Multitargeted Recombinant Ad5 PSA/MUC-1/Brachyury-Based Immunotherapy (TriAdeno) Vaccine With IL-15 Superagonist N-803 in Participants With Clinically Localized Prostate Cancer Undergoing Active Surveillance

Phase II Trial of a Multitargeted Recombinant Ad5 PSA/MUC-1/Brachyury-based Immunotherapy (TriAdeno) Vaccine With IL-15 Superagonist N-803 in Participants With Clinically Localized Prostate Cancer Undergoing Active Surveillance

Background:

Prostate cancer is the second most common cause of cancer-related death among men in the United States. Early-stage, low-grade prostate cancer is managed with active monitoring. However, 35% of men with this cancer will need treatment within 5 years because of tumor growth. Researchers want to know if a new vaccine that targets 3 anti-cancer proteins (TriAdeno) plus a drug (N-803) approved for bladder cancer can help stop prostate tumors from growing.

Objective:

To test TriAdeno and N-803 in people with early-stage prostate cancer.

Eligibility:

People aged 18 years and older with early-stage low- or medium-risk prostate cancer.

Design:

Participants will be screened. They will have a physical exam with blood tests. They will have a test of their heart function. They will have an imaging scan. They may have a rectal exam.

TriAdeno is injected under the skin of the upper thigh; N-803 is injected under the skin of the abdomen. Participants will be treated in up to four 21-day cycles. They will get both injections on the first day of each cycle.

Participants may opt to complete a memory aid: They may record all of their symptoms for 7 days after each injection. They may also complete a questionnaire about their prostate symptoms.

Blood tests, imaging scans, and other tests will be repeated during the study.

A tissue sample (biopsy) of the tumor will be collected during or after cycle 2; a second biopsy may be taken about 1 year later.

Participants will have follow-up phone calls for 5 years....

Study Overview

• Status: Not yet recruiting
• Conditions: Neoplasms; Neoplasms by Histologic Type; Adenocarcinoma; Carcinoma; Neoplasms, Glandular and Epithelial; Prostate Cancer
• Intervention / Treatment: Biological: TriAdeno vaccine; Drug: N-803

Detailed Description

Background:

• Prostate cancer (PCa) is the most common non-cutaneous cancer and second most common cause of cancer-related death among men living in the United States.
• With increasing detection of localized, low-grade PCa in the prostate-specific antigen (PSA) screening era, active surveillance of PCa has emerged as a viable management strategy in selected, favorable risk population. Though active surveillance is the preferred management strategy for low-grade PCa and an option for selected favorable, intermediate risk disease according to the National Comprehensive Cancer Network (NCCN), up to 35 percent of men will need radical therapy within 5 years due to progression of PCa.
• Vaccine strategies represent a novel therapeutic approach in the prevention and possible treatment of early-stage PCa. A new trivalent vaccine which targets 3 tumor associated antigens (PSA, brachyury, and MUC-1) has been shown to induce an immune response in a Phase I study of patients with metastatic castrate-resistant PCa.
• N-803 is an IL-15 agonist that activates and expands T cells and NK cells. N-803 enhances anti-tumor activity in combination with tumor-targeted vaccines. Clinically, multiple studies have demonstrated the safety of tumor-targeted vaccine in combination with PD-1/PD-L1 blockade. Adding N-803 to PD-1/PD-L1 blockade can produce antitumor responses in disease states where responses to PD-1/PD-L1 alone would not be expected.
• The TriAdeno vaccine has not been evaluated in populations with early stage, low grade PCa.

Primary Objective:

-To determine the effect of an Ad5 PSA/MUC-1/brachyury-based immunotherapy vaccine (TriAdeno) with IL-15 superagonist N-803 on immune infiltration of the local tumor environment by comparing pre- and post-treatment CD8+ and CD4+ T-cell density within the malignant portion of prostate biopsies in participants on active surveillance for low and intermediate risk prostate cancer

Eligibility:

• Biopsy-proven, organ confined low or intermediate risk adenocarcinoma of the prostate
• Age >=18 years
• Serum PSA <20 ng/mL (or <10 ng/mL for participants being treated with 5-alpha reductase inhibitors)
• Eastern Cooperative Oncology Group (ECOG) performance status <=1

Design:

• This is an open-label, non-randomized Phase II trial of TriAdeno vaccine given concurrently with N-803 in participants with localized, early stage, low and intermediate risk PCa on active surveillance.
• The TriAdeno vaccines will be administered subcutaneously (SC) at doses of 5x1011 viral particles (VP) on Day 1 of every 21-day cycle for up to four (4) cycles.
• N-803 will be administered SC at 15 mcg/kg on Day 1 of every 21-day cycle for up to four (4) cycles.
• Up to 49 participants may be treated.

