A non-invasive method to fight liver cancer shows great promise

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Scientists working on cancer treatments have managed to get rid of large parts of liver tumors using ultrasound, allowing the body’s immune system to eliminate the rest of the cancerous masses in rats.

Researchers have developed a non-invasive sound technology that breaks down liver tumors in rats, clears cancer cells and boosts the immune system. This could, according to a press release, lead to improved cancer outcomes in humans.

The researchers used noninvasive sound technology to break down 50-75% of the liver tumor volume, leaving the rest to the rats’ immune systems. The results were impressive: 80% of the rats were cancer free, with no recurrence or metastases.

“Even if we don’t target the entire tumor, we can still regress the tumor and also reduce the risk of future metastasis,” says Zhen Xu, professor of biomedical engineering at the University of Michigan and corresponding author of the study. published study. in Cancer.

The noninvasive sound technology also boosted the rats’ immune responses, which likely explains why the untargeted part of the tumor eventually regressed and the cancer stopped spreading.

The treatment is called histotripsy: the authors write that it is “a new technique that mechanically disrupts tumors through precisely controlled acoustic cavitation”.

“Histotripsy was pioneered by researchers at the University of Michigan in the United States and relies on a process called cavitation – creating an empty space inside something solid – to eradicate cancer.” This is a relatively new technique that is currently being tested in human liver cancer trials in the United States and Europe.

The 700 kHz, 260-element histotripsy ultrasound transducer used in Prof. Xu’s lab. (Marcin Szczepanski/Chief Multimedia Storyteller/Michigan Engineering)

In most cases of cancer, the entire tumor cannot be targeted because it may be too large, too advanced or too difficult to reach. This recent study decided to leave behind a viable intact tumor while targeting and partially destroying only a portion of each mass with sound. That way, the Michigan Medicine and Ann Arbor VA Hospital team could verify the approach’s effectiveness under less-than-ideal conditions.

“Histotripsy is a promising option that can overcome the limitations of currently available ablation modalities and provide safe and effective noninvasive ablation of liver tumors,” says Tejaswi Worlikar, PhD student in biomedical engineering at the University of Michigan.

“We hope that our insights from this study will motivate future preclinical and clinical investigations of histotripsy toward the ultimate goal of clinical adoption of histotripsy therapy for patients with liver cancer.”

Worldwide, liver cancer is the third leading cause of cancer death. In 2020, an estimated 830,180 people worldwide died from the disease.

The authors note that “symptoms associated with liver cancer may not appear at an early stage, putting patients at increased risk for lymph node and distant metastases, further reducing their 5-year survival rate to approximately 3 to 11%. Even after treatment, the high prevalence of tumor recurrence and metastasis highlights the clinical need to improve liver cancer outcomes.

“In fact, metastases represent [more than] 90% of all cancer-associated deaths, and metastatic progression is primarily regulated by complex signaling pathways between the primary tumor and stromal cells, particularly immune cells. »

Engineers at the University of Michigan (UM) have managed to organize the sound waves used by a typical ultrasound into a machine for the treatment of cancer. A big advantage of histotripsy is that it does not have harmful side effects such as radiation therapy and chemotherapy, the popular approaches currently used to treat cancer.

“Our transducer, designed and built at UM, delivers high-amplitude, one-microsecond ultrasound pulses — acoustic cavitation — to focus on the tumor specifically to break it up,” Xu explains. “Traditional ultrasound devices use lower amplitude pulses for imaging.”

The UM transducer sends microsecond long pulses which then generate microbubbles in the targeted tissues. Bubbles that, according to a press release, expand and collapse rapidly. The press release describes the mechanical stresses that kill cancer cells as “violent but extremely localized” that breaks the structure of the tumor.

Xu’s lab at the University of Michigan has been working on histotripsy cancer treatments since 2001, which culminated in the #HOPE4LIVER clinical trial sponsored by HistoSonics, a University of Michigan spin-off company. Lately, the group’s research has produced “promising results” on the treatment of histotripsy on brain therapy and immunotherapy.

Source: TRTWorld and agencies

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