Phase II Trial of the Combination of Ixazomib, Lenalidomide, and Dexamethasone in High-Risk Smoldering Multiple Myeloma

• Published in: Blood 2019-11, Vol.134 (Supplement_1), p.580-580
• Main Authors: Bustoros, MD, Mark, Nadeem, Omar, Sperling, Adam S, Bianchi, Giada, Ardente, Lily, Redd, Robert A., Prescott, Julia, Frey, Erin, Guimond, Kathleen, Styles, Rachel, Hornburg, Kalvis, Savell, Alexandra, Su, Nang Kham, Bindra, Govind, Boehner, Cody J, Reyes, Kaitlen, Leblebjian, Houry, Warren, Diane, Munshi, Nikhil C., Laubach, Jacob P., Anderson, Kenneth C., Richardson, Paul G., Ghobrial, Irene M.
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2019-128519

Background.This study aimed to determine the progression-free survival and response rate using early therapeutic intervention in patients with high-risk smoldering multiple myeloma (SMM) using the combination of ixazomib, lenalidomide, and dexamethasone. Methods.Patients enrolled on study met eligibility for high-risk SMM based on the newly defined criteria proposed by Rajkumar et al. (Blood 2014). The treatment plan was designed to be administered on an outpatient basis where patients receive 9 cycles of induction therapy of ixazomib (4mg) at days 1, 8, and 15, in combination with lenalidomide (25mg) at days 1-21 and dexamethasone at days 1, 8, 15, and 22. The induction phase was followed by ixazomib (4mg) and lenalidomide (15mg) maintenance for another 15 cycles. A treatment cycle was defined as 28 consecutive days for a total of 24 months period. Bone marrow samples of all patients were obtained before starting therapy for baseline assessment for minimal residual disease (MRD) testing, whole-exome sequencing (WES), and RNA sequencing of plasma and bone marrow microenvironment cells. Moreover, blood samples were obtained at screening and before each cycle for isolating cell-free DNA (cfDNA) and circulating tumor cells (CTCs). Results.In total, 53 of the planned 62 patients have been enrolled in this study from February 2017 to May 2019. The median age of the patients enrolled was 61 years (range, 41 to 84) with 22 male (41.5%). The analysis was conducted on patients who have completed at least 1 cycle of therapy (n=45). The median follow-up for the trial is 14.4 months (range: 2- 27.6). Interphase fluorescence in situ hybridization (iFISH) was successful in 37 patients (82.2%). High-risk cytogenetics (defined as the presence of t(4;14), 17p deletion, and 1q gain) were found in 20 patients (54%). The median number of cycles completed was 14 cycles (range: 1-24). According to the study's inclusion criteria, baseline markers showed that 15, 14, and 13 patients had 3, 4, and 5 high-risk features, respectively. Moreover, 24 patients (53.3%) met the criteria of high-risk SMM, according to the Mayo 2018 model. The most common grade 3 adverse events were hypertension (6.3%), hypophosphatemia (4.2%), and rash (4.2%). Grade 4 thrombocytopenia and neutropenia were each reported in 4.4% of patients, and hyperglycemia was reported in 2.2%. Stem cells were collected in all eligible patients by the end of the induction phase. As of the abstract date, the overall respon