Sipuleucel-T (Sip-T) in Combination With N-803 in Metastatic Androgen Pathway Modulation Resistant (mAPMR) Prostate Cancer

August 6, 2026 updated by: Washington University School of Medicine

A Phase Ib Study Evaluating the Safety and Tolerability of Sipuleucel-T (Sip-T) in Combination With N-803 in Patients With Metastatic Androgen Pathway Modulation Resistant (mAPMR) Prostate Cancer

This phase Ib single-center open-label de-escalation study uses a modified 3+3 design to determine the safety, tolerability, and recommended phase II dose (RP2D) of the combination of standard of care Sip-T and N-803 in patients with metastatic androgen pathway modulation resistant (mAPMR) prostate cancer. Patients will receive treatment for up to 8 weeks.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
30

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • United States
    • Missouri
      • St Louis, Missouri, United States, 63110
        • Washington University School of Medicine
        • Sub-Investigator:
          • Jingqin Rosy Luo, Ph.D.
        • Contact:
        • Principal Investigator:
          • Russell K Pachynski, M.D.
        • Sub-Investigator:
          • Peter Oppelt, M.D.
        • Sub-Investigator:
          • Eric Knoche, M.D.
        • Sub-Investigator:
          • Melissa Reimers, M.D.
        • Sub-Investigator:
          • Jade Tao, Ph.D.
        • Sub-Investigator:
          • Mark Sundermeyer, M.D.
        • Principal Investigator:
          • Daniel Thorek, Ph.D.
        • Sub-Investigator:
          • John Visconti, D.O.
        • Sub-Investigator:
          • Wilbur Song, M.D.

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Histologically or cytologically confirmed prostate adenocarcinoma.
  • Imaging- or biopsy-proven metastatic disease. May have any type or location of metastases (bone, lymph node, visceral).
  • Prior treatment must include either orchiectomy or luteinizing hormone-releasing agonist or antagonist treatment with documented testosterone ≤ 50 ng/dL.
  • Eligible for standard of care Sipuleucel-T.
  • Recovery to baseline or ≤ grade 1 from toxicities related to any prior treatments, unless AEs are clinically nonsignificant and/or stable on supportive therapy.
  • At least 18 years of age.
  • ECOG performance status ≤ 2

  • Adequate bone marrow and organ function as defined below:

    • Absolute neutrophil count ≥ 1,500 K/cumm without granulocyte colony-stimulating factor support
    • Platelets ≥ 100,000 K/cumm without transfusion
    • Hemoglobin ≥ 10.0 g/dL
    • Total bilirubin ≤ 1.5 x IULN
    • AST(SGOT) and ALT(SGPT) ≤ 2.5 x IULN
    • Calculated creatinine clearance ≥ 50 mL/min by Cockcroft-Gault
  • PSA ≤ 200 ng/mL.
  • Ability to understand and willingness to sign an IRB approved written informed consent document. Legally authorized representatives may sign and give informed consent on behalf of study participants

Exclusion Criteria:

