That particular FDA page you linked isn't guidance or a list of official requirements; it's just a general overview of how drugs are developed. In that sense, it's pretty clear that the FDA page is saying that, in general, drugs are only brought to Ph3 after showing signs of efficacy in Ph2 [because sponsors don't want to risk a Ph3 if there are no signs of efficacy]. It's not saying that signs of efficacy are mandated by the FDA before Ph3.
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