Ultrasound-mediated targeted drug delivery generated by multifocal beam patterns: an in vitro study

Human clinical trial using diagnostic ultrasound and microbubbles to enhance neoadjuvant chemotherapy in HER2- negative breast cancer

Background

In vivo and in vitro experiments have demonstrated that diagnostic ultrasound combined with microbubbles (USMB) can enhance tumor chemotherapy, but few clinical studies have explored the effect of USMB in human HER2-negative breast cancer. We aimed to compare USMB combined with neoadjuvant chemotherapy (NAC) with NAC alone in the treatment of human HER2-negative breast cancer.

Methods

Patients (n=10) enrolled in the study were treated with TAC (taxane – (docetaxel), anthracycline – (epirubicin or doxorubicin liposomes), and cyclophosphamide) and ultrasound using a commercial clinical ultrasound scanner for 20 min after each chemotherapy session, followed by intermittent injections of SonoVue^® to induce sonoporation and enhance therapeutic efficacy. Contrast-enhanced ultrasound (CEUS) was used to record tumor perfusion before and after ultrasound treatment.

Results

After completion of chemotherapy, the maximum tumor diameter of patients in the combined treatment group (n=10) was significantly smaller than that in the control group (n=16) (p=0.017). Although the combined treatment group had higher overall response and clinical benefit rates than those in the control group, there was no statistically significant difference in RECIST between the combined treatment group and the control groups (p=0.590). More patients in the combination therapy group achieved pathologic complete response than in the control group (p=0.014). For combined treatment, CEUS revealed that the peak intensity, mean transit time, and area under the curve were higher after treatment than before treatment (p<0.001, p<0.001, p=0.003, respectively). Combined therapy did not cause additional toxicity or increase side effects.

Conclusion

USMB and chemotherapy can be combined in a clinical setting using commercially available equipment, without additional toxicity, and may improve the efficacy of NAC in HER2-negative breast cancer.

In Vitro Carcinoma Treatment Using Magnetic Nanocarriers under Ultrasound and Magnetic Fields

Nowadays, tumor hypoxia has become a more predominant problem for diagnosis as well as treatment of cancer due to difficulties in delivering chemotherapeutic drugs and their carriers to these regions with reduced vasculature and oxygen supply. In such cases, external physical stimulus-mediated drug delivery, such as ultrasound and magnetic fields, would be effective. In this work, the effect of simultaneous exposure of low-intensity pulsed ultrasound and static magnetic field on colon (HCT116) and hepatocellular (HepG2) carcinoma cell inhibition was assessed in vitro. The treatment, in the presence of anticancer drug, with and without magnetic carrier, significantly increased the reactive oxygen species production and hyperpolarized the cancer cells. As a result, a significant increase in cell inhibition, up to 86%, was observed compared to 50% inhibition with bare anticancer drug. The treatment appears to have relatively more effect on HepG2 cells during the initial 24 h than on HCT116 cells. The proposed treatment was also found to reduce cancer cell necrosis and did not show any inhibitory effect on healthy cells (MC3T3). Our in vitro results suggest that this approach has strong application potential to treat cancer at lower drug dosage to achieve similar inhibition and can reduce health risks associated with drugs.

Docetaxel-loaded lipid microbubbles combined with ultrasound-triggered microbubble destruction for targeted tumor therapy in MHCC-H cells

BACKGROUND

Efficient and targeted delivery of cytotoxic drugs is still a challenge in the fight against cancer. Ultrasound-targeted destruction of cytotoxic drug-loaded lipid microbubbles (LMs) might be a promising method. This study aimed to explore the antitumor effects of docetaxel-loaded LM (DLLM) combined with ultrasound-targeted microbubble destruction (UTMD) on liver cancer.

MATERIALS AND METHODS

DLLMs were made by a mechanical vibration technique. The effects of docetaxel, DLLM alone, and DLLM + UTMD on cell viability and cell proliferation (Cell Counting Kit-8 assay) of MHCC-H cells and HepG2 cells were tested. The effects on cell cycle (flow cytometry) and apoptosis (flow cytometry and immunoblotting) of MHCC-H cells were tested. Solid fast-growing tumor mouse models were established and were randomized to blank LM + UTMD (controls) or DLLM + UTMD. Tumor volume was compared between the two groups.

RESULTS

DLLMs had an 18%±7% drug-loading capacity, an 80%±3% encapsulation efficiency, and a mean particle size of 2,845 nm (75% range 1,527-5,534 nm). Compared to the other groups, DLLM + UTMD decreased the proliferation and increased the apoptosis of MHCC-H cells. DLLM + UTMD resulted in the inhibition of a higher proportion of cells in the G1 phase. Compared to the control group, the tumor volume in mice receiving DLLM + UTMD was smaller.

CONCLUSION

DLLM + UTMD can increase the proportion of cells arrested in the G1 phase, decrease tumor cell proliferation, and induce MHCC-H cell apoptosis. The growth of solid tumors in mice was inhibited. These results could provide a novel targeted strategy against liver cancer.

In Vitro Investigation of the Individual Contributions of Ultrasound-Induced Stable and Inertial Cavitation in Targeted Drug Delivery

Ultrasound-mediated targeted drug delivery is a therapeutic modality under development with the potential to treat cancer. Its ability to produce local hyperthermia and cell poration through cavitation non-invasively makes it a candidate to trigger drug delivery. Hyperthermia offers greater potential for control, particularly with magnetic resonance imaging temperature measurement. However, cavitation may offer reduced treatment times, with real-time measurement of ultrasonic spectra indicating drug dose and treatment success. Here, a clinical magnetic resonance imaging-guided focused ultrasound surgery system was used to study ultrasound-mediated targeted drug delivery in vitro. Drug uptake into breast cancer cells in the vicinity of ultrasound contrast agent was correlated with occurrence and quantity of stable and inertial cavitation, classified according to subharmonic spectra. During stable cavitation, intracellular drug uptake increased by a factor up to 3.2 compared with the control. Reported here are the value of cavitation monitoring with a clinical system and its subsequent employment for dose optimization.

Ultrasound assisted particle and cell manipulation on-chip

Ultrasonic fields are able to exert forces on cells and other micron-scale particles, including microbubbles. The technology is compatible with existing lab-on-chip techniques and is complementary to many alternative manipulation approaches due to its ability to handle many cells simultaneously over extended length scales. This paper provides an overview of the physical principles underlying ultrasonic manipulation, discusses the biological effects relevant to its use with cells, and describes emerging applications that are of interest in the field of drug development and delivery on-chip.