SAN DIEGO – After cessation of imatinib therapy in patients with chronic myeloid leukemia (CML), there were no differences in molecular relapse-free survival (MRFS) between patients with prior 4.5 log reduction but detectable disease and those with undetectable disease, according to a study presented at the American Society of Hematology (ASH) 58th Annual Meeting and Exposition.1
“Several studies have shown that in a proportion of patients with deep molecular response, treatment can be successfully stopped,” said Markus Pfirrmann, PhD, Institut für Medizinische Informationsverarbeitung, Biometrie und Epidemiologie (IBE), Ludwig-Maximilians-Universität München, Germany.
Because duration of MR4 was a prognostic factor associated with MRFS after TKI discontinuation in the EURO-SKI trial and depth of response is suspected to influence MRFS, researchers investigated the impact on MRFS of deep molecular response status at the time of treatment cessation.
Investigators analyzed data from 357 participants of EURO-SKI, of whom 33 (9%) “MR4 only” (status A), 125 (35%) had “MR4.5, detectable disease” (status B), and 199 patients (56%) had “MR4.5, undetectable disease” (status C).
Results showed that 61% (95% CI, 42-77) of status A (MR4) patients were still in at least major molecular response at 6 months compared with 58% (95% CI, 53-63) of status B or C (MR4.5) patients (odds ratio, 1.11; 95% CI, 0.54-2.32).
To reduce bias, researchers conducted a propensity score-matching analysis by matching 119 status B patients with 119 status C patients, which continued to show a non-significant difference in MRFS between the 2 groups.
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“Refined statistical analyses combined with adherence to laboratory recommendations support unbiased analyses when differentiating detectable and undetectable disease,” explained Dr Pfirrmann.
- Pfirrmann M, Mahon FX, Guilhot J, et al. No differences in molecular relapse-free survival after stopping imatinib treatment of chronic myeloid leukemia between patients with prior 4.5 log reduction (MR4.5) but detectable and patients with undetectable disease in the EURO-SKI trial. Paper presented at: American Society of Hematology (ASH) 58th Annual Meeting and Exposition; December 3-6, 2016; San Diego, CA.