Immune Modulation During Palynziq® Treatment in Adults (IMPALA)

Recruiting now · Phase 4

Conditions studied: Phenylketonuria

In brief

Study 165-401 is a Phase 4, open-label study designed to examine the concomitant use of methotrexate (MTX) to suppress immune responses to Palynziq and improve tolerability and efficacy in adults with PKU.

Key facts

Study ID

NCT07477691

Run by

BioMarin Pharmaceutical

People needed

12

Starts

2026-05-29

Expected to finish

2027-09-30

Last updated by the study team

2026-06-17

Who can join

Age: 18 and older, up to 65. Sex: any. Healthy volunteers: not accepted.

You may qualify if…

• Adults between 18 and 65 years old
• Have a confirmed diagnosis of phenylketonuria (PKU)
• Are in generally good health based on medical evaluation
• Are willing and medically eligible to receive Palynziq and methotrexate (MTX) Cohort A: Have never taken Palynziq before and are willing to start it during the study Cohort B: Have blood > 600 μmol/L after taking Palynziq for at least 24 weeks, are on a daily dose of at least 20mg and unable to increase the dose further
• Agree to use required contraception if they or their partner could become pregnant
• Are willing to carry two epinephrine devices at all times during Palynziq treatment

You may not qualify if…

• Pregnant, breastfeeding, planning to become pregnant, planning to father a child, or not using effective birth control if applicable
• Have a known severe allergy or hypersensitivity reaction to methotrexate (MTX), Palynziq, or other PEG-containing medications
• Have a serious active infection or a history of severe or recurrent infections
• Have significant medical conditions that may affect safety or participation (such as serious heart, lung, liver, kidney, immune, neurological, psychiatric, or cancer-related conditions)
• Have a history of substance or alcohol abuse within the past 12 months
• Have had an organ transplant or are taking chronic immunosuppressive medications
• Are currently taking medications that are not allowed in the study, including other PKU treatments besides Palynziq
• Are using, or plan to use, injectable PEG-containing medications other than Palynziq during the study
• Have major surgery planned during the study participation period
• Are currently participating in another clinical study involving Palynziq
• In the opinion of the study doctor, are not a suitable candidate for the study or may have difficulty complying with study requirements

Where it is running

• UT Southwestern Medical Center — Dallas, Texas, United States (enrolling)
• Children's Hospital Colorado — Aurora, Colorado, United States
• University Of South Florida Medical Center — Tampa, Florida, United States
• Ann & Robert H. Lurie Children's Hospital of Chicago — Chicago, Illinois, United States
• Indiana University School of Medicine — Indianapolis, Indiana, United States
• University of Minnesota Medical School — Minneapolis, Minnesota, United States
• University of Rochester Medical Center (URMC) — Rochester, New York, United States
• Oregon Health & Science University (OHSU) - PARENT — Portland, Oregon, United States
• University of Pittsburgh Medical Center (UPMC) - Children's Hospital of Pittsburgh — Philadelphia, Pennsylvania, United States
• University of Utah Hospital — Salt Lake City, Utah, United States
• UCLA Dept. of Human Genetics — Los Angeles, California, United States
• Children's Hospital of Wisconsin — Milwaukee, Wisconsin, United States

Full record on ClinicalTrials.gov

Trial information comes from ClinicalTrials.gov and is refreshed daily. TrialsForMe does not provide medical care and does not run the studies it lists.