Riddles don’t seem to be popular anymore for entertaining kids, now that they use devices for games and amusements. In the “good old days” there was a kind of riddle in which one thing is improbably crossed with another, as in “What do you get when you cross a chicken with a centipede?” The answer, “Drumsticks for everyone,” is supposed to be amusing. Who does riddles anymore? Not many folks.
However, there is a new approach to treating advanced cancers that sounds like such a riddle, but it’s no joke. In fact, it’s a serious revolution in medicine that’s rapidly gaining traction. What do you get when you cross cancer therapeutics with diagnostics? Theranostics.
What is theranostics?
Theranostics is recent innovation in customized cancer care, but the principle originated in the late 1930s. A research team from the Massachusetts Institute of Technology and the thyroid group of Massachusetts General Hospital were exploring the use of man-made iodine isotopes (radioactive iodine) to diagnose a noncancerous condition called hyperthyroidism (overactive thyroid gland). The chief architect of the study was Dr. Saul Hertz. It was already known that thyroid cells selectively take up iodine, which they need to manufacture certain hormones. Dr. Hertz and his team used rabbits to demonstrate that the gland would eagerly take up the iodine isotopes too. Not only does the isotope reveal thyroid physiology on imaging, but Dr. Hertz also envisioned that it could be adapted to treat thyroid cancer with radioactivity at the level of the cancer cell. On March 31, 1941, he was the first to diagnose and treat a thyroid cancer patient with radioactive iodine.[i] This was the birth of theranostics.
Today, there is a profound commitment to personalized, patient-centered care. Theranostics takes advantage of cancer cells’ natural processes in an individual patient by utilizing a triple-purpose man-made agent that can diagnose, deliver targeted treatment to cancer cells, and monitor treatment response. This is advanced medicine at atomic and molecular levels.
In general, cancer cells are more vulnerable to the effects of radiation than healthy cells, though too much radiation can harm normal cells causing them to die off or mutate into cancer. The advantage of atomic isotopes is they can form molecular bonds with substances that are selectively attractive to cancer cells without harming healthy cells. This is called radiolabeling. In PET/CT scans, the isotope is called a radiotracer, and in therapeutic radiolabeling it’s called a radioligand. When cancer cells’ receptors take up a radiotracer, their presence and location “lights up” on imaging such as PET/CT scans. With theranostics, the same molecule used for imaging can be labeled with radioligands for targeted delivery of a lethal but short-lived dose of radioactive isotopes to tumor cells.
With the development of genomic testing, and isotope-based imaging, we can access more information than ever before on an individual’s cancer. This is crucial, because cancers like prostate cancer are hardly homogeneous. Instead, cell lines vary in terms of their biological, hormonal, genetic and molecular characteristics. Did you know that over 200 cell types and subtypes are available for laboratory research? This underscores the importance of customizing treatments for patients with advanced or metastatic disease.
Theranostics and prostate cancer
One of the most promising theranostic approaches for metastatic prostate cancer (PCa) is a molecule that is highly expressed on prostate cancer cells, especially in more advanced. It is called prostate-specific membrane antigen (PSMA), and it acts as a receptor for preferentially picking up certain molecules that attach via the receptors to the cancer cell. This property affords excellent potential for PSMA-directed theranostics:
In patients with advanced prostate cancer, PSMA might have a role in detecting disease spread through both positron emission tomography and single-photon emission computed tomography imaging, while treating prostate cancer systemic localizations with radioligand therapy.[ii]
Unlike chemotherapies that can have miserable side effects, the theranostics approach is kinder on patients because it is targeted directly to the cancer cells that have specialized receptors for them. The type of radioligand used, and the dose, are tailored to the clinical profile of a patient’s disease.
With ongoing research and clinical trials, we can expect to hear much more about this promising new branch of cancer treatment. Its utilization is increasing not just in PCa but in other cancers as well. Stay tuned for more news about therapeutic innovations for men with metastatic PCa in this new age of personalized treatment.
NOTE: This content is solely for purposes of information and does not substitute for diagnostic or medical advice. Talk to your doctor if you are experiencing pelvic pain, or have any other health concerns or questions of a personal medical nature.
[i] Hertz, B. A tribute to Dr. Saul Hertz: The discovery of the medical uses of radioiodine. World J Nucl Med. 2016 JanMar; 18(1):8-12.
[ii] Farolfi A, Fendler W, Iravani A, Haberkorn U et al. Theranostics for Advanced Prostate Cancer: Current Indications and Future Developments. Eur Urol Oncol. 2019 Mar;2(2):152-162. doi