Ann: Dimerix Successfully Passes Efficacy Interim Analysis, page-154

Not the full statistical plan. However it could be something along the lines like the snapshot at the end, taken from a trial design paper for a current study in FSGS called ClopiD4FSGS which can be found online. They disclose the futility threshold based on proteinuria and what will lead them to make a call on whether the trial is futile or not. That shows real transparency without biasing or affecting integrity of trial. You're right, no law that says DMX has to divulge the futility threshold they chose and I doubt 99% of investors or ASX would care. More a question of why wouldn't you disclose it if you're confident you can explain/defend it.
all a bit moot though as this futility interim was based on an surrogate which isn't the final endpoint anyway. that is GFR slope and I'd suggest this drug will stand or fall on what it does to that, not proteinuria.