Drug targeting using thermally responsive polymers and local hyperthermia

Area of Science:

• Biomedical Engineering
• Materials Science
• Oncology

Background:

• Solid tumors often exhibit altered physiology, including elevated temperatures.
• Targeted drug delivery remains a challenge in cancer therapy.
• Thermally responsive polymers offer potential for stimuli-responsive drug carriers.

Purpose of the Study:

• To investigate a novel thermal targeting method for enhanced drug delivery to solid tumors.
• To evaluate the efficacy of elastin-like polypeptides (ELPs) and poly(NIPAAM-co-AAm) as thermally responsive drug carriers.
• To determine the effect of localized hyperthermia on polymer accumulation within tumors.

Main Methods:

• Synthesis of two thermally responsive polymers: genetically engineered ELP and a copolymer of N-isopropylacrylamide (NIPAAm) and acrylamide (AAm).
• In vivo fluorescence video microscopy to track polymer-rhodamine conjugate delivery in murine ovarian tumor models.
• Application of focused hyperthermia to tumors to achieve temperatures above physiological levels.

Main Results:

• Tumor heating to 42°C resulted in approximately a twofold greater accumulation of an ELP (LCST 40°C) compared to non-heated tumors.
• Similar, though less pronounced, enhanced accumulation was observed for the poly(NIPAAM-co-AAm) carrier in heated tumors.
• These findings demonstrate selective accumulation of thermally responsive polymers in hyperthermic tumors.

Conclusions:

• Localized hyperthermia significantly enhances the accumulation of specific thermally responsive polymers in solid tumors.
• Conjugation of drugs to these polymers, combined with localized heating, represents a promising strategy for improving targeted cancer therapy.
• This thermal targeting method offers a potential approach to increase drug concentration at the tumor site, potentially improving therapeutic efficacy.