Prostate drug sits at the center of this dementia and brain health question.
A new class of prostate cancer drugs is making it possible to shrink tumors without ever removing the prostate gland, and the early clinical results are striking. In a Phase 1 trial presented at the ASCO Genitourinary Cancers Symposium in February 2026, an experimental immunotherapy called VIR-5500 achieved an 82% rate of PSA reduction by half or more in men with metastatic castration-resistant prostate cancer — patients who had already failed a median of four prior treatment lines. Meanwhile, Bayer’s targeted alpha radiotherapy injection, 225Ac-PSMA-Trillium, shrank tumors in 46% of patients with measurable disease, with 83% seeing their cancer stabilize. These are not marginal gains. For men facing a disease that has historically demanded radical surgery, these gland-sparing approaches represent a genuine shift in what treatment can look like.
The idea of treating prostate cancer without removing the organ is not entirely new — hormone therapies and radiation have long served as alternatives to surgery. But what distinguishes the current wave of drugs is their precision. Treatments like VIR-5500 and 225Ac-PSMA-Trillium target a protein called PSMA that sits on the surface of prostate cancer cells, allowing them to deliver their payloads directly to tumors while largely sparing healthy tissue. Add to that the final results from the EMBARK trial showing a 40% reduction in overall deaths with an enzalutamide-based combination, and the landscape for men with prostate cancer looks meaningfully different than it did even three years ago. This article walks through the most promising gland-sparing prostate cancer treatments backed by recent clinical data — from immunotherapies and radioligand injections to drug combinations and focal ablation techniques — including what the trials actually showed, where the limitations are, and what these advances might mean for the future of prostate cancer care.
Table of Contents
- Which Prostate Drugs Can Shrink Tumors Without Removing the Gland?
- How VIR-5500 Works — and Where It Falls Short
- Bayer’s Radioactive “Smart Missile” — 225Ac-PSMA-Trillium
- Pluvicto and Enzalutamide — Proven Options Available Now
- Focal Therapy — Treating the Tumor, Not the Whole Gland
- The Role of PSMA — Why This Protein Changed Everything
- What Comes Next for Gland-Sparing Prostate Cancer Treatment
- Conclusion
- Frequently Asked Questions
Which Prostate Drugs Can Shrink Tumors Without Removing the Gland?
Several drugs now in clinical trials or already approved by the FDA have demonstrated the ability to shrink prostate tumors without requiring surgical removal of the gland. The most notable among them target PSMA, a protein abundantly expressed on prostate cancer cells. VIR-5500, developed by Vir Biotechnology, is a “dual-masked” T-cell engager immunotherapy that essentially introduces the immune system’s killer T-cells to cancer cells that are evading detection. In its Phase 1 dose-escalation trial, 58 heavily pretreated men with metastatic castration-resistant prostate cancer were enrolled, and at doses of 3,000 µg/kg or higher given every three weeks, 45% of RECIST-evaluable patients — five out of eleven — experienced objective tumor shrinkage. That is a remarkable response rate in a population where most available treatments have already failed. On the radiotherapy side, 225Ac-PSMA-Trillium from Bayer uses a molecular “homing device” to find PSMA on cancer cell surfaces and deliver a radioactive alpha-particle payload that kills the cell from within.
In the Phase 1 PAnTHa trial conducted at the Institute of Cancer Research and The Royal Marsden, 83% of patients saw their PSA halved, and at the recommended dose of 125 kBq/kg, the objective response rate reached 71%. For comparison, Pluvicto (lutetium-177 PSMA-617), the first FDA-approved radioligand therapy for prostate cancer, reduced overall mortality by 38% and disease progression by 60% in its pivotal VISION Phase III trial. All three of these treatments work by seeking out cancer cells and destroying them in place, without a scalpel ever touching the prostate. It is worth noting that these drugs are not interchangeable. VIR-5500 harnesses the immune system, while 225Ac-PSMA-Trillium and Pluvicto deliver radiation directly to tumor cells. The choice between them — when choices become available — will likely depend on factors like PSMA expression levels, prior treatment history, and how a patient’s body handles each drug’s side-effect profile. this is precision oncology in the truest sense: matching the right weapon to the right target in the right patient.
