If Kevetrin is not introducing poisons into the bo

If Kevetrin is not introducing poisons into the body as prior cancer treatments had to do to be effective what about it caused side effects at higher dosage levels in test animals?  Playing devil's advocate, as it seems side effects are about the only possible worry most have for the trials, if they do find adverse effects can the molecule be altered to make it easier to tolerate should that become necessary?  Maybe as they keep learning more about it they will be able to make it stronger in potency without any increase in side effects.

Not really worried about the side effects, just trying to learn more about Kevetrin, if such info is even available at the current time.