PCF Scientific Retreat 2021 Top Stories For Patients: Promising Treatments
The Prostate Cancer Foundation (PCF) held the 28th Annual Scientific Retreat virtually over four days in late 2021. Once again, researchers, industry partners, clinicians, patient advocates, and others were able to join from anywhere in the world to discuss the latest findings in prostate cancer research, treatment, and survivorship. PCF’s Dr. Andrea Miyahira has identified the top stories for patients. Here are two examples of promising new treatment approaches for advanced prostate cancer.
PRINCE Trial Shows Potential For Combination of LuPSMA + Pembrolizumab
Shahneen Sandhu, MBBS
Peter MacCallum Cancer Centre, Australia
Summary: LuPMSA is an emerging treatment for advanced prostate cancer that is anticipated to gain FDA approval in the next few months. The results of a recent clinical trial combining LuPSMA with pembrolizumab showed significant promise, with 73% of patients experiencing at least a 50% decline in PSA, and some patients having ongoing complete responses.
177Lu-PSMA-617 (LuPSMA) is a groundbreaking new “seek and destroy” therapy that delivers a radioactive molecule to prostate cancer cells. It significantly improves overall survival in patients with metastatic castration-resistant prostate cancer (mCRPC). However, patients treated with LuPSMA eventually progress, and further optimization is needed. Radiation therapies are thought to cause cancer cells to die in a way that alerts the immune system, and thus may synergize with immunotherapy.
Dr. Sandhu and team led the PRINCE trial to test the combination of LuPSMA with the immunotherapy drug pembrolizumab in 37 patients with mCRPC. Results were encouraging, with 73% of patients seeing their PSA drop by at least 50%. At 24 weeks, 65% of patients had radiographic progression-free survival (rPFS; no worsening of disease on scans). Some patients have had deep and durable responses: For instance, one case was presented in which an 81-year old man experienced a complete response lasting over 60 weeks. Side effects were consistent with those observed for LuPSMA and pembrolizumab alone.
Further studies are needed to define the impact of adding pembrolizumab to LuPSMA on rPFS and overall survival.
Harnessing Immune Cells to Kill Prostate Cancer
Oliver Sartor, MD
Summary: Bi-specific antibodies are a promising investigational class of treatments for advanced prostate cancer that leverage the body’s immune system to kill tumor cells. Early-phase clinical trials show efficacy for several different bi-specific antibodies. Future studies will test new agents and address mechanisms of resistance.
There is a crucial need for effective treatments for metastatic castration-resistant prostate cancer (mCRPC). One option involves immunotherapy, helping the body’s T-cells to recognize, bind to, and kill cancer cells. Bi-specific antibodies are specially-designed proteins that have two (hence the “bi”) parts and can bind to T-cells and tumor cells simultaneously. When these treatments are infused into the patient, they find their way to the tumor, bringing the T-cells with them.
As one example, AMG 160 is a bi-specific antibody that binds to prostate-specific membrane antigen (PSMA) with one of its “arms” and T-cells with the other. In a phase 1 study, nearly 70% of patients had a reduction in PSA. Certain precautions are taken to lessen side effects associated with stimulating the immune system. AMG 160 is being tested in combination with other medicines, and a number of other therapies in this class are in early-stage clinical development for the treatment of prostate cancer.