A Study of Vobramitamab Duocarmazine in Participants With Metastatic Castration Resistant Prostate Cancer and Other Solid Tumors (Tamarack)

January 21, 2026 updated by: MacroGenics

A Phase 2, Open-label, Study of Vobramitamab Duocarmazine in Participants With Metastatic Castration-resistant Prostate Cancer and Other Solid Tumors

Study CP-MGC018-03 is an open-label, two-part, Phase 2 study. Part 1 of the study will enroll participants with metastatic castration-resistant prostate cancer (mCRPC) previously treated with one prior androgen receptor axis-targeted therapy (ARAT). ARAT includes abiraterone, enzalutamide, or apalutamide.

Participants may have received up to 1 prior docetaxel-containing regimen, but no other chemotherapy agents.

This part of the study will assess the efficacy and tolerability of vobramitamab duocarmazine (MGC018) in two experimental arms (2.0 mg/kg every 4 weeks [Q4W] and 2.7 mg/kg Q4W) . Approximately 100 participants will be randomized 1:1.

Part 2 of the study will enroll participants with locally advanced or metastatic solid tumors. Participants must have progressive following at least 1 prior line of standard chemotherapy for advanced or metastatic disease. Participants will receive vobramitamab duocarmazine at a dose of 2.7 mg/kg every 4 weeks. Up to 200 participants may be enrolled in Part 2.

In both parts, vobramitamab duocarmazine will be administered intravenously (IV) in clinic on Day 1 of each 4-week cycle. Vobramitamab duocarmazine will be administered until criteria for treatment discontinuation are met. Participants will undergo regular testing for signs of disease progression using computed tomography (CT) scans, magnetic resonance imaging (MRI), bone scans, and prostate-specific antigen (PSA) blood tests. Routine examinations and blood tests will be performed and evaluated by the study doctor.

Study Overview

Status

Terminated

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Actual)

