PSMA-Targeted PET Imaging

Doctors use imaging tests to monitor prostate cancer and see if it has spread to other parts of the body. Magnetic resonance imaging (MRI) and bone scans are standard tests used to evaluate prostate cancer. However, these tests may not be useful if it is unclear where prostate cancer may have spread.¹

In these cases, a new imaging test called prostate-specific membrane antigen (PSMA)-targeted positron emission tomography (PET) imaging can be used. As of early 2022, 2 drugs for PSMA-targeted PET imaging have been approved by the US Food and Drug Administration.

Your doctor can help you decide whether this new imaging method is right for you.

How do PSMA-targeted PET imaging drugs work?

PSMA-targeted PET imaging drugs help doctors monitor prostate cancer. Doctors use them in certain cases to see whether the cancer has spread to other parts of the body or if the cancer has returned following previous treatment.^2,3

Doctors give these drugs by intravenous (into the vein) injection. The drugs are designed to bind to a protein called PSMA. Prostate cancer cells often have much higher levels of PSMA than noncancerous cells. This means PSMA-targeted drugs will stick to and help identify prostate cancer cells.^2,3

PSMA-targeted PET imaging drugs are considered radioactive. These drugs can be detected by PET imaging. This allows doctors to see PSMA-positive cancers in imaging tests. Doctors then use this information to decide on the best possible treatment.^2,3

Examples of PSMA-targeted PET imaging drugs

As of early 2022, 2 PSMA-targeted PET imaging drugs for men with prostate cancer are approved by the FDA. These include:^4,5,6

• Gallium 68 PSMA-11 (Ga 68 PSMA-11)
• Piflufolastat F 18 (PylarifyⓇ)

Ga 68 PSMA-11 and Pylarify are meant for men whose prostate cancer:^4,5

• May have spread to another part of the body and is potentially curable with surgery or other therapies, or
• Seems to have returned based on high prostate-specific antigen (PSA) levels

Clinical trials confirmed that Ga 68 PSMA-11 and Pylarify can identify where prostate cancer has spread. The drugs can also detect sites where prostate cancer has returned. This provides doctors with important information for deciding on treatment.^4,5

In early 2022, the FDA also approved:^6-8

• Pluvicto^TM (lutetium Lu 177 vipivotide tetraxetan) – A targeted radioligand therapy (RLT) for men with PSMA-positive metastatic castration-resistant prostate cancer (mCRPC) who were previously treated with other anticancer drugs. Examples include androgen receptor (AR) pathway inhibitors and taxane-based chemotherapy.
• Locametz^® (kit for the preparation of gallium Ga 68 gozetotide) – A radioactive diagnostic imaging agent that can be used in a PSMA PET scan to find people who can be treated with Pluvicto, have suspected recurrence and metastasis (spread of cancer).

What are the possible side effects?

The most common side effects of Ga 68 PSMA-11 include:^2,4,6

• Nausea
• Diarrhea
• Dizziness

The most common side effects of Pylarify include:^3,5

• Headache
• Altered taste
• Fatigue

The most common side effects of Pluvicto include:⁷

• Fatigue
• Dry mouth
• Nausea
• Anemia (low red blood cell count)
• Decreased appetite
• Constipation

The most common side effects of Locametz include:⁸

• Fatigue
• Nausea
• Constipation
• Vomiting

These are not all the possible side effects of PSMA-targeted PET imaging drugs. Talk to your doctor about what to expect when taking these drugs. You also should call your doctor if you have any changes that concern you when taking PSMA-targeted PET imaging drugs.

Things to know

Your doctor will perform PET imaging about 1 to 2 hours after giving you the imaging agent. They will tell you to drink water before and after injection. This helps make sure you stay hydrated and can urinate before PET imaging. This can reduce exposure to radiation.^4,5

There is a potential risk for misdiagnosis from PSMA-targeted PET imaging drugs. This can happen if the drugs bind other types of cancer or non-cancerous cells. Like any radioactive drug, there are also radiation risks. Receiving these radioactive drugs contributes to lifetime radiation exposure.^2,3

To minimize radiation exposure to others, your doctor may advise you to avoid contact with anyone living with you. You may need to avoid children and people who are pregnant for longer. Talk to your doctor about exposure and steps to take after taking these drugs.⁹

Some machines do a PET scan at the same time as an MRI or other imaging tests. This can give better detail about areas that show up on the PET scan. PSMA-targeted PET imaging drugs are not yet available in all imaging centers. Talk to your doctor to find a place that uses these new methods.¹

Before beginning treatment for prostate cancer, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you are taking. This includes over-the-counter drugs.