Fluorescein isothiocyanate-conjugated Annexin V in combination with propidium iodide (PI) labelling is a widely used flow cytometric assay for quantifying apoptotic and necrotic cells in anticancer studies. However, increasing evidence suggests that double-positive cells, or the Annexin V⁺/PI⁺ fraction, may represent not only late apoptosis but also different modalities of regulated cell death, including necroptosis, pyroptosis, ferroptosis, and cuproptosis. By collating findings from preclinical studies across different cancer cells, this review highlights the need for consensus in interpreting Annexin V⁺/PI⁺ populations. In the absence of molecular and/or microscopy data, this fraction is more appropriately classified as undergoing 'late-stage cell death'. In short, establishing standardised interpretive criteria is crucial to enhance understanding, facilitate cross-study comparability, and improve the translational relevance of anticancer research.
Hassan et al. (Sun,) studied this question.