What is Lu PSMA (Lutetium-Prostate Specific Membrane Antigen) Therapy?

Lu177 PSMA Therapy is a treatment for patients with prostate cancer, especially those who have become refractory to conventional therapy. Lutetium PSMA therapy helps to slow down the growth of the cancer cells, reduce the size of the tumours and most importantly improve the quality of life of the patients by reducing the pain caused by the cancer.

Many prostate cancers, in particular those that have spread or become resistant to hormonal therapies, express a unique receptor on their cell surface called Prostate Specific Membrane Antigen (PSMA). When Prostate Cancer metastasizes i.e. spreads to other parts of the body, the PSMA receptor is expressed over the sites of metastases as well.

How does Lu PSMA Therapy Work?

Lutetium-177 is a radioactive substance that emits beta radiation, a destructive kind of radiation. Lutetium-177 is bound to a small peptide which attaches to the PSMA receptor expressed on the cancer cell surface. The Lutetium 177 – PSMA complex, thus attached to the prostate cancer cell, then emits killing radiation causing cell death of the cancer cell. Since the penetration of the emitted beta particle is very small, the surrounding normal cells are spared.

How is the Therapy Done?

Lu177 PSMA is administered intravenously. The patient is admitted to the hospital for 24 hours. A kidney function scan called a MAG3/EC scan is done prior to the administration of the Lu177 PSMA.

What are the Side Effects of Lu PSMA Therapy?

Lu177 PSMA is well tolerated. The most common side effects are a slightly dry mouth, fatigue and nausea. There may also be a slight fall in the white blood cells and platelets about 2 – 3 weeks after the Lu177 PSMA administration.

What is the Response Rate With Lu PSMA Therapy?

The response rates of Lu177 PSMA depend on the tumour biology of prostate cancer, the initial Gleason Score, the extent of disease and the responses to prior therapies. Typically, more than 70% of patients demonstrate a reduction in S. PSA and a shrinkage of tumours following Lu177 PSMA therapy.

When would the doctor consider using this Therapy?

Lu PSMA Therapy is a very specific therapy and is used for managing metastatic Prostate Cancer or when Prostate Cancer is no longer responsive to other types of treatment.

What are the Treatment Schedules with Lu PSMA Therapy?

Most patients undergo three-four treatment cycles at intervals of 8-12 weeks. The number of cycles and the interim duration may vary between individuals depending on the response and interim assessments.

Why should I choose the nuclear medicine therapy center at Fortis Memorial & Research Institute (FMRI), Gurugram (Haryana, India)?

The Nuclear Medicine Therapy Centre at FMRI was one of the first institutes to offer Radio-ligand Therapy with Lu PSMA, and today, the center receives patients from the country and from across the world.

Peptide Receptor Radionuclide Therapy (PRRT): A Comprehensive Clinical Overview

Summary (10 sec read)

Dr. Ishita Sen explains - Peptide Receptor Radionuclide Therapy (PRRT) is an advanced, targeted treatment for neuroendocrine tumors (NETs) that express somatostatin receptors. It offers significant benefits over chemotherapy, including better tumor targeting, fewer side effects, symptom relief, and improved survival rates. PRRT is especially effective for advanced-stage, metastatic, or inoperable NETs.

What is PRRT?

Peptide Receptor Radionuclide Therapy (PRRT) is a cutting-edge molecular technique designed to treat neuroendocrine tumors (NETs), which express somatostatin receptors. These tumors can arise in various parts of the body, such as the pancreas, small and large bowel, lungs, and even adrenal glands, known as pheochromocytomas, or along the sympathetic chain, referred to as paragangliomas. PRRT uses a radiolabeled peptide, such as Lutetium-177 (Lu-177) or Yttrium-90 (Y-90), to target and deliver radiation directly to these tumor cells, leaving healthy tissue largely unaffected.

Dr. Ishita Sen explains PRRT as "a molecular technique in which a radioisotope, labeled with a small body that targets a particular receptor known as the somatostatin receptor, is used to treat neuroendocrine tumors." These tumors, according to Dr. Ishita Sen, "can arise from various parts of the body and can cause symptoms depending on the type of hormone secreted by the tumor."

