Abstract Disclosures
Abstract:
Background: To explore the time to secondary resistance after rechallenge with T in MRCLPS patients who were responding to T at the time of discontinuation. Methods: Since September 2002, 62 patients with recurrent myxoid liposarcoma received T at our institution.
According to RECIST, 2/62 patients had a complete response (CR), 34/62 a partial response (PR) (CR+PR = 58%), 18/62 (29%) a stable disease (SD) and 8/62 (13%) a progression disease (PD).
Median PFS was 14 months. Among the 54/62 patients who obtained a stable disease or a partial response after the first assessment, 28/54 interrupted treatment in absence of progression, while 26/54 patients received T until progression disease. Time to secondary resistance was defined as time from the first cycle of T to progression, whenever it occurs (including under T reintroduction).
Results: In the 28 pts in whom Trabectedin was interrupted (11 for surgery of the residual disease, 1 for radiotherapy , 3 for toxicity and 13 for shared decision with clinician) , this was done after a median of 14 cycles (range = 6-21) and the median PFS was 24 months. 17 of them resumed treatment at the time of progression (F = 8, M = 9, median age = 51, range = 32-76). After rechallange, no PD was seen at first assessment, and time to secondary resistance was 48 months. In the 26 pts who went on with T until progression, PFS (i.e., time to secondary resistance) was 11 months.
Conclusions: Rechallenge with T may be successful in selected patients with myxoid liposarcoma primarily responding to the drug and stopping it after a while. In this series, the choice to continue or stop the drug after response was of course at the discretion of the clinician, and selection biases are likely.
Prospective studies on optimization of treatment strategy with T in MRCLPS are worthwhile.