What Patients with Prostate Cancer Should Know About PSMA Imaging and Therapy

Prostate cancer begins when cells in the prostate gland start to grow out of control. These cancerous cells may remain in the prostate or metastasize and spread to other parts of the body such as the bones, lymph nodes, liver, or lungs. 

Prostate-specific membrane antigen (PSMA) is a protein found on the surface of prostate cancer cells. PSMA-targeting can be used to locate, identify, or treat cancerous cells in both the prostate as well as cancerous cells that have metastasized in other organs. This targeting can involve attaching a radionuclide, a particle that gives off radiation, to different molecular agents, most often monoclonal antibodies or small molecule targeting agents (also known as peptides, ligands, or inhibitors). This combination attaches to the PSMA receptors located in the cancer cells. 

PSMA positron emission tomography (PET) scans are an imaging technique approved by the U.S. Food and Drug Administration (FDA). PSMA PET is able to precisely locate prostate cancer cells using a radioactive imaging agent that binds to prostate cancer cells to help localize them. This drug is injected into the body and attaches itself to PSMA proteins expressed by prostate cancer patients. The PET scan is then able to detect and pinpoint the prostate cancer tumors.

Weill Cornell Medicine was one of the first centers in the United States offering this technology for patients. PSMA PET is able to identify whether the cancer has spread beyond the prostate gland with higher accuracy than other imaging methods. 

The team at the Weill Cornell Medicine Genitourinary (GU) Oncology Program has been a pioneer for PSMA-targeted therapies for many years. PSMA-targeted radionuclide therapies lead the combination of radionuclide and molecular agents directly to the PSMA cell receptors. The ability for the targeting agents and the PSMA receptors to join together provides this therapy the ability to precisely target prostate cancer cells.  

In March 2022, the FDA approved 177Lu-PSMA-617 (also known as Lu 177 vipivotide tetraxetan or Pluvicto) for the treatment of patients with metastatic castration-resistant prostate cancer. Dr. Scott Tagawa, director of the Weill Cornell Medicine Genitourinary (GU) Oncology Program, was a member of the steering committee for the trial evaluating this treatment that led to the approval. 

“The first availability of tumor-targeted radionuclide therapy on a commercial basis will allow patients with more limited resources that might not have been able to travel for a clinical trial or overseas to receive the benefit of this treatment. The first successful phase 3 trial allows us in research to optimize the treatment, study it in earlier disease states, and explore combinations with other therapies with scientific merit. Even after this approval, I encourage clinical trial participation and/or referrals.”

Scott Tagawa, MD, MS

Weill Cornell Medicine will be one of the first centers able to offer this therapy to patients immediately for both our existing patients and those who may be referred to us if their local provider doesn’t immediately have access to this therapy.  

Our team continues to lead and participate in a number of clinical trials aimed at ongoing testing and research for additional PSMA-targeted imaging and treatment. We are one of few centers in the world currently able to provide treatment plans that involve both PSMA-PET imaging and multiple PSMA-targeted therapies for our patients, as well as the opportunity to participate in these types of clinical trials in order to further develop PSMA technology.  

The Weill Cornell Medicine Genitourinary (GU) Oncology Program provides top-notch care, knowledge, and expertise for our patients. We offer new patient appointments, second opinions, and ongoing care for people with genitourinary cancers, including prostate cancer. To learn more or to make an appointment with one of our physicians, please call us at 646-962-2072. If interested in a clinical trial, please email us at guonc@med.cornell.edu.

NYC Prostate Cancer Virtual Mini Summit

The Annual NYC Prostate Cancer Summit has been taking place virtually this year as a four-part webinar series for prostate cancer patients and loved ones. We are pleased to be able to come together online while the pandemic prevents us from gathering in-person. Each part of the FREE virtual series features different topics and speakers, and offers unprecedented access to some of the field’s foremost experts! We hope you’ll join us for this webinar series.

Advances in therapeutics have led to improvements in both survival and quality of life for men with advanced or metastatic prostate cancer. Get the latest information about how physicians can more clearly detect where prostate cancer has traveled in the body and the most cutting-edge therapies for patients. Part 3 – Advanced Prostate Cancer Treatment Updates is taking place on Wednesday, May 12 at 7pm ET. The program is free to attend, but RSVP is required. Register today!

Register now – http://bit.ly/summitpart3

Mark your calendar and sign up for Part 4 – Genetic Links: Family History, Precision Medicine & More on Thursday, July 15th at 7PM ET. Precision medicine is changing the way physicians approach prostate cancer care, using information about the prostate cancer genetics and a patient’s inherited genetic makeup to develop individualized treatment plans. Cutting-edge research advances in prostate cancer biology are shaping treatment breakthroughs and guiding the development of new therapeutics and clinical trials. All prostate cancer patients and family members are welcome.

Register now – http://bit.ly/summitpart4

View Part 1 and Part 2 Webinar Recordings On-Demand:

If you missed any of the earlier webinar sessions or would like to re-watch the recordings, Part 1 “Living with Prostate Cancer” and Part 2 “Newly-Diagnosed: What Are My Treatment Options” of the series can be viewed On-Demand.

Learn more and sign up for the entire webinar program series at prostatesummit.org.

Visit http://www.prostatesummit.org to learn more and participate in this free, virtual webinar series.

