Horizon Discovery Group has entered an agreement to acquire the CombinatoRx service business and related assets from Zalicus Inc., a biopharma company that discovers and develops novel pain treatments, for $8.0 million. The new business will become Horizon CombinatoRx, Inc., a subsidiary of Horizon.   Horizon CombinatoRx will be located in a 23,000-sq.-ft. lab with office space in Cambridge, MA, providing a base for operations and future growth in North America. It will provide access to its com...