  • Rapidly progressing disease or symptomatic prostate cancer as assessed by the investigator.
  • Prior immunotherapy (e.g., anti-PD-1, anti-PD-L1, anti-CTLA4) within the 6 months prior to enrollment.
  • Prior systemic radiotherapy (such as Ra-223, Lu177-PSMA) within the 6 months prior to enrollment. Prior palliative radiation therapy for bone metastasis within 2 weeks or any other radiation therapy within 4 weeks before first dose of study treatment is allowed. Prior definitive radiation therapy for localized prostate cancer is allowed.
  • Prior exposure to Sipuleucel-T.
  • Ongoing systemic immune suppression (oral steroids equivalent to 10 mg daily prednisone or less are allowed; topical, inhaled, and intra-articular steroids are allowed).
  • Currently receiving any other investigational therapeutic or imaging agents.
  • Patients with known brain metastases or cranial epidural disease unless adequately treated with radiotherapy and/or surgery (including radiosurgery) and stable for at least 4 weeks prior to first dose of study treatment after radiotherapy or at least 4 weeks prior to first dose of study treatment after major surgery (e.g., removal or biopsy of brain metastasis). Subjects must have complete wound healing from major surgery or minor surgery before first dose of study treatment. Eligible subjects must be neurologically asymptomatic and without corticosteroid treatment at the time of first dose of study treatment.
  • A history of allergic reactions attributed to compounds of similar chemical or biologic composition to Sipuleucel-T or N-803 or other agents used in the study.
  • Uncontrolled intercurrent illness including, but not limited to: ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, or cardiac arrhythmia. Patients with a known history or current symptoms of cardiac disease, or history of treatment with cardiotoxic agents, should have a clinical risk assessment of cardiac function using the New York Heart Association Function Classification; to be eligible for this trial, patients should be a class 2B or better.
  • HIV-infected if not on effective anti-retroviral therapy with undetectable viral load for 6 months. Patients with HIV who are receiving effective anti-retroviral therapy and have had an undetectable viral load for at least 6 months are eligible. HIV testing not required in the absence of known history of infection.
  • Evidence of chronic hepatitis B virus (HBV) that is detectable on suppressive therapy. Patients with evidence of chronic HBV infection with undetectable HBV viral load on suppressive therapy are eligible. HBV testing not required in the absence of known history of infection.
  • History of hepatitis C virus (HCV) infection that has not been cured or that has a detectable viral load. Patients with a history of HCV that has been treated and cured are eligible. Patients with HCV infection who are currently on treatment and have an undetectable HCV viral load are eligible. HCV testing not required in the absence of known history of infection.
  • Uncontrolled infection with hepatitis A.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Non-Randomized
  • Interventional Model: Sequential Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Cohort 1: Dose level 0 Starting dose: N-803 + SIP-T
Patients will receive standard dose (>50 million CD54+ cells) subcutaneous (SC) SIP-T on Day 1, 15 and 29 and 15 mcg/kg SC dose of N-803 24 hours after SIP-T on Day 2, 16, and 30.
Biological: Sipuleucel-T
Sipuleucel-T is a cellular therapeutic vaccine given in 3 complete doses at 2-week intervals intravenously.
Other Names:
  • Provenge
  • SipT
Biological: N803
N-803 is a biologic that is administered subcutaneously in the abdominal area.
Experimental: Cohort 1: Dose level -1: N-803 + SIP-T
Patients will receive standard dose (>50 million CD54+ cells) subcutaneous (SC) SIP-T on Day 1, 15 and 29 and 10 mcg/kg SC dose of N-803 24 hours after SIP-T on Day 2, 16, and 30.
Biological: Sipuleucel-T
Sipuleucel-T is a cellular therapeutic vaccine given in 3 complete doses at 2-week intervals intravenously.
Other Names:
  • Provenge
  • SipT
Biological: N803
N-803 is a biologic that is administered subcutaneously in the abdominal area.
Experimental: Cohort 1: Dose level -2: N-803 + SIP-T
Patients will receive standard dose (>50 million CD54+ cells) subcutaneous (SC) SIP-T on Day 1, 15 and 29 and 6 mcg/kg SC dose of N-803 24 hours after SIP-T on Day 2, 16, and 30.
Biological: Sipuleucel-T
Sipuleucel-T is a cellular therapeutic vaccine given in 3 complete doses at 2-week intervals intravenously.
Other Names:
  • Provenge
  • SipT
Biological: N803
N-803 is a biologic that is administered subcutaneously in the abdominal area.
Experimental: Cohort 2: N-803 + SIP-T
Patients will receive standard dose (>50 million CD54+ cells) subcutaneous (SC) SIP-T on Day 1, 15 and 29 and recommended phase 2 dose (RP2D) of N-803 24 hours after SIP-T on Day 2, 16, and 30. An additional dose of N-803 will occur on Day -5 or 5 days before first SIP-T dose.
Biological: Sipuleucel-T
Sipuleucel-T is a cellular therapeutic vaccine given in 3 complete doses at 2-week intervals intravenously.
Other Names:
  • Provenge
  • SipT
Biological: N803
N-803 is a biologic that is administered subcutaneously in the abdominal area.
Experimental: Cohort 3: N-803 + SIP-T
Patients will receive standard dose (>50 million CD54+ cells) subcutaneous (SC) SIP-T on Day 1, 15 and 29 and RP2D of N-803 24 hours after SIP-T on Day 2, 16, and 30. An additional dose of N-803 will occur on Day 37.
Biological: Sipuleucel-T
Sipuleucel-T is a cellular therapeutic vaccine given in 3 complete doses at 2-week intervals intravenously.
Other Names:
  • Provenge
  • SipT
Biological: N803
N-803 is a biologic that is administered subcutaneously in the abdominal area.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Frequency of dose-limiting toxicities (Cohort 1 only)
Time Frame: Start of treatment (day 1 dose of Sip-T) through 14 days following the last dose of N-803 (total time up to 44 days)
As assessed via CTCAE v6.0. Dose limiting toxicities will be evaluated according to protocol.
Start of treatment (day 1 dose of Sip-T) through 14 days following the last dose of N-803 (total time up to 44 days)
Recommended Phase II Dose (RP2D) (Cohort 1 only)
Time Frame: Start of treatment (day 1 dose of Sip-T) through 14 days following the last dose of N-803 for all participants in Cohort 1 (total time up to 44 days)
RP2D is defined as the highest dose of N-803 that has an overall DLT rate of less than 33% in total of 6 patients.
Start of treatment (day 1 dose of Sip-T) through 14 days following the last dose of N-803 for all participants in Cohort 1 (total time up to 44 days)
Number of severe (grade 3+) adverse events measured via CTCAE v6.0
Time Frame: Start of treatment through 100 days after last dose of N-803 (total time up to 137 days)
Start of treatment through 100 days after last dose of N-803 (total time up to 137 days)
Number and type of adverse events measured via CTCAE v6.0
Time Frame: Start of treatment through 100 days after last dose of N-803 (total time up to 137 days)
Start of treatment through 100 days after last dose of N-803 (total time up to 137 days)

