MDM4 and neoplasm: Champiat et al. (2017) and Saâda-Bouzid et al. (2017) found no association between HPD and baseline tumor load, previous treatment line, tumor histology, type of immunotherapy, or number of metastatic sites. To date, five clinical variables—aging, female sex, higher serum lactate dehydrogenase (LDH) concentration, metastasis burden, and local recurrence of the cells in the irradiation area—have been identified as potentially associated with HPD, as have specific genomic mutations including MDM2/MDM4 amplification and EGFR aberrations.