Gater, Paul R.

Abstract Background and Significance: Waldenström's Macroglobulinemia (WM) is an indolent B cell disorder characterized by proliferation of clonal lymphoplasmacytic lymphocytes in the bone marrow, lymph nodes, as well as liver and spleen, and secreting a monoclonal IgM Protein. WM is a rare disorder with about 1,700 cases diagnosed in the U.S. each year. There have been significant advances in the management of patients with WM in the last decade, with Bruton's tyrosine kinase (BTK) inhibitors (ibrutinib and zanubrutinib) emerging as a major treatment advancement in this disease. Currently, both BTK inhibitors are approved for the treatment of WM patients with newly diagnosed as well as relapsed/refractory (R/R) disease. BTK inhibitors are effective for the therapy of WM, especially among patients with MYD88 mutation, although the response rates are lower in patients with CXCR4 mutations. In addition, these drugs can cause cardiac side effects such as atrial and ventricular arrhythmias as well as an increased risk of bleeding/bruising. Thus, these drugs can be difficult to use in patients who are older and have cardiac comorbidities. BCL-2 overexpression is well described in a number of B cell malignancies, including WM, leading to inhibition of apoptosis of malignant cells. BCL-2 inhibition with venetoclax has been tested in patients with R/R WM and showed excellent activity with an overall response rate (ORR) of 85% and very good partial response (VGPR) rate of 19%. The therapy was overall well tolerated with no evidence of cardiac toxicity. Given the excellent activity and tolerability of Venetoclax in WM, we are conducting a national cooperative group randomized phase 2 trial comparing ibrutinib+rituximab (IR) vs. venetoclax+rituximab (VR) in patients with newly diagnosed WM. Our hypothesis is that with this trial, we have the potential to develop a more effective therapy targeting BCL-2 for patients with untreated WM, that does not have cardiac or hemostatic toxicity. In addition, we are testing use of a fixed duration therapy with these regimens. Study design and methods: The ongoing clinical trial () is being conducted through the Southwest Oncology Group (SWOG) and is enrolling at multiple SWOG, ECOG, and ALLIANCE centers throughout the US. Major inclusion criteria include 1) newly diagnosed WM confirmed by biopsy and measurable disease (≥0.5 g/dl IgM type paraprotein), 2) meeting WM-related clinical criteria to initiate therapy (cytopenias, B symptoms, bulky lymphadenopathy, neuropathy, hyperviscosity) 3) adequate blood counts (ANC >1000, HGB ≥7.5, PLT ≥50,000), 4) eGFR ≥30 ml/min, 5) adequate liver function tests (total bilirubin ≤1.5 x ULN and AST, ALT and alkaline phosphatase ≤3 x ULN), 6) Zubrod performance status ≤2, 7)prior treatment with single-agent R allowed as long as >6 months prior to registration. Once enrolled the patients will be randomized 1:1 to IR vs. VR. I will be started at 420 mg daily at start of therapy while V will be given at 400mg daily during cycle 1 week 1 and then increased to 800 mg daily from cycle 1 day 8 onwards. R will be given weekly x 4 in cycles 2 and 5. Dose adjustments for both I and V can be done depending on toxicity. Therapy will be given for 2 years and then the patients will be observed off treatment. Patients with disease progression during these 2 years of therapy can cross-over to the other arm. The primary endpoint of the study is rate of VGPR or better. With 41 eligible participants per arm (total N=82), this design has 80% power to reject the null hypothesis of a 25% VGPR rate, given the alternative of a 50% VGPR rate, with a one-sided alpha of 10%. To account for an anticipated 10% ineligibility rate, approximately 46 participants will be accrued per arm (92 total). Current enrollment stands at 15 patients. The secondary end points include ORR, complete response rate, major response rate, progression free and overall survival rates.

