Medium dose of TPF chemotherapy with concurrent radiotherapy and immunotherapy for locally advanced esophageal squamous cell carcinoma.

e16123 Background: Concurrent chemoradiotherapy is the standard treatment for local advanced esophageal squamous cell carcinoma (ESCC), but the prognosis is still poor. Triple drug chemotherapy containing taxanes exhibits good anti-tumor activity for ESCC, however, high toxicity limits its application. We hope to improve its tolerance by reducing the dosage, and enhance efficacy by combination of immunotherapy. Methods: ESCC patients with Local advanced or stage IV without hematogenous metastasis were enrolled. The 4/9 dose in the dual drug chemotherapy was adopted, in detail: paclitaxel, 60mg/m 2 ; cisplatin, 30mg/m 2 ; fluorouracil, 1000mg/m 2 (TPF). One cycle of TPF induction chemotherapy and anti-PD1 monoclonal antibody (pembrolizumab, 200mg; or sintilimab, 200mg) was used 3 weeks before concurrent chemoradiotherapy with 2 cycles of TPF, and one cycle of TPF consolidation chemotherapy and immunotherapy was used 4 weeks after radiotherapy. And immunotherapy was maintained for 2 years. Results: From March 2021 to October 2023, 46 patients were enrolled. The median age was 68 (range: 50-79) years, 34 (73.9%) patients were male, 23 (50%) patients were stage IV, and 11 (23.9%) patients were with a history of previous tumors. Thirty-three (71.7%) patients received simultaneous integrated boost (SIB) radiotherapy, with 61.6Gy for PTV-G, and 50.4Gy for PTV-C. As of January 2025, the median follow-up time was 27 months (range: 3-46). The 1-year and 2-year progression free survival (PFS) were 80.4% and 62.8%, respectively, and the median PFS was not achieved. The 1-year and 2-year overall survival (OS) were 87.0% and 76.3%, respectively, and the median OS was not achieved. In the univariate analysis, patients with SIB radiotherapy (p = 0.019), and consolidation chemotherapy (p = 0.016) were associated with better PFS. There were no grade IV bone marrow toxicity, except 11 (23.9%) patients with grade IV lymphopenia. One (2.2%) patient experienced grade II radiation pneumonitis, and 1 (2.2%) patient experienced grade IV radiation pneumonitis. Conclusions: The medium dose TPF concurrent chemoradiotherapy combined with immunotherapy has shown good tumor control and tolerability, and is worthy for further study.