Local administration of large surface area microparticle docetaxel to solid carcinomas induces direct cytotoxicity and immune-mediated tumoricidal effects: preclinical and clinical studies

Prostate cancer chemotherapy by intratumoral administration of Docetaxel-Mesoporous silica nanomedicines

Docetaxel (DTX) is a recommended treatment in patients with metastasic prostate cancer (PCa), despite its therapeutic efficacy is limited by strong systemic toxicity. However, in localized PCa, intratumoral (IT) administration of DTX could be an alternative to consider that may help to overcome the disadvantages of conventional intravenous (IV) therapy. In this context, we here present the first in vivo preclinical study of PCa therapy with nanomedicines of mesoporous silica nanoparticles (MSN) and DTX by IT injection over a xenograft mouse model bearing human prostate adenocarcinoma tumors. The efficacy and tolerability, the biodistribution and the histopathology after therapy have been investigated for the DTX nanomedicine and the free drug, and compared with the IV administration of DTX. The obtained results demonstrate that IT injection of DTX and DTX nanomedicines allows precise and selective therapy of non-metastatic PCa and minimize systemic diffusion of the drug, showing superior activity than IV route. This allows reducing the therapeutic dose by one order and widens substantially the therapeutic window for this drug. Furthermore, the use of DTX nanomedicines as IT injection promotes strong antitumor efficacy and drug accumulation at the tumor site, improving the results obtained with the free drug by the same route.

Quantitative imaging of doxorubicin diffusion and cellular uptake in biomimetic gels with human liver tumor cells

Novel tumor-on-a-chip approaches are increasingly used to investigate tumor progression and potential treatment options. To improve the effect of any cancer treatment it is important to have an in depth understanding of drug diffusion, penetration through the tumor extracellular matrix and cellular uptake. In this study, we have developed a miniaturized chip where drug diffusion and cellular uptake in different hydrogel environments can be quantified at high resolution using live imaging. Diffusion of doxorubicin was reduced in a biomimetic hydrogel mimicking tissue properties of cirrhotic liver and early stage hepatocellular carcinoma (373 ± 108 µm2/s) as compared to an agarose gel (501 ± 77 µm2/s, p = 0.019). The diffusion was further lowered to 256 ± 30 µm2/s (p = 0.028) by preparing the biomimetic gel in cell media instead of phosphate buffered saline. The addition of liver tumor cells (Huh7 or HepG2) to the gel, at two different densities, did not significantly influence drug diffusion. Clinically relevant and quantifiable doxorubicin concentration gradients (1-20 µM) were established in the chip within one hour. Intracellular increases in doxorubicin fluorescence correlated with decreasing fluorescence of the DNA-binding stain Hoechst 33342 and based on the quantified intracellular uptake of doxorubicin an apparent cell permeability (9.00 ± 0.74 × 10-4 µm/s for HepG2) was determined. Finally, the data derived from the in vitro model were applied to a spatio-temporal tissue concentration model to evaluate the potential clinical impact of a cirrhotic extracellular matrix on doxorubicin diffusion and tumor cell uptake.

Intratumoral Injection of Large Surface Area Microparticle Taxanes in Carcinomas Increases Immune Effector Cell Concentrations, Checkpoint Expression, and Synergy with Checkpoint Inhibitors: A Review of Preclinical and Clinical Studies

This review summarizes development of large surface area microparticle paclitaxel (LSAM-PTX) and docetaxel (LSAM-DTX) for local treatment of primary carcinomas with emphasis on immunomodulation. Intratumoral (IT) delivery of LSAM-PTX and LSAM-DTX provides continuous, therapeutic drug levels for several weeks. Preclinical studies and clinical trials reported a reduction in tumor volume (TV) and immunomodulation in primary tumor and peripheral blood with increases in innate and adaptive immune cells and decreases in suppressor cells. Increased levels of checkpoint expression of immune cells occurred in clinical trials of high-risk non-muscle-invasive bladder cancer (LSAM-DTX) and unresectable localized pancreatic cancer (LSAM-PTX). TV reduction and increases in immune effector cells occurred following IT LSAM-DTX and IT LSAM-PTX together with anti-mCTLA-4 and anti-mPD-1, respectively. Synergistic benefits from combinatorial therapy in a 4T1-Luc breast cancer model included reduction of metastasis with IT LSAM-DTX + anti-mCTLA-4. IT LSAM-PTX and LSAM-DTX are tumoricidal, immune enhancing, and may improve solid tumor response to immune checkpoint inhibitors without additional systemic toxicity.

Intracystic injection of large surface area microparticle paclitaxel for chemoablation of intraductal papillary mucinous neoplasms: Insights from an expanded access protocol

AIMS

A novel large surface area microparticle paclitaxel (LSAM-PTX) has unique properties of long retention in cystic spaces while maintaining high drug concentration. We prospectively evaluated the safety and response of EUS-guided fine needle injection (EUS-FNI) of LSAM-PTX to chemoablate branch duct (BD)-IPMNs.

METHODS

Subjects diagnosed with BD-IPMNs exhibiting at least one worrisome criteria and considered non-surgical were enrolled in a multicenter clinical trial (NCT03188991) and subsequently included in an Expanded Access Protocol (EAP) where they received EUS-FNI of LSAM-PTX (15 mg/mL).

RESULTS

Six BD-IPMNs measuring (mean ± SD) 3.18 ± 0.76 cm in diameter among 5 subjects (mean age: 66 years) were treated by EUS-FNI of LSAM-PTX. A mean of 4 doses of LSAM-PTX (mean dose/cyst: 73 ± 31 mg) were administered, and subjects were followed for up to 32 months. The mean volume reduction/cyst ranged from 42 to 89% (9.58 ± 5.1 ml to 2.2 ± 1.1 ml (p = 0.016)). The mean surface area reduction ranged from 31 to 83% (21.9 ± 8.7 cm2 to 5.7 ± 2.5 cm2 (p = 0.009)). Higher dosing-frequency of EUS-FNI of LSAM-PTX significantly correlated with a reduction in cyst volume (R2 = 0.87, p = 0.03) and surface area (R2 = 0.83, p = 0.04). Comparing pre- and post-ablation samples, molecular analysis of the cyst fluid revealed a loss of IPMN-associated mutations in 5 cases (83.3%), while reemergence was observed in 1 case and persistence in 1 case. Intracystic changes (fibrosis/calcification) were observed in 83.3% (n = 5). One subject developed mild acute pancreatitis (1 of 22 EUS-FNIs of LSAM-PTX).

CONCLUSION

In this EAP, EUS-FNI of LSAM-PTX into BD-IPMNs was safe and resulted in volume and surface area reduction, morphological changes, and loss of pathogenic mutations.