Meaningful response criteria for myelodysplastic syndromes

Standardizing response criteria for myelodysplastic syndromes (MDS), a clinically and biologically heterogeneous group of disorders, has been historically challenging. The International Working Group (IWG) response criteria, first proposed in 2000 and modified in 2006 and 2018, represent the best effort by a group of international experts to define a set of clinically meaningful end-points in MDS. These criteria have been adopted in many MDS clinical trials, allowing for comparisons of response across trials. However, clinical experience has also revealed some limitations of these criteria, and most of the end-points proposed by the IWG require further validation. In this review, we present a critical analysis of the current MDS response criteria from both a practical standpoint and based on currently available clinical trial data. Potential areas for improvement in the criteria are highlighted, which may be considered in future iterations of the response criteria.