Release Date: 04-Apr-2023
Conventional treatment approaches like chemotherapy, surgery and radiation have been the pillars of cancer treatment for decades. As research progressed, more novel and non-invasive methods to treat cancer were developed and many of them are now leading the market globally. Similarly, non-invasive therapies like photodynamic and photothermal therapy were also incorporated into the cancer therapeutics domain. Lately, a more evolved procedure namely sonodynamic therapy is gaining traction from medical practitioners for its unique mechanism of action. This novel therapy uses ultrasound to kill cancer cells in a targeted manner. Because of this, it has been deemed as a promising emerging therapeutic strategy for cancer treatment.
Ultrasound waves were already being used for the treatment of solid cancers because of the lesser adverse effects associated with them and more tumor eradication properties compared to conventional procedures. This therapeutic procedure was commonly known as high intensity focused ultrasound (HIFU) and involved the use of a machine capable of delivering strong beams of ultrasound to the cancer site. Taking notes from the success and working mechanisms of photodynamic and photothermal therapies, researchers then combined ultrasound therapy with a chemical sensitizer that killed cancer cells in a more targeted way, in a process called sonodynamic therapy. The interaction of this sonosensitizer with the ultrasound led to the generation of reactive oxygen species (ROS), including singlet oxygen and hydroxyl radicals, which kill targeted cancer cells via apoptosis and necrosis.
The inclusion of photodynamic and photothermal therapies in mainstream cancer therapies is also a recent step but they both are highly limited to only superficial cancers because of the inability of the light used to penetrate into deeper tumors. Because of this, sonodynamic therapy is becoming more prominent among these three. To even better the anti-cancer effects of this therapy, efforts have been made to identify the most effective sonosensitizers. These have led to the identification of some existing drugs that can be used as sonosensitizers. Doxorubicin, a chemotherapy medication approved 1974 in the treatment of cancer and regarded as one of the strongest chemotherapy drugs developed till date, showed potential for this.
In addition, the conjugation of doxorubicin and triphenylphosphonium processed as a sonosensitizer was seen to accumulate in the nucleus of cancer cells, and the irradiation with ultrasound effectively killed these cancer cells in a targeted manner, showing the promising nature of this drug combination as a sonosensitizer. This combination was evaluated in the HeLa cell line and its therapeutic effects in humans is required to expand its application into human cancer patients.
Regardless of the existing drugs that can work as sonosensitizers, companies working on developing sonodynamic therapies are preferring to make the sonosensitizers themselves to be sure of the effects it can cause rather than using drugs which can have unpredicted side effects. For instance, SonALAsense, the company that first navigated sonodynamic therapy into clinical trials, has developed proprietary intravenous formulation of aminolevulinic acid (ALA), which is administered to patients before exposing them to non-thermal energy from the Exablate 4000 Type 2.0 MRI-guided focused ultrasound device, which generates the required reactive oxygen species to induce necrosis and apoptosis in cancer cells. SonALAsense is now conducting phase I/II clinical trials in patients with glioma and glioblastoma multiforme.
The procedure by which cancer is treated is undergoing a monumental change right now, and there are more and more novel processes being researched on. Research articles are being published as a result of these studies on emerging topics like high intensity focused ultrasound and sonodynamic therapy. These new therapies have the potential to improve the current treatment strategies while maintaining the quality of life of cancer patients. In the future, it is anticipated that this new therapy will be combined with other therapies like targeted therapy and immunotherapy, in order to treat cancers that were previously thought to be incurable.