2. Academic Validation
  3. Development of thermosensitive resiquimod-loaded liposomes for enhanced cancer immunotherapy

Development of thermosensitive resiquimod-loaded liposomes for enhanced cancer immunotherapy

  • J Control Release. 2021 Feb 10;330:1080-1094. doi: 10.1016/j.jconrel.2020.11.013.
Hua Zhang 1,  Wei-Lun Tang 2,  Azadeh Kheirolomoom 1,  Brett Z Fite 2,  Bo Wu 2,  Kenneth Lau 2,  Mo Baikoghli 3,  Marina Nura Raie 2,  Spencer K Tumbale 2,  Josquin Foiret 2,  Elizabeth S Ingham 4,  Lisa M Mahakian 4,  Sarah M Tam 4,  R Holland Cheng 3,  Alexander D Borowsky 5,  Katherine W Ferrara 6
Affiliations

Affiliations

  • 1 Department of Radiology, Stanford University, Palo Alto, CA 94304, USA; Department of Biomedical Engineering, University of California, Davis, CA 95616, USA.
  • 2 Department of Radiology, Stanford University, Palo Alto, CA 94304, USA.
  • 3 Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA.
  • 4 Department of Biomedical Engineering, University of California, Davis, CA 95616, USA.
  • 5 Center for Comparative Medicine, University of California, Davis, CA 95616, USA.
  • 6 Molecular Imaging Program, Department of Radiology, Stanford University, 3165 Porter Drive, Palo Alto, CA 94304, USA. Electronic address: [email protected].
PMID: 33189786 DOI: 10.1016/j.jconrel.2020.11.013
Abstract

Resiquimod (R848) is a Toll-like Receptor 7 and 8 (TLR7/8) agonist with potent antitumor and immunostimulatory activity. However, systemic delivery of R848 is poorly tolerated because of its poor solubility in water and systemic immune activation. In order to address these limitations, we developed an intravenously-injectable formulation with R848 using thermosensitive liposomes (TSLs) as a delivery vehicle. R848 was remotely loaded into TSLs composed of DPPC: DSPC: DSPE-PEG2K (85:10:5, mol%) with 100 mM FeSO4 as the trapping agent inside. The final R848 to lipid ratio of the optimized R848-loaded TSLs (R848-TSLs) was 0.09 (w/w), 10-fold higher than the previously-reported values. R848-TSLs released 80% of R848 within 5 min at 42 °C. These TSLs were then combined with αPD-1, an immune checkpoint inhibitor, and ultrasound-mediated hyperthermia in a neu deletion (NDL) mouse mammary carcinoma model (Her2+, ER/PR negative). Combined with αPD-1, local injection of R848-TSLs showed superior efficacy with complete NDL tumor regression in both treated and abscopal sites achieved in 8 of 11 tumor bearing mice over 100 days. Immunohistochemistry confirmed enhanced CD8+ T cell infiltration and accumulation by R848-TSLs. Systemic delivery of R848-TSLs, combined with local hyperthermia and αPD-1, inhibited tumor growth and extended median survival from 28 days (non-treatment control) to 94 days. Upon re-challenge with reinjection of tumor cells, none of the previously cured mice developed tumors, as compared with 100% of age-matched control mice. The dose of R848 (10 μg for intra-tumoral injection or 6 mg/kg for intravenous injection delivered up to 4 times) was well-tolerated without weight loss or organ hypertrophy. In summary, we developed R848-TSLs that can be administered locally or systematically, resulting in tumor regression and enhanced survival when combined with αPD-1 in mouse models of breast Cancer.

Keywords

Breast cancer; Immunotherapy; Resiquimod; Thermosensitive liposomes; αPD-1.

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