A Phase 3 interventional study of DTX401 and Placebo in Glycogen Storage Disease Type IA, sponsored by Ultragenyx Pharmaceutical Inc. Completed at 20 sites in 9 countries. Open to participants aged 8 Years and older. Per ClinicalTrials.gov, last updated 2026-10-14.
Sponsored by Ultragenyx Pharmaceutical Inc · Phase 3, Interventional, and Treatment
The primary objectives of this study are to evaluate the efficacy of DTX401 to reduce or eliminate dependence on exogenous glucose replacement therapy to maintain euglycemia and to maintain or improve the quality of glucose control.
Study DTX401-CL301 is a phase 3 study to determine the efficacy and confirm the safety of DTX401 in patients 8 years and older with glycogen storage disease type Ia (GSDIa).
Participants were randomized 1:1 to DTX401 or placebo group and followed closely for 48 weeks. At week 48 eligible participants crossed over and received DTX401 if they had previously received placebo or placebo if they had previously received DTX401 and were followed closely for an additional 96 weeks. After completion of week 144 or early withdrawal, participants were offered enrollment into a Disease Monitoring Program (DMP) where they will be followed for at least 10 years post DTX401 infusion.
In Japan, there was a single open label study arm and all participants were treated with DTX401. At week 48, Japanese participants were offered enrollment into a Disease Monitoring Program (DMP) where they will be followed for at least 10 years post DTX401 infusion.
361 studies on the registry are indexed under Glucose Metabolism Disorders; 38 are open to participants now.
This study's enrollment of 52 is below the median of 60 across 308 interventional studies indexed under Glucose Metabolism Disorders.
Browse Glucose Metabolism Disorders studies →Ultragenyx Pharmaceutical Inc is the lead sponsor of 63 studies on the registry; 8 are open to participants now.
Of its 16 completed or terminated interventional studies of FDA-regulated products, 12 (75%) have results posted.
Counted across the registry records on this site, refreshed daily.
Key Inclusion Criteria:
Key Exclusion Criteria:
Note: additional inclusion/exclusion criteria may apply, per protocol
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
Biopsy and archival tissue
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ALT and AST (liver enzymes)
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Bilirubin
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants received a single peripheral intravenous (IV) infusion of placebo on Day 1 along with a placebo-to-match (PTM) of the prophylactic steroid regimen of prednisolone. At Week 48, participants received a single peripheral IV infusion of 1.0 × 10\^13 genome copies per kilogram \[GC/kg\]) of DTX401 along with a prophylactic steroid regimen of prednisolone.
Genetic: DTX401 · Other: Placebo · Drug: Oral prednisolone · Drug: Placebo for oral prednisolone
Participants received a single peripheral IV infusion of 1.0 × 10\^13 GC/kg of DTX401 on Day 1, along with a prophylactic steroid regimen of prednisolone. At Week 48, participants received a single peripheral IV infusion of placebo with a PTM of the prophylactic steroid regimen of prednisolone.
Genetic: DTX401 · Other: Placebo · Drug: Oral prednisolone · Drug: Placebo for oral prednisolone
Participants received a single peripheral IV infusion of 1.0 × 10\^13 GC/kg of DTX401 on Day 1, along with a prophylactic steroid regimen of prednisolone.
Genetic: DTX401 · Drug: Oral prednisolone
nonreplicating, recombinant, adeno-associated virus (AAV) serotype 8 (AAV8)
Also known as: pariglasgene brecaparvovec
Normal Saline infusion
Participants who receive DTX401 solution will receive oral prednisolone
Participants who receive placebo will receive placebo oral prednisolone to maintain the study blind
Main Study: Percent Change From Baseline to Week 48 in Daily Cornstarch Intake (Grams)
The least square (LS) mean and standard error (SE) are based on mixed-model for repeated measures (MMRM) analysis.
Time frame: Baseline, Weeks 24, 30, 36, 42 and 48
Japan Cohort: Percent Change From Baseline to Week 48 in Daily Cornstarch Intake (Grams)
Time frame: Baseline, Weeks 24, 30, 36, 42 and 48
Main Study: Change From Baseline to Week 48 in Number of Total Daily Doses of Cornstarch
The LS mean and SE are based on MMRM analysis.
Time frame: Baseline, Weeks 24, 30, 36, 42 and 48
Japan Cohort: Change From Baseline to Week 48 in Number of Total Daily Doses of Cornstarch
Time frame: Baseline, Weeks 24, 30, 36, 42 and 48
Main Study: Change From Baseline to Week 48 in Percentage of Glucose Values in Hypoglycemic Range (Less Than (<) 70 Milligrams Per Deciliter (mg/dL) [3.9 Millimoles Per Liter (mmol/L)])
The LS mean and SE are based on MMRM analysis.
Time frame: Baseline, Weeks 24, 30, 36, 42 and 48
Japan Cohort: Change From Baseline to Week 48 in Percentage of Glucose Values in Hypoglycemic Range (< 70 mg/dL [3.9 mmol/L])
Time frame: Baseline, Weeks 24, 30, 36, 42 and 48
Main Study: Patient Global Impression of Change (PGIC) Assessment Score at Week 48
The PGIC captures the participants' perspective on changes in their glycogen storage disease type Ia (GSDIa) since the start of the study using a 7-point response scale ranging from much improved (+ 3) to much worse (- 3). The total score ranges from + 3 to - 3, with a higher score indicating best outcome.
