If an application is invited to be submitted through the Fast-Track Resubmission pilot, is it required to be re-submitted?

No, invitations to participate in the pilot can be declined. The deadline to decide whether to ACCEPT OR DECLINE the invitation will be indicated in the Fast-Track Resubmission invitation letter. If the decision is made not to accept the invitation, a Letter of Intent (LOI) may be resubmitted in a future cycle.