PRRT Versus Conventional Treatment?

Compared to conventional treatments, such as surgery, external beam radiation, and chemotherapy, PRRT offers a more targeted, less invasive approach. Surgery remains the preferred method for early-stage localized NETs, but it is often unsuitable for metastatic or inoperable tumors. Chemotherapy, while effective in aggressive forms of cancer, tends to be less effective in well-differentiated, slow-growing neuroendocrine tumors, which are often refractory to such treatment.

PRRT provides a targeted alternative by focusing on somatostatin receptors overexpressed by the tumor cells. This precision minimizes damage to surrounding healthy tissues, making PRRT particularly effective for patients with advanced or metastatic NETs. Dr. Ishita Sen emphasizes that “chemotherapy does not work for these tumors, and the treatment of choice is a targeted therapy called PRRT.” This underscores the distinct advantage of PRRT in cases where traditional treatments fall short.

PRRT Versus Chemotherapy?

Chemotherapy affects rapidly dividing cells indiscriminately, including healthy cells, leading to systemic toxicity and a host of side effects. PRRT, on the other hand, selectively targets tumor cells that express somatostatin receptors, offering fewer side effects and improved outcomes. In Dr. Ishita Sen’s words, “PRRT reduces tumor burden and improves survival while giving patients significant symptomatic relief.” This specificity makes PRRT superior to chemotherapy for neuroendocrine tumors, especially those that are well-differentiated and slow-growing.

The NETTER-1 trial, a pivotal study on PRRT, demonstrated significantly longer progression-free survival (40 months) in patients receiving Lutetium-177 PRRT compared to those receiving high-dose somatostatin analogs alone (8 months). Additionally, PRRT has been shown to provide partial tumor shrinkage in 20-30% of patients and disease stabilization in 70-80% of cases.

What is the PRRT Success Rate?

The success rate of PRRT is impressive, especially in patients with metastatic or inoperable neuroendocrine tumors. Dr. Ishita Sen explains that PRRT can “reduce tumor burden, improve patient survival, and provide significant symptomatic relief.” This includes managing symptoms such as diarrhea, hypoglycemia, and flushing, which result from the hormone secretion by neuroendocrine tumors. PRRT not only extends survival but also improves the quality of life for patients by reducing the symptoms associated with these tumors.

Studies have shown that overall survival rates for PRRT-treated patients range from 63 to 72 months, depending on the stage and type of the neuroendocrine tumor. PRRT provides long-term disease control for many patients, significantly extending their life expectancy.

What to Expect After PRRT Treatment?

After undergoing PRRT, most patients experience mild side effects, including fatigue, nausea, and abdominal discomfort. These symptoms usually subside within a few days. Blood tests are routinely performed to monitor for potential side effects like low blood cell counts and kidney function changes, as PRRT can cause mild bone marrow suppression. Dr. Ishita Sen notes that PRRT “not only reduces the tumor burden but also provides relief from symptoms like diarrhea, flushing, and hypoglycemia,” which are common in neuroendocrine tumor patients.

Patients are also advised to avoid close physical contact with others for about a week post-treatment due to residual radioactivity. Most patients can resume normal activities shortly after their treatment, although fatigue may persist for some time.

How Long Are You Radioactive After PRRT?

The duration of radioactivity after PRRT depends on the isotope used. Lutetium-177, with a half-life of 6.7 days, is largely eliminated from the body within the first week after treatment. Dr. Ishita Sen explains that the radiopharmaceutical injected into the bloodstream “targets the somatostatin receptors on tumor cells, leaving normal cells unharmed since they do not express these receptors.” After 7 days, the residual radioactivity is minimal, allowing patients to return to their usual routines.

Long-Term Side Effects of PRRT?

The long-term side effects of PRRT are generally mild compared to conventional therapies such as chemotherapy. The most significant long-term concern is bone marrow suppression, which can lead to anemia, leukopenia, and thrombocytopenia. In rare cases, patients may experience nephrotoxicity, particularly with Yttrium-90-based PRRT, although this is mitigated by the use of Lutetium-177, which has a better safety profile for the kidneys.

