Phase II Trial of Weekly Bortezomib in Combination with Rituximab in Untreated Patients with Waldenstrom's Macroglobulinemia.
Authors: Ghobrial Irene M. , Padmanabhan Swaminathan , Badros Ashraf Z. , Leduc Renee , Rourke Meghan , Chuma Stacey , Kunsman Janet , Warren Diane , Harris Brianna , Sam Amy , Anderson Kenneth C. , Richardson Paul , Treon Steven , Matous Jeffrey 
Published: October 2019

Abstract
Abstract 3752
Poster Board III-688

INTRODUCTION
This study aimed to determine activity and safety of weekly bortezomib and rituximab in patients with untreated Waldenstrom's Macroglobulinemia (WM). Prior studies using twice a week bortezomib in this population showed high responses, but significant neuropathy.

METHODS
Patients who had symptomatic WM and were not previously treated were eligible. All patients received bortezomib IV weekly at 1.6 mg/m2 on days 1, 8, 15, q 28 days x 6 cycles, and rituximab 375 mg/m2 weekly on cycles 1 and 4. Dexamethasone was not added. Primary endpoint was the percent of patients with at least a minor response. Patients were encouraged to receive herpes zoster prophylaxis but it was not mandated.

RESULTS
Twenty-six patients were treated. At least minimal response or better was observed, assessed using serum protein electropheresis, in 24/26 cases (92%) with 2 patients (8%) in complete remission (CR)/near CR, 15 (54%) in partial response (PR), and 7(27%) in minimal response (MR). Two patients (8%) had stable disease. By using IgM by nephlometry, all 26 patients (100%) had at least a minor response, with 2 (8%) CR, 15 (58%) in PR and 9 (35%) with minor response. The median time of follow up is 11.2 months (range, 3-18.6). To date, six (23%) patients have developed progressive disease or required a new therapy. A single patient has died due to disease progression. The median progression-free survival and overall survival have not been reached. The most common grade 3 and 4 therapy related adverse events included anemia in 3 patients, lymphopenia in 2 patients; neutropenia, leucopenia, thrombocytopenia, pneumonia, fatigue, allergic reaction and nausea and vomiting in 1 patient for each. Five patients developed grade 2 peripheral neuropathy including 4 did who did not have neuropathy at baseline. It required dose reductions in cycles 4 and 5 and these neuropathies resolved to grade 1 or less with follow up. One case developed grade 1 herpes zoster reactivation in cycle 1.

CONCLUSIONS
The combination of weekly bortezomib and rituximab showed significant activity and minimal neurological toxicity in patients with untreated WM.

Disclosures:
Ghobrial: Millennium: Honoraria, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau. Anderson:Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Millennium: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Richardson:Keryx Biopharmaceuticals: Honoraria. Treon:Millennium: Honoraria, Research Funding, Speakers Bureau; Celgene: Honoraria, Research Funding, Speakers Bureau; Genentech: Honoraria, Research Funding, Speakers Bureau. Matous:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Cephalon: Membership on an entity's Board of Directors or advisory committees.