By Michael Erman
NEW YORK (Reuters) -U.S. Senator Elizabeth Warren sent the nation's top patent regulator a letter urging close scrutiny of Merck & Co's requests for new patents on its blockbuster cancer treatment Keytruda, saying further efforts to protect the drug could be an abuse of the system.
"It is not at all clear that Merck is doing anything other than extending its monopoly power over the drug," Warren wrote to Kathi Vidal, director of the United States Patent and Trademark Office (PTO) in the letter sent on Wednesday and seen by Reuters.
Senator Bernie Sanders, as well as Representatives Katie Porter and Pramila Jayapal also signed the letter. All four members of Congress are Democrats.
They expressed particular concern over Merck's efforts to patent a subcutaneous version of the currently infused drug, which Reuters reported on late last year.
They wrote that Merck’s use of dozens of patents to fend off Keytruda competitors "appear(s) to be an example of the anti-competitive business practices ... that we have long been
concerned about."
Merck in a statement said it is "continuously innovating to enhance the benefits of Keytruda in order to reach greater numbers of patients and to increase efficacy and convenience of the treatment."
"When appropriate, Merck protects this additional innovation through the filing of patent applications, particularly when we view the innovation as novel, useful and non-obvious," a Merck spokesperson said by email.
Merck, which reported $20.9 billion in 2022 sales of Keytruda, has relied on the immunotherapy to fuel its growth.
The treatment, first approved in 2014, harnesses the body's own immune system to fight cancers with dramatic results. Against advanced lung cancer, it has led to a five-year survival rate in about one-quarter of people compared to 5% historically for the disease.
It initially demonstrated impressive survival benefits in the deadliest form of skin cancer and has since been approved for many types of cancer.
The members of Congress wrote that subcutaneous injections do not represent novel improvements for drugs, as "medications have been injected under the skin since insulin was discovered in 1921."
They urged Vidal to "give close scrutiny to any of Merck’s requests for new patents for Keytruda, and reject those that do not clearly meet the agency’s standards."
Clinical studies have shown that patients prefer subcutaneous injections to intravenous administration, which can be time-consuming and invasive.
Merck said the easier-to-use formulation of Keytruda will be particularly important for treatment of earlier stage disease, as patients may be on therapy for a longer duration.