Systematic Reviews of the Clinical Efficacy and Safety of First-Line Treatments for Patients with Mantle Cell Lymphoma

Introduction

Mantle cell lymphoma (MCL) is a rare and aggressive form of Non-Hodgkin's lymphoma (NHL) with poor survival outcomes. High-dose chemotherapy followed by autologous stem cell transplantation (ASCT) is recommended as first-line therapy in younger patients. However the comparative efficacy of such regimens, and of alternative therapy options (for patients unable to tolerate chemotherapy + ASCT), remain unclear. A comprehensive understanding of the current evidence is therefore required.

Methods

Two systematic reviews (SRs) were developed to identify efficacy and safety data for therapies used in the first-line treatment of MCL. One review identified randomised controlled trials (RCTs) and the other non-randomised studies (NRSs). Searches were carried out in EMBASE, MEDLINE, and the Cochrane Central Register of Controlled Clinical Trials electronic databases. Additionally, conference materials were screened from ASH, EHA, ESMO and ASCO proceedings from the last 2 years. All review methodologies were performed according to Cochrane best practice guidelines

Results

The RCT SR was run in August 2017 and updated in April 2018. Overall, 2,787 abstracts were screened. The SR included 9 full-text articles and data from 2 conference proceedings, together reporting a total of 7 independent studies.

Across the RCTs, the most commonly investigated treatment regimens were rituximab + cyclophosphamide + doxorubicin + vincristine + prednisone (R-CHOP), and bendamustine + rituximab (BR). Frequently reported primary endpoints were response rates and progression-free survival (PFS).

Table 1 presents the PFS and overall survival (OS) data reported in the included RCTs. Data from the RCT reporting on intensive induction chemotherapy followed by ASCT are separated from regimens that did not include ASCT.

There were notable differences in median PFS rates, between both patients receiving ASCT versus patients not receiving ASCT and also between the two ASCT treatment arms. In pharmacotherapy studies, PFS ranged from 14.4 to 35.4 months, whereas the two arms of the ASCT RCT reported 51.6 and 109.2 months, respectively. Similar trends were observed in OS: the only result for patients undergoing ASCT (117.6 months) was higher than any result reported in patients not receiving transplant (range 40 - 60 months). However, study heterogeneity may affect the appropriateness of directly comparing these results.

Frequently reported grade 3-4 adverse events included anemia, infusion-related reactions, nausea, neutropenia and thrombocytopenia (four of seven RCTs reported each event).

The NRS SR was run in April 2018. A total of 3,290 abstracts were screened and 75 full papers were assessed. The SR included 25 full-text articles and 6 conference proceedings, together reporting a total of 18 independent single-arm studies.

Several of the NRSs investigated treatment regimens that have not been described in RCT studies, including: R-CHOP with alternating or sequential rituximab + cytarabine (maxiCHOP), and cyclophosphamide + vincristine + doxorubicin + dexamethasone alternating with high dose methotrexate or cytarabine + rituximab (hyperCVAD + R).

Across the NRSs, the longest median PFS was 8.5 years (102 months), in patients treated with maxiCHOP (who were young/ASCT-eligible patients). This outcome was reported in a patient population who had responded to induction therapy and were treated with consolidative ASCT.

Across all studies there was heterogeneity in the eligible patient population, with some studies focusing on unfit patients and others focusing on high-dose-therapy-eligible patient populations. Many studies also reported maintenance or consolidation treatments, which would influence the long-term outcomes of the patients.

Conclusions

These SRs highlight the paucity of directly comparable evidence on the efficacy and safety of therapies for patients with MCL. Although there are some marked differences in patient outcomes according to therapy regimen, considerable heterogeneity in study design and patient populations make direct comparison difficult. Despite this, these SRs highlight that MCL remains a difficult subtype of NHL to treat, with short survival highlighting the high unmet need. With new and emerging therapies, additional research is essential to understand optimal regimens for first-line MCL.

Table 1.

View largeDownload slide

Table 1.

View largeDownload slide

Close modal