Two liver sections of a patient with neuroendocrine cancer, showing metastases (encircled white spots) on computed tomography with contrast enhancement before (left) and after (right) radionuclide therapy with 177Lu-octreotate. There is an impressive reduction in the number and size of the metastases (90% according to the radiologist). (Courtesy of Prof. Jean François Chatal, Nantes, France)
In 1942, the first patients affected with hyperthyroïdia were treated with Iodine 131. Four years later, it was demonstrated that on the same basis it was possible to destroy all metastases in a patient suffering from thyroid cancer. Thyroidal nodules selectively accumulate radioactive iodine. These results had a major impact on Nuclear Medicine because they have proven without a shadow of a doubt that this technique had a great potential. In 1951, iodine 131, in the form of sodium iodide, became the first radiopharmaceutical to be approved by the Food and Drug Administration. Until today, iodine 131 remains the most used therapy for thyroid tumor treatment with an exceptional high rate of success.
Unfortunately, iodine is a unique case of an atom that accumulates in a single tissue. The development of new radiotherapeutics had to switch to combined molecules, radionuclides linked to vectors. So far applications were limited by the absence of specificity of these vectors. In the meantime, local applications in therapy were developed with radioactive particles as for example in radiosynovectomy (local treatment of polyarthritis with radioactive substance) or sentinel node detection (breast tumor proliferation control). Also Samarium-153 or Strontium-89 are used in bone metastases treatment but only for pain palliation applications. With the development of antibodies in the 80’s, a new gap in technology was fulfilled, but the first successful labeled antibodies for therapy only came on the market at the beginning of this century. Both parts of this technology, human origin biologics and radioactive substances, can only advance with high investments based on a high level expertise. The new generation of radiopharmaceuticals will now be developed with simplified vectors engineered from these heavy, expensive and difficult to manipulate antibodies.
