Synthetic Multi-Peptide Molecules That Target Cancer Cells and Activate the Immune System | Research

The takeaway

Researchers built modular peptide-based molecules that simultaneously bind cancer cells and stimulate innate immune responses, providing insights into how multivalency enhances targeting and therapeutic potential.

Multivalency boosts avidity
Increasing the number of cancer-targeting peptide moieties on a single construct significantly enhanced binding strength through avidity effects

What the researchers found

Using solid-phase peptide synthesis and chemoselective ligations, researchers constructed a series of targeted immune system engagers (ISErs) bearing different numbers and combinations of: two cancer-targeting 'binder' peptides (targeting ephrin A2 and integrin α3 receptors) and one immune-stimulating 'effector' peptide (targeting formyl peptide receptors). The study demonstrated that multivalency and receptor density significantly influence avidity effects — binding strength increased with more binding moieties. Both cancer cell binding and immune cell stimulation activities were characterized across the constructs.

Why it matters

Most bispecific and multivalent cancer immunotherapies rely on complex and expensive recombinant antibody production. Peptide-based approaches are simpler to manufacture, more modular, and allow systematic optimization. By engaging both the cancer cell and the immune system with a single synthetic molecule, these ISErs represent a new class of potential cancer therapeutics that could be more accessible and customizable.

How the study worked

Peptide building blocks were synthesized using solid-phase peptide synthesis and assembled into multivalent/multispecific constructs via chemoselective ligation chemistry. Cancer cell binding was measured against ephrin A2 and integrin α3-expressing tumor cell lines. Immune cell stimulation was assessed through formyl peptide receptor activation of innate immune cells. Various architectures were compared to understand avidity effects.

What this study cannot tell us

This is an in vitro study without animal models or clinical data. The peptide constructs' in vivo stability, biodistribution, and pharmacokinetics were not assessed. Cancer cell binding and immune stimulation were measured separately — synergistic anti-tumor effects were not demonstrated in a model system. The specific peptide targets (ephrin A2, integrin α3) may have limited specificity for some tumor types. Manufacturing scalability was not addressed.

How to read the evidence

This is a chemical biology study published in ChemBioChem demonstrating proof-of-concept for peptide-based immune engagers. The focus is on synthesis methodology and binding characterization, representing early-stage drug design research.

When this study was published

Published in 2018, this study is about 8 years old but remains relevant as peptide-based immunotherapy alternatives continue to be developed and the principles of multivalent design are increasingly applied.

The bigger picture

Cancer immunotherapy has been dominated by antibody-based drugs, but peptide-based alternatives offer advantages in cost, manufacturing simplicity, and modularity. This study demonstrates that peptide chemistry can achieve the multivalent binding and immune engagement previously limited to engineered antibodies. As peptide synthesis technology advances, these modular immune engagers could complement or replace more complex biologic drugs.

Questions still open

Do these peptide-based ISErs show anti-tumor activity in animal cancer models when both binding and immune stimulation work together?
How do peptide ISErs compare to bispecific antibodies in terms of in vivo half-life, efficacy, and manufacturing cost?
Can the modular design be expanded to include additional tumor-targeting or immune-modulating peptides for enhanced specificity?

Common questions

What are immune system engagers and how do they work?

Immune system engagers (ISErs) are molecules designed to act as bridges between cancer cells and immune cells. One part of the molecule grabs onto the cancer cell, while another part activates nearby immune cells to attack. By putting both functions into a single synthetic peptide construct, researchers create a targeted weapon that directs the immune system specifically against tumors.

Why use peptides instead of antibodies for cancer immunotherapy?

Antibodies are large, complex proteins that are expensive to produce and difficult to modify. Peptides are much smaller and can be made chemically with precise control over their design. This makes it easier to create modular, customizable molecules, combine multiple functions, and potentially manufacture them at lower cost — making targeted immunotherapy more accessible.

Read the original research

Synthetic Cancer-Targeting Innate Immune Stimulators Give Insights into Avidity Effects.

Chembiochem : a European journal of chemical biology, 19(5), 459-469

View on PubMed ↗Publisher’s paper ↗

Citation

Conibear, Anne C; Pötgens, André J G; Thewes, Karine; Altdorf, Claudia; Hilzendeger, Clarissa; Becker, Christian F W. (2018). Synthetic Cancer-Targeting Innate Immune Stimulators Give Insights into Avidity Effects.. Chembiochem : a European journal of chemical biology, 19(5), 459-469. https://doi.org/10.1002/cbic.201700522