Dasatinib and Nilotinib for CML
Executive Summary
1.6. Conclusions
1.6.1. Chronic phase CML
Effectiveness data are limited, but dasatinib and nilotinib appear efficacious in terms of obtaining cytogenetic and hematological responses in both IMR and IMI populations.
The extent to which greater frequency and/or degrees of response which may impact on long term outcomes is more difficult to conclude given the limited nature of the evidence base.
In particular, only one trial has compared either agent (dasatinib) with high dose imatinib.
The findings of this open label study, that higher proportions of patients experience positive responses to dasatinib than high dose imatinib are importantly confounded by substantial cross over at an early point in follow up.
In terms of cost effectiveness, it is extremely difficult to reach any conclusions regarding either agent in the IMR population. (IMR- resistant to imatinib)
All three models (Novartis, PenTAG and BMS) are seriously flawed in one way or another, again as a consequence of the paucity of data appropriate to construct robust decision analytic models with currently available data.
The economic picture is similar for people who are intolerant of imatinib, for whom even less data exist, and this comparison is made more difficult in structural terms by lack of clarity about what constitutes the appropriate comparator in current practice.
The findings of effectiveness studies suggest, perhaps unsurprisingly, that better responses are shown in people for whom second line therapy is indicated as a consequence of imatinib intolerance than in those who are resistant to first line imatinib.
However, reflecting the uncertainty about duration of therapy in particular, this ranking seems reversed in our economic analyses.
1.6.2. Accelerated and Blast Phase CML
The economic evaluations carried out by the manufacturers of nilotinib and dasatinib are seriously undermined by the absence of evidence on high dose imatinib in these
populations.
In response to this, both models assume that the effectiveness of imatinib therapy can be adduced from evidence obtained in an imatinib-naïve population using normal dose imatinib.
In addition to this factor, problems exist in all evaluations with Dasatinib and Nilotinib for CML
Executive Summary
With respect to cost estimates and only in the blast phase analysis of dasatinib (in which the new TKI dominates) do findings appear robust to changes in parameter assumptions.
1.6.3.
Suggested future research questions and priorities.
There are several randomised clinical trials of the interventions underway. It is perhaps surprising given the oral nature of the interventions and thus the relative ease of blinding of a study, that these are all open studies.
We feel that a three-way, double blind, randomized clinical trial of dasatinib, nilotinib and high dose imatinib would be the most useful addition to the scant existing evidence base
critical shortcomings: (somewhat paraphrased) in that the model used is parametised on the the basis of observation of MCyr and PFS defined and measured in different ways. Double blind 3 way RCT's would very likely produce a different cost utiilty picture.
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Sandy