Epistemic limitations of measurable residual disease in haematological malignancies.

The growing use of measurable residual disease (MRD) assays across haematology-oncology creates an urgent need for clinicians and researchers to reflect on the biological and clinical rationale of this class of biomarkers. In this Viewpoint, we critically examine two premises behind MRD's use in haematology-oncology, focusing on its biological plausibility as a predictive biomarker and surrogate endpoint, and the evidence needed for it to influence decision making in haematological cancers. Examining these premises leads us to advocate for the establishment of more robust biological and clinical evidence to ensure the clinically useful and safe application of MRD. Although achieving the eradication of cancer cells in the form of undetectable MRD seems an attractive goal in haematology-oncology, we highlight the epistemic limitations of this biomarker and need for more clinical evidence to guide its effective use.