Keytruda Patent Expiry: When Will Generic Keytruda Be Available?

When you hear Keytruda, a leading immunotherapy drug used to treat multiple cancers by helping the immune system target tumor cells. Also known as pembrolizumab, it has transformed survival rates for melanoma, lung cancer, and other aggressive diseases. But Keytruda isn’t cheap—costing over $150,000 a year in the U.S. That’s why everyone’s watching its patent expiry like a clock ticking toward relief.

Keytruda’s main U.S. patent expires in 2028, but that doesn’t mean generics will appear overnight. Drugmakers use legal tricks—like Paragraph IV certifications, a strategy under the Hatch-Waxman Act where generic companies challenge patents before they expire—to delay competition. Some patents cover specific uses, delivery methods, or formulations, and each one can add years of exclusivity. Even after the core patent falls, companies may still hold secondary patents on things like packaging or dosing schedules. This is why drug patent litigation, the legal battles between brand and generic makers over intellectual property can drag on for years.

When generics finally arrive, they won’t be exact copies. Because Keytruda is a biologic—not a traditional pill—its copy is called a biosimilar. These are highly similar but not identical, and they require extra testing to prove safety. The first biosimilar to Keytruda could arrive as early as late 2028, but widespread availability? That’s more likely 2030 or later. Meanwhile, authorized generics and patient assistance programs are the only real ways to lower costs now.

What’s clear is this: the clock is running. Every day closer to patent expiry brings more pressure on manufacturers to lower prices, more interest from generic companies, and more hope for patients stuck paying out-of-pocket. The posts below dig into how drug patents work, how companies stretch them, what happens when they finally expire, and how patients can prepare for the shift. You’ll find real examples—from how Hatch-Waxman Act, a law that balances innovation with access to cheaper drugs changed the game for pills like statins, to how cancer drug pricing affects real families. No fluff. Just what you need to know before the next big change hits.