Abstract
Bexarotene, a synthetic retinoid ligand for the retinoid X receptor (RXR), is a highly active agent in the treatment of relapsed or refractory CTCL with a response rate of ~45% (
Arch Dermatol 137: 581–93, 2001
; J Clin Oncol 19: 2456–71, 2001
). Interferon alfa has a similar response rate although the doses and responses in the literature have varied. Promising results have been reported with combinations of retinoids and interferon alfa, including bexarotene (J Am Acad Dermatol 50: 375–9, 2004
). To explore this combination, a phase II trial was designed in which patients with CTCL were treated with bexarotene 300 mg/m2/day for at least 8 weeks. If less than a complete response was seen at this time, interferon alfa-2b at a dose of 3 million units escalated to 5 million units subcutaneously 3 times weekly was added for another 8 weeks. Responding patients could continue treatment beyond 16 weeks. Twenty-two patients with CTCL were enrolled in the trial: median age 58 years (22–79); 9 males, 13 females, TNM stages: IB (3), II (7), III (4), IV (8). One patient had no prior treatment; the rest had relapsed or refractory disease with a mean of 49 months from initial diagnosis to enrollment. Four patients had previously received bexarotene and 2 interferon alfa. Seventeen patients completed 16 weeks of treatment and are assessable for response, 1 has not completed 16 weeks and 4 received less than 16 weeks (1 early death, 1 non-compliant, 1 withdrawal of consent because of side effects, and 1 myocarditis, probably not treatment-related). Using reproducible objective criteria for response utilized in the single agent bexarotene trials cited above (Primary Endpoint Classification), 6 of 17 patients achieved a partial response and 1 a complete response (objective response rate 41%, 95% confidence intervals 18%–67%). Three of the 6 partial responses occurred with bexarotene alone at 8 weeks. Median duration of response was 2.7 months, range 1.1–7.6 months. Reversible grade 3 or 4 toxicities seen in more than 1 patient were hypercholesterolemia (2 pts.), hypertriglyceridemia (4 pts.), neutropenia (3 pts.), lymphopenia (2 pts.) and elevated AST in 2 patients. Lipid lowering agents were used in all patients. Six patients died, all of progressive disease from 1.6–29.9 months following initiation of treatment. The major response rate for the combination of bexarotene and interferon alfa is similar to that for bexarotene alone. Despite the wide confidence intervals that indicate that a small advantage might be missed by not increasing accrual, the clinical usefulness of this combination is limited by the inconvenience of interferon injections. Further trials in CTCL are planned combining bexarotene with other agents, including active cytotoxics.Author notes
Corresponding author
2005, The American Society of Hematology
2004
