Romidepsin

Istodax

Romidepsin is a natural-product anticancer peptide, a bicyclic depsipeptide isolated from the soil bacterium Chromobacterium violaceum. A depsipeptide is a peptide in which one or more of the usual amide bonds is replaced by an ester bond, and romidepsin's structure includes a disulfide bond that is central to how it works. It belongs to the class of histone deacetylase (HDAC) inhibitors — drugs that change how genes are switched on and off. Romidepsin is a prodrug: it enters cells relatively inert, and once inside, its disulfide bond is reduced to release a free thiol group. That thiol reaches into the active site of HDAC enzymes and binds their zinc atom, blocking their activity. HDACs normally remove acetyl groups from histones (the proteins DNA wraps around) and other proteins; inhibiting them leads to a more open chromatin state and altered gene expression that, in susceptible cancer cells, drives cell-cycle arrest and programmed cell death (apoptosis). Romidepsin is given by intravenous infusion and is approved for cutaneous T-cell lymphoma (CTCL) in patients who have had at least one prior systemic therapy. It had also been approved for peripheral T-cell lymphoma (PTCL) under accelerated approval, but that indication was withdrawn after a confirmatory trial did not meet its goal; its CTCL approval remains. Its notable safety considerations include effects on the heart's electrical activity (QT and ECG changes), low blood counts, nausea, and fatigue, so patients are monitored with attention to electrolytes and cardiac status. Romidepsin is a prescription oncology medicine used under specialist supervision; it is not a wellness or research 'peptide' in the lifestyle sense.