Why Clinical Trials Matter for Men with Stage 4 Prostate Cancer
When prostate cancer spreads to other parts of the body and stops responding to hormone therapy, doctors call it metastatic castration-resistant prostate cancer, or mCRPC. At this stage, finding new treatment options is critical. That is where Lu-177 PSMA therapy has made a real difference, and the evidence behind it is growing fast.
Over the past few years, large clinical trials have tested this targeted treatment in thousands of men. The results have already changed what doctors offer patients, and in 2022 and again in 2025, those results led to major regulatory decisions. This article covers the key trials, what they found, and what the findings may mean for your care.
If you are new to Lu-177 PSMA therapy and want to understand how it works before looking at trial data, our guide What Is Lu-177 Therapy? A Patient-Friendly Guide to How It Works, What to Expect, and Whether It Might Be Right for You is a good place to start.
How Lu-177 PSMA Therapy Works — in Brief
Prostate cancer cells often carry large amounts of a protein called prostate-specific membrane antigen, or PSMA. Lu-177 PSMA therapy uses a targeting molecule that seeks out this protein. Attached to that molecule is a small dose of radioactive lutetium-177. This agent targets PSMA expressed on the surface of prostate cancer cells with a beta-emitting isotope, delivering radiation directly to tumors while sparing much of the surrounding healthy tissue.
To qualify, patients need a PSMA PET scan first. Patients must have a positive PSMA PET scan to confirm that their cancer cells express enough PSMA for the treatment to reach them.
The VISION Trial: The Landmark Study That Started It All
The phase 3 VISION trial is the most important piece of evidence behind Lu-177 PSMA therapy. It enrolled men who had already tried hormone-targeting drugs (called androgen receptor pathway inhibitors, or ARPIs) and one or two rounds of chemotherapy, and whose cancer kept growing.
Radioligand therapy with Lu-177 PSMA-617 prolonged imaging-based progression-free survival and overall survival when added to standard care in patients with advanced PSMA-positive metastatic castration-resistant prostate cancer, according to the trial's published conclusions.
In concrete numbers, the VISION trial confirmed that Lu-177 PSMA-617 improved overall mCRPC patient survival from 11.3 to 15.3 months compared to standard care alone. That is a meaningful gain for men with few options left.
The trial also tracked quality of life and pain. Research on the VISION quality-of-life data found that Lu-177 PSMA-617 plus standard of care delayed time to worsening in health-related quality of life and time to skeletal events compared with standard of care alone. For men with bone metastases, delaying painful bone events is a meaningful outcome on its own.
Based on VISION's results, the FDA approved Lu-177 PSMA-617 in March 2022 for men with PSMA-positive mCRPC who had already received an ARPI and taxane-based chemotherapy.
The TheraP Trial: Lu-177 PSMA Versus Chemotherapy
While VISION compared Lu-177 PSMA therapy to standard care, the phase 2 TheraP trial took a different approach. It compared Lu-177 PSMA therapy directly against cabazitaxel, a chemotherapy drug often used in this setting.
The TheraP trial showed improved PSA response with Lu-177 PSMA, and the objective response rate favored Lu-177 PSMA at 49%, compared to 24% with cabazitaxel. The trial also found that Lu-177 PSMA had lower toxicity than chemotherapy, which matters for men managing side effects.
TheraP was smaller and not designed to prove a survival difference on its own, but its findings pointed the same direction as VISION: Lu-177 PSMA therapy may offer real benefits over existing options, with a manageable side-effect profile. In both the TheraP and VISION trials, Lu-177 PSMA-617 had a good safety profile, with common adverse events being fatigue, nausea, dry mouth, marrow suppression and diarrhea.
The PSMAfore Trial: Earlier Treatment, Better Results
One key question researchers asked was whether Lu-177 PSMA therapy works before chemotherapy. The phase 3 PSMAfore trial was designed to find out.
PSMAfore enrolled men with PSMA-positive mCRPC whose disease had progressed on one ARPI but who had not yet received taxane-based chemotherapy. They were randomly assigned to receive either Lu-177 PSMA therapy or a switch to a different ARPI. The trial met its primary endpoint, with a clinically meaningful and statistically significant benefit in radiographic progression-free survival in patients with PSMA-positive mCRPC after previous ARPI therapy.
The numbers were striking. Lu-177 PSMA-617 significantly improved radiographic progression-free survival, doubling it from 5.5 months with alternate ARPIs to 12 months. Radiographic progression-free survival measures how long a patient's cancer does not visibly grow on scans, which is a direct indicator of how well treatment is controlling the disease.