How VIR-5500 Works — and Where It Falls Short
VIR-5500’s mechanism is elegant in concept. As a PRO-XTEN dual-masked T-cell engager, the drug is designed to remain inactive until it reaches the tumor environment, where its “masks” are cleaved off, activating the molecule and allowing it to simultaneously bind to PSMA on cancer cells and CD3 on T-cells. This forced introduction triggers the T-cells to attack. The dual-masking is a critical safety feature — without it, T-cell engagers can wreak havoc throughout the body by activating the immune system indiscriminately. The safety data so far has been encouraging. In the Phase 1 trial, no dose-limiting toxicities were reported, and Grade 3 or higher treatment-related adverse events occurred in only 12% of patients. Cytokine release syndrome — a potentially dangerous immune overreaction that has plagued other T-cell engager therapies — occurred in 50% of patients but was generally limited to Grade 1, meaning mild symptoms like fever and chills that resolved without serious intervention.
For a class of drugs that has historically struggled with toxicity, this is a meaningful improvement. However, the caveats here are important. This remains a Phase 1 trial with 58 patients, all of whom had metastatic castration-resistant disease and had been through a median of four prior lines of therapy. The 45% objective response rate, while promising, comes from a small evaluable subset of just 11 patients. If your oncologist mentions VIR-5500, understand that it is not yet approved, it is not available outside of clinical trials, and its long-term durability of response is still unknown. Phase 1 results are proof-of-concept — they tell us the drug works and appears safe, but they do not yet tell us how long responses last or whether this translates into longer survival. Larger, randomized Phase 2 and Phase 3 trials will need to confirm these findings before VIR-5500 becomes a standard treatment option.
Bayer’s Radioactive “Smart Missile” — 225Ac-PSMA-Trillium
Bayer’s 225Ac-PSMA-Trillium represents a different strategy entirely: rather than rallying the immune system, it delivers targeted radiation. The drug is an injectable that homes in on PSMA-expressing cells and unleashes alpha particles — a form of radiation with extremely high energy but very short range. Alpha particles travel only a few cell diameters, which means they can obliterate a cancer cell while barely touching its neighbors. This is in contrast to traditional external beam radiation, which must pass through healthy tissue to reach the tumor. The Phase 1 PAnTHa trial results, first disclosed at ASCO GU 2026, were notable on several fronts. Of 24 patients with measurable disease, 46% experienced tumor shrinkage and 83% had their disease stabilized. At the recommended dose, the PSA50 response rate hit 83% and the objective response rate climbed to 71%.
Administration was straightforward: an injection every six weeks for up to four doses. The most common side effect was mild dry mouth — a far cry from the incontinence and erectile dysfunction that shadow surgical approaches. There were no dose-limiting toxicities and no treatment-related deaths. One specific advantage of 225Ac-PSMA-Trillium is its potential role for patients who have already received Pluvicto. Because Pluvicto uses beta-emitting lutetium-177 while 225Ac-PSMA-Trillium uses alpha-emitting actinium-225, the two therapies have different mechanisms of cell killing. Alpha particles cause more complex, harder-to-repair DNA damage. This raises the possibility that 225Ac-PSMA-Trillium could work in cancers that have become resistant to beta-emitting radioligands, though this hypothesis still needs to be tested in larger trials. For now, it remains investigational and is not commercially available.
Pluvicto and Enzalutamide — Proven Options Available Now
While VIR-5500 and 225Ac-PSMA-Trillium are still in early clinical trials, two gland-sparing treatments are already available and supported by more robust evidence. Pluvicto (lutetium-177 PSMA-617) earned FDA approval on March 23, 2022, making it the first approved radiotherapeutic specifically for prostate cancer. The VISION Phase III trial demonstrated a 38% reduction in overall mortality and a 60% reduction in disease progression in men with metastatic castration-resistant prostate cancer. In 2025 and 2026, the FDA expanded Pluvicto’s approval to earlier lines of treatment, allowing patients with PSMA-positive mCRPC to receive it before chemotherapy — a shift that means some men can now delay or avoid taxane-based regimens altogether. A randomized trial further showed that men receiving Pluvicto went a median of 17.6 months without disease progression, compared to 7.4 months with stereotactic body radiation therapy alone. The EMBARK trial, with its final results presented at ESMO in Berlin on October 19, 2025, and published in The New England Journal of Medicine, addressed a different patient population: men with high-risk biochemically recurrent prostate cancer, meaning cancer that has returned based on rising PSA levels after initial treatment. The combination of enzalutamide plus leuprolide acetate reduced overall deaths by 40.3% compared to leuprolide alone, with 8-year overall survival rates of 79% versus 69.5%.
