Cancer > The Science Behind Theranostics

The Science Behind Theranostics

By Alison Caldwell, Ph.D. Illustrations by Tim West

A groundbreaking approach called theranostics is emerging as a powerful tool in the fight against cancer. Combining the words "therapeutic" and "diagnostic," theranostics, also called theragnostics, represent a significant leap forward in precision medicine, offering hope to patients who may have exhausted traditional treatment options. At Mayo Clinic, home to the largest radiopharmaceutical practice in the world by volume, innovation is fueling the next generation of radiopharmaceutical innovations, including in theranostics.

How do theranostics combine therapy and diagnosis, and how do they compare to other cancer treatments?

How Do Theranostics Work?

Radioactive pharmaceutical agents used in theranostics have two key components: a targeting component, such as an antibody, that binds to specific molecules or proteins on cancer cells, and a radioactive compound that can be used either for imaging the cancer or for destroying it.

First, the patient is given a radiopharmaceutical agent for imaging the cancer. The targeting molecule attaches to the surface of the cancer cells, while the radioactive isotope emits low-energy radiation that can be visualized and mapped using imaging techniques like PET scans.

Once the tumor locations are identified, the same targeting molecule is then coupled with a higher-energy radioactive isotope. When given to a patient, this targeted radiation selectively kills the cancer cells that the drug binds to, while minimizing damage to surrounding healthy tissues.

The key advantages of theranostics are that they enable precision medicine by binding to specific molecular targets on a patient's tumors. They then use that binding to allow for both diagnosis and selective treatment of the cancer with radiation therapy. Clinicians can determine exactly where the treatment will go and assess if the radioisotope therapy will be effective for an individual patient because both the imaging solution and the treatment use the same molecule. This personalized approach aims to improve outcomes and reduce side effects compared to traditional cancer treatments.

While theranostics may seem cutting-edge, their roots trace back to the 1940s with the use of radioactive iodine to treat thyroid cancer. However, recent advances have dramatically expanded the technology’s potential. The field now combines chemistry, advanced nuclear physics, and state-of-the-art scanning technology to develop new imaging techniques and treatment options previously thought impossible.

How Do Theranostics Compare to Other Kinds of Cancer Treatments?

Compared to traditional cancer therapies, theranostics offer an innovative approach that combines diagnostic and therapeutic capabilities in a single agent. Conventional treatments such as chemotherapy, external beam radiation and surgery have been the mainstays of cancer treatment for decades. However, these methods often lack the precision of theranostics. Chemotherapy, for instance, circulates throughout the entire body, potentially causing widespread side effects as it targets both cancerous and healthy rapidly dividing cells. External beam radiation, while more localized than chemotherapy, still affects a defined area that may include healthy tissue surrounding the tumor. Surgery, though precise in removing visible tumors, may not address microscopic spread of cancer cells and is not always feasible depending on the tumor's location.

By using a targeting molecule that specifically binds to cancer cells, radiopharmaceutical agents can deliver diagnostic imaging capabilities and therapeutic radiation directly to the tumor sites, wherever they may be in the body. This targeted approach could potentially reduce side effects on healthy tissues and allow for real-time monitoring of treatment efficacy. Furthermore, the diagnostic component of theranostics enables personalized treatment planning, as clinicians can assess whether a patient's cancer expresses the target molecule before proceeding with therapy, while traditional chemotherapy requires a waiting period following treatment to determine if it’s been effective. While theranostics are not a replacement for all existing cancer therapies and may be used in combination with other treatments, they represent a significant advancement in the pursuit of more effective and less toxic cancer care.

How Is Mayo Clinic Driving Innovation in Theranostics?

Mayo Clinic's approach to theranostics is multifaceted, encompassing clinical expertise, research and development, and collaborative partnerships, expanding treatment options and personalized medicine. The Mayo Clinic Comprehensive Cancer Center has recruited top talent, including pioneers in the field with decades of experience in cancer treatment and research. Mayo Clinic is actively developing new technologies and conducting clinical trials, and studies are underway to understand how a person's genetic profile may influence their susceptibility to side effects from radiopharmaceutical treatments, paving the way for more tailored treatment approaches.

In addition to internal efforts, Mayo Clinic has forged strategic alliances with industry leaders, and researchers are investigating new targeting molecules, such as fibroblast activation protein inhibitor (FAPI). FAPI shows promise for imaging and potentially treating pancreatic cancer.

The applications for theranostics are expected to expand beyond current Food and Drug Administration-approved treatments for neuroendocrine tumors and prostate cancer. Clinical trials are underway to explore its potential in melanoma, earlier cancer stages, and other hard-to-treat cancers.

The future of cancer treatment looks more promising than ever. Theranostics represent a significant step forward in the quest for more effective, personalized cancer care, offering hope to patients and pushing the boundaries of what is possible in modern medicine. The ongoing advancements in theranostics highlight the potential for transformative changes in cancer diagnosis and treatment, positioning this field at the forefront of precision medicine.