What Are the Side Effects of Lu-177 PSMA Therapy?

Lu-177 PSMA therapy is a treatment for advanced prostate cancer, and many people may not have heard of it yet. Next to chemotherapy, it is generally the gentler option. Gentler doesn’t mean there’s nothing to deal with, though. Lu-177 PSMA therapy side effects tend to begin small: a flat, tired feeling, a mouth that never seems wet enough, a stomach that’s off for a few days.

According to Dr. Gayana Shankaramurthy, a Nuclear Medicine Specialist in Bangalore at KIMS Hospitals, “Most side effects turn out to be mild and ease with time. Blood and kidney tests between cycles let the team spot the serious ones early, often well before any symptoms show.”

Numbers from the phase III VISION trial show how often each one turned up.

These are all-grade figures, and every one of them showed up more often than in the comparison group. Nausea is usually mild and tends to hit in the week after an infusion. Dry mouth has a simple cause: salivary glands carry PSMA too, so they soak up a little of the radiation. In the trial it mostly stayed mild. For some people it lingers. How the treatment fits into wider prostate cancer care is covered under Theranostics in Prostate Cancer.

The serious ones mostly involve the blood.

Blood counts. The bone marrow can slow down. In VISION, roughly one patient in eight developed severe anemia, and about one in twelve had low platelets. Low lymphocytes landed in the same range. Platelets are what stop a small cut from turning into a long bleed, so when they drop, bruises show up easily and nosebleeds last longer. Anemia, if it gets severe, sometimes needs a blood transfusion.

Kidneys. Kidneys do the clearing here. A blood test for kidney function comes before each cycle. Fewer than one in ten patients in VISION had a kidney effect.

Treatment changes. About 12% of patients stopped treatment early because of side effects. Across the board, serious events were commoner with the added therapy, roughly 53% against 38% on standard care alone. That gap is why the blood tests are never skipped.

Lu-177 PSMA therapy is given in cycles to people with advanced prostate cancer, and each cycle goes ahead only after the latest results are reviewed. The treating team looks over a handful of results before each cycle. First comes the PSMA PET/CT scan, which shows whether the cancer has enough PSMA to respond. After that, blood counts and kidney function need to sit inside safe limits. Past treatments, how fit the patient is, and any new symptoms all get a say as well. If a number starts sliding, the dose can be delayed or cut back. Pushing on regardless isn’t the plan. 

• Most people deal with tiredness, a dry mouth and some nausea, and these usually ease off.
• Blood counts are where the serious risk sits, so they’re tested every cycle.
• Kidneys are checked before each infusion because the drug leaves through them.
• A poor test result can mean a delay, a smaller dose, or stopping.
• Fever, unusual bleeding or vomiting that won’t stop needs a call to  the doctor same day.

References:

1. Hematotoxicity and Nephrotoxicity in Prostate Cancer Patients Undergoing Radioligand Therapy with [177Lu]Lu-PSMA I&T. Cancers, 2022. National Institutes of Health, PMC. https://pmc.ncbi.nlm.nih.gov/articles/PMC8833540/
2. Retrospective analysis of early side effects and response after 177Lu-PSMA radioligand therapy in metastatic prostate cancer. National Institutes of Health, PMC. https://pmc.ncbi.nlm.nih.gov/articles/PMC4477007

Disclaimer:This blog is for educational purposes only and isn’t a substitute for professional medical advice.