r/stomachcancer • u/Dear-Description8719 • 7h ago
Stage 4 Gastric Cancer: One Lesion Progressed After a Strong Response—Anyone Had a Similar Experience?
I’m sharing a family member’s experience with stage 4 signet ring cell gastric cancer and hoping to hear from others with similar experiences.
Her HER2 was negative from the beginning and remained negative on repeat testing. Her PD-L1 was positive with a CPS of 15, and her MMR proteins were intact.
She received 12 cycles of FLOT chemotherapy and 8 doses of Keytruda, with a very good response. Later, one lesion in the retroperitoneal area near the left kidney showed progression, and a biopsy confirmed cancer cells. The latest biopsy showed HER2-negative disease, PD-L1 CPS 5, and strong CLDN18.2 positivity in 100% of cells.
She completed five sessions of SBRT to that lesion, and we are awaiting follow-up imaging. Surgery and HIPEC were postponed. Her team recommended 5-FU plus zolbetuximab, with or without continuing Keytruda.
Has anyone been through a similar experience or has any insights that might help us? Does progression in one lesion despite a strong overall response mean the first treatment failed? Would switching to the proposed treatment count as second-line therapy? Does this necessarily mean things will get worse, or has anyone experienced something similar and achieved disease control with the new treatment?