Irish pharmaceutical company Shire plc has leased 343,000 square feet at 500 Kendall St. in Cambridge for a new rare disease research hub.

The lease with BioMed Realty takes effect in the third quarter of 2018 with Shire taking occupancy in early 2019. The company has existing labs at the adjacent 650 Kendall St.

Combined, the facilities will create a campus including research, clinical development, medical affairs and business development, Shire announced Tuesday.

Sanofi Genzyme is vacating 500 Kendall St. in 2018 for a new 251,000-square-foot headquarters at 50 Binney St. being developed by Alexandria Real Estate Equities.

Shire already has a large suburban footprint with more than 3,000 Massachusetts employees spread across over 2 million square feet of office, lab and manufacturing facilities in Lexington, Waltham, Belmont, North Reading and Burlington. The company currently has nearly 400 positions available in Massachusetts. The Kendall Square facility will employ 1,000 people, the Boston Globe reported.

“By expanding our presence in Cambridge, with its close proximity to best-in-class hospitals, research institutions, universities and a thriving biotechnology community, we will strengthen our ties with the early innovators around us to shape the next generation of breakthrough therapies for patients with high unmet needs,” Shire CEO Flemming Ornskov said in a statement.

Transwestern brokered the 12-year lease.