Imatinib versus interferon-α (IFN-α) plus ara-c for patients with newly diagnosed chronic-phase (CP) chronic myeloid leukemia (CML) from the Mexican Institute of Social Security (IMSS) perspective: 72 months number needed to treat (NNT) to achieve a complete cytogenetic response (CCyR)

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17542 Background: Imatinib mesylate(IM) is the standard of care for CML because it has demonstrated high and durable responses as well as survival advantage over IFN based therapy (Hochhaus, Blood (ASH Annual Meeting Abstracts) 2007.110: 25). Reed et al, estimated the survival for a newly diagnosed CP-CML patient treated with imatinib was 19.07 years vs. 9.09 years with IFN/Ara-C (Reed, Pharmacoeconomics in press). IM has been included in the Mexican National Basic Formulary as first-line agent and as second-line agent after IFN. CCyR has been established as an effective measure for treatment efficacy in CML, furthermore CCyR is associated to prolonged survival on CML patients. In this study, the NNT approach was used to compared IM with IFN/ Ara-C from the Mexican public healthcare system's perspective. Methods: NNT represents the number of patients that need to be treated with a new intervention in order to achieve one additional event, and is a powerful approach that can be used to make sense of numerical results from clinical trials. The NNT was calculated by the inverse of CCyR at 72 months. A key requirement for an NNT analysis is that all outcomes must be considered over similar time periods. The rates of CCyR at 72 months for IM and IFN/Ara-C as first line treatment for CML-CP were obtained from the International Randomized Interferon vs. STI571 (IRIS) Study update. Results: The 72-month CCyR rate for IM was 82% vs. 12% for IFN/Ara-C. The NNT for IM was 15 patient versus 8.33 for IFN plus Ara-C. For every 1.15 patients treated with IM, 1 patient will achieve a CCyR by 72 months. However, in order to achieve a CCyR with IFN plus Ara-C by 72 months, 7.18 more patients need to be treated, a 7.24- fold difference in NNT to achieve a CCyR, favoring IM. Conclusions: The NNT to achieve a CCyR by 72 months with IM is much lower than that with IFN plus Ara-C in newly-diagnosed CP-CML patients. Further analysis including the total cost of treatment (drug cost and cost to treat adverse events) from Mexico will be conducted to assess the cost-effectiveness comparing IM with IFN/Ara-C in CML-CP patients from the IMSS perspective. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Novartis Novartis