The treatment combination of obinutuzumab, bendamustine and dexamethasone achieved a deeper response than the previous line of treatment in five patients with Waldenström's macroglobulinemia.

Background: Rituximab is already a standard part of the treatment of patients with Waldenström's macroglobulinemia. However, a small proportion of patients develop intolerance to rituximab during administration or the treatment is not very effective. In these patients, we are faced with the question of whether another anti-CD20 monoclonal antibody can be used and what result will be achieved.

Patient population and methods: Between 2020 and 2022, we administered the new anti-CD20 monoclonal antibody obinutuzumab in combination with bendamustine and dexamethasone in five patients with Waldenström's macroglobulinemia (WM). All patients completed eight cycles of the indicated treatment. Two of them received second-line treatment, another two received third-line treatment, and one patient received this treatment as part of fourth-line treatment. We did not observe significant toxicity (grade III and IV) in any patient.

Results: All five patients achieved a deeper treatment response (once complete response, 4-times very good partial response) than in previous lines of treatment. At a median follow-up after treatment of 29 months (range 28-48), the disease relapsed in one patient only, the others are in remission.

Conclusion: Obinutuzumab in combination with bendamustine is a very effective treatment alternative for WM. In the described five patients, obinutuzumab with bendamustine and dexamethasone achieved a deeper therapeutic response than the previous treatment lines. Obinutuzumab represents a drug that will be of great benefit to selected patients with WM.