The most significant results were found in the treatment of cutaneous T-cell lymphoma (CTCL) and other peripheral T-cell lymphomas (PTCLs).In 2004, romidepsin received Fast Track designation from the FDA for the treatment of cutaneous T-cell lymphoma, and orphan drug status from the FDA and the European Medicines Agency for the same indication.The FDA approved romidepsin for CTCL in November 2009 and approved romidepsin for other peripheral T-cell lymphomas (PTCLs) in June 2011.A randomised, phase III trial of romidepsin + CHOP chemotherapy vs CHOP chemotherapy for patients with peripheral T cell lymphoma returned negative results, having no significant impact on progression free survival or overall survival. Pre-clinical HIV study
In 2014, PLOS Pathogens published a study involving romidepsin in a trial designed to reactivate latent HIV virus in order to deplete the HIV reservoir. Latently infected T-cells were exposed in vitro and ex vivo to romidepsin, leading to an increase in detectable levels of cell-associated HIV RNA. The trial also compared the effect of romidepsin to another histone deacetylase inhibitor, Vorinostat

Autism study in animal model
A study involving romidepsin in an animal study that showed that a brief treatment with low amounts of romidepsin could reverse social deficits in a mouse model of autism. Pharmacodynamics
In a Phase II trial of romidepsin involving patients with CTCL or PTCL, there was evidence of increased histone acetylation in peripheral blood mononuclear cells (PBMCs) extending 4–48 hours. Expression of the ABCB1 gene, a marker of romidepsin-induced gene expression, was also increased in both PBMCs and tumor biopsy samples.
Romidepsin, also known as Istodax,  is an anticancer agent used in cutaneous T-cell lymphoma (CTCL) and other peripheral T-cell lymphomas (PTCLs). Romidepsin is a natural product obtained from the bacterium Chromobacterium violaceum, and works by blocking enzymes known as histone deacetylases, thus inducing apoptosis. It is sometimes referred to as depsipeptide, after the class of molecules to which it belongs. Romidepsin is branded and owned by Gloucester Pharmaceuticals, now a part of Celgene. History
Romidepsin was first reported in the scientific literature in 1994, by a team of researchers from Fujisawa Pharmaceutical Company (now Astellas Pharma) in Tsukuba, Japan, who isolated it in a culture of Chromobacterium violaceum from a soil sample obtained in Yamagata Prefecture. It was found to have little to no antibacterial activity, but was potently cytotoxic against several human cancer cell lines, with no effect on normal cells; studies on mice later found it to have antitumor activity in vivo as well.The first total synthesis of romidepsin was accomplished by Harvard researchers and published in 1996. Its mechanism of action was elucidated in 1998, when researchers from Fujisawa and the University of Tokyo found it to be a histone deacetylase inhibitor with effects similar to those of trichostatin A. Clinical trials
Phase I studies of romidepsin, initially codenamed FK228 and FR901228, began in 1997. Phase II and phase III trials were conducted for a variety of indications.