FDA has given Gloucester Pharmaceuticals’ cutaneous T-cell lymphoma (CTCL) drug, Istodax®, the go-ahead for use in patients who have received at least one prior systemic therapy. Istodax is a histone deacetylase (HDAC) inhibitor and is expected to be commercially available in January 2010.
“In our market research and in talking to physicians who treat T-cell lymphoma patients, we realized that a key need was a new treatment that would have a sustained response duration,” remarks Jean Nichols, Ph.D., president and COO. “We believe that Istodax provides this substantial advantage and we are particularly happy with the duration of response we’ve observed in the two trials conducted for CTCL.”
Dr. Nichols also points out that while there are three other drugs on the market for CTCL—Ontak® (Eisai), Targretin (Eisai), and Zolinza (Merck & Co.), Istodax does not have as many restrictions as the other three treatments. For example, Ontak is sanctioned specifically for use in CTCL that expresses the CD25 component of the interleukin-2 (IL-2) receptor. Additionally, Targretin is indicated to treat skin problems arising from CTCL, while Istodax has shown efficacy in various other features of the disease like lymph-node and visceral involvement as well as abnormal circulating T-cells, called Sézary cells.
Approval was based upon two prospective multicenter, single-arm studies that enrolled 167 patients in the U.S., Europe, and Australia. Study 1 was sponsored by Gloucester, which included 96 patients with confirmed CTCL after failure of at least one prior systemic therapy. NCI sponsored Study 2, which involved 71 patients with a primary diagnosis of CTCL who received at least two prior skin-directed therapies or one or more systemic therapies. In Study 1, 71% of the patients had Stage IIB or greater disease, and 87% of the patients in Study 2 had Stage IIB or greater disease.
Patients were treated with Istodax at a starting dose of 14 mg/m2 infused over four hours on days 1, 8, and 15 every 28 days. The primary efficacy endpoint for both studies was overall objective disease response rate (ORR) defined as the proportion of patients with confirmed complete response (CR) or partial response (PR). CR was defined as no evidence of disease and PR as ≥50% improvement in disease. Objective disease response was evaluated according to a composite endpoint that included assessments of skin involvement, lymph-node and visceral involvement, and Sézary cells. Secondary endpoints in both studies included duration of response and time to response.
The ORRs in these two trials were similar (34% and 35% in Study 1 and Study 2, respectively) and CR rates were the same (6%). The median response duration was 15 months in Study 1 and 11 months in Study 2. Median time to first response was two months in both studies. Median time to CR was six months in Study 1 and four months in Study 2.
The most common adverse reactions in Study 1 were nausea, fatigue, infections, vomiting, and anorexia, and those in Study 2 were nausea, fatigue, anemia, thrombocytopenia, ECG T-wave changes, neutropenia, and lymphopenia.
Gloucester Pharmaceuticals recently raised $29 million in a Series D financing. This money allowed it to support the development of Istodax, which was developed by Gloucester and the NCI. Gloucester is conducting a late-stage trial in peripheral T-cell lymphoma (PTCL) and anticipates data in 2010. The drug is also being investigated in multiple myeloma (Phase II) and solid tumors (Phase I).
Istodax received orphan-drug designation from the FDA and EMEA for the treatment of non-Hodgkin T-cell lymphomas, which include CTCL and PTCL.