You must be confusing the Australian FDA with the US FDA.
" In addition, since 1971, the FDA has required that all proposed clinical studies be reviewed by an institutional review board. Technically, unless otherwise notified, the sponsor can begin clinical studies within thirty days (if the IRB approves). The FDA can, however, terminate an IND at any time; thus in practice the FDA must approve the IND proposal. The IND stage of drug approval is broken into three phases. The FDA exerts considerable control over all phases of the clinical trial process, and at any stage the FDA can and often does request additional clinical trials and changes in trial protocols."
Because of the previous safety, the success of the 2a trial and the results provided via video of the 3 CUPs, the FDA approved the protocol changes to the IND which is the current 2b.