Abstract Introduction: While the incidence of multiple myeloma (MM) is 2-3 fold higher in Black compared to white individuals, the impact of racial differences on treatment outcomes remains unclear due to the confounding effect of socioeconomic barriers and disparities in access to effective therapies and clinical trials. In this study, we explored the relationship between race, social deprivation, and outcomes in newly diagnosed MM (NDMM) patients (pts) receiving modern therapies with triplet or quadruplet regimens. Methods: Pts with NDMM diagnosis, who received first line treatment between 2015-2025, and had data available on response and survival outcomes were identified through the ASH Research Collaborative MM Data Hub (a real-world database with pts across 11 U.S. institutions). Data on patient demographics (age, race, ethnicity, sex), disease risk status (ISS/R-ISS stage, FISH cytogenetics), treatment regimens (triplet vs quadruplet, anti CD38 monoclonal antibody-based vs not), and disparity measures were abstracted from electronic medical records. Race and ethnicity were self-reported by pts. Social Deprivation Index (SDI) score was calculated based on ZIP code, where higher scores reflect greater deprivation. Progression free survival (PFS) was defined as time from start of treatment until progression or death. Overall survival (OS) was defined as time from start of treatment until death from any cause. Kaplan-Meier methods were used to compare PFS and OS between groups, and cox regression models with log-rank tests were used to evaluate the influence of various factors on outcomes. Results: A total of 1,743 patients were identified; 1,116 (63.8%) identified as non-Hispanic White (NHW) and 402 (23.3%) as non-Hispanic Black (NHB) [note: 85 pts (4.9%) were Hispanic but not included due to limited numbers]. The median age (years) at the start of treatment (61.8 vs. 65.6) was lower for NHB compared to NHW pts (p<0.001). The proportion of females was greater in NHBthan NHW pts(53.5% vs. 41.1%, p=0.0016). Median SDI scores were significantly higher for NHBcompared to NHW pts (68.4 vs. 39.4; respectively; p<0.001), reflecting significantly higher rates of social deprivation. While NHB ptshad higher rates of advanced stage disease (ISS III 26.9% vs. 20.9%, p=0.009), lower rates of autologous stem cell transplant (ASCT) (56.7% vs. 63.6%, p=0.014), and longer median time from treatment initiation to ASCT (6.5 vs. 5.9 months, p=0.043), the rates of standard risk cytogenetics on FISH (72.3% vs. 77.6%), and utilization of CD38 monoclonal antibody-based regimen (29.9% vs. 27.7%) were similar between the two groups. Best response after treatment initiation was similar between the NHB and NHW pts (p=0.12) with complete response 45.7% vs. 52.6% and very good partial response 37.3% vs 34.7%; respectively. However, time to best response (months) was longer in NHB pts (7.2 vs. 6.5, p=0.005). Median follow-up for OS was 4.2 years (95% CI 3.9-4.4; 182 OS events) and for PFS was 1.3 years (95% CI: 1.1-1.6; 302 PFS events) across the two groups. Unadjusted PFS was similar for NHB vs NHW pts (HR=1.05, 95% CI: 0.81- 1.36; median: 5.0 vs 4.9 years; 3-year PFS: 66% vs. 71%). Similarly, unadjusted OS was not significantly different in NHB vs NHW pts (HR=1.12, 95% CI: 0.79-1.59; 5-year OS: 86.4% vs 85.6%). Higher SDI scores were significantly associated with worse OS (HR=1.07, 95% CI: 1.02-1.12; p=0.0065) but not PFS (HR=0.99, 95% CI: 0.95-1.02; p=0.46). Though not statistically significant, univariate analyses indicated a greater impact of high SDI scores (≥70, 75th percentile across all pts) in NHW (HR=1.45, p=0.068) than in NHB pts (HR=0.78, p=0.35) for OS. Adjusting for age, sex, ISS stage, and SDI, NHB did not appear to have worse OS (HR=0.75, 95% CI: 0.35-1.60; p=0.46) or PFS (HR=1.23, 95% CI: 0.78-1.96; p=0.37) compared to NHW pts. Conclusions: Our study represents a diverse population enriched for pts who received modern day standard of care frontline therapies including triplet and quadruplet regimens with or without ASCT. Based on SDI scores, higher social deprivation levels were seen in NHB compared to NHW pts without a difference in outcomes between the two races. Our analysis supports that higher social deprivation among different races rather than race and ethnicity alone may drive differential outcomes and adjustment for factors like SDI is critical to interpretation of survival outcomes by race.