Engineered enzymes for cystinuria treatment

The invention describes engineered primate cystathionine-gamma-lyase (CGL) enzymes with specific amino acid modifications to efficiently degrade L‑cystine and L-cysteine. These enzymes are designed to treat cystinuria by reducing cystine levels in the body, preventing cystine stone formation.

Background

Cystinuria is a genetic disorder caused by mutations in the SLC3A1 and SLC7A9 genes, leading to the defective reabsorption of cystine in the kidneys. Due to the low solubility of cystine, it forms crystals and stones in the urinary tract. Existing treatments, such as hyper diuresis and the use of thiol-containing drugs, aim to increase cystine solubility or reduce its concentration in the urine.

However, these treatments often come with significant adverse effects, including gastrointestinal intolerance, rash, joint pain, and other toxicities, which limit their long-term use and effectiveness. Furthermore, surgical interventions like percutaneous nephrolithotomy and shock wave lithotripsy, while effective, are costly and invasive, making them less desirable for patients who frequently form cystine stones. Thus, there is a pressing need for therapies that can effectively reduce cystine levels in the body without causing significant side effects or requiring invasive procedures.

Technology description

The patented invention involves engineered primate cystathionine-gamma-lyase (CGL) enzymes that have been modified to degrade both L-cystine and L‑cysteine efficiently, thus a promising treatment for cystinuria. These modified enzymes contain specific amino acid substitutions that enhance their catalytic activity and reduced immunogenicity, making them suitable for human therapy. The invention also includes methods for linking these enzymes to heterologous peptide sequences or polysaccharides to improve their stability and half-life in vivo. Additionally, it also covers nucleic acids encoding these modified enzymes, vectors for their expression, and therapeutic formulations for their administration. The therapeutic applications involve reducing cystine levels in patients' plasma, serum, and urine, thereby preventing or reducing the formation of cystine stones.

This technology is differentiated by its focus on engineering human or primate-derived CGL enzymes to improve their therapeutic efficacy and safety. The specific amino acid substitutions enhance the enzymes' catalytic activity, making them more effective at degrading L-cystine and L-cysteine. This is particularly important for treating cystinuria, where defective kidney transporters lead to cystine stone formation. By reducing immunogenicity, the modified enzymes are less likely to trigger adverse immune responses, allowing for repeated dosing and long-term treatment. Furthermore, the ability to link these enzymes to stabilizing agents like heterologous peptides or polysaccharides extends their half-life in the body, reducing the frequency of administration. The inclusion of nucleic acids and vectors for expressing these enzymes enables scalable production and potential gene therapy applications, broadening the scope and impact of this therapeutic approach.