Senator questions Merck over patent strategy for blockbuster cancer drug Keytruda

A U.S. senator is pressing pharmaceutical giant Merck over its patenting and pricing practices for the blockbuster cancer drug Keytruda, escalating congressional scrutiny of industry strategies that can delay lower-cost rivals from reaching the market.

Sen. Maggie Hassan (D-N.H.), ranking member of the Senate Finance Subcommittee on Health Care, said that Merck and other drug companies often file excessive patents to extend their monopolies and keep more affordable versions of their pricey drugs out of reach. In a letter to Merck CEO Robert Davis, the lawmaker asked the company to detail patent actions connected to both the Keytruda intravenous version, which has been on the market for over a decade, and its new injectable version of the drug, which launched last year.

“I continue to have serious concerns about how Merck’s anti-competitive practices have boosted profits at the expense of patients,” Hassan wrote in her letter, sent this week. She added she has noted in previous years how “these kinds of patent gimmicks have allowed Merck to delay other companies from selling lower cost versions of this medication, all while raising the price of Keytruda in the U.S. year after year.”

Hassan cited a finding from the International Consortium of Investigative Journalists’ recent Cancer Calculus investigation that Merck’s new injectable version of Keytruda “could help Merck generate billions of dollars and delay competition into the 2030s.”

ICIJ’s Cancer Calculus revealed how Merck uses pricing, patent and dosing strategies to turn the life-saving medicine into one of the world’s best selling drugs — while leaving many patients around the world struggling to access it. The company and other cancer research businesses filed 1,212 patent applications in 53 jurisdictions, which can extend Keytruda’s control of the market. Keytruda carried high list prices that have strained the budgets of even wealthy nations, ranging from more than $80,000 for a year of treatment in Germany, $93,000 in Lebanon, and $130,000 in Colombia, to as much as $208,000 in the U.S. The exorbitant prices and desperate patients have fueled a counterfeit market, with incidents of fake Keytruda surfacing in public hospitals in Mexico. High costs and restrictive insurance protocols have also forced many patients into long, grueling legal battles just to access the drug.

A Merck spokesperson did not respond to a request for comment sent by ICIJ on Thursday. Earlier this year, the company told ICIJ and its global media partners that it is a “common myth” that companies use many patents to block competition, and said more patents do not determine when generics or biosimilars enter the market.

An ICIJ analysis identified at least 1,212 patent applications that form part of the Keytruda patent family in 53 countries, regions, and territories. ICIJ found that Merck’s secondary patents could potentially extend Keytruda’s exclusivity in the U.S. until at least 2042, which may delay cheaper alternatives for hundreds of thousands of patients over the next 15 years. Keytruda’s primary patents are set to expire in 2028.

Hassan’s letter included 10 questions the senator seeks answers to and asked Davis to respond by no later than July 20.

She asked why Merck is using a large number of secondary patents for Keytruda and how it justifies that strategy; whether this approach delays biosimilar competition and keeps prices high for patients, and what Merck is doing to make sure lower-cost alternatives can reach patients once the main patents expire. The letter also asks whether the shift from intravenous Keytruda to an injectable version could be used to extend market exclusivity and delay lower-cost competition.

In her letter, Hassan describes an exchange with Davis during a 2024 Senate hearing, in which she pressed him about the tactics that have allowed Merck to “delay other companies from selling lower cost versions” of Keytruda while raising the price of the drug annually. At the time, Davis said the system needs both patent protection and a strong biosimilar and generic market, and that he would not block an intravenous biosimilar of Keytruda after key patents expire.

“Despite these statements, existing patents for [intravenous] Keytruda and a new form of the medication may help block or minimize competition from biosimilars for years,” Hassan wrote.

The inquiry is part of a broader congressional push to address prescription drug pricing, patent disputes, and alleged “product hopping” strategies that some lawmakers say can delay cheaper alternatives from reaching patients. One of the bills being considered is the Medication Affordability and Patent Integrity Act, sponsored by Hassan and Sen. Josh Hawley (R-MO). The proposed law, which aims to reform patent review and facilitate the entry of generics and biosimilars to the market, was advanced by the Senate Committee on Health, Education, Labor, and Pensions in June.