Obinutuzumab and venetoclax induced complete remission in a patient with ibrutinib-resistant non-nodal leukemic mantle cell lymphoma.

We herein report the case of a 73-year-old male patient who was diagnosed with leukemic non-nodal MCL. This patient had received six cycles of bendamustine, which resulted in a transient remission, and a second-line therapy with ibrutinib, which unfortunately failed to induce remission. We started a treatment with single-agent obinutuzumab at a dose of 20 mg on day 1, 50 mg on day 2-4, 330 mg on day 5, and 1000 mg on day 6. The laboratory analysis showed a rapid decrease of leukocyte count. Four weeks later, we repeated the treatment with obinutuzumab at a dose of 1000 mg q4w and started a therapy with venetoclax at a dose of 400 mg qd, which could be increased to 800 mg qd from the third cycle. This combination therapy was well tolerated. The patient achieved a complete remission (CR) after three cycles of obinutuzumab and venetoclax. To date, the patient has a progression-free survival of 17 months under ongoing obinutuzumab maintenance q4w. This is the first report about obinutuzumab and venetoclax induced CR in rituximab-intolerant patient with an ibrutinib-resistant MCL. This case suggests that obinutuzumab- and venetoclax-based combination therapy might be salvage therapy in patients with ibrutinib-resistant MCL.