Injectable Nano-in-Gel Vaccine for Spatial and Temporal Control of Vaccine Kinetics and Breast Cancer Postsurgical Therapy

Breast cancer is the most commonly diagnosed cancer, and surgical resection is the first choice for its treatment. With the development of operation techniques, surgical treatment for breast cancer is evolving toward minimally invasive and breast-conserving approaches. However, breast-conserving surgery is prone to an increased risk of cancer recurrence and is becoming a key challenge that needs to be solved. In this study, we introduce a one-shot injectable nano-in-gel vaccine (NIGel-Vax) for postoperative breast cancer therapy. The NIGel-Vax was constructed by mixing protein antigens with PEI-4BImi-Man adjuvant and then encapsulated in a hydrogel made with oxidized dextran (ODEX) and 4-arm PEG-ONH₂. Using 4T1 tumor-extracted proteins as antigen, the NIGel-Vax achieved a 92% tumor suppression rate and a 33% cure rate as a postoperative therapy in the 4T1 tumor model. Using the tumor-associated antigen trophoblast cell-surface antigen 2 (TROP2) protein as the antigen, NIGel-Vax achieved a 96% tumor suppression rate and a 50% cure rate in triple-negative breast cancer (TNBC) models. This design provides an encouraging approach for breast cancer postoperative management.