The trial investigators called this an “almost unprecedented” reduction in death risk for this setting. However, enzalutamide monotherapy, while showing a 17% lower death risk, did not reach statistical significance, suggesting that the combination approach is necessary to achieve the full benefit. The tradeoff between these two treatments comes down to disease stage and biology. Pluvicto is indicated for PSMA-positive metastatic castration-resistant disease — advanced cancer that has spread and no longer responds to standard hormone therapy. The enzalutamide-leuprolide combination addresses an earlier point in the disease trajectory, where cancer has recurred biochemically but may not yet have developed visible metastases. Neither is a substitute for the other; they occupy different lanes in the treatment pathway. The critical point for patients is that both approaches preserve the prostate gland while delivering meaningful survival benefits.
Focal Therapy — Treating the Tumor, Not the Whole Gland
Beyond systemic drugs and radioligands, a growing body of evidence supports focal therapy — techniques that destroy tumors within the prostate while leaving the rest of the gland intact. High-intensity focused ultrasound (HIFU), cryotherapy, and irreversible electroporation (IRE) are the leading approaches. Rather than flooding the body with drugs or radiation, focal therapy takes aim at the specific lesion identified on imaging, a strategy sometimes compared to a lumpectomy for breast cancer versus a full mastectomy. The evidence base has matured considerably. The FARP randomized trial found that focal ablation had similar treatment failure rates at three years compared to radical prostatectomy — the gold standard surgical approach. The HIFI trial showed that whole-gland or subtotal HIFU achieved comparable short-term oncologic outcomes to surgery while delivering better functional preservation.
In practical terms, men treated with focal therapy experienced fewer problems with incontinence and erectile dysfunction. For a disease where quality of life after treatment weighs heavily on decision-making, this is not a trivial distinction. The limitation is that focal therapy works best for localized, well-defined tumors. Men with multifocal disease, high Gleason scores across multiple regions, or cancer that has begun to extend beyond the prostate capsule may not be good candidates. There is also the question of long-term follow-up. While three-year data look comparable to surgery, prostate cancer is a disease measured in decades, and we do not yet have the 10- or 15-year outcomes that would definitively establish focal therapy as equivalent to radical treatment. Patients considering focal therapy should have a frank conversation with their urologist about whether their specific cancer characteristics make it a reasonable option, or whether the risk of undertreating a more aggressive tumor outweighs the quality-of-life benefits.
The Role of PSMA — Why This Protein Changed Everything
Nearly all of the most promising gland-sparing therapies share a common thread: PSMA, or prostate-specific membrane antigen. PSMA is a protein found on the surface of prostate cancer cells, and it is overexpressed in the vast majority of prostate tumors — especially in aggressive, advanced disease. This makes it an almost ideal molecular target. Pluvicto, VIR-5500, and 225Ac-PSMA-Trillium all rely on PSMA to find and engage cancer cells, whether they are delivering radiation, recruiting T-cells, or both.
But PSMA expression is not universal. A small percentage of prostate cancers are PSMA-negative or express the protein at low levels, and these patients would not benefit from PSMA-targeted therapies. This is why PSMA PET scans have become a critical part of treatment planning — they map where PSMA-expressing cancer cells are hiding throughout the body and determine whether a patient is eligible for targeted treatment. If your oncologist recommends a PSMA PET scan, it is not just another imaging study. It is the gateway to an entire class of precision therapies that could change the trajectory of your disease.
What Comes Next for Gland-Sparing Prostate Cancer Treatment
The trajectory of prostate cancer treatment is moving unmistakably toward greater precision and less collateral damage. The next several years will bring larger trials of VIR-5500 and 225Ac-PSMA-Trillium, and if their early Phase 1 results hold up, FDA approvals could follow. Meanwhile, researchers are already exploring combination strategies — pairing radioligand therapies with immunotherapies or hormonal agents to see whether attacking cancer from multiple angles simultaneously can produce deeper, more durable responses. The expansion of Pluvicto into earlier treatment lines is a preview of this trend: as drugs prove themselves in the most advanced settings, they migrate forward to treat patients sooner, when the cancer is more vulnerable.
