Romidepsin is primarily used in the treatment of cutaneous T-cell lymphoma (CTCL) and peripheral T-cell lymphoma (PTCL), particularly in patients who have not responded to other therapies. It works by inhibiting histone deacetylase, which helps to regulate gene expression and can lead to the death of cancer cells. This makes it a valuable option for those with relapsed or refractory forms of these cancers. Additionally, its ability to induce cell cycle arrest and apoptosis in malignant cells has sparked interest in exploring its potential for treating other types of cancers and diseases involving abnormal cell growth. Research is ongoing to evaluate its efficacy in combination with other therapies and in broader oncological applications.