Papaverine, an isoquinoline-type alkaloid reported to inhibit LDHA, is currently undergoing clinical trials as a radiosensitizer aimed at reducing tumor hypoxia and enhancing the radiotherapy response in A549 non-small cell lung cancer cell (NSCLC) and EO771 breast cancer xenografts (Kapp and Whiteley, 1991; Benej et al., 2018). The gene discussed is LDHA; the disease is breast cancer.