Activity-improved human Asparaginase for Cancer therapy

Amino acid depletion therapy offers a promising approach to cancer treatment. It makes use of the differences between healthy and cancerous cells when processing nutrients. Some enzymes kill cancer cells by removing amino acids from the blood. Asparaginase (ASNase) is an FDA-approved enzyme used to treat acute lymphoblastic leukemia (ALL). ALL is the most common cancer in children. ASNase turns asparagine into aspartic acid and ammonia. This reduces the amount of asparagine in the blood and stops leukemic cells getting the asparagine they need to make DNA, RNA and protein, selectively which kills them but not healthy cells. Today's clinics use enzymes from bacteria. They cause many different side effects, but the main one is hypersensitivity (i.e. allergic reactions due to antigenicity).

Challenge

Therapeutic asparaginases need to be highly reactive to efficiently remove asparagine from the blood. Ideally, they should not be antigenic. In fact, antigenicity is the main reason for treatment failure. In addition, bacterial ASNase exhibits low glutaminase activity, which inevitably leads to additional side effects. The solution is to use human variants instead. However, natural human ASNase is unsuitable for therapeutic use due to its low basal activity at the concentrations of asparagine in the blood.

Our Solution

By rational design of structure-based variants for the human asparaginase, scientists at the University of Göttingen have made a big improvement in its catalytic properties. What's more, these variants no longer show allosteric regulation, which is a huge step forward. The scientists have also made very limited deviations from the human sequence to prevent immunogenicity or to keep it very low (as little as one change!), which is a huge step forward. This is a real game-changer because it could allow for the administration of higher or more frequent doses compared to drugs with bacterial origin.

Advantages

  • Design of structure-based variants of the human asparaginase with improved catalytic properties.
  • Variants no longer show allosteric regulation.
  • Variants are very similar to the human sequence.
  • Potential administration of higher or more frequent doses than achievable with enzymes of bacterial origin.

New human asparaginase (ASN) variants are highly effective in leukemia cells (black line: control). T cells (Jurkat T-ALL) used to study leukemia (ALL) were treated for 8 days at the indicated doses of (A) bacterial ASN, (B) new human ASN variant (Fl_loop) with amino acids 297-318 replaced by amino acids 297-316 of closely related guinea pig ASN, or (C) new human ASN variant with amino acid substitution H298Q. Note that Jurkat T-ALL cells are intrinsically resistant to asparaginase, and knockdown of GSK3α is known to highly sensitize these cells to asparagine shortage.


New human asparaginase (ASN) variant is highly effective in leukemia xenografts.

Treatment of ALL patient-derived xenograft (PDX) cells: PDXs were generated by engraftment of viably frozen leukemic cells
into immunodeficient mice. Subsequently, PDX cells were seeded in growth medium and treated with vehicle (PBS control),
bacterial ASN (bASNase) or new human ASN variant (mhASNase = Fl_loop). Relative viability was assessed (two different PDXs are shown).

Applications

Cancer treatment: Amino acid depletion therapy using novel human asparaginase variant.

Development Status

Human asparaginase variants were successfully tested in cancer cells and patient-derived ALL xenografts.

Patent Status

A priority patent application has been filed (Applicant: Georg August University of Göttingen public law foundation and Hannover Medical School (MHH)).

References

Preliminary R&D results in:
Eulig N.: Mechanistic and structural characterization of human L-asparaginases. 2024. eDiss University of Göttingen

Contact

Dr. Stefan Uhle
Patent & Innovation Manager Life Science
E-Mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
Tel.: +49 551 30724 154
Reference: BioC-2532-SUG

Tags: Therapy, Life science

Search

A subsidiary of

Georg-August-Universität Göttingen