If history is any guide, there's no reason to think the
failure of Targacept
Inc. and AstraZeneca
plc's first flexible-dose Phase III trial of TC-5214 automatically
means the program is dead. However, the partners probably will have to succeed
in two of the remaining three depression trials to have a shot at approval. Two
of those are fixed-dose studies - which some data suggest are less likely than
flexible-dose studies to succeed.
Even among drugs that prove to
be effective, subjective entry criteria and endpoints plus high placebo
response rates in major depressive disorder (MDD) trials lead to high failure
rates.