The co-pay for Keytruda may vary depending on various factors such as insurance coverage, income, and eligibility criteria. Keytruda is a prescription drug used to treat different types of cancer, and its cost can be high. According to the Merck Access Program website [3], eligible patients may receive financial assistance for Keytruda treatment. The program offers co-pay assistance, which can cover up to $25,000 per year, depending on the patient's income and insurance coverage. The website also provides a hotline number to call for more information on financial assistance. The Keytruda website [2] also provides information on financial support for eligible patients. Patients can find information on co-pay assistance, patient assistance programs, and free drug programs. Additionally, the Drug Patent Watch website [1] provides information on the patent status of Keytruda and its expiration date. However, the website does not provide information on the co-pay for the drug. In conclusion, the co-pay for Keytruda may vary depending on various factors, and eligible patients can receive financial assistance through the Merck Access Program or other patient assistance programs.

Sources:
[1] https://www.drugpatentwatch.com/p/biologics/tradename/KEYTRUDA
[2] https://www.keytruda.com/financial-support/
[3] https://www.merckaccessprogram-keytruda.com/hcc/affordability.html