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MCL Landscape Shifting With Combo Regimens on Horizon

Gina Columbus @ginacolumbusonc
Published: Sunday, Mar 26, 2017

Andre Goy, MD

Andre Goy, MD

Investigators have been working on novel approaches to improve outcomes in both the frontline and relapsed/refractory settings of mantle cell lymphoma (MCL) with the use of current FDA-approved agents in combination. New clinical endpoints are also beginning to take priority in MCL research, such as minimal residual disease (MRD) negativity.

Such explorative regimens can be seen in findings from a phase II study presented at the 2016 ASH Annual Meeting. With the goal of reducing the hematologic toxicities associated with cytarabine, researchers treated patients with rituximab (Rituxan) at 375 mg/m2, bendamustine at 70 mg/m2, and cytarabine at a 500-mg/m2 dose (RBAC500). Prior trial results showed that the 800-mg/m2 dose of cytarabine was too difficult to tolerate.

Results showed that the treatment was, indeed, less toxic as frontline therapy for elderly patients with MCL and has the potential to be a new standard of care in this setting.

“The future of MCL is really broader than we think,” explains Andre Goy, MD. “We have a lot of novel options, particularly in the patients who are high risk and don’t benefit, such as those with p53 or 17p deletions. The concept of MRD negativity in MCL is going to be something really critical to achieving an early response, complete response (CR), and molecular CR, as it has a clear impact on progression-free survival (PFS) and overall survival (OS).” 

In an interview with OncLive, Goy, chairman and director, chief of Lymphoma, and director of Clinical and Translational Cancer Research at John Theurer Cancer Center, Hackensack Medical Center, highlights what researchers can expect next in the field of MCL in both the frontline and relapsed/refractory settings given the recent pivotal data from clinical trials.

OncLive: What changes are you seeing in the frontline setting of MCL?

Goy: In the frontline setting of MCL, the consensus is that the patients who are fit can actually benefit with a dose-intensive regimen—a cytarabine-containing regimen—with or without stem cell transplant consolidation. This is because it gives a PFS in excess of 5 to 7 years, so that became sort of the standard after a large randomized trial that confirmed a benefit with cytarabine.

The reason is that you achieve a deeper, early CR and molecular CR in those patients. In MCL, MRD status is really becoming something very important.

Where do we go to improve on this? MRD is being looked at; we are trying to see if we can develop maintenance strategies. This has been looked at in the LyMa trial, which was 4 cycles of R-DHAP, instead of R-CHOP, followed by high-dose therapy and transplant. The data were presented at the 2016 ASH Annual Meeting with a benefit in PFS and OS by 3 years of maintenance with rituximab versus observation. The benefit of maintenance has been proven both in the elderly and younger patients.

That is where the field is, and we are looking at additional ways to improve this maintenance. There are trials looking at “R-squared”—rituximab plus lenalidomide (Revlimid)—as maintenance versus rituximab alone to see if we can get better control of the disease. The goal of the trial is to attain a more durable response, because the problem in MCL is that it becomes chemotherapy resistant.

The high-dose therapy or dose-intensive strategies are not easily feasible in patients who are elderly, and the median age of diagnosis is in the mid-to-late 60s, so there are opportunities to improve on the default standard of R-CHOP, which is definitely not sufficient. By 2 years, 75% of patients progress.

What are some interesting ongoing clinical trials exploring novel approaches?

There were trials looking at R-CHOP combined with bortezomib (Velcade). The activity with single-agent bortezomib in the relapse setting is a 33% response rate and 8% CR rate. It is quite durable for refractory patients.

This trial randomized patients to the combination of bortezomib plus R-CHOP versus R-CHOP alone. The results showed a dramatic improvement—close to 60% improvement in PFS at 14 to 27 months and a significant improvement in CR rate in the experimental arm. That became one of the new standards in the frontline setting, and the first newly approved standard of combining our chemotherapy with a novel agent. 

Bendamustine and rituximab (BR) has been used a lot in the elderly MCL population because it is easier to tolerate and it is noninferior to R-CHOP, as seen from the StiL trial. Now, this is being looked at in combination with bortezomib with a CR rate in excess of 50%. It is promising enough to develop a randomized trial that is ongoing, with BR plus or minus bortezomib followed by a second randomization of rituximab versus R-squared as maintenance. The results are obviously not out; the trial is not completed yet. This is really trying to build up and bring a novel agent into the frontline setting. 

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Community Practice Connections™: Addressing Post-Transplant Obstacles: Current and Emerging Strategies to Evolve the Standard of Care for Patients With Graft-Versus-Host DiseaseMar 28, 20192.0
2017 Year in Review™: Clinical Impact of Immunotherapies in the Treatment of CancerMar 30, 20191.75
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