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

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. 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. 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. 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.