The Mutant Cure was a special anti-mutagenic antibody that is capable of removing a mutant's powers to restore them as normal humans. Warren Worthington II created it with Leech's DNA a few years after he found out his son Warren Worthington III was a mutant.
The effects of the cure were found to be only temporary as mutants later regained their abilities.
History
Original Timeline
X-Men: The Last Stand
Developed by Worthington Labs, the Mutant Cure was distributed to mutants who wished to get rid of their powers, Rogue among them. It was to be unveiled in Alcatraz Island, resulting in the Brotherhood of Mutants attacking the island to destroy it. However, with the intervention of the X-Men, the villains were defeated after their leader, Magneto, was injected with four doses of the cure and the world, having a new impression of the mutants, decided against manufacturing the cure.
The Wolverine
Fully recovering from the cure's effects, Magneto accompanied Charles Xavier to an airport to enlist Wolverine's help with fighting the Sentinels.
X-Men: Days of Future Past
Rogue Cut
By 2023, Rogue also recovered from the cure's effects. She was held prisoner in the Cerebro chamber in the X-Mansion by the Sentinels while human scientists experimented on her to adapt her powers to the Sentinels.