Résumé
The T3 trial is a multicenter Phase IB dose escalation study that evaluates the safety, feasibility and efficacy of three Temsirolimus-based chemotherapy regimens: Temsirolimus(Torisel™)-CHOP-Rituximab (T-R-CHOP), Temsirolimus(Torisel™)-FC-Rituximab (T-R-FC) and Temsirolimus(Torisel™)-Dexamethasone-aracytine-Rituximab (T-R-DHA) for the treatment of patients with relapsed/refractory Mantle Cell Lymphoma (MCL). The choice of the chemotherapy regimen was left to the decision of local investigator. The primary objective of the T3 was to assess the feasibility and incidence of dose limiting toxicities (DLT) during the two first cycles for each chemotherapy regimen in order to determine the maximal tolerate dose (MTD) in a 3+3 dose escalating design. Dose levels of Temsirolimus (administrated at D2, 8 and 15) were as followed: 25mg level 1; 50mg level 2 and 75mg level 3 and 15 mg in level -1. Patients were planned to receive at least 4 cycles. After 4 cycles, response was evaluated and then patients could continue treatment for 2 additional cycles or receive another treatment according to investigator’s decision. The T3 trial started in November 2011 and so far 38 patients have been enrolled (32 patients are evaluable to date; median age of 69y; range 56 -79). Before inclusion into the T3 trial, patients had received a median of 1 (range 1-3) line of treatment including autologous stem cell transplantation in 15 cases.
Nine patients were included in the R-CHOP group (ORR after 4 cycles was 55,6%). In level 1, two patients out of 3 experimented DLT (grade 3: lymphopenia and GI hemorrhage). In level -1 (n=6), one DLT has been reported (grade 3 thrombocytopenia). In the T-R-FC group (n=12; ORR after 4 cycles was 41,7%), 6 patients were included in level 1 and 3 experimented DLT (grade 3: thrombocytopenia and leukopenia). In cohort -1 (n=6), 4 DLTs were reported. Eleven patients were included in the T-R-DHA group (ORR after 4 cycles was 80%). One DLT was suspected during toxicity review in level 1 (n=3) and was not confirmed as a DLT by the Safety Committee, hence the decision to pass to superior dose level. Then 6 patients (3+3) were included in level 2 (50mg) where 1 DLT was reported. However, only one patient received complete schema of temsirolimus with 3 injections because of hematology toxicity. Thus, it has been decided to add 3 additional patients at level 1 (25mg). These patients are currently under treatment.
In conclusion, hematological toxicity grade 3 was the major concern of the three temsirolimus-based chemotheprapy regimen. Administration of Temsirolimus at D15 was frequently skipped. However, 51,6% of patients reached at least a PR after 4 cycles and the T-R-DHA group was the safest, in which, 50% of patients reached CR after 4 cycles. Thus, Temsirolimus plus high dose aracytine based-chemotherapy regimens provides good disease control with an acceptable tolerability profile for patients with relapsed MCL.