(UroToday.com) The 2025 American Society of Clinical Oncology (ASCO) Genitourinary (GU) Annual Symposium held in San Francisco, CA between February 13–15, 2025 was host to a prostate cancer poster session. Dr. Ravi Madan presented the preliminary results of a 6-months PSMA follow-up study prospectively monitoring patients with prostate-specific membrane antigen (PSMA)-positive recurrence prostate cancer.
PSMA PET imaging has been shown to have improved performance characteristics, compared to conventional imaging, for localizing sites of disease recurrence in biochemically recurrent prostate cancer patients following definitive surgery/radiotherapy.1 Metastasis-directed radiotherapy to sites of PMSA-positive disease is commonly performed, but Dr. Madan noted that high-level evidence conclusively demonstrating its long-term benefit remains lacking. PSMA+ recurrent prostate cancer (PSMArpc) is often defined and treated as metastatic castration sensitive prostate cancer (mCSPC), yet PSMA imaging alone as an eligibility criterion was never studied in the mCSPC trials. PSMArpc requires better understanding to define at-risk patients.
NCT05588128 is an ongoing prospective study enrolling patients with recurrent prostate cancer following definitive and possibly salvage therapies. Patient eligibility criteria are as follows:
- ≥1-year post-definitive therapy
- Prostate-specific antigen (PSA) level ≥0.5 ng/mL
- Testosterone ≥100 ng/dL
- Negative findings on conventional CT and bone scans
- Lymph nodes (LNs) up to 1.5 cm and prior therapies are permitted.
At study entry, all patients underwent baseline PSMA imaging. If positive, this was repeated every 6 months. Otherwise, if negative, it was done annually. Conventional CT and bone scans were also annually performed. Patients were allowed to receive radiation or systemic therapy for ≤6 months while remaining on study. The trial aims to enroll up to 350 patients with a planned follow-up up to five years.
Since March 2023, over 100 patients have been enrolled, with 73 evaluable after the six-month PSMA scan/follow-up. The median age was 71 years, median PSA was 2.8 ng/mL, and median PSA doubling time was 11.1 months (30% <6 months).
A descriptive analysis revealed:
- Overall PSMA findings: Of the 73 evaluable patients, 48 were PSMA-positive metastases, 10 were PSMA-negative, and 15 had only local disease findings
- Among those who had evidence of PSMA+ nodal disease:
- Single +LN: 15
- 2–3 +LNs: 8
- 4 +LNs: 4
- ≥5 +LNs: 16
- Bone and serosal disease: 6 patients had positive bone findings on PSMA, but negative bone scans; 3 patients had PSMA+ serosal nodules.
Following baseline PSMA imaging:
- 3 patients received radiation therapy for solitary LNs (only 1 demonstrated resolution with PSA decline).
- 1 patient initiated androgen deprivation therapy (ADT).
- 1 patient received salvage radiation.
- 4 patients enrolled in a National Cancer Institute (NCI) clinical trial without ADT.
At the six-month follow-up:
- Only 2 patients progressed to metastatic disease (both with positive bone scans).
- No patients developed LNs beyond eligibility size criteria.
- No new visceral metastases were detected.
Dr. Madan concluded that preliminary data from this ongoing, prospective study suggests that PSMArpc represents an indolent disease course, with minimal risk of clinically relevant progression over six months. This study continues to accrue at the NCI and aims to refine risk stratification for high-risk PSMArpc. These findings may inform the risk-benefit assessment for aggressive treatment strategies and future clinical trial designs in PSMArpc.
Presented by: Ravi A. Madan, MD, Medical Oncologist, Head of Prostate Cancer Clinical Research, Center for Cancer Research, National Cancer Institute, Bethesda, MD
Written by: Rashid K. Sayyid, MD, MSc – Robotic Urologic Oncology Fellow at The University of Southern California, @rksayyid on Twitter during the 2025 Genitourinary (GU) American Society of Clinical Oncology (ASCO) Annual Meeting, San Francisco, CA, Thurs, Feb 13 – Sat, Feb 15, 2025.
Reference:- Hofman MS, Lawrentschuk N, Francis, RJ, et al. Prostate-specific membrane antigen PET-CT in patients with high-risk prostate cancer before curative-intent surgery or radiotherapy (proPSMA): A prospective, randomized, multicentre study. Lancet 2020 Apr 11;395(10231):1208-1216.