A Phase II Clinical Trial of Rituximab, Cyclophosphamide, Bortezomib, and Dexamethasone (R-CyBor-D) in Relapsed Low Grade and Mantle Cell Lymphoma

Abstract Introduction Non-Hodgkin lymphoma responds to single agents such as cyclophosphamide, combination therapy such as CVP and immunotherapy with monoclonal antibodies such as rituximab. There is no consensus on the optimal treatment for relapsed low grade or mantle cell lymphoma. Based on the success and tolerability of combining alkylating agents with proteasome inhibitors in multiple myeloma, a phase II clinical trial of rituximab, cyclophosphamide, bortezomib, and dexamethasone (R-CyBor-D) was designed to explore the efficacy and safety of this combination in relapsed low grade and mantle cell lymphoma (MCL). Methods This trial enrolled relapsed patients at Mayo Clinic from October 2008 to March 2014. Eligibility required age≥18; biopsy proven follicular grades 1 or 2 lymphoma (FL), MCL, small lymphocytic lymphoma/chronic lymphocytic leukemia, marginal zone B-cell lymphoma, or Waldenström’s macroglobulinemia (WM); life expectancy >3 months; ECOG PS 0, 1 or 2; measurable disease; Hb ≥8g/dl, ANC ≥1200/uL, platelet ≥75,000/uL, creatinine ≤1.5xULN, total bilirubin ≤1.5xULN, alkaline phosphatase ≤3xULN, AST ≤3xULN; and willingness to sign informed consent. Women of child bearing potential had pregnancy testing and all patients followed recommendations for contraception. Treatment included rituximab 375 mg/m2 IV on day 1 and oral cyclophosphamide 300 mg/m2, IV bortezomib 1.3 mg/m2, and oral dexamethasone 40 mg on days 1, 8, 15, and 22 in a 28-day cycle. Treatment was continued two cycles beyond best response or a maximum of 12 cycles. Allopurinol 300 mg on days 0-14 for the first cycle was strongly recommended. Results 21 patients were enrolled prior to study closure due to slow accrual. Bortezomib was initially given on days 1, 4, 8, and 11 in the first 16 patients, but was subsequently modified to days 1, 8, 15, and 22 due to significant peripheral neuropathy (PN). Median age was 69 years (range 51-80) and 13 (62%) were male. 62% had stage IV disease and 17 (81%) had 2 or more prior treatments with 3 (14%) having prior autologous stem cell transplantation. Histologies included FL-I (n=6), FL-II (n=2), MCL (n=8), and WM (n=5). Patients completed a median of 4 cycles of treatment (range 1-12), discontinuing due to 9 (43%) completion per protocol, 4 (19%) progression, 5 (24%) adverse events, 1 (5%) patient refusal, and 2 (10%) other reasons. Median follow-up is 32.8 months (0.9-54.8). CR or PR as best response was observed in 13 (62%, 95% CI 38-82%; 4 CR [19%], 9 PR [43%]) patients. By histology, CR or PR was observed in 7 (88%) FL patients (4 CR, 3 PR); 2 (25%) MCL patients (both PR), and 4 (80%) WM patients (all PR). CR or PR was observed in 10/16 (62%; 4 CR, 6 PR) before and 3/5 (60%; all PR) after the change in bortezomib schedule. Among 13 patients with CR or PR, median duration of response was 25.9 months (95% CI 8.0-not reached). Median PFS and OS were 11.6 months (95% CI 3.8-not reached) and 54.8 months (95% CI 24.6-54.8), respectively. At least one Gr≥3 adverse event at least possible related was observed in 14 (67%) patients, the most common being leucopenia (7, 33%), neutropenia (7, 33%), thrombocytopenia (6, 29%), anemia (5, 24%), PN (5, 24%), and fatigue (3, 14%). Peripheral sensory neuropathy at least possibly related was Gr1, Gr2, and Gr3 in 5 (24%) patients each, with a lower rate observed for patients after the change in bortezomib schedule (before 13/16 [81%] Gr≥1, after 2/5 [40%] Gr≥1). Among 14 patients who completed a baseline and at least one post-baseline FACT/GOG-NTX additional concerns questionnaire, 10 (71%) reported clinically meaningful (≥3-point) worsening in patient-reported neurotoxicity (8/11 [73%] before and 2/3 [67%] after the change in bortezomib schedule). Conclusions Our results suggest R-CyBor-D is a safe and effective combination in patients with relapsed low grade and mantle cell lymphomas. High response rates were seen in FL and WM. The majority of significant AE’s were hematologic. However, sensory neuropathy was common with twice weekly dosing of bortezomib and lessened with weekly dosing. Determination of optimal treatment regimens in this population remains an unmet need. Additional clinical trials including larger patient numbers are necessary to confirm these observations. This trial was sponsored by Millennium Disclosures Off Label Use: bortezomib was used in combination therapy to treat relapsed low grade lymphomas and Waldenstrom's macroglobulinemia. Bergsagel:Novartis: Research Funding; Constellation Pharmaceutical: Research Funding; OncoEthix: Research Funding; MundiPharma: Research Funding. Tiedemann:Janssen: Honoraria. Reeder:Millennium, Celgene, Novartis: Research Funding.

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