Diffuse large B-cell lymphoma (DLBCL) is the most common form of non-Hodgkin lymphoma, rising in incidence among older populations. The standard of care for the approximate one-third of DLBCL patients who do not achieve remission with R-CHOP (rituximab plus cyclophosphamide, doxorubicin, vincristine and prednisone) is salvage high-dose chemotherapy followed by consolidative autologous stem cell transplant, which leads to long-term disease-free survival for only 10-20 percent of relapsed/refractory patients. Patients who relapse within a year of initial therapy, those who relapse after transplant, and those who are ineligible for transplant due to age or comorbidities face the most significant unmet treatment need.
With an eye toward improving therapeutic options and outcomes for this patient population, the Lymphoma Program team, led by Dr. Jia Ruan, collaborated with colleagues nationwide and contributed significantly to a study examining the maximum tolerated dose and preliminary safety and activity of a novel three-drug combination – ibrutinib plus lenalidomide and rituximab – in treatment of relapsed/refractory DLBCL. The team’s encouraging findings were published in the American Society of Hematology’s Blood journal.
The study population consisted of 45 transplant-ineligible DLBCL patients whose disease returned after at least one prior therapy. Patients received oral ibrutinib daily, intravenous rituximab on every first day of six 28-day cycles, and oral lenalidomide on the first 21 days of each cycle. The treatment was provided as continuous chronic therapy in an outpatient clinic setting for as long as patients could derive benefit.
Forty-four percent of patients responded to the triplet, and 28 percent achieved a complete response. The combination performed particularly well (ORR: 65%, CR: 41%) in patients with non-germinal center b cell (non-GCB) DLBCL, a molecular subtype based on disease cell of origin that is not typically associated with favorable prognosis. Common treatment side effects included gastrointestinal complications, fatigue, myelosuppression (reduced blood cell production), hypokalemia (low blood potassium), peripheral edema and skin rash. Side effects could be monitored and mitigated by dose adjustment in the outpatient setting.
“This novel treatment consists of two oral agents typically used to treat B-cell lymphoma, plus the anti-CD20 antibody rituximab, and can be easily administered in the clinic or patient’s home,” said Dr. Jia Ruan. “This effective low-intensity approach makes it very appealing to a broad range of R/R DLBCL patients in need of treatment.”
Led by Dr. Jia Ruan, clinical investigators at four medical centers across the United States launched a phase two clinical trial in 2011 to evaluate the novel biological pairing of lenalidomide plus rituximab as induction (initial) and maintenance (relapse prevention) therapy. The team’s treatment goals were to provide disease control and extend survival, while maintaining quality of life.
Of 36 evaluable patients, about 92 percent responded to treatment, with 64 percent achieving complete remission. At five-year follow-up, 77 percent of participants were alive and well, and 64 percent remained free of disease progression.
To determine how well the lenalidomide plus rituximab combination works, the team also measured the status of minimal residual disease (MRD) – the small amount of cancer cells that may be left after treatment that have the potential to lead to relapse. Eight out of a subset of ten evaluable patients tested MRD-negative.
Overall, the chemotherapy-free drug combination has produced durable remission rates with potential to achieve MRD-negative remissions. Chronic maintenance therapy with lenalidomide and rituximab has manageable side effects, including infections, cytopenias (low blood count), and some expected secondary primary malignancies.
This outcome represents a major stride in treatment and care of the MCL patient population, who harbor a rare and generally incurable disease where intensive chemotherapy regimens do not necessarily translate to cure and may not be tolerated by all patients.
“The introduction of novel agents – including the immunomodulatory agent lenalidomide and Bruton’s tyrosine kinase (BTK) inhibitors ibrutinib and acalabrutinib, which are FDA-approved for MCL – is poised to transform MCL management by making effective ‘chemo-free’ treatment accessible to all patients in both relapsed/refractory and frontline settings,” says Jia Ruan, MD, PhD.
Mantle cell lymphoma (MCL) is a rare subtype of non-Hodgkin lymphoma that occurs primarily in older adults. The disease is typically managed in the initial treatment setting with a combination of chemotherapy and immunotherapy, which tends not to be curative and may impart toxic side effects in some patients.
In search of an effective, less toxic treatment option for those afflicted by MCL, Dr. Jia Ruan and colleagues explored an alternative regimen free of conventional chemotherapy – lenalidomide plus rituximab – to be used in the initial treatment setting. Their multi-center phase II clinical trial of the novel biological pairing was the first-ever study of a non-chemotherapy first-line MCL treatment approach.
Thirty-eight MCL patients enrolled in the trial from July 2011 to April 2014. They received lenalidomide on days 1-21 of a 28-day cycle, and rituximab was administered four times per week during the first cycle, then once every other cycle. The first 12-cycle treatment was considered induction, or initial therapy, and was followed by a maintenance phase, in which therapy is provided to prevent relapse. Treatment was continuous until disease progression, and patients had the option to cease therapy after three years if in remission.
At the 2017 American Society of Hematology Annual Meeting, the researchers examined the long-term outcomes of the trial in a 5-year follow-up analysis to reveal that the drug combination shows promise for effective management of MCL, with the majority of trial participants doing well and maintaining good quality of life. About 90 percent of patients responded to the therapy, and over 60 percent remain in remission.
The research team also measured minimal residual disease (MRD) in patients’ blood, the small number of cancer cells that may be left after treatment that have the potential to grow and cause the patient to relapse. In the small subset of patients with available tumor tissues for MRD analysis, about 80 percent of patients were found to be MRD negative, further demonstrating the novel treatment regimen’s activity and feasibility as an additional therapeutic option for people with MCL.
“We are encouraged by the quality and durability of the responses with the biologic doublet of lenalidomide plus rituximab as initial therapy for mantle cell lymphoma,” said Dr. Ruan. “We hope to bring this active combination to larger studies where it can be combined with other agents and compared to conventional chemotherapy.”