Need Advice - Treating Cat for Cancer - Fenben?

The vet is not sure, but thinks he may have digestive system cancer. He is eating fine, but has lost weight and shows inflammation in his intestines and has bad gas issues. I feed him very clean food and he doesn't get shots, so it's not those things causing this.

Ive read that Fenben, CBD and Artemisinin could work. Has anyone tried these with success on a cat? I need to know dosage and length of time to give it. Also, can they be given at the same time? Any other treatments?

Any help is deeply appreciated!!!