Presence of hyperdiploidy and history of tobacco use in African American patients with SMM.

Abstract

8062 Background: Smoldering multiple myeloma (SMM) has a clinically variable course in progression to active myeloma (MM). Accurate risk stratification is essential in identifying which patients may benefit from early therapeutic intervention. Current models do not account for the potential impact of race on risk of progression to SMM. Here, we seek to identify independent risk factors for progression in African American (AA) versus white patients in a real-world single institutional database of SMM patients. Methods: We retrospectively identified 224 patients (pts) with untreated SMM from 2007 to 2021 treated at our institution. Patient demographics and disease characteristics were obtained from our IRB-approved myeloma database. TTP was defined as the time from diagnosis of SMM to diagnosis of active MM, estimated by Kaplan-Meier and compared by log-rank test. Univariate analyses were performed using Cox proportional hazard models for TTP. Results: A total of 224 pts (AA 35%, white 47%, other/unknown 17%) were identified with median age 62y (range 32-82). Median follow-up was 4.3y in Whites and 5y in AA pts. Notable characteristics include M/F 45%/54%, IgG/IgA/FLC 76%/17%/6%, 30% current/past smoker (median 15 pack-years), 12% alcohol use (≥10 drinks/wk), 45% with BMI > 30. Multiple cytogenetic abnormalities were defined as presence of ≥2 of the following: t(4;14), t(14;16), gain(1q21), del(1p), del(13), or del(17p). The median TTP (mTTP) was 6.8 [95% CI (3.7, 8.2)] years in whites and 5.6 [95% CI (4.6, 11.8)] years in AA. On univariate analysis, M-spike > 1.5, involved K/L ratio > 12, and bone marrow PC > 20% were associated with increased risk of progression for both AA and whites (all p < 0.05). As expected, gain of 1q21 was associated with increased risk of progression for both groups, though more pronounced in AA (HR 2.94, p = 0.025) versus whites (HR 2.33, p = 0.013). Hyperdiploidy was associated with shorter mTTP in AA (HR 3.03, p = 0.004) compared to whites (HR 1.39, p = 0.3). Multiple cytogenetic abnormalities was associated with shorter mTTP in whites (HR 2.63, p = 0.004) but was not statistically significant in AA (HR 2.63, p = 0.104). Interestingly, tobacco use was associated with shorter mTTP in Blacks (HR 2.94, p = 0.005) but not in whites (HR 0.96, p = 0.85). Conclusions: Understanding the potential impact of racial background on progression from SMM to MM is critical in the appropriate management of all patients with SMM. In this database, with a large proportion of AA patients, hyperdiploidy and +1q portend high risk of progression in AA patients. Further study is needed to better classify these potential differences to ensure risk stratification models are applicable to all patients.