Promising Activity of Bortezomib, Rituximab, and Dexamethason (BORID) in Patients with Relapsed Mantle Cell Lymphoma.

Bortezomib (B) belongs to a new class of anti-cancer agents, the proteasome inhibitors, and has documented activity in multiple myeloma. Moreover, recent data indicate that B is also effective in other B-cell malignancies, most notably in mantle cell lymphoma (MCL). Phase II studies revealed remission rates between 40 and 55% of patients with relapsed or refractory MCL. Preclinical studies suggest that B has synergistic activity with rituximab (R), which provides a rationale for the exploration of such a treatment combination. We have therefore initiated a phase II study in relapsed/chemotherapy refractory MCL in order to evaluate the activity and safety of B in combination with R and dexamethasone (BORID). A treatment cycle consists of B at 1.3 mg/m² administered on days 1, 4, 8, and 11, R at 375 mg/m² administered on day 1, and dexamethasone 40 mg orally on days 1 to 4. Cycles are repeated every 3 weeks for a total of 6 treatment cycles. Patients with progressive MCL after at least one prior line of therapy (including CHOP or a CHOP-like regimen) are eligible. Up to now, we have enrolled 7 patients at a median age of 65 years (range, 52 to 74 years); they had received one to 6 lines of prior therapy including R in 5 of them and high-dose chemotherapy followed by autologous stem cell transplantation in 2 patients. Severe adverse events (> grade II) included 3 infections (herpes zoster, bacterial pneumonia, pneumonia of potential viral origin), grade III peripheral neuropathy in one patient, and nodular skin infiltrates in one patient. All adverse events were managable by standard means of supportive care and prolongation of the treatment interval between cycles. No severe hematological toxicity has yet been encountered. Of 6 patients evaluable for efficacy, 5 have achieved a response (1 CR, 4 PR), and 1 patient experienced stable disease. The patient in CR (previously treated by R-CHOP, autologous transplantation, and R plus thalidomide) was also negative for disease activity by PET scanning. None of the patients has yet progressed at 4 to 9 months after initiation of BORID. Recruitment of patients is ongoing, and updated results will be presented. Data obtained thus far indicate that BORID has promising activitiy and managable toxicity in patients with relapsed MCL, which warrants further investigation not only in MCL but also in other B-cell lymphomas.