Update in PSMA-Targeting for Imaging and Therapy

Prostate-specific membrane antigen (PSMA) is a protein concentrated on the surface of prostate cancer cells with limited expression on other locations in the body.  As covered previously on the blog, PSMA can be exploited for both imaging and treatment utilizing either large monoclonal antibodies or small molecule targeting agents

PSMA-targeting entails attaching a radionuclide (a particle that gives off radiation) to an antibody or small molecule designed to recognize and bind to PSMA. Research into PSMA-targeting has led to promising investigational treatments and transformed how we can detect prostate cancer. In December 2020, the U.S. Food and Drug Administration (FDA) gave limited approval for 68Ga-PSMA11 PET scans for patients with high-risk localized prostate cancer and patients with rising prostate specific antigen (PSA) levels following radiation or surgery. This form of FDA approval allowed for specific facilities in California to use this agent outside of the clinical trial environment. 68Ga-PSMA PET, which has been used elsewhere in the world without strict regulation, allows doctors to better detect recurrent and hidden prostate cancer and consequently, to choose the best type of therapy for each patient.

Weill Cornell has a dedicated team of physicians that study and interpret 68Ga-PSMA PET imaging. Numerous studies have demonstrated that 68Ga-PSMA PET is more effective than traditional scans (such as CT or MRI) in finding metastatic prostate cancer (sites where the cancer has spread elsewhere, including microscopically) and in a small head-to-head study was also better than 18F-fluciclovine (Axumin) PET/CT. There are a number of ongoing trials at Weill Cornell and elsewhere evaluating the use of PSMA targeted imaging, which currently remain the only way to obtain PSMA PET outside of California, with additional approvals of PSMA PET agents expected in the first half of 2021.

At the 2021 Genitourinary (GU) Cancers Symposium, researchers presented a head-to-head comparison of 68Ga-PSMA11 PET vs. MRI in detecting and staging localized prostate cancer (disease mainly confined within the prostate) in 74 patients. The two imaging methods had similar performance, with PSMA PET a little better for tumors outside of the prostate and MRI better for identifying tumor invasion of structures adjacent to the prostate. It may be that the combination of both methods will further enhance prostate cancer staging and a study is currently being done at WCM to evaluate this combination.

Additionally, a number of studies on PSMA-therapeutics were presented at the 2021 Genitourinary Cancers Symposium. There is an ongoing trial investigating PSMA-targeted radionuclide therapy (PSMA-TRT) with radioactive iodine in combination with the prostate cancer drug enzalutamide; radioactive iodine (Iodine-131) is conjugated to the small molecule 1095. An initial study of 10 patients receiving PSMA-directed/TGFβ-insensitive CAR-T cells (immune cells that have been engineered to recognize PSMA) demonstrated safety and efficacy. In this study, 60% of patients experienced PSA decline, ranging from 11.6 to 98.3%, and post-treatment biopsies demonstrated CAR-T cells infiltrating the tumor microenvironment. Furthermore, there is an ongoing clinical trial of a bispecific antibody (REGN5678) that connects PSMA with immune cells, which can subsequently destroy the cancer cell; this bispecific antibody is combined with a medication called cemiplimab that further strengthens the body’s immune response. 

There are multiple agents utilizing PSMA small molecules to carry the beta-emitting radionuclide lutetium-177 (177Lu) to PSMA-positive areas in the body (mostly areas of cancer spread). Updated results of a prospective head-to-head comparison of 177Lu-PSMA-617 vs. cabazitaxel (a type of chemotherapy) in 200 patients with advanced prostate cancer were presented at the 2021 Genitourinary Cancers Symposium.  In the data initially shared at ASCO 2020, the main objective was met, with more patients receiving 177Lu-PSMA-617 having PSA response compared to cabazitaxel chemotherapy.  In the updated report, patients receiving 177Lu-PSMA-617 had longer disease control (both by PSA measurements and scans), with fewer side effects and more improvements in quality-of-life. Recently, VISION, the multicenter phase III clinical trial comparing 177Lu-PSMA-617 + standard of care against standard of care alone in patients with advanced metastatic prostate cancer, has shown that patients receiving 177Lu-PSMA-617 lived longer and had longer disease control. Full results will be presented at an upcoming research conference, and we hope that this study leads to FDA approval in the future.

In general, tumors spread to other parts of the body via the bloodstream. The ability to capture these tumor cells, called circulating tumor cells (CTCs), has led to significant prognostic information along with the ability to study the cells as part of a “liquid biopsy”.  When a number of different types of therapy is able to decrease or clear CTCs from the circulation, those therapies generally make patients live longer.

Scans before and after treatment with PSMA-targeted radionuclide therapy (PSMA-TRT).

Weill Cornell researchers examined several sequential prospective clinical trials utilizing various PSMA-TRT agents. In an analysis of 116 patients, 70% treated with PSMA-TRT and with CTC counts before and after therapy had a decline in CTC counts. Some PSMA-targeting agents (i.e. the carrier molecules) may have anti-cancer effects on their own. While it appears that agents labeled with radioactive particles are more effective, some patients treated with anti-PSMA antibody J591 alone had control of CTC counts.

Alpha and beta-emitting radionuclides have different properties.  In 2020, we presented preliminary information at ASCO that a single dose of the potent alpha-emitter actinium-225 (225Ac) linked to antibody J591 (225Ac-J591) was safe, and despite lack of selection of patients with PSMA PET and prior 177Lu-PSMA therapy in the majority, 60% had PSA decline.

At the 2021 GU Cancers Symposium, investigators presented the design of WCM’s ongoing clinical trial investigating either fractionated (2) or multiple-dose (1-4 doses) of 225Ac-J591.  This study (NCT04506567) is one of many PSMA-targeted therapeutic clinical trials open at Weill Cornell Medicine and NewYork-Presbyterian Hospital.

%d bloggers like this: