The company is responsible for the creation of the Mutant Cure. They required Leech's DNA in order to create it, and they keep him in their primary lab to help continue providing the cure. The company has many facilities around the country, but the primary laboratory is located on Alcatraz island, where the widely known prison has been turned into, as Worthington described, a source of freedom for the mutants in need of a cure.
The primary lab on Alcatraz was attacked by Magneto and his Brotherhood of Mutants. The lab's private army attempted to fight off Magneto's attack using "cure"-loaded plastic guns. Despite the X-Men's best efforts to help protect the lab, they managed to save Leech, while the lab has been destroyed by Jean Grey.
It is unknown if Worthington Labs continues to provide the cure afterwards. The primary lab on Alcatraz is destroyed, and while Worthington survives, Leech was enrolled in Xavier's School for Gifted Youngsters , now headmastered by Storm.