Background: Bortezomib (B) belongs to a new class of anti-cancer agents, the proteasome inhibitors, and has documented activity in multiple myeloma and mantle cell lymphoma (MCL). Preclinical studies suggest that B has synergistic activity with rituximab (R), which provides a rationale for the exploration of treatment combinations. We therefore evaluated the activity and safety of B in combination with R and dexamethasone (BORID) in patients with relapsed and refractory MCL (phase II trial).

Methods: 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 (pts) achieving a response received 4 additional doses of R as maintenance (every 8 weeks). Pts with progressive MCL after at least one prior line of therapy (including CHOP or a CHOP-like regimen) were eligible.

Results: We have completed enrollment of 16 pts (median age, 67 years; range, 48 to 75 years) after a median of 3 lines of prior therapies (range, 1 to 6, prior rituximab in 88%; thalidomide in 50%; high-dose therapy in 31%; a fludarabine-containing regimen in 31%). Median time between start of frontline therapy and study inclusion was 42 months (range, 11 to 98 months). Severe adverse events (> grade II) included infections (herpes zoster in 2 pts, bacterial pneumonia, mucosal candidiasis), peripheral neuropathy (3 pts), fatigue (2 pts) and vasculitic skin infiltrates in 3 pts. Thrombopenia (< 50 G/L) occured in 2 pts. All adverse events were managable by standard means of supportive care and prolongation of the treatment interval between cycles. Overall response rate was 69% (11 of 16 pts), with 6 pts achieving a CR (38%; confirmed by PET-scan in 5 pts) and 5 pts reaching a PR. Skin infiltrates (histologically proven T-cell infiltrates) preceded achievement of CR in 2 pts. Remission status appeared to be associated with progression-free survival (PFS): Patients in CR had longer PFS (29+, 24+, 21+, 12+, 12, and 10+ months) compared to patients in PR (median 8.5 months, range 6 – 15).

Conclusions: BORID has promising activitiy (69% overall response rate; CR rate 38%) and managable toxicity in this patient population with predominantly heavily pretreated MCL. Achievement of a CR emerged as an important factor for sustained disease control. Further evaluation of this regimen, in particular in pts at an earlier phase of the disease, is warranted.

Author notes

Disclosure: No relevant conflicts of interest to declare.