# A novel sustained-release immunotoxin for treatment of glioblastoma multiforme

> **NIH NIH R21** · DUKE UNIVERSITY · 2020 · $168,758

## Abstract

Project Summary/Abstract
Glioblastoma multiforme (GBM) is the most common and malignant primary brain tumor despite extensive
treatment measures and intense research effort. There is an urgent need for innovative therapies that can
improve upon the current —largely ineffectual— clinical standard of care. Motivated by this need, the objective
of this proposal is to synthesize and test a novel, GBM-specific, highly potent immunotoxin and prolong its
bioavailability by sustained release from an intratumorally injected, gel-like polypeptide depot. The bioactive
component of the drug —an Affibody-toxin fusion— is internalized upon high affinity binding of the targeting
protein —the Affibody— to GBM cell-specific receptors. The bacterial toxin fused to the Affibody is an
exceptionally powerful drug, as it is highly cytotoxic regardless of cell cycle status. However, injection of biologics
is limited by their high solubility and rapid clearance from the tumor. To address this problem, we will create a
depot the enables sustained intratumoral release by genetic fusion of a third component —an elastin-like
polypeptide (ELP)— a thermally responsive peptide polymer that transitions from a soluble to an insoluble
coacervate phase upon in vivo injection, leading to the formation of an intratumoral drug depot. The kinetics of
release from this depot will be optimized using a library of ELPs with a range of phase transition behaviors. In
preliminary studies, we have demonstrated picomolar potency of our Affibody-immunotoxin-ELP fusion in GBM
cell lines in vitro and anticipate that the intratumoral injection of this immunotoxin depot formulation in vivo will
result in slow dissolution into the surrounding tissue and enhanced efficacy compared to existing immunotoxin
treatments that can only achieve sustained application through delivery by external osmotic pumps. The
proposed work is significant because it improves upon previously investigated GBM-specific immunotoxins by:
1) enhancing targeting by use of a structurally robust Affibody, 2) increasing valency and therefore avidity through
recombinant fusion of multiple Affibody domains, 3) improving biocompatibility with an engineered, non-
immunogenic toxin; and 4) creating a fusion that can be injected into tumor tissue as a liquid but which
instantaneously transitions into an insoluble and viscous material driven solely by body heat. The proposal is
innovative in its design where the targeting moiety, drug and depot are modular —enabling easy swapping of
different modules— and can be engineered into a single polypeptide that can be recombinantly produced at high
yield in bacteria and are easily purified, thereby making this a highly generalizable and clinically translational
technology.

## Key facts

- **NIH application ID:** 9859391
- **Project number:** 5R21CA237705-02
- **Recipient organization:** DUKE UNIVERSITY
- **Principal Investigator:** Ashutosh Chilkoti
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $168,758
- **Award type:** 5
- **Project period:** 2019-02-01 → 2021-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9859391

## Citation

> US National Institutes of Health, RePORTER application 9859391, A novel sustained-release immunotoxin for treatment of glioblastoma multiforme (5R21CA237705-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9859391. Licensed CC0.

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