AstraZeneca has begun construction on a $100 million R&D expansion at the company’s Waltham, MA facility. The expansion will accommodate up to 100 additional researchers who will join the more than 450 existing employees focused on discovering treatments for infectious diseases and cancer.

“This is the right investment at the right time, as hospital-acquired infectious diseases — also known as superbugs — are on the rise and cancer remains the third leading killer in the world,” said Tony Zook, president and chief executive officer of AstraZeneca U.S. “This expansion is a strategic global decision to increase our capabilities at R&D Boston because Massachusetts gives us access to some of the leading scientific talent, potential partners and collaborators, and emerging science in a worldwide biotechnology hub.”

Since the opening of AstraZeneca R&D Boston, scientists there have discovered three potential drugs that are under development to treat different cancers including breast, ovarian, thyroid, and prostate cancer, and two novel-class candidate drugs to potentially treat serious incidences of skin infections, chronic bronchitis, and pneumonias, according to the company.

“We have a remarkable team of researchers here in Boston that is focused on discovering novel agents for the treatment and cure of serious infections and cancer. This expansion will provide critical space to support future delivery in these two areas of breaking science and profound unmet medical need,” said Jan Lundberg, executive vice president, head of Global Discovery Research.

Construction of the 132,000-sq.-ft. facility is scheduled to conclude by mid-2009. Upon completion, the total size of the AZ research facility will be 382,000 sq. ft. AZ established a research presence in Boston in 1995. In 2000, the company opened its state-of-the-art research facility in Waltham, where it has continued to invest and expand, growing from 170,000 sq. ft. to the current 250,000-sq.-ft. facility.

The architect for the project is KlingStubbins, whose offices are based in Cambridge, Mass. and Philadelphia, Pa. Construction management is being provided by Bovis Lend Lease LMB Inc’s Boston office in association with The Richmond Group of Hopkinton, Mass. The design of the additional buildings will continue the theme created by Swedish architect Gert Wingardh.