• Study Type: Interventional
• Enrollment (Estimated): 52
• Phase: Phase 2

Contacts and Locations

• Study Contact: Name: Peter A Pinto, M.D.; Phone Number: (240) 858-3700; Email: pp173u@nih.gov
• Study Contact Backup: Name: Genevieve C Fromm; Phone Number: (240) 858-3663; Email: genevieve.fromm@nih.gov

Study Locations

• United States
  • Maryland
    • Bethesda, Maryland, United States, 20892
      • National Institutes of Health Clinical Center
      • Contact: National Cancer Institute Referral Office; Phone Number: 888-624-1937; Email: ncimo_referrals@mail.nih.gov

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

• INCLUSION CRITERIA:
• Histologically confirmed diagnosis of organ confined, low- or intermediate-risk PCa (Gleason grade group 1 or 2) identified in at least one prostate biopsy core. Biopsies performed at outside institutions should have Gleason score confirmed at the NCI by a genitourinary (GU) pathologist.
• Participants must be on active surveillance.
• Pre-study treatment tissue availability (at least one formalin-fixed paraffin embedded [FFPE] biopsy core or one H and E-stained slide and at least 5 unstained slides) obtained between 3 and 24 months prior to treatment initiation is mandatory for study initiation.
• Serum PSA level of <20 ng/mL (or <10ng/mL for participants being treated with 5- alpha-reductase inhibitors)
• Clinical stage <=T2a by digital rectal exam (DRE)
• Age >=18 years
• Eastern Cooperative Oncology Group (ECOG) performance status <=1.

• Adequate organ and marrow function as defined below:

  • Absolute neutrophil count (ANC) >=1.0 x 109/L
  • Hemoglobin (Hgb) >=9 g/dL
  • Platelets >=75,000/mcL
  • Prothrombin International Normalized Ratio (INR) <1.5 x upper limit of normal (ULN)
  • Partial thromboplastin time (PTT) <1.5 x ULN
  • Total bilirubin <1.5 x ULN
  • Aspartate aminotransferase (AST) <=2.5 x ULN
  • Alanine aminotransferase (ALT) <=2.5 x ULN
  • Creatinine <=1.5 x ULN

OR

--Calculated Creatinine clearance >=40 mL/min/1.73 m2 for individuals with creatinine levels above institutional normal (using either Chronic Kidney Disease Epidemiology Collaboration [CKD-EPI] equation)

• Treatment with steroid therapy must have a washout of at least 6 weeks prior to initiation of study treatment. Physiologic (replacement) doses of steroids as well as nasal, topical, or inhaled steroids are allowed.
• Vaccination with a live (attenuated) vaccine (e.g., FluMist(R)) or a killed (inactivated)/subunit vaccine (e.g., PNEUMOVAX(R), Fluzone(R)) must occur not sooner than 28 days or 14 days, respectively, prior to initiation of study treatment.
• Participants must agree to use an effective method of contraception (barrier, surgical sterilization, abstinence) for the duration of the study treatment and up to one (1) month after the last vaccine injection. We also will recommend participants with female partners of childbearing potential to ask them to be on highly effective birth control (hormonal, intrauterine device [IUD], surgical sterilization). Participants must not freeze or donate sperm within the same period.
• Participants must be able to understand and willing to sign a written informed consent document.

EXCLUSION CRITERIA:

• Prior treatment for PCa by surgery, radiation, local ablative (i.e., cryosurgery or highintensity focused ultrasound), or androgen-deprivation therapy.
• Evidence of PCa with metastatic disease.
• Prior treatment with adenovirus-based vector immunotherapy, adenovirus-based vaccines, or investigational vaccines.
• Prior solid organ or bone marrow transplant.
• Immunodeficiency or splenectomy.
• Presence of a known active acute or chronic infection, including human immunodeficiency virus (HIV), confirmed by PCR, and hepatitis B virus (HBV) and hepatitis C virus (HCV), as determined by hepatitis B surface antigen (HBsAg) and HCV serology.
• History of autoimmune disease (active or past), except for autoimmune-related thyroid disease, type I diabetes, and vitiligo if the condition(s) is well controlled.
• History of heart disease, such as congestive heart failure (class II, III, or IV defined by the New York Heart Association functional classification), history of unstable or poorly

controlled angina, or history (<1 year prior to initiation of study therapy) of ventricular arrhythmia.

