The intent to acquire Libtayo was announced on 2 June this year.
The two companies entered into an immuno-oncology license and collaboration agreement in 2015.
As per the terms of the earlier deal, Sanofi and Regeneron had equally divided the global operating profits and co-commercialised the Libtayo in the US.
Sanofi was exclusively responsible for commercialising the drug outside the US.
Through the latest deal, Regeneron will have exclusive rights to develop, commercialise, and manufacture the Libtayo across the world.
A fully human monoclonal antibody, Libtayo targets the immune checkpoint receptor PD-1 on T cells.
At present, the drug is approved as cemiplimab-rwlc monotherapy to treat certain patients with advanced cutaneous squamous cell carcinoma (CSCC), advanced non-small cell lung cancer (NSCLC) and advanced basal cell carcinoma (BCC) in the US as well as other countries.
As per the terms of the deal announced in June, Sanofi receives an upfront payment of $900m from Regeneron, along with an 11% royalty on the worldwide net sales of Libtayo.
Sanofi also receives $100m in regulatory milestone payments after the receipt of first approval of Libtayo plus chemotherapy to treat NSCLC, either by the US FDA or European Commission (EC).
Regeneron said: “There is no financial or accounting impact to second quarter 2022 financial results as a result of the Libtayo transaction.”
Last month, Regeneron and Sanofi received US FDA approval for Dupixent (dupilumab) to treat moderate-to-severe atopic dermatitis in children aged six months to five years.