Temsirolimus in the treatment of relapsed and/or refractory mantle cell lymphoma

Patients with mantle cell lymphoma (MCL) have a poor prognosis; consequently, new therapeutic approaches, such as rapamycin and its derivates, mammalian target of rapamycin (mTOR) inhibitors, are warranted. Temsirolimus (also known as CCI-779), a dihydroester of rapamycin, in MCL cell lines inhibited mTOR, downregulated p21 and v-Raf, and induced autophagy. The first clinical trial in MCL patients was performed using 250 mg of temsirolimus weekly for 6-12 cycles. The overall response rate was 38%; the median time to progression was 6.5 months, median overall survival was 12 months, and the median duration of response was 6.9 months. At lower dose (25 mg/week), the overall response rate was 41%, median overall survival was 14 months, and time to progression was 6 months. In another trial, 162 patients were randomly assigned to receive temsirolimus at 2 different doses (175 mg/week for 3 weeks, then 75 mg or 25 mg/week) or a treatment chosen by the investigator among the most frequently adopted single agents for treatment of relapsed MCL. Patients treated with 175/75 mg of temsirolimus had significantly higher response rates and longer progression-free survival than those treated with investigator's choice therapy. These data support the use of mTOR inhibitors for the treatment of MCL, probably in combination with other agents, such as antiangiogenic drugs or histone acetylase inhibitors.