Critically short telomeres produce apoptosis, cell senescence and chromosomal instability in tissue culture and animal models. Variations in telomere length have been reported in severe aplastic anemia (SAA) but their clinical significance is unknown.
To investigate the relationship between telomere length and clinical outcomes in SAA.
Design and Setting
Single institution analysis of SAA patients treated in sequential prospective protocols at NIH from 2000 to 2008.
We retrospectively analyzed pre-treatment leukocyte age-adjusted telomere length in 183 patients with SAA consecutively enrolled into immunosuppression protocols with anti-thymocyte globulin plus cyclosporine for correlation with clinical outcomes.
Main Outcomes Measures
The outcomes studied were hematologic response, relapse, clonal evolution and survival.
There was no relationship between hematologic response and telomere length with response rates of 56.5%, 54.3%, 60%, and 56.5% in the first (n=46), second (n=46), third (n=45), and fourth quartiles (n=46), respectively. In multivariate analysis, telomere length was associated with relapse, clonal evolution, and mortality. Evaluated as a continuous variable, telomere length inversely correlated with the probability of hematologic relapse (HR=0.16; 95% CI, 0.03–0.69; p=0.01). The rate of clonal evolution was higher in patients in the first quartile (24.5%; 95% CI, 8.7%–37.5%) compared to quartiles 2–4 (8.4%; 95% CI, 3.2%–13.3%; p=0.009), and evolution to monosomy 7 or complex cytogenetics was more common in the first quartile (18.8%; 95% CI, 3.5%–31.6%) compared to quartiles 2–4 (4.5%; 95% CI, 0.5%–8.2%; p=0.002). Survival between these two groups differed, with 66% (95% CI, 52.9%–82.5%) surviving 6 years in the first quartile compared to 83.8% (95% CI, 77.3%–90.9%) in quartiles 2–4 (p=0.008).
In a cohort of patients with severe aplastic anemia receiving immunosuppressive therapy, telomere length was unrelated to response, but was associated with risk of relapse, clonal evolution, and overall survival.