PIK3R3 and neoplasm: In order to further characterize the metabolic profile of CMS3‐enriched brain metastases, we identified a metabolic gene signature, comprising CHAC2, CA8, PIK3R3, CYP26B1, DHRS9, UGT8, and RET, that we found specifically upregulated in CMS3‐classified tumor samples, both in the discovery as well as the validation cohort.