PSMAfore also tracked tumor response closely. The objective response rate favored the Lu-177 PSMA-617 arm at 51% versus 15%, with a complete radiologic response observed in 21.1% of Lu-177 PSMA-617-treated patients compared to 2.7% in the ARPI switch arm.
PSMAfore also recorded a PSA50 response — meaning the PSA level dropped by at least half — in 58% of Lu-177 PSMA-617-treated patients, versus 20.4% of patients in the ARPI switch arm. A falling PSA level often signals that the cancer is responding.
Quality of life data from PSMAfore, presented at the 2024 ASCO Annual Meeting, added further weight. Lu-177 PSMA-617 delayed time to worsening in self-reported pain and health-related quality of life versus a change of ARPI in taxane-naive patients with PSMA-positive mCRPC.
What the PSMAfore Results Mean for the FDA Approval
The PSMAfore data directly led to a regulatory change. The FDA approval of Lu-177 PSMA-617 is now expanded to patients with mCRPC who have received an ARPI and who are considered appropriate to delay taxane-based chemotherapy, provided they also have a positive PSMA PET scan.
This March 2025 expansion matters because Lu-177 PSMA therapy can now be considered earlier — before chemotherapy — for men who meet the criteria. This is hopeful news for patients who have seen their disease progress on an ARPI, since it opens the door to this targeted approach sooner in the treatment process.
If you have already exhausted hormone therapy and are wondering what comes next, our article My Prostate Cancer Stopped Responding to Hormone Therapy — What Are My Options Before Chemotherapy? covers the landscape of choices in more depth.
The UpFrontPSMA Trial: Looking Even Earlier
Researchers are pushing further. The UpFrontPSMA trial tested Lu-177 PSMA therapy in men with newly diagnosed metastatic prostate cancer, meaning cancer that had spread before any standard treatments had been tried.
The results, published in Lancet Oncology and presented at ESMO 2024, were encouraging. Researchers found that 41% of patients who received Lu-177 PSMA therapy achieved undetectable PSA at 48 weeks, compared to 16% in the standard-care group — a key marker suggesting deep responses.
This trial is still phase 2 and involves a smaller group of patients, so its findings need confirmation in larger studies. Even so, it suggests that Lu-177 PSMA therapy may eventually move earlier in the treatment pathway.
What the Trial Evidence Tells Us About Side Effects
All trials tracked safety carefully. Across VISION, TheraP, and PSMAfore, Lu-177 PSMA therapy was generally well tolerated, though side effects do occur.
- Fatigue is the most commonly reported symptom across trials.
- Dry mouth (xerostomia) occurs because salivary gland cells also carry some PSMA.
- Nausea is common but usually mild and manageable.
- Blood count changes — including anemia — may occur and are monitored with regular blood tests.
- Kidney function is tracked throughout treatment.
In the PSMAfore quality-of-life analysis, the incidence of grade 3 or higher adverse events was 34% in the Lu-177 PSMA-617 arm versus 44% in the ARPI change arm — suggesting that Lu-177 PSMA therapy may carry a lower burden of severe side effects than switching to another hormone drug.
If you want to understand eligibility requirements more fully, including how the PSMA PET scan works and what criteria your doctor will consider, see our plain-language guide: Am I a Candidate for Lu-177 PSMA Therapy? A Plain-Language Guide to Eligibility for Men with Metastatic Castration-Resistant Prostate Cancer.
What These Trials Do Not Yet Tell Us
Clinical trials provide strong evidence, but they also have limits. A few honest caveats:
- Overall survival in PSMAfore was harder to measure because many patients in the control arm crossed over to receive Lu-177 PSMA therapy after their cancer progressed, which complicated survival comparisons.
- Not every patient responds. Response rates vary across trials. Your doctor will use your PSMA PET scan, PSA level, overall health, and prior treatments to estimate how likely you are to benefit.
- Long-term data are still coming in. Most of these trials are relatively recent, and researchers are still following patients to gather data on longer-term outcomes.
- Combination strategies are being studied. Researchers are looking at whether combining Lu-177 PSMA therapy with other agents — such as PARP inhibitors — may produce better results. Those trials are ongoing.
What This Means for Your Treatment Conversation
The evidence from VISION, TheraP, PSMAfore, and UpFrontPSMA points in a consistent direction: Lu-177 PSMA therapy may help slow disease progression and preserve quality of life in men with advanced PSMA-positive prostate cancer. The treatment window has also expanded. It is no longer limited to the very last line of therapy.
