Extended Pharmacokinetics Improve Site-Specific Prodrug Activation Using Radiation

Area of Science:

• Oncology
• Radiochemistry
• Pharmacology

Background:

• Radiotherapy is a common cancer treatment that can activate prodrugs.
• Achieving sustained and localized prodrug activation in tumors remains a challenge.
• Off-target tissue toxicity is a concern with current methods.

Purpose of the Study:

• To develop novel radiation-activated chemotherapy prodrugs.
• To establish a computational framework for understanding prodrug pharmacokinetics and pharmacodynamics (PK/PD).
• To demonstrate sustained and localized *in vivo* prodrug activation.

Main Methods:

• Synthesis of novel phenyl-azide-caged, radiation-activated drug-conjugates.
• Focus on an albumin-bound prodrug of monomethyl auristatin E (MMAE).
• In vivo efficacy and toxicity studies in mice.
• Computational modeling of PK/PD behaviors.

Main Results:

• The albumin-bound MMAE prodrug effectively blocked tumor growth in mice.
• Achieved a 130-fold greater concentration of activated drug in irradiated tumors versus unirradiated tissue.
• Demonstrated 7.5-fold higher efficiency compared to a non-albumin-bound prodrug.
• Exhibited no significant toxicity compared to free or cathepsin-activatable drugs.

Conclusions:

• Extended prodrug circulation can enhance localized and cumulative drug activation.
• This approach is particularly beneficial for payloads with low vascular permeability and diffusivity.
• The study provides a quantitative PK/PD framework and proof-of-concept for improved localized cancer therapy.