# Maximizing the safety profile of a novel cancer therapeutic via the de-immunization of an engineered mammalian asparaginase

> **NIH NIH R43** · ENZYME BY DESIGN, INC. · 2020 · $149,999

## Abstract

Project Summary:
This application is being submitted in response to the Notice of Special Interest (NOSI) identified as NOT-CA-
20-012. The goal of this supplement is to build upon the amazing progress made in the parent Phase 1 SBIR in
developing a less immunogenic asparaginase (ASNase) by adding pivotal studies that would demonstrate its
reduced immunogenicity, potent anti-ALL action, and superior safety profile. ASNases are enzyme drugs that
systemically deplete asparagine from the blood and are a mainstay of treatment for acute lymphoblastic leukemia
(ALL), a cancer of white blood cells and the most common pediatric cancer. Despite being highly effective in the
treatment of pediatric ALL, ASNases are associated with a multitude of toxic side effects, some so severe as to
be fatal. Their high toxicity precludes routine treatment in adult ALL, contributes to a much lower cure rate of
<40% for adults, and prevents their use in other hematological malignancies (e.g. acute myeloid leukemia) and
solid tumors (e.g. pancreatic cancer), despite strong preclinical efficacy evidence. The two main sources of
toxicity are L-glutaminase (GLNase) co-activity and immunogenicity due to their bacterial origins. Since
the toxic side effects can prevent or terminate treatment, there is a clear unmet clinical need for an safer
ASNase with reduced immunogenicity and without GLNase co-activity. We are currently developing an
ASNase that addresses both problems - it is devoid of GLNase co-activity and mammalian in origin,
specifically guinea pig (GpA). We truncated and further humanized GpA to further reduce the risk of
immunogenicity. In our active Phase 1 SBIR, we identified potential antigenic epitopes and engineered
deimmunized variants (GpA369hum-DI; >84% identity to the human homolog compared to ~25% identity for current
ASNases), whose lessened ability to stimulate a T cell response will be confirmed in the grant’s last two months.
While clinical immunogenicity is extremely complex and impacted by many intrinsic and extrinsic factors, we are
mitigating this risk by assessing potential immunogenicity issues at this early preclinical stage to avoid possible
failure in the clinic, where costs are much higher, and patients’ lives are at risk. This supplemental grant will
enable us to demonstrate reduced immunogenicity caused by cytokine release syndrome (Aim 3) as well as
provide critical preclinical evidence of in vivo bioavailability and efficacy of GpA369hum-DI in both B- and T-cell
ALL (Aim 1) and a superior safety profile in toxicology studies (Aim 2). This will strengthen our Phase 2 SBIR
application by establishing preclinical feasibility, de-risking our lead candidate before entering clinical trials, and
provide evidence of its value propositions to enhance its attractiveness for commercialization to private investors.

## Key facts

- **NIH application ID:** 10134911
- **Project number:** 3R43CA243759-01S1
- **Recipient organization:** ENZYME BY DESIGN, INC.
- **Principal Investigator:** Amanda M Schalk
- **Activity code:** R43 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $149,999
- **Award type:** 3
- **Project period:** 2019-07-05 → 2021-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10134911

## Citation

> US National Institutes of Health, RePORTER application 10134911, Maximizing the safety profile of a novel cancer therapeutic via the de-immunization of an engineered mammalian asparaginase (3R43CA243759-01S1). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10134911. Licensed CC0.

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