Abemaciclib is a well-known CDK4/6 inhibitor. Although it is known to be an effective treatment for breast cancer, its action against other forms of cancer has not been determined. Canine malignant melanoma is a common cancer in dogs and is quite aggressive. It is thought that targeting the same CDK4/6 pathway may be effective in this type of cancer too.
In Vitro Testing
Recently, a research team at Seoul National University tested this possibility. They tested five canine malignant melanoma cell lines with a wound healing assay and vacuolization inhibition determination. The cells were treated with various levels of abemaciclib or a combination of abemaciclib and fenbendazole together. Of these five cell lines, the one with highest sensitivity and synergistic response to the treatments was selected for further in vivo study.
In Vivo Testing
For the in vivo study, a mouse model was first inoculated with the most responsive cell line, UCDK9M5, and the tumor allowed to develop to a standard size. Then, the treatment was administered by oral gavage once a day for 13 days. The tumor size was measured throughout the duration of the experiment.
Results
The results showed that this type of treatment was both effective and well-tolerated. The combined treatment possibly showed a synergistic effect. Further research will be needed to confirm it. These chemicals are both cell cycle inhibitors, but each targets a different phase, so together they have the potential to be more powerful.
Further research on treatment of canine melanoma may benefit both dogs and humans. Malignant melanoma remains fatal in both animals, and canine melanomas hold a unique value as a translational model.
As found by comparative oncology, canine melanomas turn out to be close models for human melanomas. This is particularly useful because several rare human melanoma subtypes have canine counterparts that are frequently observed naturally occurring in dogs. Therefore, developing treatment for a type of cancer in dogs that is rather common may translate well as treatment for what is a rare cancer in humans.
Kim S, Choi J, Suh Y, et al. Abemaciclib induces G1 arrest and lysosomal dysfunction in canine melanoma cells: synergistic effects with fenbendazole. Front Vet Sci. 2025 Jun 26:12:1603686. PMID: 40642276