Keytruda, a drug manufactured by Merck & Co, was first approved by the U.S. Food and Drug Administration (FDA) in 2014 for a specific use. However, the first FDA approval for Keytruda's use in any solid tumor with a specific genetic feature was granted in 2017 [3].

The initial FDA approval in 2014 was for Keytruda to be used in treating advanced melanoma [1]. Keytruda is a type of drug known as a programmed death receptor-1 (PD-1) blocking antibody, which works by blocking the PD-1 pathway, helping the body's immune system attack cancer cells [2].

Later, in May 2017, the FDA expanded Keytruda's approval to include treatment of adult and pediatric patients with solid tumors that have a specific genetic feature (microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR)) [3]. This marked the first time the FDA had approved a cancer treatment for any solid tumor with a specific genetic feature [3].

In summary, Keytruda was first approved by the FDA for use in advanced melanoma in 2014, and its use in any solid tumor with a specific genetic feature was approved in 2017.

Sources:
[1] <https://www.drugpatentwatch.com/p/biologics/tradename/KEYTRUDA>
[2] <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5679831/>
[3] <https://www.fda.gov/news-events/press-announcements/fda-approves-first-cancer-treatment-any-solid-tumor-specific-genetic-feature>