PIK3CA and neoplasm: Of note, although the positive ctDNA PIK3CA-mutated patients received similar magnitude of benefit from alpelisib as for the tissue-based detection (HR = 0.55) in the SOLAR-1 study [50], negative ctDNA result did not preclude the presence of a PIK3CA mutation [51], imposing the analysis on tumor tissue and the need for obtaining a metastatic biopsy in patients with ctDNA-negative result and reflex testing in the primary tumor when biopsy from metastatic lesion is not feasible.