Which cancer did keytruda treat initially?

What cancer was Keytruda (pembrolizumab) first approved to treat?

Keytruda was initially approved for melanoma, specifically for the treatment of patients with advanced (unresectable or metastatic) melanoma who were not eligible for ipilimumab treatment and whose tumors no longer responded to other therapy. [1]

Why do people also mention other cancers when talking about Keytruda’s early use?

After the initial melanoma approval, Keytruda’s label expanded quickly as additional clinical trials supported its use in other cancers. Those later approvals can make it look like Keytruda started with multiple cancer types, but the first approval was for melanoma. [1]

Source

1. https://www.drugs.com/newdrugs/2014-10-2.html