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
PSA30 Response
Time Frame: Start of treatment to completion of follow-up (up to 26 months)
PSA response rate is defined as the proportion of subjects who have PSA response as defined by at least 30% reduction in PSA level from baseline measured twice at least 3 weeks apart. PSA response is measured per PCWG3 criteria.
Start of treatment to completion of follow-up (up to 26 months)
PSA50 Response
Time Frame: Start of treatment to completion of follow-up (up to 26 months)
PSA response rate is defined as the proportion of subjects who have PSA response as defined by at least 50% reduction in PSA level from baseline measured twice at least 3 weeks apart. PSA response is measured per PCWG3 criteria.
Start of treatment to completion of follow-up (up to 26 months)
PSA90 Response
Time Frame: Start of treatment to completion of follow-up (up to 26 months)
PSA response rate is defined as the proportion of subjects who have PSA response as defined by at least 90% reduction in PSA level from baseline measured twice at least 3 weeks apart. PSA response is measured per PCWG3 criteria.
Start of treatment to completion of follow-up (up to 26 months)
Radiographic progression-free survival (PFS)
Time Frame: Start of treatment to date of progression or death or last follow-up (up to 26 months)
rPFS is defined as the duration of time from start of treatment to time of radiographic progression by PCWG3 or time of death or last follow-up, the event that occurs first. Patients who have not experienced either event at the time of analysis will be censored at their last radiographic scan date. All radiographic response criteria are assessed per PCWG3 criteria.
Start of treatment to date of progression or death or last follow-up (up to 26 months)
Failure-free survival (FFS)
Time Frame: Start of treatment to date of any progression events or last follow-up (up to 26 months)
Failure-free survival which is defined from date of treatment start to date of any progression events (radiographic progression, biochemical recurrence, or death, whichever is earlier) or date of last follow-up if experiencing no events
Start of treatment to date of any progression events or last follow-up (up to 26 months)
Time to next therapy (TTNT)
Time Frame: Through completion of follow-up (up to 26 months)
Through completion of follow-up (up to 26 months)
Overall survival (OS)
Time Frame: Start of treatment to death or last follow-up (up to 26 months)
Overall survival is defined as the date of treatment start to date of death or date of last follow-up.
Start of treatment to death or last follow-up (up to 26 months)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Washington University School of Medicine

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
ImmunityBio, Inc.
Dendreon

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Russell K Pachynski, M.D., Washington University School of Medicine

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
November 30, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
April 14, 2029

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
January 31, 2031

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
August 6, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
August 6, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
August 10, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
August 10, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
August 6, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
August 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 26-x147

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

De-identified individual participant data that underlie the results reported will be available for investigators with approval by an independent review committee.

IPD Sharing Time Frame

Data will be made available beginning 9 months and ending 36 months following publication.

IPD Sharing Access Criteria

Investigators who have approval to use the data by an independent review committee.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

Yes

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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