The anticancer agent doxorubicin has been widely used in the treatment of a variety of hematological malignancies and solid tumors. Despite doxorubicin’s efficiency in eradicating tumor cells, severe damage to healthy tissues, along with cardiotoxicity, limits its use in clinics. To overcome adverse side effects, improve patient safety, and enhance therapeutic efficacy, we have designed a thermally responsive biopolymer doxorubicin carrier that can be specifically targeted to tumor tissue by locally applying mild hyperthermia (41 degrees C).

The developed drug vehicle is composed of: a cell penetrating peptide (SynB1) to promote tumor and cellular uptake; thermally responsive Elastin like polypeptide (ELP); and the (6-maleimidocaproyl) hydrazone derivative of doxorubicin (DOXO-EMCH) containing a pH-sensitive hydrazine linker that releases dox in the acidic tumor environment. We used the in vivo imaging system, IVIS, to determine the biodistribution of doxorubicin-delivered ELP in MDA-MB231 triple negative human breast cancer cell line xenografts in nude mice. Tumor bearing mice were treated with a single IV injection of 10 mg/kg doxorubicin equivalent dose with free doxorubicin, thermally responsive SynB1 ELP 1-DOXO, and a thermally nonresponsive control biopolymer, SynB1 ELP 2-DOXO. Following a 2 hour treatment with hyperthermia, tumors showed a 2-fold higher uptake when treated with SynB1 ELP 1-DOXO compared to free doxorubicin. Accumulation of the thermally non-responsive control SynB1 ELP2 -DOXO was comparable to free doxorubicin, indicating that an increase in dox accumulation with ELP is due to aggregation in response to thermal targeting. Higher levels of SynB1 ELP1 -DOXO and SynB1 ELP2 -DOXO with respect to free doxorubicin were observed in kidneys. Fluorescence intensity from hearts of animals treated with SynB1 ELP1 - DOXO show a 5-fold lower accumulation of doxorubicin than the same dose of free doxorubicin. SynB1-ELP1-DOXO biopolymers demonstrated a 6-fold increase in tumor/heart ratio in comparison to free doxorubicin, indicating preferential accumulation of the drug carrier in tumors.

Overall, thermally targeted polymers are a promising therapy to enhance tumor targeting and uptake of anticancer drugs and to minimize free drug toxicity in healthy tissues, representing a great potential for clinical application.

Citation Format: Sonja Dragojevic, Jung Su Ryu, Felix Kratz, Drazen Raucher. Targeted delivery via Elastin Like Polypeptide: Biodistribution of a doxorubicin derivative in MDA-MB231 human breast cancer xenografts in mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3106. doi:10.1158/1538-7445.AM2017-3106