IL-15 Superagonist With or Without Vaccine in Biochemically Recurrent Prostate Cancer After Previous Stereotactic Body Radiation Therapy

Background: Biochemically recurrent prostate cancer (BCR) occurs when prostate-specific antigen (PSA) levels in the blood rise after surgery or radiation. BCR affects 30,000 to 50,000 men each year. Researchers want to know if a drug (N-803) alone or combined with a vaccine (ETBX-071) can reduce PSA in BCR prostate cancer after radiation. Objective: To test a study drug alone and combined with a vaccine in people with BCR prostate cancer who have been treated with targeted radiation to areas of recurrent prostate cancer in the past. Eligibility: People aged 18 years and older with BCR prostate cancer who have previously undergone treatment with stereotactic body radiation therapy (SBRT). Design: Participants will be screened. They will have a physical exam with blood tests. They will have tests of their heart and kidney function. They will have 3 different imaging scans of their tumors. N-803 is injected under the skin of the abdomen. ETBX-071 is injected under the skin of thigh. Participants will be divided into 2 groups: 1 group will get N-803 alone; 1 group will get both N-803 and ETBX-071. The drug or drugs will be given on the first day of 21-day treatment cycles. Participants will have 8 treatment cycles. Participants will have a follow-up visit 3 weeks after their last dose of the study drugs. Blood tests and all 3 imaging scans will be repeated. Follow-up visits will continue every 4 to 8 weeks for 5 years. These visits will include a positron emission tomography (PET) scan every 6 months.

NCT Number	NCT07686380
Lead Sponsor	National Cancer Institute (NCI)
Conditions	Recurrent Prostate Cancer, Prostate Cancer
Enrollment	65 participants
Start Date	2026-08-19
Primary Completion	2029-01-30 (estimated)
Study Completion	2029-01-30 (estimated)
Updated on ClinicalTrials.gov	2026-08-14