Dr. Ishita Sen highlights the importance of regular monitoring during and after PRRT to detect any early signs of organ damage, particularly in the liver and kidneys. Routine follow-ups with blood tests and imaging studies help track both tumor response and potential side effects.

PRRT for Neuroendocrine Tumors?

PRRT is particularly effective for neuroendocrine tumors that express somatostatin receptors, making it an ideal treatment for gastro-entero-pancreatic neuroendocrine tumors (GEP-NETs) and other somatostatin receptor-positive tumors. Dr. Ishita Sen explains that the radiopharmaceutical “seeks out somatostatin receptors on the tumor cells, allowing for precise targeting.” This makes PRRT highly suitable for patients with metastatic or inoperable tumors, where surgery is not an option.

Neuroendocrine tumors can secrete hormones, leading to a range of symptoms based on the type of hormone produced. PRRT can alleviate many of these symptoms by reducing tumor size and hormone secretion, improving patients' overall quality of life.

Also Read

Can you live for 20 years after prostate removal?

Combating Xerostomia: Botox Shows Promise in Actinium-225 Therapy

Unlocking Advanced PRRT Combination of PRRT and Chemo for treating Neuroendocrine Tumors

Patients With Nets Survive For Many Years With PRRT

Yttrium-90 (Y-90) Radioembolization: A Comprehensive Guide for Liver Cancer Treatment

Alpha Emitters Are 5 Times More Potent Than Beta Emitters By Dr. Ishita B. Sen

Frequently Asked Questions

What is the PRRT Procedure?

The PRRT procedure typically involves intravenous administration of a radiopharmaceutical that targets somatostatin receptors. Patients undergo multiple treatment cycles, usually spaced 6-8 weeks apart. Dr. Ishita Sen notes that each treatment session involves injecting the radiopharmaceutical, which then “enters the bloodstream and seeks out the somatostatin receptors on tumor cells,” delivering targeted radiation to the cancer cells.

Each session lasts about 3-4 hours, and patients are monitored for immediate side effects. Post-treatment care includes safety protocols to minimize radiation exposure to others, and most patients are able to return home the same day.
Learn about PRRT Side Effects.

PRRT is generally well-tolerated, with the most common side effects being mild nausea, fatigue, and abdominal discomfort. Dr. Ishita Sen emphasizes that PRRT is “a very targeted process that spares surrounding healthy cells.” More serious side effects, such as bone marrow suppression or nephrotoxicity, are rare and typically managed with regular monitoring and supportive care. Overall, PRRT offers a more favorable side-effect profile than traditional treatments like chemotherapy.
PRRT Therapy Cost.

The cost of PRRT varies depending on the country and healthcare system. In the United States, the cost of a full course of PRRT (four cycles) can exceed $200,000. In Europe, treatment is generally more affordable, ranging from €60,000 to €100,000. PRRT is more cost-effective in countries like Turkey, Thailand, Malaysia, and India, where treatment costs range from $30,000 to $80,000.
Post-PRRT Treatment and Prognosis.

After PRRT, patients require regular follow-up visits to monitor the effectiveness of the treatment and manage any long-term side effects. This includes routine blood tests and imaging studies to assess tumor response. The therapeutic effects of PRRT may continue for several months after the last treatment cycle, providing long-term disease stabilization for many patients.

According to Dr. Ishita Sen, PRRT not only reduces tumor burden but also improves survival outcomes and symptom control, particularly for patients with advanced-stage or metastatic neuroendocrine tumors. Studies have shown that PRRT significantly extends survival, with many patients achieving disease stabilization for several years after treatment.

Peptide Receptor Radionuclide Therapy (PRRT) continues to show remarkable efficacy in the treatment of neuroendocrine tumors. As Dr. Ishita Sen puts it, “PRRT offers a targeted approach that not only prolongs life but also significantly improves the quality of life for patients with advanced neuroendocrine tumors.”

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