LONGECITY

Wikipedia page on Tianeptine says:

Phase I clinical trials were completed in Belgium and the U.S. in May and June 2009, respectively.[45] For reasons that are unclear, development of tianeptine was discontinued in both countries in January 2012.[45]

Does anyone know why the trials were discontinued?

Probably worked better and faster without side-effects compared to crappy SSRIs.

In September 2012, France started treat tianeptine as narcotic. Hints of that, or knowledge of issues that led on the policy change probably were already in the air in early 2012.

Also getting drug approved by the FDA is very expensive. US patent for tianeptine synthesis is from 1973, so unless they figured out how to re-patent it somehow, they were not going to make any profit. If the patent is about to expire or expired, or if drug doesn't have large market potential, it doesn't make financial sense to get FDA approval. 

Agomelatine still has active patents, but the liver test requirements are probably going to keep it's market share in 0.5-3% range of antidepressant sales, so it is not going to be worth it to get FDA approval for it either.