At the speed of sound
Ultrasound effectively delivered drugs to tumor cells
Natalia Pelezneva, Naked Science
Oxford researchers have successfully completed the first phase of trials of drug delivery technology to liver tumor cells using an ultrasound beam. The technique helped to increase the concentration of the drug in cells compared to the traditional administration of the drug. The description of the technology is published in the journal The Lancet Oncology (Lyon et al., Safety and feasibility of ultrasound-triggered targeted drug delivery of doxorubicin from thermosensitive liposomes in liver tumours (TARDOX): a single-centre, open-label, phase 1 trial).
Chemotherapeutic drugs are highly toxic, so scientists are working on new ways of spot delivery of such drugs – this will not damage healthy cells of the body. Previously, it was proposed to use special nanoparticles and even spermatozoa for this.
The new technology is based on the existing method of drug delivery using thermosensitive liposomes. Liposomes are artificially created rounded "bubbles" of several layers of lipids (fats) separated by water layers. They can penetrate into cells, where intracellular organoids destroy the shell of the "bubble", releasing its contents. Thermosensitive liposomes begin to break down only at a relatively high temperature – usually above 38C – so that the drug does not leave the capsule ahead of time.
To release the drug from such a liposome, the target cell must be point-heated to the desired temperature. The authors of the new technique used focused intensive ultrasound for this. The first stage of the study involved 10 patients with inoperable liver tumors who had already undergone traditional chemotherapy. They were intravenously injected with the antibiotic doxorubicin, placed in thermosensitive liposomes, which are destroyed when heated to 39.5 C.
According to scientists, the new technique made it possible to deliver the drug to cells much more efficiently. The concentration of doxorubicin in tumors after the procedure in seven out of 10 patients was on average 3.7 times higher than with traditional administration. In the remaining three, it was comparable to the concentration during the standard procedure. Two weeks later, positron emission computed tomography (PET-CT) recorded the response of heated cells to therapy, while the neighboring cells did not change in any way.
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