Investors in the last pre-IPO financing by Prosensa Holding N.V. (NASDAQ:RNA) have seen their prospective return slashed to 3x from better than 9x after this month's drisapersen blowup. That syndicate will have to hold its breath for a little longer, as the lockup period for that private round extends into November.

In January 2012, a group led by new investor New Enterprise Associates provided Prosensa with €22.7 million ($30.5 million) to help fund an