TP53 and neoplasm: Interestingly, patients with a presence of PIK3CA or TP53 mutation but low tumor burden had similar PFS outcome with those with a high tumor burden but with no PIK3CA or TP53 oncogenic mutations (median PFS 5.8 vs 5.6 months), suggesting that the oncogenic mutations of PIK3CA and/or TP53 exerted additional resistance to the treatment of ET-base regimens in addition to the tumor burden status that was associated with worse PFS.