Objective:To observe the expression differences of IGFBP-3 antigen in different eukaryotic cells,and the optimal antigen was screened for calibration materials evaluation to develop IGFBP-3 antigen diagnostic kit.Methods:Human IGFBP-3 gene was respectively cloned into Pichia pastoris expression vector pPIC9K and mammalian expression vector pCMV,and then transformed into Pichia pastoris GS115,HEK293 cell and CHO cell for gene expression.Activity analysis and purification of the expressed prod-ucts were performed with Ni-NTA and SDS-PAGE,and calibrating performance of the purified antigen was analyzed with IGFBP-3 test kit.Results:IGFBP-3 antigen was easily degradable during the expression process,and only the HEK293 cells enabled to obtain the full-length antigen,and reactivity and stability of the calibration products using antigen expressed in HEK293 cells could meet the calibration material requirements for diagnostic kits,laying a solid foundation for further development of IGFBP-3 diagnostic kits.Conclusion:IGFBP-3 expressed by HEK293 cells is more suitable for calibration materials preparation.

Objective:To study the combined use of neoadjuvant chemotherapy and immunotherapy in patients with borderline resectable pancreatic cancer.Methods:The clinical data of patients with pancreatic cancer who were planned to undergo perioperative treatment before surgical treatment at the Fifth Medical Center of PLA General Hospital from January 2019 to June 2021 were retrospectively studied. Of 22 patients with pancreatic cancer, there were 10 males and 12 females, aged (56.0±10.2) years old. Preoperative treatment with chemotherapy (nab-paclitaxel and S-1, AS) and immunotherapy regimen before surgery were given. The baseline characteristics, treatment efficacy, surgical pathology and prognosis were analyzed.Results:Of 22 patients who were treated with neoadjuvant chemotherapy combined with programmed death-1 (PD-1) monoclonal antibody, 11 patients (50%) had tumors in the head, neck and uncinated process of pancreas. On radiographic assessment, one patient achieved CR (4.5%, 1/22), 9 patients PR (40.9%, 9/22), and 11 patients SD (50.0%, 11/22). All patients subsequently underwent R 0 resection. The postoperative pTNM staging showed 91% (20/22) of patients were in stage IA-IIB, 31.8% (7/22) of patients had pT2, 63.6% (14/22) had N0, and 1 patient had pCR. Thirteen patients (54.2%, 13/22) received postoperative adjuvant therapy. The median recurrence-free survival (RFS) was 6.4 months and the median time to progression (TTP) was 12.8 months. The median overall survival of patients was not reached. Postoperative pathology TNM staging IIA to III ( HR=3.63, 95% CI: 1.18-11.20, P=0.025) and postoperative pathology T2-3 stage ( HR=2.02, 95% CI: 1.01-5.05, P=0.049) were significantly associated with RFS. Postoperative pathology TNM stages IIA to III ( HR=2.39, 95% CI: 1.04-5.50, P=0.041) and postoperative pathology T2-3 stage ( HR=2.53, 95% CI: 1.26-5.09, P=0.009) were significantly associated with TTP. Conclusion:AS combined with PD-1 monoclonal antibody showed good efficacy as a neoadjuvant therapy for patients with borderline-resectable pancreatic cancer.