Background Benboubker et al. recently reported the results of lenalidomide + dexamethasone (Ld) in transplant-ineligible patients with melanoma versus the standard treatment, with a difference between medians of 4.3 months in progression-free survival (PFS). Nevertheless, as seen in the shape of the curves, difference in median survival (DMS) may not provide a good estimate of the survival benefit.
Purpose To reanalyse the survival benefit of lenalidomide from the PFS curves using an area-under-the curve (AUC)-based method.
Material and methods Kaplan-Meier PFS and OS curves were extracted from Benboubker et al.’s article. Graphical AUC methods were applied to continuous Ld vs. standard treatment curves and compared to DMS. The AUC was calculated according to a previously published method.1 Vertical cutting lines at the tail ends of the graphs were made based on the number of patients at risk. It was agreed that this cut-off point was defined as placing at least 10 at-risk patients in each group or 30 in total. The AUC method quantified the difference between areas, and the results were expressed in time units. Photoshop-CS6 was used for graphical AUC calculation.
Results AUC-based reanalysis of PFS curves included 67.5% patients with 47 months of follow-up, at least 30 patients remaining at risk. PFS was 17.0 vs. 14.3 months, a benefit of 2.7 months in favour of continuous Ld. For OS, with 43.5% patients analysed and 50 months of follow-up, the AUC method showed a benefit of 5.3 months (25.5 vs. 20.2).
Conclusion AUC-based analysis showed a shorter survival benefit than the difference in median survival. This is probably related to the shape of the curves, which diverged at the medium zone of the graph. OS reanalysis is very limited because the observation time is insufficient to provide mature data.
References and/or Acknowledgements
Alegre-DelRey EJ, et al. Area-based measures for assessing survival benefit in Kaplan-Meier’s curves. ESMO Congress, Amsterdam 2013. URL: http://eccamsterdam2013.ecco-org.eu/scientific-programme/searchable-programme.aspx#anchorScpr (accessed 08/10/2014)
References and/or AcknowledgementsNo conflict of interest.
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