While startups winding down operations isn't a point of celebration, leaders of local startups say the success of former Arch Oncology and Adarza employees landing new roles, specifically at other startups, highlights a key milestone for St. Louis’ startup economy: It’s reached critical mass. It’s a sign that St. Louis has enough startups, specifically in biosciences, that when a company doesn't work out, which inevitably will happen with startups, individuals can still find opportunities and advance their careers.