Time frame: Week 48
Japan Cohort: PGIC Assessment Score at Week 48
The PGIC captures the participants' perspective on changes in their GSDIa since the start of the study using a 7-point response scale ranging from much improved (+ 3) to much worse (- 3). The total score ranges from + 3 to - 3, with a higher score indicating best outcome.
Time frame: Week 48
Main Study: Change From Baseline to Week 48 in Time to Hypoglycemia (< 54 mg/dL [3.0 mmol/L]) During the Controlled Fasting Challenge (CFC)
The LS mean and SE are based on MMRM analysis.
Time frame: Baseline, Weeks 36 and 48
Japan Cohort: Change From Baseline to Week 48 in Time to Hypoglycemia (< 54 mg/dL [3.0 mmol/L]) During the CFC
Time frame: Baseline, Weeks 36 and 48
Main Study: Change From Baseline to Week 48 in Percentage of Glucose Values in the Range of 70-120 mg/dL (3.9-6.7 mmol/L)
The LS mean and SE are based on MMRM analysis.
Time frame: Baseline, Weeks 24, 30, 36, 42 and 48
Japan Cohort: Change From Baseline to Week 48 in Percentage of Glucose Values in the Range of 70-120 mg/dL (3.9-6.7 mmol/L)
Time frame: Baseline, Weeks 24, 30, 36, 42 and 48
Main Study: Number of Participants With Treatment Emergent Adverse Events (TEAEs), Adverse Events of Special Interest (AESIs), Serious TEAEs, Related TEAEs, Fatal AEs, and Discontinuation From Study or Investigational Product Due to AEs
Adverse event (AE) is defined as any untoward medical occurrence associated with use of a drug in humans, whether or not considered drug related. TEAE is defined as any AE not present prior to initiation of drug treatment or any AE already present that worsens in either intensity or frequency following exposure to drug treatment. SAE is an AE that meets any of following criteria in view of either Investigator or Ultragenyx: death; life-threatening; inpatient hospitalization or prolongation of existing hospitalization; disability/incapacity; congenital anomaly/birth defect not present at screening; other important medical events. AESIs are events of scientific or medical interest specific to drug treatment requiring further investigation and close monitoring to further characterize them. Hepatic reactions (vector-induced hepatic effects) were AESIs for this study and were defined as clinically significant increases in aminotransferase levels (AST/ALT) in the judgment of Investigator.
Time frame: PEAP Arms - TEAEs with onset from Day 1 to Week 48; Crossover and Follow-up - Placebo to DTX401 Arm: TEAEs with onset after Week 48 dosing with DTX401 to Week 144; Crossover and Follow-up DTX401 Arm: TEAEs from Week 48 to Week 144
Japan Cohort: Number of Participants With TEAEs, AESIs, Serious TEAEs, Related TEAEs, Fatal AEs, and Discontinuation From Study or Investigational Product Due to AEs
AE is defined as any untoward medical occurrence associated with use of a drug in humans, whether or not considered drug related. TEAE is defined as any AE not present prior to initiation of drug treatment or any AE already present that worsens in either intensity or frequency following exposure to drug treatment. SAE is an AE that meets any of following criteria in view of either Investigator or Ultragenyx: death; life-threatening; inpatient hospitalization or prolongation of existing hospitalization; disability/incapacity; congenital anomaly/birth defect not present at screening; other important medical events. AESIs are events of scientific or medical interest specific to drug treatment requiring further investigation and close monitoring to further characterize them. Hepatic reactions were considered to be important identified risk for this study and were defined as clinically significant increases in aminotransferase levels (AST/ALT) in the judgment of Investigator.
Time frame: Day 1 to Week 48
Main Study: Percent Change From Baseline to Week 96 in Daily Cornstarch Intake (Grams)
Time frame: Baseline, Week 96
Main Study: Change From Baseline to Week 96 in Number of Total Daily Doses of Cornstarch
Time frame: Baseline, Week 96
Main Study: Change From Baseline to Week 96 in Percentage of Glucose Values in Hypoglycemic Range (Less Than (<) 70 Milligrams Per Deciliter (mg/dL) [3.9 Millimoles Per Liter (mmol/L)])
Time frame: Baseline, Week 96
Main Study: Patient Global Impression of Change (PGIC) Assessment Score at Week 96
The PGIC captures the participants' perspective on changes in their glycogen storage disease type Ia (GSDIa) since the start of the study using a 7-point response scale ranging from much improved (+ 3) to much worse (- 3). The total score ranges from + 3 to - 3, with a higher score indicating best outcome.
