Fig. 6: Molecular and clinical timeline of the four cases.

A Case 1—High TMB & immunotherapy. Liquid biopsy in May 2021 revealed high TMB (15 mut/Mb) together with KIT, PIK3CA, CDK12, DNMT3A, KMT2D, and TP53 alterations after prior chemotherapy. The patient was enrolled in a trial of anti-PD1 plus anti-CTLA4 with inguinal radiotherapy, achieving a durable partial response and no detectable disease on the latest PET scan. B Case 2—RAD51C mutation & PARP inhibition. Liquid biopsy in July 2021 identified a RAD51C A354fs*34 mutation (high VAF) along with EGFR, KMT2D, NFE2L2, and PBRM1 alterations. The patient was treated in a trial combining anti-PD1 therapy with a PARP inhibitor, achieving a transient partial response before subsequent radiological progression. C Case 3—FGFR2 K659N & FGFR inhibitor. Following multiple metastatic relapses after chemoradiotherapy and systemic treatment, liquid biopsy in June 2023 detected FGFR2 K659N as well as NF1, PTEN, TP53, DNMT3A, FGF6, KMT2D, and NBN mutations. The patient initiated FGFR-targeted therapy in a clinical trial, with early disease stability followed by progression. D Case 4—PIK3CA E453K & PI3K pathway inhibition. After recurrent metastatic progression despite multiple systemic treatments and surgery, liquid biopsy in May 2024 revealed PIK3CA E453K together with TP53 E294* and BCL2L1 amplification. The patient was enrolled in a PIK3CA-inhibitor clinical trial, showing stable disease on first follow-up CT imaging.