At a dedication of the new Jeffrey Leiden Center for Cell and Genetic Therapies in Boston’s Seaport, Vertex Pharmaceuticals unveiled plans to build another 344,000 square foot facility in the Seaport to support the company’s growth of its cell and genetic therapies programs. With the completion of this new site expected in 2025, Vertex will occupy 1.9 million square feet of real estate in the Seaport across five sites, making it the largest biotech in Boston in terms of square footage.