Try this
Working only with the number of patients in the group receiving the drug,

vary the number of patients in the red and green boxes separately, exploring the entire range of number of patients;

vary the number of patients in the red and green boxes, but keep the proportions fixed; e.g. for every patient added to the red box, add two to the green box;

swap the number of patients in the red and green boxes.
Keep a close look at how the probability of cure changes with the changing number of patients in the red and green boxes.
Working with the number of patients in both groups,

vary the number of patients in each group separately, using the same number of patients in the red and green boxes within each group;

vary only the number of patients in the green box for the placebo group, keeping the number of patients in the remaining three boxes fixed.
This time, look at how the belief about the effectiveness of the drug is changing. Note that we do not distinguish between a positive and a negative effect; a drug that lowers the probability of cure clearly has an effect, albeit undesirable.