Phase I/II Trial Of Everolimus, Bortezomib and Rituximab In Relapsed Or Relapsed/Refractory Waldenstrom's Macroglobulinemia
Authors: Ghobrial Irene M. , Boswell Erica N , Chuma Stacey , Banwait Ranjit , Hanlon Courtney , Leblebjian Houry , Warren Diane , Mostyn Patrick , Masood Farzana , Richardson Paul G. , Treon Steven Peter , Matous Jeffrey 
Published: October 2019

Abstract

Introduction
The phase I aimed to determine the safety and maximum tolerated dose of the combination of everolimus and rituximab, or everolimus, bortezomib, and rituximab and the phase II study aimed to examine response and safety of the combination of all 3 agents in relapsed and/or relapsed/refractory Waldenstrom Macroglobulinemia. This trial was based on our preclinical studies that demonstrated synergistic activity of everolimus and bortezomib with rituximab in WM.

Methods
Eligibility criteria include: 1) patients with relapsed or relapsed/refractory WM with any number of prior lines of therapy, including everolimus and bortezomib 2) not completely refractory to rituximab 3) measurable disease by monoclonal IgM protein in the serum and lymphoplasmacytic cells in the bone marrow, 4) Not receiving chemotherapy > 3 weeks, or biological/novel therapy for WM > 2 weeks. A cycle is 28 days and a total of 6 cycles are given, followed by everolimus maintenance until Progression. The phase I trial included two stages with a total of four dose levels. In stage A, patients received everolimus at the recommended dose orally daily for 28 days and rituximab at the recommended dose IV on days 1, 8, 15, and 22 every 28 days at cycle 1 and 4 only. In stage B, patients received everolimus at the recommended dose orally daily for 28 days, bortezomib at the recommended dose IV on days 1, 8, 15 every 28 days, and rituximab at the recommended dose IV on days 1, 8, 15, and 22 every 28 days at cycle 1 and 4 only. For the phase II study, patients received everolimus 10 mg daily, bortezomib IV 1.6mg/m2 on days 1, 8, 15 every 28 days, and rituximab 375mg/m2 IV on days 1, 8, 15, and 22 every 28 days at cycle 1 and 4 only. Patients were assessed for response after every cycle. Subjects who had a response continued on therapy for a total of 6 cycles, and then continued on to maintenance therapy with everolimus alone until progression

Results
Forty-Six patients were enrolled in this phase I/II clinical trial from April 2009 to July 2013. The median age is 65 (range, 47–84) yrs and the median lines of prior therapy is 5 (range, 1–9) with 45 (98%) patients receiving prior rituximab and 23 (50%) receiving prior bortezomib. The median number of cycles on therapy was 19.5 (range, 0–39). Overall, this combination therapy is very well tolerated. Grade 4 toxicities included: neutropenia (4.3%), leukopenia (2.2%), thrombocytopenia (13%), lymphopenia (2.2%) and hypertriglyceridemia (2.2%). Grade 3 toxicities included: neutropenia (13%), leukopenia (13%), anemia (10.9%), lymphopenia (8.7%), pneumonitis (4.3%), SGPT (4.3%), neuropathy (4.3%), Herpes zoster reactivation (4.3%), (2.2%) bacterial endocarditis, (2.2%) congestive heart failure, (2.2%) hearing loss, hyperglycemia (4.3%) hypernatremia (4.3%) and 1(2.2%) subject had an incarcerated inguinal hernia with small bowel obstruction. Two patients discontinued therapy due to grade 3 anemia. For the phase II study, sixteen patients are currently evaluable for response, including 2 (13%) complete response (CR), 11 (68%) partial response and 1 (6%) minimal response (MR), for an overall response rate including MR of 14/16 (88%) in this relapsed/refractory population. Furthermore, overall response including MR in phase I was 1/23 (4%) complete response, 7/23 (30%) partial response and 10/23 (43%) minimal response. In phase II 1/23 (4%) complete response, 14/23 (61%) partial response and 2/23 (9%) minimal response. Additionally, 8 (17%) patients achieved stable disease.

Conclusions
The combination of everolimus, bortezomib, and rituximab is generally well tolerated, and importantly no grade 3/4 neuropathy was seen. The responses observed to date indicate that this combination is highly effective in this relapsed/refractory population. This study was supported from the FDA Office of Orphan Products Development and by Millennium/Takeda and Novartis Inc.

Disclosures:
Ghobrial: Onyx: Membership on an entity’s Board of Directors or advisory committees; BMS: Membership on an entity’s Board of Directors or advisory committees; BMS: Research Funding; Sanofi: Research Funding; Novartis: Membership on an entity’s Board of Directors or advisory committees. Richardson:Millennium: Membership on an entity’s Board of Directors or advisory committees; Johnson & Johnson: Membership on an entity’s Board of Directors or advisory committees; Novartis: Membership on an entity’s Board of Directors or advisory committees. Treon:Millennium: Consultancy. Matous:Celgene: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau.