Optimized Monothiol Thioredoxin Derivative (ORP100S) Protects In Vitro and In Vivo from Radiation and Chemotoxicity...

Area of Science:

• Biochemistry
• Pharmacology
• Cell Biology

Background:

• Human thioredoxin-1 (TRX) is a disulfide reductase with protective functions against cellular stress.
• Clinical use of recombinant TRX (rhTRX) is limited by rapid clearance and intracellular activity.
• There is a need for improved TRX variants with enhanced stability and therapeutic efficacy.

Purpose of the Study:

• To engineer and characterize a novel TRX variant, ORP100S, with improved properties for therapeutic applications.
• To evaluate the efficacy of ORP100S in mitigating acute radiation injury and chemotherapy-induced toxicity.
• To investigate the mechanisms underlying ORP100S's protective effects.

Main Methods:

• Engineering of ORP100S variant for enhanced stability and extracellular target engagement.
• Development of novel assays for TRX activity and quantification.
• In vivo studies in rodents and non-human primates exposed to ionizing radiation.
• In vitro and in vivo studies evaluating protection of hematopoietic stem/progenitor cells (HSPCs) from chemotherapy.
• Mechanistic studies involving the Kruppel-like factor 4 (KLF4)-p53 pathway and ferroptosis.

Main Results:

• ORP100S demonstrated high-yield expression and improved pharmacokinetic/pharmacodynamic properties compared to native TRX.
• ORP100S significantly mitigated lethal total-body ionizing radiation effects in vivo.
• ORP100S protected HSPCs from chemotherapy-induced toxicity in vitro and in vivo, synergistically with GM-CSF.
• ORP100S selectively inhibited ferroptosis in HSPCs via modulation of the KLF4-p53 pathway, without promoting cancer cell proliferation.

Conclusions:

• ORP100S is a rationally designed TRX variant with enhanced stability and therapeutic potential.
• ORP100S effectively mitigates acute radiation injury and chemotherapy toxicity.
• ORP100S offers a promising therapeutic strategy for improving cancer treatment safety without compromising antitumor activity.