I can't help but think about ORS, an intervention which killed loads of patients before they dialled in the dose
exactly and it is now considered the greatest medical achievement of the 20th century, saving almost 100 million lives:
https://www.amjmed.com/article/S0002-9343(24)00752-6/fulltext
(if you give cholera patients water: they die, if you give them salty water: they die, if you give them sugar water: they die, if you give strong salty sugar water: they die. But if you give them lightly salty sugar water they sit up, recover, get out of the hospital bed and go home.)
It's frustrating but in biology details matter so if you fail on one dose, sometimes abandoning the drug altogether is the wrong call.