Rationale:
Surgical resection is a primary treatment for solid tumors, but high rates of tumor recurrence and metastasis post-surgery present significant challenges. Manganese (Mn
2+
), known to enhance dendritic cell-mediated cancer immunotherapy by activating the cGAS-STING pathway, has potential in post-operative cancer management. However, achieving prolonged and localized delivery of Mn
2+
to stimulate immune responses without systemic toxicity remains a challenge.
Methods:
We developed a post-operative microenvironment-responsive dendrobium polysaccharide hydrogel embedded with Mn
2+
-pectin microspheres (MnP@DOP-Gel). This hydrogel system releases Mn
2+
-pectin microspheres (MnP) in response to ROS, and MnP shows a dual effect
in vitro
: promoting immunogenic cell death and activating immune cells (dendritic cells and macrophages). The efficacy of MnP@DOP-Gel as a post-surgical treatment and its potential for immune activation were assessed in both subcutaneous and metastatic melanoma models in mice, exploring its synergistic effect with anti-PD1 antibody.
Result:
MnP@DOP-Gel exhibited ROS-responsive release of MnP, which could exert dual effects by inducing immunogenic cell death of tumor cells and activating dendritic cells and macrophages to initiate a cascade of anti-tumor immune responses.
In vivo
experiments showed that the implanted MnP@DOP-Gel significantly inhibited residual tumor growth and metastasis. Moreover, the combination of MnP@DOP-Gel and anti-PD1 antibody displayed superior therapeutic potency in preventing either metastasis or abscopal brain tumor growth.
Conclusions:
MnP@DOP-Gel represents a promising drug-free strategy for cancer post-operative management. Utilizing this Mn
2+
-embedding and ROS-responsive delivery system, it regulates surgery-induced immune responses and promotes sustained anti-tumor responses, potentially increasing the effectiveness of surgical cancer treatments.