Dasatinib and nilotinib for imatinib-resistant or -intolerant chronic myeloid leukaemia: a systematic review and economic evaluation

Abstract

Background: Chronic myeloid leukaemia (CML) is a form of cancer affecting the blood, characterised by excessive proliferation of white blood cells in the bone marrow and circulating blood. In the UK, an estimated 560 new cases of CML are diagnosed each year.

Objectives: The purpose of this study was to assess the clinical effectiveness and cost-effectiveness of dasatinib and nilotinib in the treatment of people with imatinib-resistant (ImR) and imatinib-intolerant (ImI) CML. A systematic review of the clinical effectiveness literature, a review of manufacturer submissions and a critique and exploration of manufacturer submissions for accelerated phase and blast crisis CML were carried out and a decision-analytic model was developed to estimate the cost-effectiveness of dasatinib and nilotinib in chronic phase CML. SYSTEMATIC REVIEW METHODS: Key databases were searched for relevant studies from their inception to June 2009 [MEDLINE (including MEDLINE In-Process & Other Non-Indexed Citations), EMBASE, (ISI Web of Science) Conference Proceedings Citation Index and four others]. One reviewer assessed titles and abstracts of studies identified by the search strategy, with a sample checked by a second reviewer. The full text of relevant papers was obtained and screened against the full inclusion criteria independently by two reviewers. Data from included studies were extracted by one reviewer and checked by a second. Clinical effectiveness studies were synthesised through narrative review. ECONOMIC EVALUATION METHODS: Cost-effectiveness analyses reported in manufacturer submissions to the National Institute of Health and Clinical Excellence were critically appraised and summarised narratively. In addition, the models for accelerated phase and blast crisis underwent a more detailed critique and exploration. Two separate decision-analytic models were developed for chronic phase CML, one simulating a cohort of individuals who have shown or developed resistance to normal dose imatinib and one representing individuals who have been unable to continue imatinib treatment owing to adverse events. One-way, multiway and probabilistic sensitivity analyses were performed to explore structural and parameter uncertainty.

Results: Fifteen studies were included in the systematic review. Chronic phase: effectiveness data were limited but dasatinib and nilotinib appeared efficacious in terms of obtaining cytogenetic response and haematological response in both ImR and ImI populations. In terms of cost-effectiveness, it was extremely difficult to reach any conclusions regarding either agent in the ImR population. All three models (Novartis, PenTAG and Bristol-Myers Squibb) were seriously flawed in one way or another, as a consequence of the paucity of data appropriate to construct robust decision-analytic models. Accelerated and blast crisis: all available data originated from observational single-arm studies and there were considerable and potentially important differences in baseline characteristics which seriously undermined any process for making meaningful comparisons between treatments. Owing to a lack of available clinical data, de novo models of accelerated phase and blast crisis have not been developed. The economic evaluations carried out by the manufacturers of nilotinib and dasatinib were seriously undermined by the absence of evidence on high-dose imatinib in these populations.

Limitations: The study has been necessarily constrained by the paucity of available clinical data, the differences in definitions used in the studies and the subsequent impossibility of undertaking a meaningful cost-effectiveness analyses to inform all policy questions.

Conclusions: Dasatinib and nilotinib appeared efficacious in terms of obtaining cytogenetic and haematological responses in both ImR and ImI populations. It was difficult to reach any cost-effectiveness conclusions as a consequence of the paucity of the data. Future research should include a three-way, double-blind, randomised clinical trial of dasatinib, nilotinib and high-dose imatinib.