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Targeting Stealth liposomes in a murine model of human small cell lung cancer
J N Moreira1, R Gaspar, T M Allen
1Department of Pharmacology, University of Alberta, Edmonton, Canada.
Abstract:
Tumor accumulation and therapeutic activity of Stealth liposomes loaded with doxorubicin (DXR) were examined in Balb/c nude mice xenografts inoculated subcutaneously with the human small cell lung cancer (SCLC) cell line, H69. Mice were treated with non-targeted liposomes (SL) or liposomes targeted with antagonist G coupled to the liposome surface (SLG). SLG showed 30-44-fold higher binding to H69 cells harvested from H69 xenografts than SL. At 48 and 72 h post injection, tumor accumulation of [(125)I]tyraminylinulin-containing liposomes was shown to be dependent on liposome size but independent of the presence of the targeting ligand. Maximum tumor uptake of either SLG or SL ranged from 2 to 4% of injected dose/g of tissue. In therapeutic studies, mice received three weekly injections of 3 or 6 mg free DXR/kg or 3 or 10 mg liposomal DXR/kg at initial tumor volumes of either 7 or 33 mm(3). The therapeutic efficacy of DXR-containing SL or SLG was significantly improved over free DXR, but SLG did not improve anti-tumor efficacy relative to SL. Stealth liposomes containing DXR have potential as a therapy against human SCLC tumors.
Insights
Stealth liposomes loaded with doxorubicin (DXR) show improved efficacy against small cell lung cancer (SCLC) in mice. While targeted liposomes enhanced cell binding, both targeted and non-targeted liposomes demonstrated significant anti-tumor activity compared to free DXR.
Area of Science:
- Oncology
- Nanomedicine
- Pharmacology
Background:
- Small cell lung cancer (SCLC) remains a challenging malignancy with limited therapeutic options.
- Liposomal drug delivery systems offer potential for improved cancer treatment by enhancing drug accumulation at tumor sites.
- Stealth liposomes are designed for prolonged circulation and reduced immunogenicity, making them suitable for targeted drug delivery.
Purpose of the Study:
- To evaluate the tumor accumulation and therapeutic activity of doxorubicin (DXR)-loaded Stealth liposomes (SL) in a human SCLC xenograft model.
- To compare the efficacy of non-targeted liposomes (SL) versus ligand-targeted liposomes (SLG) in delivering DXR to SCLC tumors.
- To assess the impact of liposome size and targeting ligand on DXR delivery and anti-tumor effects.
Main Methods:
- Balb/c nude mice bearing H69 SCLC xenografts were treated with free DXR, DXR-loaded SL, or DXR-loaded SLG.
- Liposome binding affinity to H69 cells was assessed in vitro.
- Tumor accumulation of radiolabeled liposomes was quantified at different time points post-injection.
- Therapeutic efficacy was evaluated based on tumor growth inhibition and survival rates.
Main Results:
- Targeted liposomes (SLG) exhibited significantly higher binding to H69 cells compared to non-targeted liposomes (SL).
- Tumor accumulation of liposomes was dependent on liposome size but not on the targeting ligand.
- Liposomal DXR (both SL and SLG) demonstrated significantly improved anti-tumor efficacy compared to free DXR.
- SLG did not show superior anti-tumor efficacy over SL, suggesting the targeting ligand did not enhance therapeutic outcomes in this model.
Conclusions:
- Stealth liposomes loaded with doxorubicin show promise as a therapeutic strategy for human SCLC.
- Liposome targeting enhances cellular binding but does not necessarily translate to improved in vivo therapeutic efficacy in this SCLC model.
- Further optimization of liposome characteristics and targeting strategies may be warranted for enhanced SCLC treatment.