Less invasive radiotherapy thanks to medical imaging with Nanobodies

2 August 2012
Radiotherapy, also known as "irradiation" is a treatment to destroy cancer cells. For optimal treatment, the radiation therapists must apply a very high radiation dose to the whole tumor with side effects for the patient. Research teams of VIB, Vlaams Instituut voor Biotechnologie, and the Vrije Universiteit Brussel, have developed a technique to visualize which regions of the tumor cope best with radiotherapy.

Jo Van Ginderachter (VIB - Vrije Universiteit Brussel): "By distinguishing in areas with high and low resistance to radiotherapy, radiation therapists can refine their irradiation. It is only necessary to give the more resistant regions a high radiation dose, for the other regions a lower dose is sufficient. We hope that in time this can lead to fewer side effects in patients that undergo irradiation."

Macrophages detection in cancer cells
The researchers, led by Jo Van Ginderachter, Nick Devoogdt and Patrick De Baetselier developed a Nanobody® targeting the MMR protein that is produced by a specific type of macrophages that occurs in tumor cells. These macrophages are predominantly in the regions of the tumor with very low oxygen concentration, and these are the regions that are highly resistant to irradiation. The presence of macrophages in the tumor is, moreover, usually a poor prognostic factor. Macrophages promote tumor growth and metastasis through various mechanisms.

Nick Devoogdt (Vrije Universiteit Brussel): "Through our Nanobody®, for the first time, we can visualize the presence of macrophages in the tumor swelling. Nanobody® is radioactively labeled, so we can have an image of where the tumors are spreading with the use of a scanner. Thus, we learn more about the behavior of the cancer. This can be a major step forward for the prognosis determination of the patient."

Thanks to the dromedary
The Nanobody® targeting the MMR protein was made with the help of a dromedary! Dromedaries make antibodies that are much smaller and more stable than conventional antibodies. When these animals are administered recombinant MMR-molecules, they develop anti-MMR antibodies. Of these antibodies, only the fragment that binds to the protein are then kept. Since such a fragment is very small, it is called the Nanobody®. These small dimensions are also an important plus for the use of a Nanobody® for imaging creation in tumors because these small molecules easily penetrate the tumor.

Dromedaries make antibodies that are much smaller and more stable than conventional antibodies.
 (c) VIB