• Acute or chronic skin disorders that will interfere with injection into the skin of the extremities or subsequent assessment of potential skin reactions.
• Second malignancy within 3 years prior to initiation of study therapy. Note: Individuals with curatively treated non-melanoma skin cancers or non-muscle invasive bladder cancer will not be excluded.
• History of herbal products that may decrease PSA levels (e.g., saw palmetto).
• Participants who have undergone surgery within 4 weeks prior to initiation of study therapy.
• Participants receiving any other investigational agents within 30 days prior to initiation of study therapy.
• History of allergic reaction attributed to compounds of similar chemical or biological composition to the study drugs.
• Uncontrolled intercurrent illness that would limit compliance with study requirements suggested by medical history, physical examination, or standard clinical assessments such as imaging, EKG, and laboratory studies.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Arm 1; TriAdeno vaccine with N-803	Biological: TriAdeno vaccine; The TriAdeno vaccine will be administered on Day 1 of every 21-day cycle for up to 4 cycles.; Drug: N-803; N-803 will be administered on Day 1 of every 21-day cycle for up to 4 cycles.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
To determine the effect of TriAdeno vaccine with N-803 on immune infiltration of the local tumor environment	Change in the density of T-cell immune infiltrates in the malignant portions of prostate using a paired two sample t-test	Baseline/prior to treatment, C2D14 (or as late as C4D21), and optionally at 1 year

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
To assess the adverse events associated with TriAdeno vaccine and N-803	Toxicities will be reported in a descriptive fashion per type, frequency, and grade	Day 1 of each cycle, and through at least 30 days after last treatment
To determine the effect of the TriAdeno vaccines with N-803 on the change in PSA	Change in PSA will be analyzed using a paired two sample t-test.	Day 1 of each cycle after C1, 30 days after last treatment, and in follow-up about every 3 months for 1 year and every 6 months for the subsequent 4 years after the end of study therapy

Collaborators and Investigators

• Sponsor: National Cancer Institute (NCI)
• Investigators: Principal Investigator: Peter A Pinto, M.D., National Cancer Institute (NCI)

Publications and helpful links

Helpful Links

• NIH Clinical Center Detailed Web Page

Study record dates

Study Major Dates

• Study Start (Estimated): June 9, 2026
• Primary Completion (Estimated): June 15, 2027
• Study Completion (Estimated): June 15, 2028

Study Registration Dates

• First Submitted: May 7, 2026
• First Submitted That Met QC Criteria: May 7, 2026
• First Posted (Actual): May 8, 2026

Study Record Updates

• Last Update Posted (Actual): June 4, 2026
• Last Update Submitted That Met QC Criteria: June 3, 2026
• Last Verified: May 5, 2026

More Information

Terms related to this study

• Keywords: Immune Infiltration
• Additional Relevant MeSH Terms: Urogenital Diseases; Genital Diseases; Genital Neoplasms, Male; Urogenital Neoplasms; Neoplasms by Site; Genital Diseases, Male; Prostatic Diseases; Male Urogenital Diseases; Neoplasms; Prostatic Neoplasms; Carcinoma; Adenocarcinoma; Neoplasms by Histologic Type; Neoplasms, Glandular and Epithelial; ALT-803
• Other Study ID Numbers: 10001734; 001734-C

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: This study will comply with the NIH Data Management and Sharing (DMS) Policy, which applies to all new and ongoing NIH-funded research in the IRP, as of January 25, 2023, that is associated with a ZIA, with a clinical protocol that undergoes scientific review and/or will involve genomic data sharing.
• IPD Sharing Time Frame: Data will be made available as soon as possible or at the time of associated publication. Data not published in a manuscript will be shared via public source once the data set completes QC.
• IPD Sharing Access Criteria: Clinical data will be made available upon request and with the permission of the study Pl. Genomic data are made available via dbGAP through requests to the data custodians.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No