# Zwitterionic Polypeptide-Protein Conjugation for the Safe and Efficient Delivery of Therapeutic Enzymes

> **NIH NIH R21** · CORNELL UNIVERSITY · 2020 · $129,036

## Abstract

Zwitterionic Polypeptide-protein Conjugation
 for the Safe and Efficient Delivery of Therapeutic Enzymes
 PROJECT SUMMARY
One of the major obstacles that impede the wide application of therapeutic protein products is their potential
immunological response, especially for those obtained from non-human sources. Currently, the most
successful strategy to mitigate immune response induced by foreign proteins is “PEGylation”, i.e., to shield
the protein surface epitopes with polyethylene glycol (PEG). This surface conjugation strategy has been
shown to decrease to some extent immune responses to the underlying protein and more than ten PEGylated
protein products have been approved by the Food and Drug Administration (FDA). However, recent studies
both in animal models and clinical trials have demonstrated the presence of induced anti-PEG antibodies
after repeated administrations and pre-existing anti-PEG antibodies, which directly challenge the future of
this PEGylation technology. We believe that there are two shortcomings for the current PEGylation
technology: 1) the haptenic character of amphiphilic PEG leading to anti-PEG antibodies and 2) non-
degradable character of amphiphilic PEG leading to vacuolation of kidney and liver. Previously, we developed
a zwitterionic poly(carboxybetaine) (PCB) protected uricase, which was shown to be capable of maintaining
protein bioactivity, reducing the immunogenicity of encased proteins and extending their circulation time
without induced anti-polymer Abs. Extended from the zwitterionic concept, poly(EK) (PEK), a zwitterionic
polypeptide comprising of alternative lysine (K) and glutamic acid (E), has all properties of zwitterionic PCB
and is also degradable to promote its elimination from the body while PEG or PCB is not. Thus, PEK is a
great alternative beyond PEGylation, but has never been studied for its application to drug delivery. The
purpose of this R21 proposal is to explore the potential of degradable zwitterionic poly(EK) (PEK)-protein
conjugates. As a degradable version of PCB, PEK is anticipated to provide similar benefits as PCB to its
modified protein drugs while possessing excellent biodegradability. Our preliminary results showed that PEK
did not induce any anti-PEK antibodies even when it was conjugated onto highly-immunogenic keyhole limpet
hemocyanin (KLH) commonly used to boost the immunogenicity of haptens. However, significant anti-PEG
antibodies were elicited by PEG-conjugated KLH in the parallel study. In this proposal, uricase, a non-human
enzyme with strong immunogenicity, will be used as a protein target. We hypothesize and will confirm though
this study that PEK-uricase conjugates will provide a safe and efficient strategy for enzyme delivery by greatly
reducing immunogenicity, improving pharmacokinetics (PK), and enhancing pharmacodynamics (PD). Since
PEGylation has been widely used in protein therapeutics, successful completion of this project will culminate
in a new approach as an ...

## Key facts

- **NIH application ID:** 10264241
- **Project number:** 7R21EB027843-03
- **Recipient organization:** CORNELL UNIVERSITY
- **Principal Investigator:** SHAOYI JIANG
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $129,036
- **Award type:** 7
- **Project period:** 2020-09-16 → 2022-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10264241

## Citation

> US National Institutes of Health, RePORTER application 10264241, Zwitterionic Polypeptide-Protein Conjugation for the Safe and Efficient Delivery of Therapeutic Enzymes (7R21EB027843-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10264241. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*