By Mary Welch
Ligand Pharmaceuticals Inc. received an approvable letter for Targretin gel 1 percent for the topical treatment of cutaneous lesions in patients with early-stage cutaneous T-cell lymphoma (CTCL).
The approval is pending a final labeling agreement.
"I don't want to comment on what the issues are over the labeling," said Christiane Sheid, the company's vice president of finance and communications. "Let's just say we are working closely with the FDA to move forward on reaching an agreement to get this drug approved as soon as possible and get it to the appropriate people as soon as possible as well."
When approved, it will be Ligand's third FDA-sanctioned therapy for CTCL. In December, Targretin capsules for treating all stages of refractory CTCL was approved, and Ontak, a fusion protein therapy for the treatment of persistent or recurrent CTCL, was given the go-ahead in February 1999. (See BioWorld Today, Dec. 30, 1999, p. 1; and Feb. 8, 2000, p. 1.)
"Obviously, we're delighted that we're moving toward our third approval for CTCL and our fourth approval in our portfolio," Sheid said. "It's also important to note that Targretin gel will be the first topical therapy approved for CTCL by the FDA."
San Diego-based Ligand's other FDA-approved treatment is Panretin (aliretinoin) gel for Kaposi's sarcoma. (See BioWorld Today, Feb. 4, 1999, p. 1.)
When approved, the gel will be used in CTCL patients who have refractory or persistent disease after other therapies or who have not tolerated other therapies.
"It's for early-stage patients," Sheid said. "The gel is special because it's a convenient application specific to the site of the lesions."
Ligand filed the new drug application for the gel last December. It was given priority review status.
The filing was based on results from a multicenter Phase III trial conducted in the U.S., Canada, Europe and Australia with 50 patients and a multicenter Phase I/II trial with 67 patients.
Efficacy results exceeded the protocol-defined response target rates as 44 percent of patients responded and 8 percent had a complete response. Responses generally occurred within the first four months of treatment. (See BioWorld Today, Dec. 13, 1999, p. 1.)
Current treatments for early-stage disease include nitrogen mustard and carmustine, which usually are applied daily to the patient's body. Other therapies include electron beam treatment, photophoresis and Psoralen plus ultraviolet light.
CTCL, a form of non-Hodgkin's lymphoma, is a cancer of T lymphocytes (white blood cells involved in the body's immune system). The disease generally manifests itself first in the skin but will progress to other organs. Early-stage CTCL has a median survival of 10 years, but for advanced-stage patients the survival rate is less than three years. About 16,000 people in the U.S. have CTCL.
Targretin (bexarotene) is a synthetic retinoid analogue. Retinoids are naturally occurring hormones chemically related to vitamin A, and are known to 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.
Although Targretin was discovered by Ligand, it was being developed in a collaboration worth up to $190 million with Eli Lilly and Co., of Indianapolis. However, Lilly stopped Targretin's development last year, opting instead to focus on developing with Ligand second-generation RXR products for diabetes. (See BioWorld Today, Feb. 19, 1999, p. 1.)
First-quarter sales of Targretin capsules were $800,000. Ontak sales were $3.7 million. Ligand markets the products itself.
Ligand's stock (NASDAQ:LGND) closed Tuesday at $12.625, up $1.125.