For patients and families navigating a prostate cancer diagnosis today, the message is cautiously optimistic. Removing the prostate is no longer the only path to controlling this disease. Between FDA-approved radioligand therapy, drug combinations with proven survival benefits, focal ablation techniques with favorable side-effect profiles, and a pipeline of investigational agents delivering response rates that would have seemed implausible a decade ago, the options for gland-sparing treatment are expanding faster than at any point in the history of this disease. The key is working with a multidisciplinary team — urologists, medical oncologists, and radiation oncologists — who can match the right treatment to the right patient at the right time.
Conclusion
Prostate cancer treatment has entered a new era in which shrinking or eliminating tumors without removing the gland is not just an aspiration but a clinical reality backed by hard data. VIR-5500 and 225Ac-PSMA-Trillium have delivered impressive early-phase results in some of the hardest-to-treat patients. Pluvicto and the enzalutamide-leuprolide combination have crossed the threshold from experimental to proven, with FDA approval and robust Phase III evidence behind them. Focal therapies offer a gland-sparing alternative for localized disease with quality-of-life advantages that matter deeply to the men who live with the consequences of treatment.
None of these approaches is a silver bullet, and none is right for every patient. The biology of the tumor, the stage of the disease, prior treatments, PSMA expression levels, and the patient’s own priorities about side effects and quality of life all factor into the decision. What has changed is that the menu of effective, gland-sparing options is longer and more evidence-based than ever before. If you or someone you know is facing prostate cancer, ask your medical team about PSMA testing, radioligand therapies, clinical trials for newer agents, and whether focal therapy might be appropriate. The conversation about prostate cancer treatment should no longer begin and end with surgery.
Frequently Asked Questions
What is PSMA and why does it matter for prostate cancer treatment?
PSMA (prostate-specific membrane antigen) is a protein found on the surface of prostate cancer cells, often at high levels in aggressive tumors. It serves as a molecular target for drugs like Pluvicto, VIR-5500, and 225Ac-PSMA-Trillium, allowing them to deliver treatment directly to cancer cells. A PSMA PET scan determines whether a patient’s cancer expresses enough of this protein to benefit from targeted therapies.
Is Pluvicto available to all prostate cancer patients?
No. Pluvicto is FDA-approved for men with PSMA-positive metastatic castration-resistant prostate cancer. Patients must first undergo a PSMA PET scan to confirm their cancer expresses the target. As of 2025-2026, its approval has been expanded to earlier treatment lines, allowing some patients to receive it before chemotherapy, but it is not indicated for localized or hormone-sensitive prostate cancer.
How does focal therapy compare to surgery for prostate cancer?
Randomized trials like FARP and HIFI have shown that focal therapy techniques — including HIFU and cryotherapy — achieve similar cancer control rates to radical prostatectomy at three years while preserving better sexual and urinary function. However, focal therapy is best suited for localized, well-defined tumors, and long-term data beyond three years are still limited.
What are the side effects of VIR-5500?
In the Phase 1 trial of 58 patients, VIR-5500 had a manageable safety profile. Cytokine release syndrome occurred in 50% of patients but was mostly Grade 1 (mild fever and chills). Serious (Grade 3 or higher) treatment-related adverse events occurred in only 12% of patients, and no dose-limiting toxicities were reported. The drug is still investigational and only available through clinical trials.
Can 225Ac-PSMA-Trillium be used after Pluvicto stops working?
This is an area of active investigation. Because 225Ac-PSMA-Trillium uses alpha particles (actinium-225) while Pluvicto uses beta particles (lutetium-177), there is a scientific rationale that the alpha-emitting therapy could work in cancers resistant to beta-emitting radioligands. However, this has not yet been confirmed in clinical trials, and 225Ac-PSMA-Trillium is not yet approved for any indication.
Did the enzalutamide combination really reduce deaths by 40%?
Yes. The final EMBARK trial results, published in The New England Journal of Medicine and presented at ESMO in October 2025, showed that enzalutamide plus leuprolide acetate reduced overall deaths by 40.3% compared to leuprolide alone in men with high-risk biochemically recurrent prostate cancer. The 8-year overall survival was 79% in the combination group versus 69.5% with leuprolide alone.
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