The immuno-inhibitory checkpoint PD-L1, regulated by tumor cells and antigen-presenting cells (APCs), dampened the activation of T cells from the PD-1/PD-L1 axis. PD-L1-expressing APCs rather than tumor cells demonstrated the essential anti-tumor effects of anti-PD-L1 monotherapy in preclinical tumor models. Using the murine tumor model, we investigated whether anti-PD-L1 antibody increased the antigen-specific immune response and anti-tumor effects induced by the antigen-specific protein vaccine, as well as the possible mechanisms regarding activation of APCs. Anti-PD-L1 antibody combined with the PEK protein vaccine generated more potent E7-specific immunity (including the number and cytotoxic activity of E7-specific cytotoxic CD8+ T lymphocytes) and anti-tumor effects than protein vaccine alone. Anti-PD-L1 antibody enhanced the maturation of dendritic cells and the proportion of M1-like macrophages in tumor-draining lymph nodes and tumors in tumor-bearing mice treated with combinatorial therapy. PD-L1 blockade overturned the immunosuppressive status of the tumor microenvironment and then enhanced the E7 tumor-specific antigen-specific immunity and anti-tumor effects generated by an E7-specific protein vaccine through modulation of APCs in an E7-expressing small tumor model. Tumor-specific antigen (like HPV E7 antigen)-specific immunotherapy combined with APC-targeting modality by PD-L1 blockade has a high translational potential in E7-specific cancer therapy.

Adjuvant treatment in advanced-stage (stages III /IV) endometrial carcinomas in terms of tumor grades has not yet been explored. We retrospectively analyzed 194 patients with advanced-stage endometrioid endometrial carcinoma who received surgery, followed by adjuvant therapy, at National Taiwan University Hospital between January 1, 2000 and August 31, 2017. Adjuvant therapies included radiation (RT), chemotherapy alone (CT), and combined modality treatment (CMT: radiation and chemotherapy). The prognostic factors were determined from multivariate survival analyses using Cox regression models. Progression-free survival (PFS) and overall survival (OS) times were estimated with the Kaplan-Meier method. The median follow-up was 45.5 months (range: 6.2-207.9). In grade 1/2 endometrioid carcinoma, neither adjuvant CT nor CMT could prolong PFS significantly compared to RT (CT: HR 1.59, 95% CI 0.64-3.97; CMT: HR 2.03, 95% CI 0.72-5.74). Notably, maximal cytoreduction independently improved PFS (HR 0.31, 95% CI 0.10-0.90). No particular adjuvant treatment provided an OS advantage over the others for grade 1/2 endometrioid carcinomas. However, for grade 3 endometrioid carcinoma, CMT showed OS benefits (HR 0.15, 95% CI 0.03-0.89) compared to RT and CT. In conclusion, maximal cytoreduction should be the goal in patients with grade 1/2 advanced-stage endometrioid carcinomas. Based on our results, patients with grade 3 endometrioid carcinomas might benefit from adjuvant CMT.