192

Phase

  • Phase 2

Contacts and Locations

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

Study Locations

  • Australia
    • New South Wales
      • Westmead, New South Wales, Australia, 2145
        • Ramsay Health Care - Westmead Private Hospital
    • Queensland
      • Woolloongabba, Queensland, Australia, 4102
        • The University of Queensland (UQ) - Princess Alexandra Hospital (PAH)
    • Victoria
      • Malvern, Victoria, Australia, 3144
        • Cabrini Health- Malvern
      • Melbourne, Victoria, Australia, 3000
        • Peter MacCallum Cancer Centre
  • Belgium
      • Ghent, Belgium, 9000
        • Algemeen Ziekenhuis Maria Middelares
    • Brussles
      • Woluwe-Saint-Lambert, Brussles, Belgium, 1200
        • Cliniques Universitaires Saint-Luc
    • Hainaut
      • Charleroi, Hainaut, Belgium, 6000
        • (Grand Hopital de Charleroi) GHDC
    • Luxembourg
      • Libramont, Luxembourg, Belgium, 6800
        • Centre Hospitalier de Ardenne - Libramont - Clinique du Sein
    • Namur
      • Godinne, Namur, Belgium, 5300
        • Centre Hospitalier Universitaire (CHU) - Universite Catholique de Louvain (UCL) - Namur - Site Godinne (Cliniques Universitaires UCL de Mont-Godinne)
  • France
      • Brest, France, 29200
        • CHRU Brest
      • Paris, France, 75014
        • Institut Mutualiste Montsouris
    • AM
      • Nice, AM, France, 06189
        • Centre Antoine-Lacassagne
    • Bas Rhin
      • Strasbourg, Bas Rhin, France, 67200
        • Institut de cancérologie Strasbourg Europe (ICANS)
    • Gironde
      • Bordeaux, Gironde, France, 33076
        • Institut Bergonie
    • Herault
      • Montpellier, Herault, France, 34298
        • Institut régional du Cancer de Montpellier - ICM Val d'Aurelle
    • Ille Et Vilaine
      • Saint-Grégoire, Ille Et Vilaine, France, 35760
        • Centre Hospitalier Prive Saint-Gregoire
    • Sarthe
      • Le Mans, Sarthe, France, 72000
        • Clinique Victor Hugo
    • Val De Marne
      • Villejuif, Val De Marne, France, 94800
        • Gustave Roussy
    • Île-de-France Region
      • Saint-Mandé, Île-de-France Region, France, 94160
        • Hopital d'Instruction des Armees BEGIN
      • Suresnes, Île-de-France Region, France, 92150
        • Hôpital Foch
  • Italy
      • Florence, Italy, 50134
        • Radiation Oncology Unit, Azienda Ospedaliera Universitaria Careggi, University of Florence
      • Padua, Italy, 35128
        • Istituto Oncologico Veneto
      • Trento, Italy, 38122
        • Azienda Provinciale per i Servizi Sanitari - Presidio Ospedaliero S. Chiara
    • TO
      • Orbassano, TO, Italy, 10049
        • AOU San Luigi Gonzaga Oncology Department
    • Venice
      • Mestre, Venice, Italy, 30174
        • Ospedale dell'Angelo
  • Poland
    • Masovian Voivodeship
      • Otwock, Masovian Voivodeship, Poland, 05-400
        • Szpital im. Fryderyka Chopina
      • Warsaw, Masovian Voivodeship, Poland, 02-798
        • Medical Concierge Centrum Medyczne
      • Warsaw, Masovian Voivodeship, Poland, 01-748
        • Magodent Szpital Elblaska
      • Warsaw, Masovian Voivodeship, Poland, 04-073
        • Grochowski Hospital
    • WLKP
      • Konin, WLKP, Poland, 62-500
        • Przychodnia Lekarska "Komed"
    • West Pomeranian Voivodeship
      • Koszalin, West Pomeranian Voivodeship, Poland, 75-581
        • Szpital Wojewodzki im. Mikolaja Kopernika
  • South Korea
      • Gwangju, South Korea, 61469
        • Chonnam National University Hospital
      • Seoul, South Korea, 03722
        • Yonsei University Health System, Severance Hospital
      • Seoul, South Korea, 5505
        • Asan Medical Center
      • Seoul, South Korea, 07985
        • Ewha Womans University Mokdong Hospital
      • Seoul, South Korea, 03080
        • Seoul National University Hopital
      • Seoul, South Korea, 06351
        • Samsung Meical Cemter
    • Daegu
      • Bugok, Daegu, South Korea, 41404
        • Kyungpook National University Chilgok Hospital
    • Gyeonggi-do
      • Goyang-si, Gyeonggi-do, South Korea, 10408
        • National Cancer Center
  • Spain
      • Barcelona, Spain, 08003
        • Hospital del Mar
      • Barcelona, Spain, 08036
        • Hospital Clínic de Barcelona
      • Barcelona, Spain, 08036
        • Hospital de la Santa Creu i Sant Pau
      • Barcelona, Spain, 08036
        • Institut Catala d'Oncologia Hospitalet
      • Lugo, Spain, 27002
        • Hospital Universitario Lucus Augusti
      • Madrid, Spain, 28041
        • Hospital Universitario 12 de Octubre
    • Barcelona
      • Sabadell, Barcelona, Spain, 08208
        • Hospital Universitari Parc Tauli
    • Seville
      • Seville, Seville, Spain, 41013
        • Hospital Universitario Virgen Del Rocio
  • United Kingdom
      • Oxford, United Kingdom, OX3 7LE
        • Oxford University Hospitals NHS- Churchill Hospital
    • Surrey
      • Sutton, Surrey, United Kingdom, SM2 5PT
        • The Royal Marsden NHS Trust
  • United States
    • California
      • Fountain Valley, California, United States, 92708
        • Compassionate Cancer Care Medical Group
      • Los Angeles, California, United States, 90095
        • University of California Los Angeles (UCLA) Community Cancer Care
    • Florida
      • Jacksonville, Florida, United States, 32209
        • The University of Florida Health System - UF Health Urology - Jacksonville
      • Orange City, Florida, United States, 32763
        • Mid Florida Hematology and Oncology Center
    • Louisiana
      • Covington, Louisiana, United States, 70433
        • Pontchartrain Cancer Center
    • Maryland
      • Baltimore, Maryland, United States, 21231
        • The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins
    • Michigan
      • Detroit, Michigan, United States, 48201
        • Barbara Ann Karmanos Cancer Institute - Hudson-Webber Cancer Research Center
    • Minnesota
      • Minneapolis, Minnesota, United States, 55455
        • Masonic Cancer Center, University of Minnesota
    • Ohio
      • Canton, Ohio, United States, 44718
        • Gabrail Cancer Center
    • Oregon
      • Portland, Oregon, United States, 97239
        • VA Portland Health Care Services
    • South Carolina
      • Myrtle Beach, South Carolina, United States, 29572
        • Carolina Urologic Research Center
    • Virginia
      • Charlottesville, Virginia, United States, 22908
        • University of Virginia Comprehensive Cancer Center
      • Fairfax, Virginia, United States, 22031
        • Virginia Cancer Specalists
    • Washington
      • Seattle, Washington, United States, 98109
        • Fred Hutchinson Cancer Center

