I don’t know how fast it works. According to their posts (I feel really creepy reading their history), their first round of chemo was started around Dec 23 2022. On Dec 30th they reported that their tumor has shrunken 1/3 since the first round. By Feb 3 of 2023 they had completed three rounds of treatment.
On April 15th they reported that tumor was no longer growing and thus the tumor was beaten.
16 months before this incident, they had another kind of cancer. So it is infuriating that their doctors didn’t run tests till it was almost too late. They state they are Germany, so maybe the doctors there are extra conservative with running test.