A multicenter clinical study: personalized medication for advanced gastrointestinal carcinomas with the guidance of patient-derived tumor xenograft (PDTX).

Background: Establish patient-derived tumor xenograft (PDTX) from advanced GICs and assess the clinical value and applicability of PDTX for the treatment of advanced gastrointestinal cancers.

Methods: Patients with advanced GICs were enrolled in a registered multi-center clinical study (ChiCTR-OOC-17012731). The performance of PDTX was evaluated by analyzing factors that affect the engraftment rate, comparing the histological consistency between primary tumors and tumorgrafts, examining the concordance between the drug effectiveness in PDTXs and clinical responses, and identifying genetic variants and other factors associated with prognosis.

Results: Thirty-three patients were enrolled in the study with the engraftment rate of 75.8% (25/33). The success of engraftment was independent of age, cancer types, pathological stages of tumors, and particularly sampling methods. Tumorgrafts retained the same histopathological characteristics as primary tumors. Forty-nine regimens involving 28 drugs were tested in seventeen tumorgrafts. The median time for drug testing was 134.5 days. Follow-up information was obtained about 10 regimens from 9 patients. The concordance of drug effectiveness between PDTXs and clinical responses was 100%. The tumor mutation burden (TMB) was correlated with the effectiveness of single drug regimens, while the outgrowth time of tumorgrafts was associated with the effectiveness of combined regimens.

Conclusion: The engraftment rate in advanced GICs was higher than that of other cancers and meets the acceptable standard for applying personalized therapeutic strategies. Tumorgrafts from PDTX kept attributes of the primary tumor. Predictions from PDTX modeling closely agreed with clinical drug responses. PDTX may already be clinically applicable for personalized medication in advanced GICs.