Keytruda is a brand name medication that contains the active ingredient pembrolizumab, which is a type of immunotherapy used to treat cancer. According to Drug Patent Watch [1], the patent for Keytruda is set to expire in 2028, which means that generic versions of the drug may become available after that date.

Currently, there are no generic versions of Keytruda available on the market. According to Healthline [2], the cost of Keytruda can vary depending on several factors, such as the dosage, the frequency of treatment, and the location. However, it is generally an expensive medication, with a list price of around $13,000 per month.

In comparison, Imfinzi is another immunotherapy drug used to treat cancer, and it is also available as a brand name medication. According to Healthline [2], the cost of Imfinzi is similar to that of Keytruda, with a list price of around $12,000 per month.

It is difficult to predict the exact cost difference between Keytruda and its generic versions, as they are not yet available on the market. However, it is likely that the cost of generic versions will be significantly lower than that of the brand name medication. According to FiercePharma [3], when a drug goes off-patent, the price typically drops by around 80% within the first year of generic competition.

In conclusion, Keytruda is currently an expensive brand name medication used to treat cancer, with a list price of around $13,000 per month. Generic versions of the drug are not yet available on the market, but it is likely that their cost will be significantly lower than that of the brand name medication once they become available.

Sources:
[1] https://www.drugpatentwatch.com/p/biologics/tradename/KEYTRUDA
[2] https://www.healthline.com/health/drugs/imfinzi-vs-keytruda
[3] https://www.fiercepharma.com/special-report/top-15-blockbuster-patent-expirations-coming-decade