Pivotal trial
A pivotal trial, sometimes called a pivotal study, is industry shorthand rather than a regulatory term: it means a trial a company intends to serve as one of the adequate and well-controlled investigations that support an approval decision.
Why it matters here
Because nobody confers the label, in our view the word should be read as a statement of intent and not a status. A sponsor can call a trial pivotal on the day it opens; whether it was adequate and well-controlled is decided afterwards, by a regulator, on the design. That gap is where a reader gets value. The questions worth asking of any trial described as pivotal are what it was controlled against, whether the comparison was concurrent, and whether the primary endpoint was fixed before anyone was unblinded. Two trials can both be called pivotal and answer different questions, and when they do, netting their numbers together produces a figure that describes nothing.
The United States regulation behind the word does not use it. 21 CFR 314.126(a) says: "The purpose of conducting clinical investigations of a drug is to distinguish the effect of a drug from other influences, such as spontaneous change in the course of the disease, placebo effect, or biased observation... Reports of adequate and well-controlled investigations provide the primary basis for determining whether there is 'substantial evidence' to support the claims of effectiveness for new drugs." (eCFR.) The same regulation lists the acceptable control types, which include a placebo concurrent control and a dose-comparison concurrent control. Both are legitimate. They do not support the same claim.
That distinction is not theoretical here. In Issue 6 we separated Compass's two Phase 3 trials: "COMP005 is the placebo-controlled pivotal, a 3.6-point MADRS separation against an inert placebo. COMP006, the one that just read out at six months, is a dose comparison." We called the design "defensible, even clever, because a fixed inert placebo makes unblinding trivial in a drug patients can plainly feel", and then said what it costs: "it changes what 'confirmed' means."
We have used the word in its ordinary industry sense throughout, including in Issue 3, Issue 4 and Issue 11, where the brenipatide depression pivotals are described by their own official titles as adjunctive treatment.