Phase II trial and prediction of response of single agent tipifarnib in patients with relapsed/refractory mantle cell lymphoma: a Groupe d'Etude des Lymphomes de l'Adulte trial.

PURPOSE: Farnesyltransferase (Ftase) was identified by gene-expression profiling and by preclinical evaluation in in vitro and in vivo mantle cell lymphoma (MCL) models as a rational therapeutic target in MCL, one of the most refractory B-cell lymphomas. We conducted a multicenter phase II study of a potent Ftase inhibitor, tipifarnib, in patients with relapsed or refractory MCL.
METHODS: Tipifarnib was administered at 300 mg orally twice daily for the first 21 days of each 28-day cycle for 4 cycles, and in case of response for 6 cycles. Study endpoints were objective response at 4 and 6 cycles, progression free survival (PFS), overall survival, and toxicity. Prediction of response was retrospectively evaluated in the initial tumor biopsy by the RASGRP1/APTX gene expression ratio, and the AKAP13 expression level.
RESULTS: Eleven patients (median age, 71 years) were enrolled. Patients received a median number of three prior therapies (range 1-11). Nine patients completed at least 3 cycles of tipifarnib. No grade III-IV hematological toxicities were recorded. One patient presented a complete response (CR) after 4 and a persistent CR at 6 cycles (ORR = 9%). Median PFS was 3 months (range 0.7-14.2). The RASGRP1/APTX gene expression ratio was higher in the responder (n = 1) while the AKAP13 expression was higher in the non-responders (n = 2). This corresponds to the expected result for predicting response to tipifarnib.
CONCLUSION: Treatment with tipifarnib relapsed or refractory MCL is associated with low response rates. Limited gene expression studies suggest that response may be associated with molecular targets.