Theranostics
The term ¡°theranostics¡± is a combination of two words: ¡°therapy¡± and ¡°diagnostics.¡± Both therapy and diagnostics are offered through theranostic procedures.
There are two steps to theranostic treatments. Each step uses radioactive materials that are given to the patient, usually through an IV infusion.
The first step is the diagnostic phase. Most patients undergoing theranostic procedures have already been diagnosed with cancer. The diagnostic phase provides information that helps doctors create a treatment plan.
This usually involves giving the patient a low-dose radiotracer, a radioactive substance that shows up on imaging exams including PET and SPECT scans. These radiotracers can be designed to attach to cancer cells. After the infusion, patients undergo an imaging exam, which gives doctors precise images of the patient¡¯s cancer.
These images provide doctors with a better understanding the cancer by answering questions like:
- How much of the radiotracer infusion makes it to the tumor?
- How quickly do the radiotracers make it to the cancer and how long do they stay?
- If there are multiple tumors, does the radiotracer reach all of them?
Doctors use this information to help determine the best treatments for patients.
In many cases, patients will then receive the ¡°therapy¡± part of theranostic treatments. In some cases, doctors decide that other treatments would be better.
For the therapy phase, patients usually receive a second, more powerful radiotracer. When this radiotracer reaches the tumor, the more powerful radiation proceeds to attack cancer cells.
What diseases are treated with theranostics?
A growing number of cancers can be treated with theranostics. These include thyroid cancer, prostate cancer, and neuroendocrine tumors. In addition, many other diseases are being treated with theranostics through clinical trials. Learn more about clinical trials at MD Anderson.
What happens during theranostic procedures?
Theranostic procedures are generally given on an outpatient basis, meaning there¡¯s usually no overnight hospital stay. Patients typically do not need anesthesia, although some may receive a light sedative.
The diagnostic and therapeutic radiotracers are usually given through an IV. Some patients also may get additional medications to help them tolerate the treatment and/or limit side effects. These medications can be given before, during or after the radiotracer infusion.
The care team will review the results from the diagnostic phase and discuss a treatment plan with the patient. If the treatment plan includes include theranostics therapy, the patient will receive a second radiotracer infusion. Generally, this can occur any time after the diagnostic study, once the plan is established.
During the therapy phase, patients will often get an imaging exam after the infusion. This exam can take place either the same day or on a follow-up visit.
Theranostics side effects
Theranostic agents provide targeted radiation therapy for patients and are usually given intravenously. Because of this targeted approach, theranostics¡¯ most common side effects are often mild with treatments generally well-tolerated.
Side effects can vary based on the exact theranostic radiotracer the patient receives. Common side effects include mild fatigue and mild gastrointestinal symptoms such as nausea. Less common side effects can include anemia and decreased kidney function.
Theranostics at MD Anderson
Choosing where to go for cancer care is one of the most important decisions you can make. At MD Anderson, patients are treated by a team of doctors that can include a medical oncologist, surgeon, radiation oncologist and interventional radiologist. They work together to design a personalized treatment plan tailored to each patient.
If your team recommends theranostics treatments, you¡¯ll get care from leaders in the field. Our doctors are among the most experienced in the world in designing theranostic treatment plans. This gives them incredible expertise when creating each procedure. These doctors partner with a team of health care providers with specialized expertise in theranostics, including nurses, technologists and pharmacists, to provide outstanding theranostics care.
And at MD Anderson you will be surrounded by the strength of one of the nation's largest and most experienced cancer centers. From support groups to counseling to integrative medicine care, we have all the services needed to treat not just the disease, but the whole person.
What is theranostics?
You may have heard the term theranostics when reading about cancer treatments, but what does it mean? The word theranostics is a combination of the words ¡°therapy¡± and ¡°diagnostics,¡± and theranostics does just that. It uses radioisotopes to first image a patient¡¯s tumor for diagnostics and then therapeutically treat that tumor.
We spoke with , a cancer systems imaging researcher, to learn more about how theranostics works.
What are radioisotopes?
Theranostics relies on radioisotopes, which are unstable variants of elements, sometimes also called radionuclides, radiopharmaceuticals or radiotracers. ¡°We have a potpourri of radioisotopes that apply to both the imaging and the therapeutics,¡± Manning says.
Radioisotopes release radiation to become more stable, which is called radioactive decay. Both the diagnostic and the therapeutic parts of theranostics take advantage of the radiation that radioisotopes give off.
Using radioisotopes for diagnostics
In the diagnostics half of theranostics, clinicians use radioisotopes for precision imaging of tumors. ¡°Every patient who comes to MD Anderson has unique features about their tumors,¡± says Manning. ¡°Radiopharmaceuticals allow us to quantify and characterize those features non-invasively. This helps us understand what treatment options would be best for a patient before we treat them.¡±
So how are radioisotopes used for diagnostic imaging? Researchers identify a target on the surface of cancer cells and a molecule that will find and bind to that specific target. Then, they link the targeting molecule with a radioisotope to form the diagnostic molecule.
