Regeneron Pharmaceuticals said on Thursday it would buy the global rights to cancer drug Libtayo from French drugmaker Sanofi SA in a deal that includes an upfront payment of $900 million.

The companies signed a collaboration agreement in 2015 under which they jointly marketed the drug in the United States, while Sanofi was responsible for selling it outside the country. Worldwide profits from Libtayo were split equally.

"This strategic acquisition is a major step towards Regeneron's goal of becoming a global oncology leader," said Leonard Schleifer, chief executive of the company. Under the new terms, Regeneron would have the sole rights to develop and market Libtayo -- which is approved in the United States and several other countries for the treatment of many types of cancer.

The drug is also under review in the United States and the European Union for the treatment of advanced non-small cell lung cancer (NSCLC) in combination with chemotherapy.

Sanofi will receive royalty of 11% on worldwide net sales of Libtayo and also be entitled to a $100 million milestone payment on the approval of Libtayo by either the FDA or the European drug regulator for NSCLC.

The French drugmaker would also be entitled to sales-related milestone payments of up to $100 million over the next two years, the companies said.

The deal follows Regeneron's buyback of about $5 billion of its shares directly from Sanofi in 2020.