Canine Cancer Treatment

May 12, 2020

Oncology company PharmAust (PAA) has found success in its canine cancer treatment trial.

Pet dogs with naive B cell lymphoma were treated with new monepantel (MPL) tablets.

Six out of seven dogs completed the “at home” treatment with their owners. One dog failed to medicate in accordance with the study and was removed from the trial in the early stages. However, this dog continued with MPL tablets and has now reached over 120 days of treatment with prednisolone added to the treatment regime.

Following 14 days of treatment, veterinarians reported that one dog achieved a partial response with more than 60 per cent reduction in total tumour burden (cancer cells). Additionally, this dog also has one lymph node (neck and head) tumour, which is regressing completely.

Four dogs have achieved stable disease, meaning the tumour is neither growing or shrinking. However, unfortunately, one of the dog’s tumour is continuing to grow.

The results showed that the tablet trial reported better results than the original MPL liquid trial.

“This outcome provides a meaningful trend, comparing favourably with the treatment used in the original “liquid” monepantel formula,” the company said.

After the 14 days of treatment, one dog with progressive disease and another with a partial response but with high liver enzymes discontinued the MPL treatment.

All four remaining dogs completed the 28-day treatment schedule, with all of the pets achieving a stable measured lymph nodes condition. A new lesion became apparent in two of those dogs and some high liver enzymes, though this did not result in clinical illness.

An unexpected outcome from this trial was, at higher dosing levels, the dogs lost appetite and weight, making it hard for owners to get the dogs to take the tables. So, reducing the target dose in future trials is anticipated to result in better outcomes with efficacy, safety and dosing.

Plasma MPL levels were recorded in all dogs and reached levels up to 50 times higher than those recorded in the human trial undertaken at the Royal Adelaide Hospital in 2014/2015.

PharmAust reported that some variability was observed in plasma levels, and unexpectedly, at the lower blood levels of MPL there were better outcomes.

“This observation may be consistent with the mechanism of action of mTOR inhibitors (class of drugs) and lends itself to reducing and optimising the future dosing of monepantel tablets,” the company explained.

The principal investigator overseeing the trial, Dr Claire Cannon, was pleased with the results.

“Monepantel appears to be showing anti-cancer activity in dogs with lymphoma and I believe that controlled phase three trials are now warranted to investigate the efficacy and safety of lower dose monepantel,” she said.

“The phase two trial results suggest that monepantel, perhaps in combination with standard of care lymphoma therapy, may represent a future prospect for treatment of dogs with this disease,” she added.

This trial has provided enough data for further evaluation of this new canine cancer therapy.

Phase two is now on hold while the PharmAust finalises its interim report for Elanco U.S., which will highlight both the efficacy parameters as well as the induction of lack of appetite and higher liver enzymes at very high dosages levels.

Elanco develops innovative products that protect and enhance animal health.

“Having the monepantel tablets achieve a 60 per cent reduction in tumour burden in one dog, with one lymph node returning to normal, is a terrific and unexpected outcome,” CEO Dr Richard Mollard said.

“The correlation of lower MPL blood levels with superior outcomes is also a very positive trend, providing flexibility for better outcomes in a future phase three trial,” he added.