Peptide cancer vaccine with STING agonist polymers achieves tumor remission in combination with checkpoint immunotherapy | Research

The takeaway

VIPER endosomolytic peptide vaccine combined with two structurally distinct STING agonist drugamers induced potent anti-tumor CD8+ T cell responses and achieved tumor remission with anti-PD-1 in melanoma and colon cancer mouse models.

Tumor remission achieved
Peptide vaccine + STING drugamers + anti-PD-1 achieved tumor remission and protective immunity in a subset of mice—a breakthrough for peptide vaccine technology

What the researchers found

Both VIPER-STING drugamers enhanced DC maturation and CD8+ T cell responses. polySTING: more tumor-infiltrating CD8+ T cells. NPSTING: more LN antigen-presenting DCs. Both: efficacy in B16-OVA melanoma and MC38 colon cancer. Combination with anti-PD-1: tumor remission + immunity in subset.

Why it matters

Peptide cancer vaccines have struggled in clinical translation due to poor immunogenicity. This platform solves two key problems: endosomal escape (VIPER) and innate immune activation (STING drugamers), achieving the elusive goal of peptide vaccine-mediated tumor remission.

How the study worked

Peptide vaccine platform (VIPER) with 2 STING drugamer structures. B16-OVA melanoma and MC38 colon cancer mouse models. DC maturation, CD8+ T cell assays, combination with anti-PD-1.

What this study cannot tell us

Mouse models only. Remission in subset of mice (not all). STING agonists can cause systemic toxicity. Manufacturing complexity of polymer-peptide-drugamer system. Human translation uncertain.

How to read the evidence

Preclinical with multiple cancer models and mechanistic analysis. Strong proof of concept for the platform.

When this study was published

Published in 2025.

The bigger picture

Combining peptide antigen delivery with innate immune stimulation through engineered polymers could finally make peptide cancer vaccines clinically viable—a decades-long goal in immunotherapy.

Questions still open

Which drugamer design (polySTING vs NPSTING) is better for human translation?
Can this platform be adapted for personalized neoantigen vaccines?
Will STING drugamer toxicity be manageable in patients?

Common questions

What is a peptide cancer vaccine?

Peptide cancer vaccines use small pieces of proteins found on cancer cells to train the immune system to recognize and attack tumors. They are safe and easy to manufacture but have historically been too weak to fight cancer alone. This study overcomes that weakness using advanced delivery technology and immune stimulants.

How does this vaccine work?

It uses three components: (1) cancer peptide antigens to identify the target, (2) VIPER polymers that help the vaccine escape cell compartments to reach the immune recognition machinery, and (3) STING drugamers that strongly activate innate immunity. Together with checkpoint immunotherapy, this triple approach achieved tumor remission in mice.

Read the original research

Peptide vaccine formulations with structurally distinct STING agonist drugamers induce discrete, efficacious antitumor responses.

Proceedings of the National Academy of Sciences of the United States of America, 122(45), e2409978122

View on PubMed ↗Publisher’s paper ↗

Citation

Song, Kefan; Nguyen, Dinh Chuong; Wang, Yonghui; Jokonya, Simbarashe; Yazdani, Omeed; Sellers, Drew L; Stayton, Patrick S; Pun, Suzie H. (2025). Peptide vaccine formulations with structurally distinct STING agonist drugamers induce discrete, efficacious antitumor responses.. Proceedings of the National Academy of Sciences of the United States of America, 122(45), e2409978122. https://doi.org/10.1073/pnas.2409978122