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

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Part 1 only: Histologically confirmed adenocarcinoma of the prostate without evidence of neuroendocrine differentiation, signet cell, or small cell features.
  • Part 2 only: Histologically confirmed SCC or the anus, melanoma, HNSCC, squamous NSCLC, or SCLC.
  • Part 1 only: Received 1 prior ARAT for metastatic or non-metastatic, castration-sensitive or castration-resistant prostate cancer. A second ARAT regimen of <60 days used as bridging to lutetium-177 is permitted. Up to 3 total prior lines of therapy for mCRPC are permitted..
  • Part 2 only: At least 1 prior line of systemic therapy for unresectable or metastatic disease and no more than 2 prior lines of cytotoxic chemotherapy. Participants with HNSCC or melanoma must have received prior PD-1 or PD-L1 inhibitor for advanced or metastatic disease.
  • All participants must have ≥ 1 metastatic lesion, according to RECIST 1.1 or PCWG3 criteria, that is present on magnetic resonance imaging (MRI), computed tomography (CT), or bone scan obtained ≤ 28 days prior to initiation of study treatment.
  • All participants must have tumor progression, according to disease-specific criteria, following their most recent anti-cancer therapy.
  • All participants must have and available archival or formalin-fixed paraffin-embedded (FFPE) tumor tissue sample for participants with metastasis to internal organs
  • All participants have acceptable physical condition and laboratory values.
  • All participants of childbearing potential must agree to use highly effective methods of birth control.
  • All participants must not be pregnant, planning to be pregnant, or breastfeeding.

Exclusion Criteria:

  • Any underlying medical or psychiatric condition impairing participant's ability to receive, tolerate, or comply with the planned treatment or study procedures.
  • Part 1 only: Received >1 prior taxane-containing regimen for prostate cancer. A second taxane regimen of <60 days used as bridging for lutetium-177 is permitted.
  • Part 1 only: Received >3 total prior therapies for mCRPC
  • Part 1 only: Participants with known BRCA or ATM mutation (germline or somatic) are not eligible unless they received prior treatment with a PARP inhibitor where available, indicated and tolerated.
  • Another hematologic or solid tumor ≥ stage 1 malignancy that completed surgery, last dose of radiotherapy, or last dose of systemic anti-cancer therapy ≤ 2 years from first dose of study treatment. Participants who had curative therapy for non-melanomatous skin cancer or for localized malignancy are eligible.
  • Untreated, symptomatic central nervous system (CNS) metastasis.
  • Prior treatment with any B7-H3 targeted agent for cancer,
  • Contradictions to the use of corticosteroid treatment
  • Prior stem cell, tissue, or solid organ transplant.
  • Part 1 only: Use of products that have published anti-prostate cancer activity or are known to decrease PSA.

