(W1230-10-58) A Stable and Scalable Gemcitabine and Paclitaxel Drug Combination Nanoparticle (DcNP) Exhibits Long-Acting Pharmacokinetics and Breast Tumor Regression in an Orthotopic 4T1 Mouse Model

Purpose: We previously reported that Drug Combination Nanoparticle (DcNP) platform can bring together physicochemical properties distinct drug combinations, including HIV drugs such as dolutegravir, tenofovir, lopinavir, lamivudine, as well as cancer drugs gemcitabine, paclitaxel, venetoclax and zanubrutinib. DcNP containing gemcitabine (G) and paclitaxel (T), referred to as GT-in-DcNP, for breast cancer treatment were labeled with indocyanine green to serve as an infrared tracer. After subcutaneous dosing, GT-in-DcNP were rapidly and preferentially taken up into the lymph, instead of blood vessels, and subsequently accumulated in lymph nodes throughout the whole body. The objective of this study is to evaluate whether subcutaneous dosing of GT-in-DcNP will enhance synchronized GT accumulation in 4T1 breast tumors in mammary fat pads that are enriched with lymphatic vessels and nodes.

Methods: An orthotopic 4T1 breast tumor mouse model is used to evaluate the lymphatic accumulation of drugs after a single subcutaneous injection of GT-in-DcNP or an equivalent free-soluble GT combination. Blood and primary tumors are collected for the drug concentration analysis. The growth rate of 4T1 tumors implanted in four fat pads of each mouse was monitored with an in vivo imaging system (IVIS).

Results: The pharmacokinetic study showed that GT-in-DcNP enhanced the co-localization of GT within tumors before the drug appeared in the plasma. This is evidenced by a higher accumulation of the drug in the primary tumors compared to the plasma (tumor-to-plasma drug ratio >1) and extended long-acting pharmacokinetics detected over 48 hours (Figure 1), compared to approximately 2 hours for free GT in the previous study. Long-acting drug level in the primary tumors through GT-in-DcNP treatment may relate to significantly greater tumor growth inhibition—by 100 to 140 times—in both sub-iliac and axillary tumors, compared to the equivalent dosing with free-and-soluble GT formulation (Figure 2).

Conclusion: Subcutaneous administration of GT-in-DcNP, compared to free-soluble GT, has significantly enhanced overall drug exposure and breast tumor inhibition. It is likely that DcNP-mediated preferential lymphatic distribution and accumulation, plus synchronized cellular GT in the breast tumor tissues, led to the overall tumor regression. These data warrant consideration for pre-clinical and clinical development of GT-in-DcNP for the treatment of breast cancer.

References: Yu J, Mu Q, Perazzolo S, Griffin J, Zhu L, McConnachie L, et al. Novel Long-Acting Drug Combination Nanoparticles Composed of Gemcitabine and Paclitaxel Enhance Localization of Both Drugs in Metastatic Breast Cancer Nodules. Pharmaceutical research. 2020;37:197. doi: 10.1007/s11095-020-02888-8.
Kraft JC, Treuting PM, Ho RJY. Indocyanine green nanoparticles undergo selective lymphatic uptake, distribution and retention and enable detailed mapping of lymph vessels, nodes and abnormalities. J Drug Target. 2018;26(5-6):494-504. Epub 2018/02/02. doi: 10.1080/1061186X.2018.1433681. PubMed PMID: 29388438; PubMed Central PMCID: PMCPMC6205717.
Griffin J, Wu Y, Mu Q, Li X, Ho RJY. Design and Characterization of a Novel Venetoclax-Zanubrutinib Nano-Combination for Enhancing Leukemic Cell Uptake and Long-Acting Plasma Exposure. Pharmaceutics. 2023;15(3). Epub 2023/03/30. doi: 10.3390/pharmaceutics15031016. PubMed PMID: 36986876; PubMed Central PMCID: PMCPMC10051515.

Acknowledgements: This work was supported in part by NIH grants AI120176, AI149665, AI148055 and CA273739. Additional support includes the University of Washington Royalty Research Fund, School of Pharmacy Faculty Innovation Fund, and the University of Washington School of Pharmacy DMTSPR Consortium. J Yu was also supported by the Pharmacological training grant T32 GM007750. The animal study was conducted according to the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health and approved by the Institutional Animal Care and Use Committee (IACUC) of University of Washington (protocol code: PROTO201600741, last approved on 16 Oct. 2023).

Figure 1. Time-course of GT-in-DcNP to sustain tumor gemcitabine levels as determined by tumor-to-plasma gemcitabine ratio. GT-in-DcNP administered subcutaneously resulted in a consistent tumor-to-plasma concentration ratios of gemcitabine above for 48-hour in both sub-illiac and axillary 4T1 tumor implanted in fat-pads.

Figure 2. Dose proportional effects of gemcitabine and paclitaxel in DcNP or free form on orthotopic 4T1 tumor inhibition. Mice with 4T1 tumors in fat-pads were treated with GT in free form at 20:2 mg/kg (∆) or GT-in-DcNP at 5:0.5 mg/kg (◊), 10:1 mg/kg (□) or 20:2 mg/kg (○) 24 hours after cancer cell inoculation. Mice were monitored for 168 h (7 days) after cell inoculation and before termination, and tumor growth was evaluated by luminescence. Panel A and B represent the luminescence signal integrations from axillary tumors and sub-iliac tumors, respectively. The mean and standard deviation of luminescence are presented (n=8-10). DcNP vs Free, *p < 0.005, ** p<0.01, ***p < 0.005, Student’s T-test.