This must be the season for drug approvals for rare lymphomas--an early Christmas gift to many patients suffering from a rare blood cancer. Folotyn (pralatrexate), which was approved in September for peripheral T-cell lymphoma came less than one month after an advisory committee recommended its approval. This time, it's patients with cutaneous T-cell lymphoma, a group of rare non-Hodgkin lymphomas that affect the skin, that are the recipients of a new treatment option.CTCL is often mistaken at first for a rash and can cause itchy, red disfiguring patches. Current treatments for CTCL can include chemotherapy, radiation, or topical therapies. A new treatment, Istodax (romidepsin) was approved on November 5 for CTCL patients who have progressed on at least one prior therapy. The Istodax approval was based on two studies that looked at a total of 167 CTCL patients who had either one or two prior therapies. The studies did not have a comparison arm. The overall response rate was about 34 percent with 6 percent of patients experiencing a complete response--a total remission from their cancer. The median length of response rate was 15 months (range of 1 to 20-plus months) in one study and 11 months (range of 1 to 66-plus months) in the second. Common side effects seen in the studies included nausea, fatigue, infection, and anemia.Istodax is a histone deacetylase (HDAC) inhibitor, a class of drugs that works by helping the cell to package its DNA correctly around proteins called histones, by either unwinding genes that control cell growth or constricting those that invite unchecked cell division. You can read more about HDAC inhibitors, including other treatments in this drug class, in our feature on epigenetics, "Medicine's New Epicenter? Epigenetics" from our Winter 2008 issue.