In the single experimental arm, patients with locally nonresectable disease were subjected to receive neoadjuvant tislelizumab (200mg) plus chemotherapy (FP regimen) for conversion therapy. If conversion therapy succeeds, patients would proceed to surgery and adjuvant therapy. Otherwise, if patients were still not resectable after the conversion therapy, they will be treated by tislelizumab plus chemotherapy with or without palliative radiotherapy .

The 1st to 3rd doses were administered concurrently with FP regimen chemotherapy, 200 mg Tislelizumab each, on D1, D22 and D43 by intravenous infusion. In patients with successful conversion, one dose of 200 mg was administered 21 days after surgery in concurrent with the 4th to 6th cycles of 5-Fu, then 6 cycles of 200 mg Tislelizumab as adjuvant therapy; in patients with failed conversion, chemotherapy combined with tislelizumab were administered, with or without radiation therapy.

Translational treatment-related AEs resulted in rates of surgery that were more than 30 days late or inoperable than originally planned

The proportion of patients whose primary tumor cell residual was less than 10% in the total number of patients enrolled after transformation therapy

Pathological complete response refers to that no tumor component or a small amount of carcinoma in situ component can be found on the horizontal line of pathological section after systemic treatment and surgical resection of the lesion.

The proportion of patients who completed R0 resection through 3 cycles of immunotherapy combined with chemotherapy in the total enrolled population.R0 finger resection margin under microscope was negative.