For decades, the development of “liquid slices” is the holy grail of oncology medicine. In theory, a blood test like liquid biopsy can detect tumors long before they are discovered through palpation, symptoms, or imaging techniques. With the blood test, there is no need to extract tissue samples from suspicious masses or lesions through surgery, and it is also possible to find the hidden tumor cells that cannot be safely reached by the needle and scalpel. Blood tests can also be used to determine the type of cancer and the best possible treatment.
However, the Holy Grail has not yet arrived, because it is difficult to find the exact signal of cancer from a tube of blood sample, but it has made great progress in recent years. “Science” published the first prospective study of large liquid slices of DNA and proteins from various cancers involving 10,000 healthy elderly women last year. This blood test called CancerSEEK was developed by a team at Johns Hopkins University in the United States and transferred to Thrive Biotech. Although it is not perfect, it has found mammography and colonoscopy. 26 kinds of malignant tumors that cannot be detected by traditional methods. London, UK, is applying a blood test developed by the biotech company Grail to conduct a large study of 25,000 adults with a history of smoking.
At present, a variety of cancer blood tests have not been approved for marketing, but because of the possibility of early detection of cancer, the U.S. Food and Drug Administration (FDA) has designated CanerSEEK as a breakthrough medical material. This year the FDA also recognized certain blood tests for specific cancers as breakthrough medical materials, such as blood tests for pancreatic cancer for high-risk groups, and other blood tests for patients who have completed cancer treatment to check for signs of recurrence. Nickolas Papadopoulos, a scientist involved in the development of CancerSEEK at Johns Hopkins University, explained that being a breakthrough medical material can “speed up the review process.”
In addition to tumor DNA and protein, liquid sections can also test other types of tumor biomarkers. The ideal blood test for cancer should be more specific (find out mutations or other biochemical signals unique to cancer) and very sensitive (even if the tumor is small, it can be detected). In order to overcome such challenges, CancerSEEK examines cancerous mutations in 16 genes and eight cancer-related proteins, and can detect these mutations and related proteins very sensitively. A study pointed out that the new version of CancerSEEK can detect more than 95% of ovarian and liver tumors, and about 70% of gastric, pancreatic and esophageal cancers, but only 33% of breast tumors and 43% of the first stage Tumor.
The ideal liquid section should also be able to determine the clear type of tumor. Anirban Maitra, a pancreatic cancer expert at the Anderson Cancer Center, said: “Different cancers often have the same mutations, so blood tests can’t tell which cancer these mutations originate from.” To solve this problem, some newer liquids The biopsy examines the epigenetic changes in gene expression, that is, whether the gene is activated or turned off, rather than the change in the gene itself. Maitra said that changes in gene expression are “more organ-specific.”
Soon, liquid biopsy will help diagnose cancer patients and enable them to receive treatment early. The FDA approved two such blood tests for the first time last year, which can be used to screen tumor DNA and allow physicians to select drugs for mutations. Scientists are exploring how to use liquid slices to detect the initial signs of recurrence in cancer patients who have completed treatment. Papadopoulos said that this kind of research on “minimal residual disease” is progressing rapidly. “The question is whether it can detect cancer early?” Answer the question. If the false positive or false negative rate of blood test results is too high, or it is easier to detect cancers that have a slow course and are not fatal, it is not very useful. Maitra said: “These biotech companies must prove that their products can be used to detect early-stage cancer. More importantly, this early detection can help improve the survival rate of patients. This is the Holy Grail in the Holy Grail. “