By Lisa Seachrist
Just two weeks after receiving an approvable letter for Targretin gel, its topical treatment for cutaneous T-cell lymphoma (CTCL), Ligand Pharmaceuticals Inc. got clearance to market the drug in early-stage CTCL.
The product now becomes the third drug developed by Ligand specifically for CTCL to garner FDA approval. Once Targretin gel is launched, the San Diego-based company will have products marketed for every stage of CTCL.
"We are moving as quickly as we can to launch this product," said Paul Maier, Ligand's senior vice president and chief financial officer. "We don't have an exact date. We obviously have to go through printing the packaging, instructions, package insert, and shipping materials. But, it's in our best interest to move expeditiously."
Targretin gel has been approved in CTCL patients with early-stage disease who have refractory or persistent disease after treatment with other therapies or who can't tolerate other therapies. It is the first topical therapy approved for CTCL and joins Targretin capsules for the treatment of all stages of refractory CTCL and Ligand's Ontak, a fusion protein therapy for the treatment of patients with later-stage recurrent or persistent CTCL. (See BioWorld Today, Dec. 30, 1999, p. 1; and Feb. 8, 2000, p. 1.)
CTCL is a form of non-Hodgkin's lymphoma. It is a cancer of T lymphocytes (white blood cells comprising a vital part of the body's immune system) that usually manifests itself first in the skin, causing itchiness. The constant itch and pain leaves patients susceptible to infection as a result of skin damage. The disease eventually can affect other organs. Approximately 16,000 people in the U.S. suffer from CTCL.
Targretin (bexaratone) is a synthetic retinoid analogue. Retinoids are naturally occurring hormones chemically related to vitamin A, and can regulate a number of cellular activities, including cell growth. They work through six receptors that can be classified into two groups: retinoid acid receptor (RAR) and retinoid X receptor (RXR). Targretin acts through RXR.
Approval for Targretin gel was based on results from a multicenter Phase III study conducted with 50 patients in the U.S., Canada, Europe and Australia. The company also submitted the results of a 67-patient Phase I/II study. In the Phase III study 44 percent of patients responded to Targretin gel therapy and 8 percent had a complete response to the treatment. Side effects of Targretin gel treatment included rash, itching and pain. (See BioWorld Today, Dec. 13, 1999, p.1.)
All of the patients in the studies had failed previous treatment for early-stage disease such as nitrogen mustard, carmustine, electron beam treatment, photophoresis and psoralen plus ultraviolet light.
"We are in the process of submitting the data to the European authorities and expect to complete the submission for Targretin gel this year," Maier said.
In addition to CTCL, Ligand is looking to expand the use of Targretin capsules into advanced breast cancer and moderate to severe psoriasis, two indications in which the company has active Phase II programs. The company also is exploring a non-Hodgkin's lymphoma indication for its injectable Ontak, a cytotoxic fusion protein.
In addition to its CTCL products, Ligand has Panretin gel on the market as a treatment for Kaposi's sarcoma.
Ligand's stock (NASDAQ:LGND) closed unchanged Thursday at $13.06.