Genstar Capital-backed ERT has agreed to acquire PHT, a company focused on the adoption of patient-driven mobile apps for improved clinical research. The deal is expected to close within the next several weeks. Acquired by Genstar in a roughly $400 million take-private LBO in 2012, ERT provides solutions for patient safety and efficacy endpoint data collection. The combined company with PHT will have a footprint throughout North America, Europe and Asia, serving all phases of clinical research. PHT has received VC backing from Rho Ventures, Boston Millennia Partners and several others.