Decoding Progression Risk in IgM-MGUS and Asymptomatic Waldenström Macroglobulinemia Through Genomic Profiling

Highlight

• Whole-exome sequencing reveals increasing mutation burden from IgM-MGUS to symptomatic Waldenström macroglobulinemia.
• Specific gene mutations (CD79B, ARID1A, CREBBP) and higher MYD88L265 variant allele frequency correlate with progression in asymptomatic WM.
• MYD88 wild-type IgM-MGUS patients have distinct genomic profiles compared to their MYD88-mutant counterparts.
• Aneuploidy burden associates significantly with the risk of progression to symptomatic disease.

Study Background

Waldenström macroglobulinemia (WM) is a rare, indolent B-cell lymphoma characterized by the presence of an IgM monoclonal protein and infiltration of lymphoplasmacytic cells in the bone marrow. Prior to the onset of symptomatic WM (sWM), patients frequently manifest precursor conditions such as IgM monoclonal gammopathy of undetermined significance (IgM-MGUS) or asymptomatic Waldenström macroglobulinemia (aWM). While these conditions carry an annual progression risk to symptomatic disease estimated between 1.5% and 12%, accurately predicting which patients will develop clinical symptoms remains challenging. Existing clinical models for risk stratification capture some progression indicators but fail to reliably distinguish stable from progressive asymptomatic patients. Therefore, elucidating genomic determinants involved in disease evolution holds promise to improve prognostication and guide early therapeutic intervention.

Study Design

The study by Bagratuni et al. employed whole-exome sequencing (WES) to comprehensively characterize the mutational landscape of IgM-MGUS and aWM patients. A total of 232 samples from 139 patients were analyzed, including nine patients with sequential samples obtained at different disease stages, enabling the tracking of genomic changes over time. The cohort was stratified into clinically stable asymptomatic WM (aWMst) and patients who progressed to symptomatic disease (aWMpr). Mutation burden, gene-specific variants, and chromosomal aneuploidies were assessed and correlated with clinical progression status. The variant allele frequency (VAF) of the recurrent MYD88 L265P mutation, a known pathogenic driver in WM, was quantitatively compared between groups. The study also contrasted genomic profiles of IgM-MGUS patients carrying wild-type (MYD88WT) versus mutant (MYD88MUT) genotypes.

Key Findings

The investigation uncovered several pivotal insights into the molecular underpinnings of disease progression from early precursor states to sWM:

1. Increasing Mutation Burden with Progression: A stepwise increase in the total number of mutations was observed as patients transitioned from IgM-MGUS through aWM to symptomatic WM, suggesting clonal evolution accompanies disease advancement.
2. Distinct Mutational Profiles in Progressors: Specific genes including CD79B, ARID1A, and CREBBP were more frequently mutated in the aWMpr group compared to stable aWM patients. These genes are implicated in B-cell receptor signaling, chromatin remodeling, and transcriptional regulation, respectively, underscoring their potential role in promoting malignant transformation.
3. MYD88 L265 Variant Allele Frequency Differences: The VAF of the MYD88 L265P mutation was significantly elevated in aWMpr patients. Higher clonal burden of this driver mutation may indicate a more aggressive disease phenotype with imminent progression risk.
4. Divergent Genomic Architecture in IgM-MGUS by MYD88 Status: Patients with MYD88 wild-type genotype demonstrated a markedly different genomic profile compared to their MYD88-mutant counterparts, consistent with previous data suggesting distinct pathogenetic pathways for MYD88WT WM-like disease.
5. Aneuploidy as a Progression Marker: The number and extent of chromosomal aneuploidies correlated significantly with progression risk, supporting their utility as cytogenetic biomarkers to refine prognostic models.

Expert Commentary

This comprehensive genomic profiling study significantly advances our understanding of the biological heterogeneity inherent in IgM-MGUS and aWM. The identification of mutational signatures and genomic instability patterns associated with progression could reshape clinical management by integrating molecular risk markers into routine assessment protocols. Despite the robust dataset, the relatively small sample size for some subgroups and the observational nature of the study highlight the need for prospective validation in larger, multicenter cohorts. Additionally, mechanistic studies are warranted to elucidate how mutations in genes such as ARID1A and CREBBP directly influence malignant transformation and immune evasion in WM precursor states.

Conclusion

Genomic profiling at the point of aWM diagnosis emerges as a promising approach to identify patients at elevated risk of progression toward symptomatic Waldenström macroglobulinemia. By combining mutation burden metrics, driver gene mutations, and chromosomal aneuploidy assessment, clinicians can enhance risk stratification beyond existing clinical models. These insights open avenues for early therapeutic intervention trials aimed at preventing or delaying symptomatic disease onset, ultimately improving patient outcomes. Future research integrating genomic data with immunophenotyping and microenvironmental analyses will further refine precision medicine strategies in this field.

Funding and ClinicalTrials.gov

The original study was supported by academic grants and institutional funding; however, specific grants or clinical trial registrations were not detailed in the source publication.

References

Bagratuni T Dr, Theologi O, Vlachos C Dr, Kollias I, Maclachlan KH, Aktypi F, Mavrianou-Koutsoukou N, Liacos CI, Taouxi K, Papadimou A, Chrisostomidou K, Sakkou M, Solia I, Theodorakou F, Favrin G, Gavriatopoulou M, Terpos E, Varettoni M, Hunter ZR, Treon SP, Maura F, Dimopoulos MA, Kastritis E. Genomic landscape of IgM-MGUS and patients with stable or progressive asymptomatic Waldenström macroglobulinemia. Blood. 2025 Sep 25:blood.2025030177. doi:10.1182/blood.2025030177. Epub ahead of print. PMID:40997305.