Patients with chemotherapy-refractory mantle cell lymphoma experience high response rates and identical progression-free survivals compared with patients with relapsed disease following treatment with single agent bortezomib: results of a multicentre phase 2 clinical trial

The recent approval of bortezomib for the treatment of mantle cell lymphoma (MCL) by the US Food and Drug Administration is based on the results of the multicentre PINNACLE study with supportive data from a number of single and multicentre Phase 2 studies. This multicentre Phase 2 study enroled 40 patients with heavily pretreated MCL. The overall response rate (ORR) was 47%, including 5 complete remissions and 14 partial remissions. Overall, these remissions are relatively durable. The ORR in relapsed and refractory patients was 50% and 43% respectively (P = 0.74), while both populations of patients exhibited essentially similar progression-free survival (PFS; 5.6 months vs. 3.9 months, P = 0.81). Responding patients experienced a PFS from bortezomib that was similar to their line of prior therapy (7.8 months vs. 8.4 months, respectively). The data showed similar responses in relapsed and refractory patients as well as remission durations similar to prior therapy, suggesting that there may be little cross-resistance with other conventional cytotoxic agents. Importantly, these data suggest that MCL patients with refractory or poorly responsive disease may still derive meaningful clinical benefit from treatment with bortezomib.