Smart Tumor-Targeting Peptides That Activate Only Where Cancer Is Present | Research

The takeaway

Protease-activated CendR peptides targeting tenascin-C bind to the tumor receptor NRP-1 only after cleavage by the cancer enzyme uPA, reducing off-target accumulation in healthy tissues like lungs.

uPA-activated
peptides bind tumor receptor NRP-1 only in the cancer microenvironment

What the researchers found

Two novel peptides (PL3uCendR and SKLG) bind tenascin-C constitutively but only activate NRP-1 binding after uPA cleavage, reducing off-target tissue accumulation while maintaining tumor penetration.

Why it matters

Off-target toxicity is a major challenge for peptide-drug conjugates and targeted nanoparticles. Protease-activated peptides that only engage their tumor-penetrating function in the tumor microenvironment could dramatically improve the therapeutic window of cancer nanomedicines.

The numbers in context

PL3 peptide (AGRGRLVR) was modified for protease activation. Off-target lung accumulation was significantly reduced.

How the study worked

Rational design and uPA-treated phage library screening on recombinant NRP-1, validated with in vitro cleavage/binding/internalization assays and in vivo biodistribution in orthotopic glioblastoma mice.

Who was studied

Tumor-bearing preclinical models with NRP-1 tissue distribution analysis

What this study cannot tell us

Preclinical mouse data only; glioblastoma model may not generalize to all tumor types; uPA expression varies across cancers; peptide stability and pharmacokinetics in humans not established; no drug payload attached for therapeutic efficacy testing.

How to read the evidence

Preliminary preclinical evidence demonstrating proof-of-concept for protease-activated tumor-penetrating peptides in glioblastoma mouse models.

When this study was published

Published in 2024, representing cutting-edge advances in smart peptide drug delivery design.

The bigger picture

This study establishes a general technology platform for making any CendR tumor-penetrating peptide protease-dependent, potentially solving the off-target problem that has limited the clinical translation of tumor-homing peptides.

Questions still open

How much does uPA-dependent activation improve the therapeutic index of peptide-drug conjugates?
Can this technology be combined with existing approved nanoparticle therapies?
Do all tumors express enough uPA to reliably activate these peptides?

Common questions

Why do cancer-targeting peptides sometimes harm healthy tissues?

Many tumor-targeting peptides bind to receptors like NRP-1 that are also present in healthy tissues, especially the lungs. This means the peptides — and any drugs attached to them — can accumulate where they're not wanted, causing side effects.

How do these new peptides solve the off-target problem?

They're designed with a built-in lock that only opens in the tumor environment. The cancer enzyme uPA acts as the key, cleaving the peptide to expose its NRP-1 binding site. In healthy tissues without uPA, the peptide remains locked and can't bind.

Read the original research

Protease-activated CendR peptides targeting tenascin-C: mitigating off-target tissue accumulation.

Drug delivery and translational research, 14(10), 2945-2961

View on PubMed ↗Publisher’s paper ↗

Citation

Tobi, Allan; Haugas, Maarja; Rabi, Kristina; Sethi, Jhalak; Põšnograjeva, Kristina; Paiste, Päärn; Jagomäe, Toomas; Pleiko, Karlis; Lingasamy, Prakash; Teesalu, Tambet. (2024). Protease-activated CendR peptides targeting tenascin-C: mitigating off-target tissue accumulation.. Drug delivery and translational research, 14(10), 2945-2961. https://doi.org/10.1007/s13346-024-01670-2