If your cancer has progressed on hormone therapy and you have not yet started chemotherapy, ask your oncologist whether a PSMA PET scan and a discussion of Lu-177 PSMA therapy belong in your next appointment. The PSMAfore data — and the resulting FDA label expansion — mean this conversation can happen much sooner than it could just a few years ago.
For men thinking about how to support their overall wellbeing during treatment, our article What Integrative Therapies and Lifestyle Changes Can Support Lu-177 PSMA Treatment in Men with PSMA-Positive Prostate Cancer? covers evidence-informed approaches that may complement your medical care.
When to Talk to Your Doctor
Speak with your oncologist or urologist soon if any of the following apply to you:
- Your PSA is rising despite ongoing hormone therapy.
- Your cancer has progressed on an ARPI and you have not yet had chemotherapy.
- You have had a PSMA PET scan and it showed PSMA-positive lesions.
- You want to know whether you meet the current criteria for Lu-177 PSMA therapy.
- You are interested in clinical trials testing this treatment in newer settings.
Bring a list of your past treatments, recent scan results, and any questions written down. A second opinion at a center experienced in radioligand therapy is always a reasonable step.
This article is for general information and is not a substitute for medical advice. Always consult your oncologist or care team about your specific situation.
Frequently asked questions
What is the most important clinical trial for Lu-177 PSMA therapy in prostate cancer?
The phase 3 VISION trial is the landmark study. It enrolled men with PSMA-positive metastatic castration-resistant prostate cancer who had already tried hormone-targeting drugs and one or two rounds of chemotherapy. The trial showed that Lu-177 PSMA therapy, added to standard care, improved median overall survival from 11.3 months to 15.3 months compared to standard care alone. It also delayed disease progression on scans and reduced the risk of painful bone events. These results led to the first FDA approval of this treatment in March 2022.
What did the PSMAfore trial find, and why does it matter?
PSMAfore was a phase 3 trial that tested Lu-177 PSMA therapy in men who had not yet received taxane-based chemotherapy, but whose cancer had progressed on an androgen receptor pathway inhibitor (ARPI). The trial found that Lu-177 PSMA therapy roughly doubled the time before cancer visibly grew on scans — 12 months versus 5.5 months with a switch to a different ARPI drug. It also showed better PSA response rates and improvements in pain and quality of life. Based on these results, the FDA expanded the approval in March 2025 so that Lu-177 PSMA therapy can now be offered before chemotherapy to eligible patients with PSMA-positive disease.
Do I need a PSMA PET scan before I can receive Lu-177 PSMA therapy?
Yes. A PSMA PET scan is required before starting Lu-177 PSMA therapy. The scan checks whether your cancer cells carry enough of the PSMA protein for the treatment to reach them effectively. If the scan shows PSMA-positive lesions — and you meet the other eligibility criteria — you may be a candidate. If the scan is negative or shows mixed results, Lu-177 PSMA therapy may not be appropriate for you. Talk to your oncologist about arranging a scan and interpreting the results.
What are the most common side effects seen in clinical trials?
Across the main trials — VISION, TheraP, and PSMAfore — the most commonly reported side effects were fatigue, dry mouth, nausea, and changes in blood counts such as anemia. Kidney function is also monitored during treatment. Severe side effects (grade 3 or higher) occurred in a proportion of patients across all trials, but in PSMAfore, the rate of severe adverse events was actually lower in the Lu-177 PSMA group than in the group that switched to a different hormone drug. Most side effects were manageable with medical support. Your care team will monitor you closely throughout treatment.
Is Lu-177 PSMA therapy being tested at earlier stages of prostate cancer?
Yes. The UpFrontPSMA trial, a phase 2 study whose results were published in Lancet Oncology in 2024, tested Lu-177 PSMA therapy in men with newly diagnosed metastatic prostate cancer — before standard therapies had been tried. The results were encouraging, with a higher rate of undetectable PSA at 48 weeks in the Lu-177 PSMA group compared to standard care. However, this was a smaller trial and the results need to be confirmed in larger phase 3 studies. Other trials are also exploring Lu-177 PSMA therapy in combination with other drugs, such as PARP inhibitors. Ask your oncologist whether any open trials match your situation.
Does Lu-177 PSMA therapy cure prostate cancer?
No treatment for metastatic castration-resistant prostate cancer is considered curative at this time. The goal of Lu-177 PSMA therapy is to slow the cancer's growth, reduce symptoms, preserve quality of life, and extend the time before the disease progresses further. Research suggests it may achieve all of these goals for many men with PSMA-positive disease, but responses vary from patient to patient. Your oncologist can help you understand what a realistic goal of treatment looks like in your specific situation.