Patients receive the diagnostic molecule via an infusion. Once inside a patient, it makes its way to the cancer cells and attaches to them. Then, clinicians use an imaging scan, usually positron emission tomography (PET), to detect the radioactive decay that the radioisotope half of the diagnostic molecule emits.
¡°Many of the patients who undergo theranostics treatment already have a cancer diagnosis, so we know the locations of their tumors,¡± notes Manning. ¡°So, we're asking other questions with theranostics imaging.¡± Those questions include:
- How quickly do the diagnostic molecules make it to the tumor and how long do they stay there?
- What fraction of the diagnostic molecules that were injected make it there?
- If there are multiple tumors, does the diagnostic molecule target all of them, ensuring that they could also be treated?
The answers to these questions help determine if the targeting molecule is a good treatment option for a patient.
Using radioisotopes for therapy
¡°If the diagnostic imaging shows that the selected cancer cell target is a good match for the patient¡¯s tumors, they'll then be treated with the therapeutic molecule,¡± Manning continues.
To create the therapeutic molecule, scientists take the same piece of the diagnostic molecule that finds and binds to a target on the cancer cell surface and attach it to a different radioisotope. ¡°Theranostics is unique in that it lets us swap the radioisotope that allows diagnostic imaging for one that will kill the cancer cells,¡± explains Manning. The therapeutic molecule is then administered via infusion and makes its way to the cancer cells.
The radioactive decay that the radioisotope gives off damages the cancer cells and their DNA, but it serves a dual purpose. ¡°We can visualize that radiation, too, which allows physicians to follow the therapy directly, noninvasively and quantitatively,¡± Manning says. ¡°We can measure how much of the therapeutic molecule got there, which is unique to theranostics.¡±
Side effects of theranostics
Radioisotopes have a characteristic called their half-life. The half-life is how long it takes for half of the total number of unstable radioisotope molecules to decay into more stable molecules that don¡¯t give off radiation.
Diagnostic radioisotopes have short half-lives, typically about an hour, so they only remain in a patient¡¯s system for a short time. Therapeutic radioisotopes usually have a half-life of three to seven days.
¡°Since the therapy half of theranostics is all about delivering radiation to the tumor, we actually prefer that the therapeutic radioisotopes stay in the tumor tissue and deliver their dose of radiation over a longer period,¡± Manning says.
¡°±«²Ô±ô¾±°ì±ð more traditional treatments, the total amount of radiation that's administered is quite low,¡± explains Manning, ¡°and the radiation is directly targeted to the cancer cells, which reduces side effects.¡± Still, some organ systems are particularly sensitive with respect to radiation, so physicians continue to monitor carefully for potential toxicity and side effects like fatigue, anemia and nausea.
What¡¯s next in theranostics research
Theranostics approaches are currently approved for use in neuroendocrine and prostate cancers. ¡°In our research endeavors at MD Anderson, we're highly motivated to find ways to deliver this approach to patients with other types of tumors or other disease sites that do not yet benefit,¡± says Manning.
One area of interest, especially for therapeutics, is alternative or improved radioisotopes. When different radioisotopes undergo radioactive decay, they produce different types of radiation, such as alpha or beta particles. ¡°The types of radiation that we can achieve with various radioisotopes give us opportunities to tailor the therapeutics molecule to the biology of individual tumors,¡± says Manning.
For example, alpha particles are extremely potent, but they can only travel a very short distance. We can take advantage of this by attaching a radioisotope that gives off alpha particles to a targeting molecule that quickly moves from the cell surface to the inside of the cell. There, the alpha particles produced by the radioactive decay are close enough to damage the cancer cell DNA, despite their short range.
In addition to new and improved radioisotopes, scientists are also researching different biological targets for the theranostics molecules to attach to. A good target candidate is abundant on the surface of cancer cells but not on the surface of healthy cells. ¡°We are very fortunate at MD Anderson to benefit from prior efforts that have characterized the surfaceome of many solid tumors, meaning what proteins are on the cancer cell surface,¡± Manning says. ¡°We have hundreds to even thousands of clinical specimens that make this research possible.¡±
Theranostics at MD Anderson
¡°We're now onboarding a research and development program focused on radioisotope theranostics that aims to be bench to bedside, taking new radioisotopes from their creation in the lab all the way to use in patient treatment,¡± Manning says. ¡°This is truly unique to MD Anderson. There are not a lot of academic institutions that could pull this off.¡±
While our patients benefit from having a radiochemistry facility on campus that produces radioisotopes, MD Anderson¡¯s culture also plays a significant role. ¡°One of the biggest assets that we have here at MD Anderson is being able to partner with our clinicians early on in the process when we are developing new theranostic approaches,¡± says Brooke Graham, director of Research Planning and Development in the Center for Advanced Biomedical Imaging. ¡°It allows us to swiftly move new breakthroughs and discoveries into clinical trials to benefit patients.¡±
¡°The physicians who see our patients on a daily basis are supported so strongly by our basic science researchers,¡± Manning adds. ¡°The direction of our theranostics research at MD Anderson is completely determined by unmet clinical needs.¡±
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