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PURPOSE: Although monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma disproportionately affect Black individuals, few epidemiologic studies have been conducted on these plasma cell disorders in Africa. Here we describe the prevalence of MGUS in Eswatini and compare our results to the landmark Olmsted County, USA study. METHODS: Between 2016 and 2017, 13,339 residents of Eswatini participated in the Swaziland HIV Incidence Measurement Survey, from which a nationally-representative biorepository was created. Plasma samples were then randomly selected and analyzed for MGUS. MGUS prevalence in Eswatini was compared to that of Olmsted County. Additionally, demographic and HIV-related associations with MGUS were assessed. RESULTS: Of the 515 samples randomly selected, the median age was 50 years (range 35-80) and 60% were female; 38.6% were HIV-positive, of whom 82.4% were on antiretroviral therapy. We found that 68 had evidence of MGUS for a prevalence of 13.2%. HIV status was not significantly associated with MGUS (OR, 1.05; 95%CI, 0.62-1.77), but among HIV-positive individuals, MGUS was less frequent for those on antiretroviral therapy (adjusted OR, 0.31; 95%CI, 0.11-0.82). The prevalence of conventional MGUS was similar between Eswatini and Olmsted County (3.4% vs 3.2-3.4%), while light-chain MGUS was significantly greater in Eswatini (12.3% vs 0.8%). CONCLUSION: Our study suggests that the incidence of MGUS is similar between ethnicities and raises the question of whether the current definition of light-chain MGUS reliably reflects a true monoclonal protein precursor state. Perhaps the current definition of light-chain MGUS may be capturing alternate etiologies, such as untreated HIV infection.
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Traditional prognostic models for newly diagnosed patients with multiple myeloma (MM), including International Staging System criteria and number of high-risk chromosomal abnormalities, are based on disease characteristics at diagnosis. However, the identification of patients at risk of more rapidly progressive MM is inherently a dynamic assessment. In a subset of patients with MM, adverse disease biology only becomes evident after the failure of first-line therapy. We define this entity as functional high-risk MM (FHRMM), encompassing relapse within 18 months of treatment initiation and/or within 12 months of frontline autologous stem cell transplantation. FHRMM is not adequately captured by traditional prognostic models, and there is a need for better understanding of mechanisms or risk factors for early relapse or progression. In this review, we explore potential definitions of FHRMM before delving into its underlying drivers based on genetic, transcriptomic, and immune cell profiling studies. Emerging data suggest that specific features of both myeloma cells and immune cells can enable the FHRMM phenotype. We conclude our review by discussing ongoing and future studies that seek to identify and intervene upon patients with FHRMM preemptively.
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BACKGROUND: Both multiple myeloma and its precursor, monoclonal gammopathy of undetermined significance (MGUS), occur twice as often within Black compared with White populations, suggesting that racial disparities lie within the development of MGUS. Nonetheless, MGUS has been studied mainly in White cohorts; the study that first described the natural history of MGUS was conducted in 97.3% White Olmsted County, Minnesota. METHODS: We determined the prevalence of MGUS among 386 Black South African (SA) men >30 years at Chris Hani Baragwanath Hospital in Johannesburg. We conducted serum protein electrophoresis and free light chain quantification to define MGUS by the same criteria as the Olmsted County studies. We also investigated the association between MGUS and various clinical factors, including human immunodeficiency virus (HIV) infection and smoking. RESULTS: We found the prevalence of MGUS to be 8.03% [95% confidence interval (CI), 5.32-10.74], nearly 1.6-fold higher than in the White Olmsted County male population. In a univariable logistic regression model, MGUS was associated with HIV status (OR, 2.39; 95% CI, 0.95-5.49), but in an adjusted model that included body mass index and cigarette use, the association was not statistically significant. Those who were current (vs. never) cigarette smokers were more likely to have MGUS in both univariable (OR, 5.60; 95% CI, 2.16-17.42) and multivariable models (OR, 4.49; 95% CI, 1.63-14.56). CONCLUSIONS: The prevalence of MGUS in Black SA men is substantially higher than in White populations and may be associated with HIV status and cigarette use. IMPACT: Racial disparities in MGUS exist and may be associated with potentially modifiable risk factors.
