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Precise Ratiometric Drug Delivery for the Treatment of Triple-Negative Breast Cancer
Rae Hyung Kang1,2, Morteza Rasoulianboroujeni1,3, Maryam Kianpour1
1Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States.
Abstract:
Triple-negative breast cancer (TNBC) remains a significant clinical challenge due to its high aggressiveness, poor prognosis, and lack of targeted therapies. Combining paclitaxel (PTX) with rapamycin (RAP), a PI3K/AKT/mTOR pathway inhibitor, has shown promise in preclinical and clinical studies, but the approach is limited by pharmacokinetic disparities and toxicity concerns. Here, we introduce Rapaxane, a formulation composed of polymeric micelles coloaded with oligo(lactic acid)8 conjugated prodrugs of PTX (oLA8-PTX) and RAP (oLA8-RAP) at an optimized synergistic ratio (5:1). We evaluated the efficacy of Rapaxane in vitro and in preclinical TNBC models, comparing it to the benchmark formulation Abraxane, the combination of parent drugs, and monotherapies using the prodrugs. In vitro, Rapaxane demonstrated notable cytotoxicity against the 4T1 and MDA-MB-231 TNBC cell lines. Ratiometric encapsulation, stability, synchronized drug release, and conversion were confirmed using dynamic light scattering (DLS) and reverse-phase high-performance liquid chromatography (RP-HPLC). Hemolysis assays indicated negligible toxicity, confirming the safety of Rapaxane for intravenous administration. In vivo, Rapaxane significantly reduced tumor growth and metastasis while improving survival rates in subcutaneous and orthotopic TNBC mouse models. Histological analysis using H&E staining, complemented by Ki-67 immunohistochemical staining, demonstrated effective inhibition of lung metastasis in Rapaxane-treated groups compared to control groups. Rapaxane's ability to maintain precise ratiometric dosing, sustain drug release, and enhance therapeutic efficacy while mitigating adverse effects underscores its potential as a next-generation therapy for TNBC. This study highlights the feasibility of nanotechnology-based ratiometric drug delivery systems in overcoming the limitations of conventional combination therapies, paving the way for more effective treatment options for aggressive cancers like TNBC.
Insights
Rapaxane, a novel nanotechnology formulation, effectively treats triple-negative breast cancer (TNBC) by combining paclitaxel and rapamycin. This advanced drug delivery system enhances efficacy and reduces toxicity in preclinical TNBC models.
Area of Science:
- Biomedical Engineering
- Nanotechnology
- Oncology
Background:
- Triple-negative breast cancer (TNBC) presents significant treatment challenges due to its aggressive nature and lack of targeted therapies.
- Current combination therapies with paclitaxel (PTX) and rapamycin (RAP) face limitations in pharmacokinetics and toxicity.
- Nanotechnology offers potential solutions for improved drug delivery and therapeutic outcomes in TNBC.
Purpose of the Study:
- To develop and evaluate Rapaxane, a polymeric micelle formulation co-delivering PTX and RAP prodrugs at a synergistic ratio for TNBC treatment.
- To assess the in vitro and in vivo efficacy, safety, and drug release characteristics of Rapaxane compared to existing therapies.
- To demonstrate the potential of nanotechnology-based ratiometric drug delivery systems for overcoming combination therapy limitations.
Main Methods:
- Formulation of Rapaxane using polymeric micelles co-loaded with oligo(lactic acid)8-conjugated PTX (oLA8-PTX) and RAP (oLA8-RAP) prodrugs at a 5:1 ratio.
- In vitro cytotoxicity assays using TNBC cell lines (4T1, MDA-MB-231).
- Characterization of encapsulation, stability, and drug release using DLS and RP-HPLC.
- In vivo efficacy studies in subcutaneous and orthotopic TNBC mouse models, including tumor growth, metastasis assessment (H&E, Ki-67 staining), and survival analysis.
- Hemolysis assays to evaluate intravenous administration safety.
Main Results:
- Rapaxane exhibited significant in vitro cytotoxicity against TNBC cell lines.
- Confirmed ratiometric encapsulation, stability, synchronized release, and conversion of oLA8-PTX and oLA8-RAP.
- Hemolysis assays showed negligible toxicity, indicating safety for intravenous use.
- In vivo studies demonstrated Rapaxane's significant reduction in tumor growth and metastasis, alongside improved survival rates in TNBC models.
- Histological analyses confirmed Rapaxane's efficacy in inhibiting lung metastasis.
Conclusions:
- Rapaxane, a nanotechnology-based ratiometric drug delivery system, effectively enhances therapeutic efficacy for TNBC.
- The formulation overcomes pharmacokinetic disparities and toxicity concerns associated with conventional PTX and RAP combinations.
- Rapaxane shows significant potential as a next-generation therapy for aggressive cancers like TNBC, highlighting the promise of advanced drug delivery systems.