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: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Part 1: MGC018 2.0 mg (Arm A)
MGC018 2.0 mg/kg every 4 weeks
Biological: vobramitamab duocarmazine 2.0 mg (Arm A)
2.0 mg/kg intravenous (IV) every 4 weeks
Other Names:
  • MGC018
Experimental: Part 1: MGC018 2.7 mg (Arm B)
MGC018 2.7 mg/kg every 4 weeks
Biological: vobramitamab duocarmazine 2.7 mg (Arm B)
2.7 mg.kg IV every 4 weeks
Other Names:
  • MGC018
Active Comparator: Part 1: Control Arm
Patients are administered abiraterone or enzalutamide
Drug: Abiraterone
1000 mg once daily
Drug: Enzalutamide
160 mg daily
Experimental: Part 2
MGC018 2.7 mg/kg every 4 weeks
Biological: vobramitamab duocarmazine
2.7 mg.kg IV every 4 weeks
Other Names:
  • MGC018

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Part 1: Six-month Radiographic Progression Free Survival (rPFS) as Determined by the Investigator
Time Frame: Assessed every 8 weeks for six months. Six month data reported.
The landmark analysis for 6 month rPFS rate will occur when all participants on Part 1 have been on study for at least 6 months.
Assessed every 8 weeks for six months. Six month data reported.
Part 2: Objective Response Rate (ORR) Per Investigator Assessment of Response Evaluation Criteria in Solid Tumours (RECIST) 1.1 Criteria
Time Frame: Every 8 weeks for the first 24 weeks, then every 12 weeks. Average duration of participation, 10 months.
The ORR is defined as the percentage of participants in the response evaluable population who achieve a best overall response of complete response (CR) or partial response (PR), per RECIST version 1.1 criterial CR is defined as disappearance of all target and non-target lesions. PR is defined as at least a 30% decrease from baseline in the sum of diameters of target lesions.
Every 8 weeks for the first 24 weeks, then every 12 weeks. Average duration of participation, 10 months.

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Part 1: ORR Per PCWG3 Criteria as Determined by the Investigator
Time Frame: Every 8 weeks for the first 24 weeks, then every 12 weeks. Average duration of participation, 10 months,
To qualify as an objective response, CR and PR require confirmation at least 4 weeks after initial observation of complete response (CR) or partial response (PR). CR + PR = ORR
Every 8 weeks for the first 24 weeks, then every 12 weeks. Average duration of participation, 10 months,
Part 1: Median Duration of Response (DoR) Per PCWG3 Criteria as Determined by the Investigator
Time Frame: Every 8 weeks for the first 24 weeks, then every 12 weeks. Average duration of participation, 10 months.
The DoR will be calculated as the time from the date of initial tumor response (CR or PR) to the date of first documented PD or death from any cause, whichever occurs first.
Every 8 weeks for the first 24 weeks, then every 12 weeks. Average duration of participation, 10 months.
Part 1: Mean Best Tumor Size Change Over Time
Time Frame: Every 8 weeks for the first 24 weeks, then every 12 weeks. Average duration of participation, 10 months.
Every 8 weeks for the first 24 weeks, then every 12 weeks. Average duration of participation, 10 months.
Part 1: Prostate-specific Cancer Antigen (PSA) Response Rate Per PCWG3 Criteria
Time Frame: Every 4 weeks throughout study participation. Average duration 10 months.
PSA response is defined as a ≥ 50% decline in PSA from baseline with PSA confirmation ≥ 3 weeks after the first documented reduction in PSA of ≥ 50%.
Every 4 weeks throughout study participation. Average duration 10 months.
Part 1: Time to PSA Progression Per PCWG3 Criteria
Time Frame: Every 4 weeks throughout study participation. Average duration of participation, 10 months.

