Scientists describe a blood-based method to monitor response to glioblastoma treatment by measuring tumor-derived particles that appear in plasma after the blood–brain barrier is opened. Glioblastoma is often fatal: most patients die within two years and only 10% are alive at five years. Many tumors invade normal brain tissue and cannot be fully removed, and many drugs cannot cross the blood–brain barrier.
An earlier clinical trial used Carthera’s SonoCloud-9 device in Lyon, France; therapeutic ultrasound opens the barrier for about an hour so the chemotherapy drug paclitaxel can enter the brain. A University of Michigan analysis showed that opening the barrier also lets tumor material enter the blood, enabling assessment with blood draws taken before and after each treatment.
The Michigan team isolated extracellular vesicles and particles (EVPs) that carry tumor genetic material and proteins. Using a lipid common on exosome surfaces, their GlioExoChip captures cancer-derived EVPs from plasma and converts samples into a liquid biopsy. They counted EVPs before and after chemotherapy and used the post/pre ratio across sessions: a rising ratio indicated a successful response, while a flat or falling ratio indicated no success. The paper appears in Nature Communications; authors include Adam Sonabend, Sunitha Nagrath, Abha Kumari and Mark Youngblood. The team has applied for patent protection, is seeking partners to commercialize the technology, and received primary funding from the National Institutes of Health. Carthera provided in-kind support and the SonoCloud-9 remains an investigational product not approved outside clinical trials.
Difficult words
- glioblastoma — aggressive brain tumor with poor survival rates
- blood–brain barrier — protective barrier that controls passage into brain
- extracellular vesicle — small particles released by cells into fluidsextracellular vesicles, EVPs
- exosome — small particle released by cells
- liquid biopsy — blood test that detects tumor material
- paclitaxel — chemotherapy drug used to kill cancer cells
- therapeutic ultrasound — sound waves used to open the blood–brain barrier
- plasma — liquid part of blood without cells
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Discussion questions
- What are the possible benefits and risks of opening the blood–brain barrier during treatment?
- How might a liquid biopsy like the GlioExoChip change care for patients with glioblastoma?
- What steps should researchers and companies take before this method becomes widely available?
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