VcR-CVAD Produces a High Complete Response Rate in Untreated Mantle Cell Lymphoma: A Phase II Study from the Wisconsin Oncology Network

Introduction: There is no standard treatment for Mantle cell lymphoma (MCL). Intensive treatment strategies such as conventional R-hyperCVAD with alternating R-cytarabine/methotrexate or autologous stem cell transplant appear to improve PFS but the effect on OS is unclear. In addition, approximately 50% of newly diagnosed patients are not candidates for intensive therapies. Novel treatment strategies are needed. We have published the results of a study using a modified R-hyperCVAD induction followed by maintenance rituximab (Kahl et al, Ann Oncol 2006). This induction strategy yielded a complete response (CR) rate of 64% and the entire treatment program yielded a median PFS of 37 months. Bortezomib (Velcade) has demonstrated promising activity in relapsed MCL (Fisher et al, J Clin Onc, 2006). We hypothesized that the incorporation of Velcade (Vc) into the induction regimen would improve the CR rate. The new regimen, VcRCVAD, was tested for safety and efficacy in a phase II study at the University of Wisconsin and within the Wisconsin Oncology Network.

Methods: Eligible patients had histologically confirmed mantle cell lymphoma, PS 0–2, and adequate end organ function. The final treatment plan included: Velcade 1.3 mg/m² days 1 and 4, rituximab 375 mg/m² IV day 1, cyclophosphamide 300 mg/m² IV over 3 hrs q 12 hrs X 6 doses days 1–3, doxorubicin 50 mg/m² continuous infusion over 48 hrs days 1–2, vincristine 1 mg IV day 3, dexamethasone 40 mg po days 1–4. Due to excessive painful peripheral neuropathy (PN), 2 dose modifications were required during the course of the study. Patients 1–7 received 1.5 mg/m² Velcade and 2 mg vincristine. Patients 8–14 received 1.3 mg/m² Velcade and 2 mg vincristine. Patients 15–30 received 1.3 mg/m² Velcade and 1 mg vincristine. Cycles were repeated every 21 days for 6 cycles and all patients received G-CSF cytokine support. Patients achieving at least a PR receive maintenance rituximab therapy for 5 years.

Results: Enrollment is complete and all 30 patients are evaluable for response to VcRCVAD induction. Baseline characteristics include median age 60.5 (48–74), 24M:6F, 26/30 (87%) stage IV, and 12 (40%) low-risk, 8 (27%) int-risk, and 10 (33%) high-risk by MIPI. 3 patients (10%) experienced PD during induction therapy and 27 (90%) responded with 23 CR/CRu (77%) and 4 PR (13%). With a median follow up of approximately 18 months, the 18-month PFS and OS are 73% and 97%, respectively. The major toxicity of this treatment regimen is painful PN and expected hematologic toxicity. 5/7 patients in cohort 1 and 3/7 patients in cohort 2 developed grade 3 painful PN and 1 patient in cohort 2 developed grade 4 painful PN. Only 1/16 patients in the final cohort experienced grade 3 painful PN. All neuropathy eventually improved to ≤ grade 2, but 10 patients require chronic medication for symptom relief. 13/167 (8%) of the treatment cycles were complicated by neutropenic fever/infection. There were no treatment related deaths.

Conclusion: The VcR-CVAD induction has produced high overall response (90%) and CR rate (77%) in a very representative MCL patient population. Comparing these data to our previous frontline MCL study, the CR rate appears to be enhanced (77% vs 64%) by the addition of Velcade. Longer follow up is needed before determining if the higher CR rate will translate into an improved PFS and OS. Because of the risk for painful PN, caution must be exercised when using vincristine and Velcade in combination. The MTD for this combination was 1 mg vincristine and 1.3 mg/m² Velcade. The encouraging complete response rate provided the rationale for ECOG study E1405, which is testing the safety and efficacy of this induction regimen in a cooperative group setting.