Rechallenge with trabectedin in patients with responding myxoid liposarcoma

Abstract

10575 Background: To determine the efficacy of rechallenge with trabectedin (T) in patients with myxoid liposarcoma who were responding to T at the time of discontinuation but subsequently developed progressive disease. Methods: Since September 2002, 32 patients with recurrent or advanced myxoid liposarcoma received T at our institution within an expanded access program. We report herein 8 patients who received T for a median of 10 cycles (range 5–15) prior to discontinuation. We used RECIST criteria to classify patient response to therapy. During the initial administration of T, a CR had been observed in 2 patients, a PR in 3 patients, SD in 2 patients, and one had had tumor shrinkage but did not meet RECIST definition of PR. The median PFS was 24 months from treatment start, and 14 months (range 9–27) from treatment-end. In 6 of the 8 patients, the treatment had been discontinued in the absence of any evidence of disease: 4 patients had undergone complete surgical resection (R0) of residual disease and 2 patients had achieved a radiological complete response (CR). The other two patients stopped treatment voluntarily, one with a partial response (PR) and one with stable disease (SD). All these patients resumed treatment at the time of progression. Results: Following rechallenge with T, no PD was seen at first assessment, and no patients had to discontinue or reduce the dose due to toxicity. Response rate according to RECIST was 50%. At a median follow up of 7 months (range 2.7–12), the median TTP has not yet been reached. Treatment is still ongoing in 5 patients. Conclusions: Rechallenge with T can be beneficial in some patients with myxoid liposarcoma. If further data confirm this, treatment of progressing patients previously responding to T may include this option. Furthermore, studies on optimization of treatment duration upfront may be worthwhile. [Table: see text]