Sound waves clear liver cancer in rats, offering hope for future non-invasive therapy
High-amplitude ultrasound pulses have been used to partially destroy liver tumors in rats, triggering the rodents’ immune system to eliminate remaining cancer cells and prevent disease from spreading or coming back. Presentation of their findings in the journal Cancerthe researchers behind the breakthrough say their technique could lead to effective, non-invasive treatments for some of the most incurable cancers in human patients.
Liver cancer certainly falls into this category and is associated with a five-year survival rate of only 18% in the United States. Although many treatment options are available, liver tumors tend to metastasize or recur after these procedures.
In their study, the authors explain that conventional cancer treatments like chemotherapy, radiation therapy and thermal ablation are effective in destroying tumors, but also trigger a somewhat unpredictable immune response that can be anti-tumor or pro-tumor. Additionally, they note that the size, location and stage of a tumor can sometimes make it impossible to target the entire tissue mass with existing treatments.
To replicate these clinical complexities, the researchers decided to destroy only a portion of each tumour, leaving behind a viable portion in the animals’ livers.
They started by inoculating 22 rats with liver cancer cells and allowed these tumors to grow for up to nine days, reaching a size of 5 to 10 millimeters (0.2 to 0.4 inches). At this point, half of the rats have been treated using a technique called histotripsy, which involves blasting tumors with one-millisecond pulses of high-amplitude ultrasound waves.
This generates an effect known as ultrasonic cavitation, whereby tiny bubbles expand and burst within the targeted tissue, causing cancer cells to be destroyed. Traditional ultrasound imaging devices, on the other hand, use lower amplitude pulses to avoid causing damage.
Despite blasting only 50-75% of each tumor mass with histotripsy, researchers noted that nine of 11 treated rats showed complete local tumor regression, with no signs of recurrence of metastases for the remainder of the study period of 12 weeks. Within days of treatment, the team detected an increase in cancer-fighting immune cells such as T cells and natural killer cells in the tumor microenvironment, indicating that histotripsy can stimulate the animals’ immune system to destroy the tumor. remaining cancer and prevent its spread. or return.
“Even if we don’t target the entire tumor, we can still regress the tumor and also reduce the risk of future metastasis,” study author Zhen Xu said in a statement. statement.
In contrast, the 11 untreated control rats showed tumor progression and had to be euthanized within three weeks of the start of the study.
“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,” said study author Tejaswi Worlikar. “We hope that the insights gained from this study will motivate future preclinical and clinical investigations of histotripsy toward the ultimate goal of clinical adoption of histotripsy treatment for patients with liver cancer.”
A clinical test involving human subjects with liver cancer is currently underway and should be completed by the middle of next year. Any replication of these preclinical results would represent a major advance in the fight against cancer.