Thanks for the clarification.

But I believe they do need some reasonable belief that it is not only not harmful but actually beneficial to continue a cohort with dosing once they have finished. Otherwise that cohort should be finished. -TOB

Continuation of treatment to first cohort is commonly allowed if no evidence of toxicity exists. Continuation does not indicate efficacy, just lack of toxicity. Do no harm. Hope alone can extend lifespan. The FDA knows this and thus allows patients to continue treatment beyond their initial cohort phase if the drug is well tolerated. -seel

So if there is no harm being done the cohort can routinely continue dosing just based upon the benefit of the hope it brings, the placebo effect.

I had wondered about this, if the doctor had the ability to continue on this basis as pulling away the last hope from a dying patient can be harmful in itself. I've seen patients with increased 'will to live' based upon some 'alternative' treatment where just their belief in a treatment was the benefit. (Or maybe it really was the treatment, but the psychological change is definitely observable, from no hope from a grim prognosis with no treatment options to hope.)

Good to know the rug isn't being pulled from under those patients, but we can't read efficacy into that PR beyond the psychological/placebo benefit.