr Mollard said that while monapantel had been previously approved in a veterinary setting for a different indication and species, the company is seeking to repurpose it as a safe and effective cancer treatment for dogs.
“So far, [our] initial trials on dogs with cancer have been successful,” he said.
“We have been pleased to see that in the first trial using the original liquid formula, six out of seven dogs achieved stable disease over the prescribed 14-day trial period, and [the same proportion] also showed a reduction in their tumour size.”
Veterinary trial centres have already been set up in New South Wales, Queensland and Western Australia to evaluate the drug in dogs which have not yet been exposed to any form of lymphoma treatment.
Additional trial sites in Melbourne and Sydney are expected to start up this quarter.
Canine lymphoma is a relatively common cancer, accounting for up to 20% of new cancer diagnoses in dogs each year.
It is most often found in middle-aged and older dogs and includes symptoms such as swellings (enlarged lymph nodes), lethargy, weight loss and loss of appetite.
Some breeds such as golden retrievers, bullmastiffs and basset hounds can be predisposed to cancer and at greater risk of developing the disease.
Research shows 50% of dogs diagnosed with B cell lymphoma will survive for around 30 days without treatment while 50% will experience a longer-term progression.
Currently, the best indicated treatment option is chemotherapy but even after this treatment, it is not uncommon for a relapse to occur within 12 months.
PharmAust’s phase IIb trial aims to give dog owners a greater choice of treatment options for their sick pet, with the end point being tumour stabilisation or disappearance.
To qualify as a participant in PharmAust’s phase IIb trial, a dog can have any stage of lymphoma but must also be feeling generally well.
Dr Mollard said immunophenotyping – or analysis of whether the cancer is a B cell or T cell type – will be covered as part of the initial screening.
Other eligibility criteria include a body weight of more than 11 kilograms; and a good quality of life, with no other significant and concurrent medical problems.
Owners must be able to transport their dogs to a trial centre and be willing to pay an initial consultation for diagnosis.
Once the pet is diagnosed with lymphoma, PharmAust will cover all clinical trial costs (including travel expenses to and from the trial centre) as well as post-trial maintenance treatment if considered beneficial.
Monepantel tablets will be administered at home and owners will be asked to keep a simple logbook during the trial period.
Pet owners interested in enrolling their dog in the trial should contact their veterinarian for further information and a referral to their nearest trial centre.
Current trial centres are at Animal Referral Hospital (Sydney); WA Veterinary Emergency and Specialty (Success); Perth Veterinary Specialists (Osborne Park); Animal Referral Hospital (Brisbane); and Veterinary Specialist Services (Brisbane).