Progress in Prostate Cancer Research: Clinical Trials of New Therapies for Advanced Prostate Cancer

Clinicians, researchers, industry partners, and others from across the globe gathered to share the latest developments in cancer research and treatment at the European Society of Medical Oncology (ESMO) Congress in late 2022. 

Presentations included two clinical trials of new therapies for advanced prostate cancer:

• Investigating a new therapy for hormone-sensitive prostate cancer
• Early data on a new PSMA-targeted treatment for castration-resistant disease

A new therapy for high-risk metastatic hormone-sensitive prostate cancer

Recent advances in the treatment of metastatic hormone-sensitive prostate cancer (mHSPC; prostate cancer that has spread outside the prostate region and is responsive to hormone therapy) include “intensification” by adding a novel hormonal therapy and/or docetaxel chemotherapy to standard ADT. However, additional options are needed, especially for patients at high risk for worsening disease.

PCF-funded researcher Rana McKay, MD, of UCSD presented an overview of a Phase 3 clinical trial of a new therapy called abemaciclib (in addition to abiraterone prednisone) in men with “high-risk” mHSPC. Abemaciclib is currently FDA-approved for patients with certain types of breast cancer. It works by blocking certain proteins that cause cancer cells to grow. 

This trial in prostate cancer, called CYCLONE-3, is currently recruiting at approximately 270 sites in 25 countries. Eligible patients have metastatic prostate cancer (defined as four or more sites in bones, OR visceral metastases such as in the lungs or liver). Trial participants will be randomized to treatment with abiraterone prednisone abemaciclib vs. abiraterone prednisone placebo. The key study outcome is time to worsening disease on imaging scans. Other outcomes include development of treatment resistance, length of life, side effects, and quality of life. 

What this could mean for patients: A potential new treatment option for mHSPC. Talk to your doctor about what treatments, including clinical trials, might be right for you. More information about this trial can be found on clinicaltrials.gov. PCF does not endorse any particular clinical trial.

Making a SPLASH: preliminary data on lutetium-PNT2002 in patients with metastatic castration-resistant prostate cancer 

In March 2022, ¹⁷⁷lutetium-PSMA-617 (Lu-PSMA) was FDA-approved for patients with metastatic castration-resistant prostate cancer (mCRPC) who had progressed on both chemotherapy and novel hormonal therapy. Lu-PSMA is a targeted treatment that binds to PSMA proteins on the surface of prostate cancer cells and delivers a tiny dose of radiation (the ¹⁷⁷lutetium), killing the cell. At PCF, we frequently get the question from patients with prostate cancer who are at an earlier stage of the disease: Can I use this type of therapy?

While not currently FDA-approved, PSMA-directed therapy in earlier stages of prostate cancer is being tested in clinical trials. Aaron Hansen, MD, PhD, of Princess Margaret Cancer Centre in Toronto presented preliminary results of the SPLASH trial. This is a phase 3 randomized study evaluating PSMA-targeting therapy in patients with mCRPC who have progressed after treatment with a novel hormonal agent and who have a positive PSMA PET scan. The therapy is called ¹⁷⁷supLu-PNT2002 and is different from the drug approved in March. 

The results from the lead-in portion of the trial, which tested safety and dosing in 27 patients, were encouraging. At one year, an estimated 44% of patients will remain free from worsening disease on imaging scans. 42% of patients saw their PSA decline by 50% or more. 11% had severe treatment-related side effects. This is a small “lead-in” study, and more data are needed, following a large number of patients over a longer time. Next steps include continuing to enroll a total of approximately 400 patients in the phase 3 trial at centers in North America and Europe.

What this could mean for patients: An additional type of PSMA-targeted treatment called ¹⁷⁷Lu-PNT2002 may prove to be effective in mCRPC before patients progress on chemotherapy. Patients with mCRPC currently have several treatment options (including clinical trials), depending on their disease course, prior therapies, and characteristics of their disease. Talk to your doctor about your options. You can find more information about the SPLASH trial here. PCF does not endorse any particular clinical trial.