A study published recently in the Proceedings of the National Academy of Sciences (PNAS) has revealed that by tagging a pair of markers that is exclusive to a common type of brain cancer yields a signal which is more specific and more obvious to cancer. The results of the research from the University of Wisconsin-Madison is significant as it holds promise for a new avenue for early tumor detection which in principle is likely to be applicable to a variety of cancers. Another feather in their cap is that the cancer treatment methods it suggests are more precise.
Haiming Luo, a UW-Madison postdoctoral researcher in the Department of Radiology and first co-author of the study shared that the idea of searching for two markers of cancer has been there for a while, but technically it was quite difficult to achieve the same.
The researchers under the direction of Weibo Cai, an associate professor of radiology and medical physics in the UW School of Medicine and Public Health and biomedical engineering in the UW College of Engineering were successful in creating antibodies which are specific to two proteins that often characteristic of brain tumors. One of these markers is called CD105 and it appears on new blood vessels that grows only in pregnancy in adult humans or at times when wounds heal. The other marker – epidermal growth factor receptor when mutated spark uncontrolled cell division in a wide range of cancers including glioblastoma.
In order to induce the ability to bind to both these markers in a structure, the researchers severed unneeded sections of each antibody, and later assembled them with a fast, reliable joint. The structure also had a fast-decaying isotope that is detectable in a PET (positron emission tomography) scanner.
Once the detection compound was purified to do away with unpaired antibodies, the remains of it were injected into mice with epidermal growth factor receptor. The researchers then waited for about 36 hours to let the detector molecules to link to tumours or to clear from normal tissue. PET scanner was then used to find the radiation they released. It was found that there was a great increase in the intensity of the signal as compared to conventional PET scanning. The other benefit was specificity while the detector linked to tumors, but they didn't connect to healthy tissue.
Typically, when PET scans are used for detecting cancer, the signal they look for is glucose metabolism- it is a biological activity that characterizes cancer or its possible causes. However, in brain various activities can mask the signal of cancer which makes cancer detection quite difficult.
Reinier Hernandez, a graduate student in medical physics and first co-author of the study opined that the study points toward a “toolkit” approach to cancer detection. He also said that studies on other tumors are moving forward based on well-known targets on particular cancers that appear in genetic databases.
Hernandez said that the new technique demonstrates a novel way to connect to tumor cells while avoiding normal tissue, and thereby it suggests a way to treat cancer rather than just identifying it. Specific treatment should eventually replace chemotherapy which doesn't just damage tumors but healthy tissues as well.
Cai opined that as an example, the two-part antibody could be joined to a strong, quick-acting unit of radiation, or to a chemical that can kill cells. They can make use of detector to assess the progress of treatment. He also added that with so much research happening in the field, we learn more about cancer and how it is different from healthy tissue. Thus, we are better equipped to detect and manipulate genes, proteins and other molecules, both for detection and for therapy.