MADRID, 16 Dic. (EUROPA PRESS) –
New research has shown, through the first human clinical trial, that current treatment of liver cancer by targeted radiation therapy given with the help of radiation-emitting glass beads can be augmented by infusing microbubbles (tiny gas bubbles surrounded by a layer of lipids) in the liver and popping those bubbles by ultrasound, according to the researchers in the journal Radiology.
Primary liver cancer is on the rise worldwide, largely due to the rise in hepatitis C infections and chronic liver disease. It is difficult to treat and kills 750,000 people a year around the world, making it the second deadliest type of cancer after lung cancer.
“This approach has been shown to be effective in preclinical studies using animal models of other solid tumors such as bladder, prostate and breast cancer,” explains John Eisenbrey, associate professor of radiology and lead author of the study. “This is the first work that shows that this approach is safe and promising in humans with liver cancer, which is very exciting. “
About 15-25% of patients with advanced disease are recommended a treatment called transarterial radioembolization, whereby radioactive glass beads are inserted into the blood vessels of the liver, and the emitted radiation provides a therapeutic dose to the tumor, destroying it.
However, the extent to which radiation can penetrate liver tissue is limited and the tumor response is highly dependent on the distance to the radioactive beads. By combining microbubbles with TARE, the synergistic approach reduces the radiation dose required to destroy tumor blood vessels and increases the effectiveness of treatment.
“The microbubbles themselves are found in commercially available ultrasound contrast agents,” says Colette Shaw, associate professor and interventional radiologist and lead clinical author of the study. “The procedure for introducing the microbubbles into the tumor involves similar techniques that are used to access blood vessels. “
When the microbubbles are hit by the ultrasound wave, they begin to vibrate and if the wave is strong enough they explode. The sheer energy from these tiny explosions causes physical and chemical damage to the blood vessels of tumors, making them more sensitive to radiation.
By directing ultrasound exactly where tumors are located, researchers can burst or destroy the bubbles right where the radiation beads are and achieve highly localized sensitization.
The pilot study included 28 patients who were randomly assigned to two treatment groups: transarterial radioembolization alone (TARE) or ultrasound-activated radioembolization and microbubble destruction (TARE + UTMD).
The team first evaluated the safety profile of the microbubbles: They did not observe changes in vital signs such as body temperature, blood pressure and heart rate in the patients who received UTMD. Importantly, UTMD did not compromise liver function and there were no additional side effects of the combined approach.
The researchers looked at 10 tumors in the TARE alone group and 15 tumors in the TARE + UTMD group, and they assessed tumor response to each treatment. 93% of tumors showed a partial or complete response to the TARE + UTMD approach, while only 50% showed a response in the TARE alone group.
The team also found that patients who received the combination therapy were also more likely to receive a liver transplant, which offers the best chance of long-term survival for patients with cirrhosis and liver cancer. These patients also lived longer and required fewer retreatments compared to those who received TARE alone.
“Even at this early stage, we have been able to show significant improvement in tumor outcomes with this combination therapy,” said Dr. Shaw. “Going forward, we are enrolling more patients to demonstrate key benchmarks in the promise of this approach “.
“Our findings are really setting the stage for a wide range of studies to be done in humans,” Dr. Eisenbrey said. “This approach could be effective in treating metastatic liver tumors, but also other types of primary cancer. The bubbles themselves can also be designed to deliver chemotherapy or oxygen as they burst. This is really the tip of the iceberg. “
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