In participants with a decrease in PSA from baseline, PSA progression is defined as a ≥ 25% increase and an absolute increase of ≥ 2 ng/mL above the nadir value, which is confirmed by a consecutive second value obtained ≥ 3 weeks later.

In participants with no decrease in PSA from baseline, PSA progression is defined as a ≥ 25% increase and an absolute increase of ≥ 2 ng/mL above the baseline value after 12 weeks.

Time to PSA progression is defined as the time from the date of randomization to the first PSA progression.
Every 4 weeks throughout study participation. Average duration of participation, 10 months.
Part 1: Duration of PSA Response Per PCWG3 Criteria
Time Frame: Every 4 weeks throughout study participation. Average duration of participation, 10 months.
Duration of PSA response is defined as the time from the date of first documented PSA response to the earliest date of PSA progression.
Every 4 weeks throughout study participation. Average duration of participation, 10 months.
Part 1: Best PSA Percent Change
Time Frame: Every 4 weeks throughout study participation. Average duration of participation, 10 months.
Every 4 weeks throughout study participation. Average duration of participation, 10 months.
Part 1: Time to First Symptomatic Skeletal Event (SSE)
Time Frame: Every 4 weeks throughout the study. Average duration of participation, 10 months.
An SSE is defined as any of the following events: new symptomatic pathological fracture, requirement for radiation therapy to relieve bone pain, spinal cord compression, or tumor-related orthopedic surgical intervention. The time to first SSE is defined as the time from the date of randomization to the first occurrence of SSE.
Every 4 weeks throughout the study. Average duration of participation, 10 months.
Number of Participants With Adverse Event (AEs), Serious AEs (SAEs), and AEs Leading to Study Treatment Discontinuation.
Time Frame: Throughout the study, average duration of participation, 10 months.
Throughout the study, average duration of participation, 10 months.
Number of Participants Who Develop Anti-drug Antibodies (ADA)
Time Frame: Every 4 weeks throughout the study, average duration of participation was 10 months.
Participant specimens were evaluated for the presence of ADA beginning a baseline and throughout the study. If at any time during the study, the results show evidence of ADA, they were counted as ADA positive. There was no time-to- event analysis nor by visit analysis of the data.
Every 4 weeks throughout the study, average duration of participation was 10 months.
Part 2: Median DoR Per Investigator Assessment of RECIST 1.1 Criteria
Time Frame: Every 8 weeks for the first 24 weeks, then every 12 weeks. Average duration of participation, 10 months.
The DoR will be calculated as the time from the date of initial tumor response (CR or PR) to the date of first documented progressive disease (PD) or death from any cause, whichever occurs first.
Every 8 weeks for the first 24 weeks, then every 12 weeks. Average duration of participation, 10 months.
Part 2: Median Progression Free Survival (PFS) Per Investigator Assessment of RECIST 1.1 Criteria
Time Frame: Every 8 weeks for the first 24 weeks, then every 12 weeks. Average duration of participation, 10 months.
PFS is defined as the time from the date of the first dose to the date of first PD per RECIST 1.1 criteria or death from any cause, whichever occurs first.
Every 8 weeks for the first 24 weeks, then every 12 weeks. Average duration of participation, 10 months.

Collaborators and Investigators

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

Sponsor

MacroGenics

Investigators

  • Study Director: Liudmila Schafer, M.D., MacroGenics

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 (Actual)

June 13, 2023

Primary Completion (Actual)

July 4, 2024

Study Completion (Actual)

January 23, 2025

Study Registration Dates

First Submitted

September 19, 2022

First Submitted That Met QC Criteria

September 19, 2022

First Posted (Actual)

September 22, 2022

Study Record Updates

Last Update Posted (Actual)

February 9, 2026

Last Update Submitted That Met QC Criteria

January 21, 2026

Last Verified

January 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • CP-MGC018-03

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

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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