Telomere shortening and associated chromosomal instability in peripheral blood lymphocytes of patients with Hodgkin's lymphoma prior to any treatment are predictive of second cancers.

PURPOSE: To investigate a potential link between telomere length, chromosomal instability, and the advent of a second cancer (SC) in patients with Hodgkin's lymphoma (HL), who are known to be at risk for SCs. This study was premised on the finding that telomere dysfunction and DNA repair pathways were related to many pathologic conditions. METHODS AND MATERIALS: Three cohorts of patients with HL were studied: 73 who were prospectively followed >5 years after diagnosis (prospective HL cohort), 28 who developed a SC (SC HL cohort), and 18 long-term survivors with no evidence of disease or complication since their initial treatment (NED HL cohort). Telomere length was analyzed by a telomeric restriction fragment assay in peripheral blood lymphocytes. Thirty healthy donors and 70 patients with a newly diagnosed solid tumor were the control population. RESULTS: Compared with controls, patients from the prospective HL cohort, before any treatment, showed age-independent shorter telomeres (mean, 8.3 vs. 11.7 kb in healthy donors; <6 kb in 18% in HL patients), increased spontaneous chromosomal abnormalities, and increased in vitro radiation sensitivity (p < 10(-4) each). After treatment, telomere shortening was associated with cytogenetic profiles characterized by the persistence of complex chromosomal rearrangement and clonal aberrations. Moreover, the two cases of SC in the prospective HL patients had short telomeres and CCR initially. In addition, the SC HL cohort was characterized by markedly short telomeres (6.6 vs. 9.7 kb in the NED HL cohort), the presence of complex chromosome rearrangements, and increased in vitro radiation sensitivity. CONCLUSIONS: An intimate relationship between pre-treatment telomere shortening, chromosomal instability, radiation sensitivity and occurrence of SC was found in HL patients.

Telomere dysfunction and telomerase reactivation in human leukemia cell lines after telomerase inhibition by the expression of a dominant-negative hTERT mutant.

As activation of telomerase represents a key step in the malignant transformation process, experimental models to develop anti-telomerase drugs provide a rational basis for anticancer strategies. We analysed the short and long-term efficacy of a stably expressed dominant-negative mutant (DN) of the telomerase catalytic unit (hTERT) in UT-7 and U937 human leukemia cell lines by using an IRES-e-GFP retrovirus. As expected, telomerase inactivation resulted in drastic telomere shortening, cytogenetic instability and cell growth inhibition in all e-GFP positive DN clones after 15-35 days of culture. However, despite this initial response, 50% of e-GFP positive DN clones with short telomeres escaped from crisis after 35 days of culture and recovered a proliferation rate similar to the control cells. This rescue was associated with a telomerase reactivation inducing telomere lengthening. We identified two pathways, one involving the loss of the DN transgene expression and the other the transcriptional up-regulation of endogenous hTERT with persistence of the DN transgene expression. Although this second mechanism appears to be a very rare event (one clone), these findings suggest that genomic instability induced by short telomeres after telomerase inhibition might enhance the probability of activation or selection of telomere maintenance mechanisms dependent on hTERT transcription.

Serum 2-hydroxyglutarate production in IDH1- and IDH2-mutated de novo acute myeloid leukemia: a study by the Acute Leukemia French Association group.

PURPOSE: Mutated isocitrate dehydrogenases (IDHs) 1 and 2 produce high levels of 2-hydroxyglutarate (2-HG). We investigated whether, in acute myeloid leukemia (AML), serum 2-HG would predict the presence of IDH1/2 mutations at diagnosis and provide a marker of minimal residual disease (MRD). PATIENTS AND METHODS: Serum samples from 82 patients at diagnosis of de novo AML (IDH1/2 mutated, n = 53) and 68 patients without AML were analyzed for total 2-HG and its ratio of D to L stereoisomers by mass spectrometry. We measured 2-HG levels and molecular markers of MRD (WT1 and NPM1) in serial samples of 36 patients with IDH1/2 mutations after induction therapy. RESULTS: In patients with AML with IDH1/2 mutations, 2-HG serum levels were significantly higher than in patients with IDH1/2 wild type (P < .001). Area under the receiver operating characteristic curve was 99%. The optimum diagnostic cutoff between IDH1/2 mutated and normal was 2 µmol/L (sensitivity, 100%; specificity, 79%). Quantification of the D/L stereoisomers increased specificity (100%; 95% CI, 83% to 100%) compared with total 2-HG (P = .031). In patients with IDH2 R172 mutations, 2-HG levels were higher relative to those with other IDH1/2 mutations (P < .05). During follow-up, serum 2-HG levels showed strong positive correlation with WT1 and NPM1 (P < .001). After induction therapy, total 2-HG serum levels < 2 µmol/L were associated with better overall (P = .008) and disease-free survival (P = .005). CONCLUSION: Serum 2-HG is a predictor of the presence of IDH1/2 mutations and outcome in these patients. Discrimination between D/L stereoisomers improved specificity.