The following article features coverage from the American Society of Hematology 2019 meeting. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

Long-term survival following bendamustine plus rituximab (B-R) treatment for Waldenström macroglobulinemia (WM) is comparable in patients who undergo an additional 2 years of rituximab maintenance therapy and those who undergo observation alone, researchers reported in at the 61st American Society of Hematology (ASH) Annual Meeting and Exposition in Orlando, Florida. The results were findings from the StiL NHL1-2008 MAINTAIN trial.

“We confirmed that induction with B-R is a highly effective treatment for WM,” reported lead study author Mathias J. Rummel, MD, PhD, of the Justus Liebig University in Giessen, Germany, and coauthors, in the study abstract.

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After a median follow-up of nearly 6.7 years (80 months), progression-free survival (PFS) and overall survival (OS) rates were comparable in patients following 2 years of rituximab maintenance and those who underwent observation following first-line B-R, they reported.

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A total of 296 patients with advanced WM and B-symptoms, anemia, or hyperviscosity syndrome were enrolled in the study and treated with up to 6 cycles of B-R plus 2 additional rituximab cycles. Patients who responded to B-R (218 individuals) were randomly assigned to receive either rituximab maintenance therapy every 2 months for 2 years (109 individuals) or to undergo observation, which the study group referred to as “watch and wait” (109 individuals).

Ninety-three percent of patients (247 of 266 evaluable individuals) responded to B-R induction therapy, with 63% (167 individuals) achieving partial remission (PR). There was 1 complete response seen (3%).

As it related to the evaluation of response to rituximab in the maintenance setting, data were only evaluable for 218 of the 296 enrolled patients at the time of the study presentation. Median baseline IgM was 32.7 g/L.

At nearly 7 years follow-up, median PFS for those in the observation cohort was 106.3 months and median PFS for patients in the maintenance treatment group was 118.4 months. The difference in PFS between groups was not significant (hazard ratio [HR], 1.21; 95% CI, 0.78-1.89; P =.3982), the difference between groups for overall survival was not significant either (hazard ratio [HR], 0.85; 95% CI, 0.46-1.55; P =.5962)

“Patients responding to B-R do have an excellent disease control with a median PFS of 10 or 9 years with or without R-maintenance.” the researchers said. “Exploratory subgroup analyses suggest that age (>65 years) appears to be a critical factor for a potential benefit of R-maintenance.”

Despite seeing no PFS or OS benefit with rituximab in the maintenance setting after B-R for WM, the researchers still came away from the study with the following conclusion: “Based on our data we can recommend B-R as first-line treatment for WM.”

Disclosure: Some of the authors disclosed financial relationships with the pharmaceutical industry. For a full list of disclosures, please refer to the original abstract.

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Rummel MJ, Lerchenmuller C, Hensel M, et al. Two years rituximab maintenance vs. observation after first line treatment with bendamustine plus rituximab (B-R) in patients with Waldenström’s macroglobulinemia (MW): Results of a prospective, randomized, multicenter phase 3 study (the StiL NHL7-2008 MA). Presented at: 61st American Society of Hematology (ASH) Annual Meeting and Exposition; December 7-10, 2019; Orlando, FL. Abstract 343.