In a laboratory in Dresden, Germany, scientists are working on a new way to see inside the body and plan better cancer treatment. Their work could help men with advanced prostate cancer that has spread — and right now, those patients often have few good options.
Prostate cancer is one of the most common cancers in men worldwide. When it spreads and hormone treatment stops working, doctors sometimes use a method called targeted alpha therapy, where radioactive molecules hunt down cancer cells and destroy them from within. The problem is figuring out exactly how much of the radioactive drug reaches the tumor — and current imaging tools often can't show that clearly enough.
Now, researchers at the Helmholtz-Zentrum Dresden-Rossendorf have tested a promising new approach. They developed a molecule that carries two different radioactive tracers at the same time. One, called lanthanum-133, creates detailed 3D images. The other, iodine-123, stays in the body longer, allowing doctors to track the molecule for up to 44 hours after injection. Both are produced at the center's own compact particle accelerator called a cyclotron.
"For the first time, our radiohybrid approach allows us to label one and the same molecule with two different diagnostic radionuclides and observe its behavior in the body over the long term without altering the molecule itself in any way," said Dr. Constantin Mamat, the study's lead researcher at the HZDR Institute of Radiopharmaceutical Cancer Research.
The molecule is designed to stick to a protein on prostate cancer cells called PSMA (short for prostate-specific membrane antigen). In experiments with human prostate cancer cells in the lab, up to 97 percent of the molecules were absorbed into the cancer cells within just 60 minutes. When tested in mice with tumors, both versions of the molecule reached the tumor equally well — a key finding that supports using this technique in humans.
The team created two versions of the molecule: one with a single arm that binds to PSMA, and one with two arms that can grab onto the tumor cell surface more strongly. Both include a special cage-like structure called Macropa that holds the radioactive metal safely, and a piece that temporarily attaches to a protein in the bloodstream to keep the molecule in circulation longer.
The imaging technique could eventually help doctors personalize radiotherapy for each patient — choosing the right dose based on how the treatment actually behaves in that person's body. The results were published in the Journal of Medicinal Chemistry. While more research is needed before this reaches patients, the early signs suggest the radiohybrid approach could make targeted alpha therapy smarter and more effective.