Ann: PD1-Vaxx Presentation at ESMO Congress 2021 Annual Meeting, page-39

It's not the ASX, its the company: https://www.claytonutz.com/knowledge/2018/july/is-your-announcement-market-sensitive

And while the ASX supposedly has "ultimate responsibility" for assessing the market-sensitivity of an announcement, I don't think the ASX actually reads any announcements much less assesses them for sensitivity (seriously). It doesn't have the staff given the number of daily announcements. For example - I've seen plenty of director and substantial shareholder change-in-holding notices provided many months after they are due, without any "please explain" from the ASX (eg have a look at TNY 7/9/21).

There is no way that IMU would have indicated that this announcement is sensitive, only for the ASX to downgrade it.

Why does IMU not believe that this announcement is price sensitive? Probably because first dosing of cohort 3 was expected some time ago, so its not really unexpected news - although you could probably argue that the expanded study is "new" news ...