Introduction: The Growing Clinical Relevance of Clonal Hematopoiesis
In recent years, the intersection of hematology and cardiology has revealed a potent new risk factor for cardiovascular disease: Clonal Hematopoiesis (CH). Defined as the expansion of hematopoietic stem cell clones harboring somatic mutations in specific driver genes—most commonly DNMT3A, TET2, and ASXL1—CH is a common feature of aging. While often termed ‘Clonal Hematopoiesis of Indeterminate Potential’ (CHIP) in the absence of hematologic malignancy, its presence is far from benign. CHIP is associated with a significantly increased risk of myocardial infarction, stroke, and heart failure, often independent of traditional risk factors like cholesterol or hypertension.
Research has increasingly pointed toward a pro-inflammatory mechanism driving this risk. Specifically, mutations in TET2 and DNMT3A have been shown to prime macrophages toward a hyper-inflammatory state, overproducing cytokines such as interleukin-1 beta (IL-1β) and interleukin-6 (IL-6). This ‘residual inflammatory risk’ has become a primary target for novel therapeutic interventions. The LoDoCo2 (Low-Dose Colchicine 2) trial previously demonstrated that 0.5 mg of colchicine daily reduced cardiovascular events in patients with chronic coronary disease. This exploratory substudy sought to determine if colchicine’s benefits might stem from an ability to alter the longitudinal dynamics of the CH clones themselves.
Highlights of the LoDoCo2 Substudy
Study Objectives and Population
The primary objective of this exploratory analysis was to evaluate whether randomization to low-dose colchicine (0.5 mg daily) vs. placebo was associated with changes in CH clone growth over time. Additionally, the researchers investigated the association between colchicine use and changes in inflammatory biomarkers (hs-CRP and IL-6) stratified by CH status.
The study analyzed 854 participants from the LoDoCo2 trial who provided 2,047 blood samples across four distinct timepoints:
1. Baseline.
2. Following a 30-day open-label colchicine run-in phase.
3. One year post-randomization.
4. At the end of the study (median follow-up of 25 months).
Advanced high-coverage targeted sequencing was utilized to detect driver mutations and quantify the variant allele frequency (VAF), which serves as a proxy for clone size.
Methodological Precision in Clonal Dynamics
To accurately assess how clones evolved, the research team employed generalized linear mixed models. This allowed for the estimation of annual percentage changes in VAF. The longitudinal nature of the data is particularly valuable, as CH is dynamic; clones can expand, remain stable, or, rarely, regress. By tracking clones at four timepoints, the study provides one of the most granular views to date of how an anti-inflammatory therapy influences the trajectory of somatic mutations in the blood.
Key Findings: Attenuating the Growth of High-Risk Clones
The results provide compelling, albeit exploratory, evidence that colchicine influences clonal evolution, with effects that vary by the specific gene mutated.
Overall Clonal Growth
In the placebo arm, CH clone size increased by an average of 14.9% annually (βtime = 0.14; 95% CI: 0.08 to 0.21). In contrast, those randomized to colchicine experienced a non-significant 6.3% increase (βtime: 0.06; 95% CI: -0.01 to 0.14). While the numerical difference suggests an attenuation of growth, the overall interaction (Pinteraction = 0.13) did not reach the threshold for statistical significance across the entire cohort.
The TET2 Connection
The most striking finding occurred among participants with TET2 mutations. In this subgroup, colchicine was significantly associated with attenuated clonal growth. Participants on placebo saw a 27% annual increase in TET2 clone size (βtime: 0.27; 95% CI: 0.16 to 0.37), whereas those on colchicine showed only a 9% increase (βtime: 0.09; 95% CI: -0.04 to 0.22). The interaction between treatment and time was statistically significant (Pinteraction = 0.04), suggesting that TET2-mutant cells may be specifically sensitive to the anti-inflammatory environment created by colchicine.
Inflammatory Biomarkers and Non-DNMT3A CH
The study also found that inflammatory signaling varied by mutation type. Among individuals with non-DNMT3A CH (which includes TET2 and other drivers), IL-6 levels rose significantly less in the colchicine group compared to the placebo group over one year (30.0% vs. 98.1% increase; Pinteraction = 0.01). This suggests that colchicine may mitigate the systemic inflammatory surge often associated with the expansion of certain CH clones.
Mechanistic Insights: Why TET2?
The differential response of TET2 vs. DNMT3A mutations is biologically plausible. Preclinical models have shown that TET2-deficient hematopoietic cells are particularly reliant on the NLRP3 inflammasome. TET2 loss-of-function leads to the upregulation of NLRP3, which in turn increases the production of IL-1β and IL-18. Colchicine is known to inhibit NLRP3 inflammasome assembly and microtubule polymerization. By disrupting this cycle, colchicine may remove the ‘pro-inflammatory fuel’ that grants TET2-mutant cells a competitive proliferative advantage over normal stem cells. In contrast, DNMT3A mutations operate through different epigenetic pathways that may be less dependent on the specific inflammatory pathways colchicine targets.
Expert Commentary and Clinical Implications
This substudy represents a significant step forward in the field of preventive cardio-oncology. While colchicine is already an established tool for secondary prevention in coronary disease, these data suggest it might also serve as a ‘disease-modifying’ agent for the underlying hematologic state of CH.
However, several limitations must be noted. As an exploratory substudy, these findings are hypothesis-generating. The P-interaction for the overall cohort was not significant, and the specific benefit observed in TET2 clones requires validation in larger, prospective cohorts. Furthermore, while the study shows an attenuation of growth, it does not show clone eradication. The clinical question remains: is slowing the growth of a clone enough to prevent the downstream cardiovascular events associated with that clone?
Clinicians should also consider that CH status is not currently part of routine cardiovascular risk assessment. However, as genetic sequencing becomes more accessible, identifying patients with TET2-CH might help personalize anti-inflammatory therapy, selecting those most likely to benefit from agents like colchicine or perhaps more targeted IL-1β inhibitors.
Conclusion
The LoDoCo2 substudy suggests that low-dose colchicine can curb the proliferative advantage of key clonal hematopoiesis driver mutations, particularly TET2. By potentially slowing the expansion of these pro-inflammatory clones, colchicine may offer a dual benefit: reducing systemic inflammation and mitigating the progression of a high-risk hematologic state. As we move toward an era of precision medicine, these findings underscore the importance of understanding the genetic landscape of our patients to better tailor cardiovascular prevention strategies.
Funding and Registration
The LoDoCo2 trial was supported by the Netherlands Organization for Health Research and Development, the National Health and Medical Research Council of Australia, and the Dutch Heart Foundation. The trial is registered at clinicaltrials.gov (NCT02552212).
References
1. Mohammadnia N, et al. Colchicine and Longitudinal Dynamics of Clonal Hematopoiesis: An Exploratory Substudy of the LoDoCo2 Trial. J Am Coll Cardiol. 2025;86(21):1983-1996.
2. Nidorf SM, et al. Low-Dose Colchicine for Secondary Prevention of Coronary Artery Disease. N Engl J Med. 2020;383(11):1070-1081.
3. Jaiswal S, et al. Clonal Hematopoiesis and Risk of Atherosclerotic Cardiovascular Disease. N Engl J Med. 2017;377(2):111-121.
4. Fiedler J, et al. TET2-loss-of-function-driven clonal hematopoiesis and cardiovascular disease. Cardiovascular Research. 2020;116(12):1918-1928.