In April 2014, the company acquired the former Dell Computer facility in Limerick and is currently transforming the site into a purpose-built facility, which will be the largest capacity biopharmaceutical production facility in Ireland.
When funding was initially announced in December 2013, a $300m investment with 300 jobs was planned to be completed by the end of 2016.
Regeneron president and chief executive officer Leonard Schleifer said: "With a growing portfolio of marketed medicines and an innovative pipeline rooted in cutting-edge science and technology, Regeneron is one of the fastest-growing global biopharmaceutical companies.
"The Limerick facility will play an essential role in ensuring Regeneron delivers on our mission to consistently and repeatedly bring new medicines to patients with serious diseases."
The company is currently carrying out recruitment to create an additional full-time, high-end specialist jobs in commercial manufacturing, process sciences, quality assurance/control and various support functions for scientists, chemists and technicians.
According to the company, 1,200 contractors were on-site to support development.
Regeneron IOPS senior vice-president and general manager Dan Van Plew said: "The entire community has gone out of its way to welcome us and help us create the momentum we need to build this site.
"Our people, your countrymen, have done something remarkable. In less than two years we have brought a dormant building back to life, and are well on our way to building a complex, high-quality facility in industry-leading time. Our hundreds of current employees, contractors and trades people are top notch.
"The decision to create 200 new full-time roles and invest an additional $350m in Limerick was an easy one to make because of our hiring and trades experiences over the last two years."
The company's 400,000ft² biologics production facility in Limerick is now operational with the first production line on track to enter validation before the end of this year.
On development of its operations in Ireland, the company has worked closely with the Department of Jobs and IDA Ireland.
