In the meantime, the first report of treatment of a patient with a HIF-2α gain-of-function PGL with the HIF-2α antagonist Belzutifan recorded a very rapid reduction in plasma chromogranin A and normetanephrines within 9 days of starting treatment, followed by a reduction in tumour size within 17 days that was sustained for 24 months (93). The gene discussed is EPAS1; the disease is neoplasm.