NEW YORK – Telomere length reliably predicts response to fludarabine-cyclophosphamide-rituximab (FCR) treatment in patients with chronic lymphocytic leukemia, according to an analysis of 278 samples from the ARCTIC and ADMIRE clinical trials of FCR in previously untreated CLL.
The findings were particularly pronounced in the immunoglobulin heavy-chain variable region gene (IGHV)–mutated patients and suggest a role for telomere measurement as a predictive tool in risk-adapted clinical trials, Kevin Norris reported in a poster at the annual International Workshop on Chronic Lymphocytic Leukemia.
Short telomere length was associated with quicker time to progression (median of 3.9 years vs. 5.5 years; hazard ratio[HR], 2.04) and reduced overall survival (OS) (median of 5.5 years vs. OS not reached; HR, 2.1), compared with long telomere length. IGHV-mutated patients with short telomeres were more than five times more likely to relapse (median progression-free survival 2.97 vs. PFS not reached; HR, 5.1), and more than four times more likely to die than were patients with long telomere length (median OS, 4.15 years vs. OS not reached; HR, 4.16), said Mr. Norris, a research associate at Cardiff (Wales) University.
The association between telomere length and FCR response was less pronounced among IGHV-unmutated patients, but those with short telomeres in this group still had an inferior response and shorter survival, compared with those with long telomeres (HR, 1.6 and 1.6, respectively), he noted.
Mr. Norris also noted that in contrast to the telomere length findings, CD38 expression and b2-microglobulin were not predictive of time to progression or OS.
“In multivariate analysis, telomere length was the dominant covariable for both PFS (HR, 2.58) and OS (HR, 2.84); when telomere length was entered into the model no other variable retained independent prognostic significance,” he and his colleagues wrote.
Telomere length in this analysis was assessed by use of the high throughput single telomere length analysis (HT-STELA) assay.
It has recently been shown that a proportion of IGHV-mutated CLL patients treated with FCR can achieve long-term remissions. The current findings demonstrate that these patients can be accurately identified by measuring telomere length, the investigators said, noting that they saw a similar pattern in patients in the UK CLL4 trial who were treated with fludarabine and cyclophosphamide
“Our results demonstrate that telomere length is the major determinant of response and survival following treatment with FCR,” they wrote. “IGHV-mutated patients with longer telomeres have a high probability of achieving a long-term remission following treatment with FCR (greater than 81% survival after 5 years). Equally, IGHV-mutated patients with short dysfunctional telomeres show a markedly inferior response to FCR and should be considered for alternative treatment options in the frontline setting.”
Patient material for this study was obtained from the UK CLL Trials Biobank, University of Liverpool, which is funded by Bloodwise. The authors reported having no other disclosures.