Rational engineering of an improved adenosine deaminase 2 enzyme for weaponizing T-cell therapies

Area of Science:

• Immunology
• Biochemistry
• Biotechnology

Background:

• Adenosine, an immunosuppressive metabolite, accumulates in solid tumors.
• Tumor-associated adenosine inhibits anti-tumor immune responses, including CAR T-cell therapies.

Purpose of the Study:

• To engineer human cells to secrete adenosine deaminase (ADA) for extracellular adenosine degradation.
• To enhance the efficacy of chimeric antigen receptor (CAR) T-cell therapies.

Main Methods:

• Investigated ADA1 and ADA2 isoforms for secretion.
• Utilized phylogenetic analysis and mutational surveys to optimize ADA2 activity.
• Developed a high-throughput screen for enhanced ADA2-mediated adenosine degradation.
• Engineered Jurkat and CAR T cells to express the optimized ADA2 variant.

Main Results:

• The high-activity ADA1 isoform is intracellular; standard secretion signals were ineffective.
• The lower-activity ADA2 isoform is naturally secreted.
• A novel, highly catalytically efficient ADA2 variant was isolated, exhibiting 30x higher extracellular adenosine degradation activity than wild-type.
• Engineered Jurkat and CAR T cells demonstrated significant extracellular adenosine degradation in vitro.

Conclusions:

• Engineered secretion of a high-activity ADA2 variant offers a promising strategy to counteract tumor immunosuppression.
• This approach has the potential to enhance the effectiveness of CAR T-cell immunotherapies against solid tumors.