Ann: Imugene HER-Vaxx Phase 2 PFS Data and Flags Three New Trials, page-339

If you examine the poster from the conference presentation you'll see tick marks in the Kaplan-Meier plot. Each tick mark represents a censored event which means the patient left the trial. For stats purposes a pt that leaves is considered to have survived. Notice that each vertical step gets larger and larger as more and more patients get censored. I suspect (just my opinion) that the trial in now underpowered and the primary endpoint won't meet statistical significance. The p value must be below 0.05 for statistical significance.
Cheers.