This phase II trial tests how well ARX788 works in treating patients diagnosed with HER2-low, locally advanced unresectable or metastatic breast cancer. ARX788 is an antibody-drug conjugate (ADC) that is given by infusion (diluted and injected slowly into veins). Antibodies are proteins which are naturally produced by the body's immune system to help fight infections. ARX788 consists of antibodies that have been attached to a toxin that has the potential to kill cancer cells. ARX788 sticks to a protein called human epidermal growth factor receptor (HER2), which is found on some breast cancer cells. Giving ARX788 may be safe and effective in treating patients with HER2-low locally advanced unresectable metastatic breast cancer.
Male or female participants age 18 years or greater with ability to provide written informed consent for the study.
Eastern Cooperative Oncology Group (ECOG) score of 0-2.
Estimated life expectancy of at least at 6 months per investigator assessment.
Ability to understand and the willingness to sign a written informed consent document.
Has a prior history of treatment with ARX-788 or auristatin analogues.
Has a history of allergic reaction to any component of ARX788.
Has exposure to any other investigational or commercial anti-cancer agents or therapies administered with the intention to treat malignancy within 14 days before the first dose of study treatment. NOTE: Anti-hormonal therapy may be administered up to 7 days prior to the first dose of study treatment.
Radiotherapy outside of the brain administered <7 days prior to first dose of ARX788
Sequential
ARX788
DrugGiven IV
Computed Tomography (CT)
Procedure/SurgeryUndergo CT or Positron Emission Tomography(PET)/CT
Biospecimen Collection
Procedure/SurgeryUndergo collection of blood samples
Amiloride
DrugOphthalmologic drops given topically to participants for an eye toxicity substudy
Objective response rate (ORR)
Objective response rate (ORR) is defined as the proportion of participants who experience complete response (CR) or partial response (PR) using Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. The ORR and corresponding two-sided exact 90% confidence intervals will be reported.
Duration of response (DOR)
Duration of response (DOR) is defined as the time between the date of first response and the date of disease progression or death, whichever occurs first, will be computed for participants with a BOR of CR or PR. Medians and corresponding two-sided 95% confidence intervals will be reported.
Overall Best Response (BOR)
Best overall response (BOR) is defined as the best response recorded from the start of the treatment until disease progression (taking as reference for progressive disease the smallest measurements recorded since the treatment started).
Disease Control Rate (DCR)
The Disease control rate (DCR) is defined as the sum of PR, CR and stable disease (SD) divided by the number of response evaluable participants All-Subjects-as-Treated(AsaT).
Median Progression Free Survival (PFS)
Progression-free survival (PFS) is defined as the time between date of first dose of study therapy and date of progression or death, whichever occurs first, will be computed for response evaluable participants (AsaT). Medians and corresponding two-sided 95% confidence intervals will be reported.
Click on the lead sponsor to view all of their trials.
Laura Huppert, MD, BA
Lead sponsor
University of California, San Francisco
Sponsor institution
Ambrx, Inc.
Collaborator
