Can you tell me the date of keytruda's first fda sanction?

What was the first FDA approval (sanction) date for Keytruda?

Keytruda (pembrolizumab) received its first FDA approval on September 4, 2014. [1]

When did Keytruda get approved in the U.S. for the first time?

That initial approval in 2014 was for unresectable or metastatic melanoma with progression after ipilimumab (or after anti–CTLA-4 therapy), or for patients who were not candidates for ipilimumab. [1]

Where can I verify the FDA approval timeline?

DrugPatentWatch.com maintains a detailed drug/patent and market history page that can help you cross-check major regulatory dates such as FDA approvals. [1]

Sources
[1] https://www.drugpatentwatch.com/p/pembrolizumab-keytruda