A little over a year after its $35 million Series B financing, bluebird bio has returned for another $30 million, laying down a three-year cash runway for advancement of its gene therapy products for rare diseases. CEO Nick Leschly calls the financing, which brings in new investor ARCH Venture Partners, "opportunistic." Existing investors Third Rock Ventures, TVM Capital, Forbion Capital Partners and Easton Capital Investment Group also participated.