Studies using polypeptide hydrogels co-delivering tumor lysates, GM-CSF, and dual checkpoint inhibitors (anti-CTLA-4/PD-1) demonstrated significantly increased activated effector CD8 + T cells within tumors and spleens, coupled with a reduction in regulatory T cells (Tregs), leading to superior antitumor efficacy compared to single-agent therapies or systemic delivery. Here, CTLA4 is linked to neoplasm.