Biomarker tests in early breast cancer: IQWiG criticizes interpretation of MINDACT data in an updated US guideline
Relevant analysis does not show an advantage, but a disadvantage of MammaPrint
The American Society of Clinical Oncology (ASCO) recently updated its guideline on biomarkers with regard to the MammaPrint test and published this update in the Journal of Clinical Oncology (JCO). On the basis of data from the MINDACT study, they concluded that in certain patient groups, MammaPrint can better identify those patients who do not require chemotherapy and that therefore this test could support decision-making on the type of treatment.
A group of authors from the German Institute for Quality and Efficiency in Health Care (IQWiG) has contradicted this conclusion in a letter to the editor: As the first prospective randomized controlled trial, MINDACT provides valuable findings on biomarker tests. However, the IQWiG authors believe that the conclusion drawn by the ASCO authors is incorrect.
Per protocol analysis insufficiently considered
The MINDACT study primarily aimed to answer a non-inferiority question, namely, whether patients with a high recurrence risk according to conventional clinical criteria, but a low recurrence risk according to the biomarker test, could omit chemotherapy. However, in these patients a per-protocol analysis showed a statistically significant disadvantage of the test for the outcome “disease-free survival”. Moreover, with an absolute risk difference of 3 percent after only 5 years, this difference reached a magnitude that had been defined as clinically relevant for other questions of MINDACT.
In addition, the IQWiG authors presented their own analysis of the published MINDACT data, which indicates that the MammaPrint test does not provide an information gain in comparison with conventional clinical criteria. However, original data from MINDACT would be required to verify this finding. In their response to IQWiG’s letter to the editor, the ASCO authors noted that IQWiG’s additional analysis was interesting and agreed that a more complete analysis of the MINDACT data would be useful if the original data could be obtained.
German S3 guideline also recently revised
An update of the German S3 guideline has also recently been published. The guideline authors incorporated the comments IQWiG made in the consultation phase. IQWiG’s doubts about MammaPrint, which the Institute had already raised in its benefit assessment of the biomarker test in December 2016, were considered in verbatim form. However, the recommendation on the use of biomarker tests in certain situations remained unchanged.