Bexarotene was evaluated in two clinical trials in 152 patients with advanced and early stage cutaneous T-cell lymphoma (CTCL) in two multicenter, open-label, historically-controlled clinical trials conducted in the U.S., Canada, Europe, and Australia.

The advanced disease patients had disease refractory to at least one prior systemic therapy (median of two, range one to six prior systemic therapies) and had been treated with a median of five (range 1 to 11) prior systemic, irradiation, and/or topical therapies. Early disease patients were intolerant to, had disease that was refractory to, or had reached a response plateau of six months on, at least two prior therapies. The patients entered had been treated with a median of 3.5 (range 2 to 12) therapies (systemic, irradiation, and/or topical).

The two clinical trials enrolled a total of 152 patients, 102 of whom had disease refractory to at least one prior systemic therapy, 90 with advanced disease and 12 with early disease. This is the patient population for whom bexarotene is indicated.

Patients were initially treated with a starting dose of 650 mg/m2/day with a subsequent reduction of starting dose to 500 mg/m2/day. Neither of these starting doses was tolerated, and the starting dose was then reduced to 300 mg/m2/day. If, however, a patient on 300 mg/m2/day of bexarotene showed no response after eight or more weeks of therapy, the dose could be increased to 400 mg/m2/day.

Tumor response was assessed in both trials by observation of up to five baseline-defined index lesions using a Composite Assessment of Index Lesion Disease Severity (CA). This endpoint was based on a summation of the grades, for all index lesions, of erythema, scaling, plaque elevation, hypopigmentation or hyperpigmentation, and area of involvement. Also considered in response assessment was the presence or absence of cutaneous tumors and extracutaneous disease manifestations.

All tumor responses required confirmation over at least two assessments separated by at least four weeks. A partial response was defined as an improvement of at least 50% in the index lesions without worsening, or development of new cutaneous tumors or non-cutaneous manifestations. A complete clinical response required complete disappearance of all manifestations of disease, but did not require confirmation by biopsy.

At the initial dose of 300 mg/m2/day, 1/62 (1.6%) of patients had a complete clinical tumor response and 19/62 (30%) of patients had a partial tumor response. The rate of relapse (25% increase in CA or worsening of other aspects of disease) in the 20 patients who had a tumor response was 6/20 (30%) over a median duration of observation of 21 weeks, and the median duration of tumor response had not been reached. Responses were seen as early as 4 weeks and new responses continued to be seen at later visits.

In one post-approval clinical trial with a total of 59 subjects (29 in 300 mg/m2/day dose group and 30 in the 150 mg/m2/day dose), the objective response rate was higher in the bexarotene 300 mg/m2/day group than in the bexarotene 150 mg/m2/day group with respect to the CA (34.5% vs 23.3%), Physicians Global Assessment (PGA) (37.9% vs 20.0%), and percent BSA involvement (34.5% vs 23.3%).

The median duration of response in the bexarotene 300 mg/m2/day group based on the CA, PGA, and percent BSA involvement was 86.5 days, 72.0 days and 60.0 days respectively. While in the bexarotene 150 mg/m2/day group the median duration of response based on the CA, PGA, and percent BSA involvement was 55 days, 119.0 days and 118.0 days respectively.

The median time to cutaneous tumor response (the time to cutaneous tumor response for a given subject is defined as the time interval from the first day of bexarotene treatment to the time of the first observation when the subject with subsequent confirmation of response meets criteria for CR, CCR or PR) in the bexarotene 300 mg/m2/day group based on the CA, PGA, and percent BSA involvement was 85 days, 98 days and 117.5 days respectively. While in the bexarotene 150 mg/m2/day group the median time to cutaneous tumor response based on the CA, PGA, and percent BSA involvement was 87 days, 57 days and 57 days respectively. In the bexarotene 300 mg/m2/day group, the median time to cutaneous tumor progression based on the CA, PGA, and percent BSA involvement was 77.5, 115.5, and 88.0 days, respectively. In the bexarotene 150 mg/m2/day group, the median time to cutaneous tumor progression was 203.0 days based on the CA and 86.0 days based on percent BSA involvement; no subject in this treatment group had cutaneous tumor progression based on the PGA.