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.
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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.
Reference
- 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.