Time frame: Week 96
Main Study: Change From Baseline to Week 96 in Time to Hypoglycemia (< 54 mg/dL [3.0 mmol/L]) During the Controlled Fasting Challenge (CFC)
Time frame: Baseline, Week 96
Main Study: Change From Baseline to Week 96 in Percentage of Glucose Values in the Range of 70-120 mg/dL (3.9- 6.7 mmol/L)
Time frame: Baseline, Week 96
| Milestone | Placebo Followed by DTX401 | DTX401 Followed by Placebo | DTX401 (Japan Cohort) |
|---|---|---|---|
| Started | 26 | 23 | 3 |
| Dosed at day 1 | 25 | 21 | 3 |
| Completed | 25 | 21 | 3 |
| Not completed | 1 | 2 | 0 |
| Withdrew: Withdrawal by subject | 0 | 1 | 0 |
| Withdrew: Reason not specified | 1 | 1 | 0 |
| Milestone | Placebo Followed by DTX401 | DTX401 Followed by Placebo | DTX401 (Japan Cohort) |
|---|---|---|---|
| Started | 25 | 21 | 0 |
| Dosed at week 48 | 19 | 17 | 0 |
| Not dosed at week 48 | 0 | 3 | 0 |
| Completed | 19 | 20 | 0 |
| Not completed | 6 | 1 | 0 |
| Withdrew: Adverse event | 1 | 0 | 0 |
| Withdrew: Withdrawal by parent/guardian | 1 | 1 | 0 |
| Withdrew: Withdrawal by subject | 1 | 0 | 0 |
| Withdrew: Reason not specified | 3 | 0 | 0 |
The least square (LS) mean and standard error (SE) are based on mixed-model for repeated measures (MMRM) analysis.
| percent change | Placebo Followed by DTX401 | DTX401 Followed by Placebo |
|---|---|---|
| Change at Week 24 | -9.21 ± 4.11 | -31.03 ± 4.52 |
| Change at Week 30 | -6.69 ± 4.13 | -35.85 ± 4.57 |
| Change at Week 36 | -7.76 ± 4.15 | -36.46 ± 4.55 |
| Change at Week 42 | -9.25 ± 4.15 | -40.06 ± 4.57 |
| Change at Week 48 | -10.37 ± 4.13 | -40.98 ± 4.55 |
| percent change | DTX401 (Japan Cohort) |
|---|---|
| Change at Week 24 | -95.17 ± 8.37 |
| Change at Week 30 | -85.51 ± 25.10 |
| Change at Week 36 | -100.0 ± 0.0 |
| Change at Week 42 | -100.0 ± 0.0 |
| Change at Week 48 | -100.0 ± 0.0 |
The LS mean and SE are based on MMRM analysis.
| number of total daily doses | Placebo Followed by DTX401 | DTX401 Followed by Placebo |
|---|---|---|
| Change at Week 24 | -0.3 ± 0.2 | -0.8 ± 0.2 |
| Change at Week 30 | -0.1 ± 0.2 | -1.2 ± 0.2 |
| Change at Week 36 | -0.1 ± 0.2 | -1.0 ± 0.2 |
| Change at Week 42 | -0.3 ± 0.2 | -1.4 ± 0.2 |
| Change at Week 48 | -0.2 ± 0.2 | -1.1 ± 0.2 |
| number of total daily doses | DTX401 (Japan Cohort) |
|---|---|
| Change at Week 24 | -2.7 ± 0.6 |
| Change at Week 30 | -2.0 ± 1.7 |
| Change at Week 36 | -3.0 ± 0.0 |
| Change at Week 42 | -3.0 ± 0.0 |
| Change at Week 48 | -3.0 ± 0.0 |
The LS mean and SE are based on MMRM analysis.
| percentage of glucose values | Placebo Followed by DTX401 | DTX401 Followed by Placebo |
|---|---|---|
| Change at Week 24 | 0.07 ± 0.85 | 1.40 ± 0.96 |
| Change at Week 30 | -0.25 ± 0.86 | 1.90 ± 0.96 |
| Change at Week 36 | -0.24 ± 0.86 | 1.27 ± 0.96 |
| Change at Week 42 | 0.18 ± 0.86 | 1.89 ± 0.96 |
| Change at Week 48 | 0.08 ± 0.86 | 3.13 ± 0.96 |
| percentage of glucose values | DTX401 (Japan Cohort) |
|---|---|
| Change at Week 24 | -3.13 ± 6.47 |
| Change at Week 30 | 0.05 ± 0.49 |
| Change at Week 36 | 0.00 ± 0.14 |
| Change at Week 42 | 0.45 ± 1.06 |
| Change at Week 48 | 0.15 ± 0.21 |
The PGIC captures the participants' perspective on changes in their glycogen storage disease type Ia (GSDIa) since the start of the study using a 7-point response scale ranging from much improved (+ 3) to much worse (- 3). The total score ranges from + 3 to - 3, with a higher score indicating best outcome.
| score on a scale | Placebo Followed by DTX401 | DTX401 Followed by Placebo |
|---|---|---|
| Main Study: Patient Global Impression of Change (PGIC) Assessment Score at Week 48 | 1.0 ± 0.3 | 1.4 ± 0.3 |
The PGIC captures the participants' perspective on changes in their GSDIa since the start of the study using a 7-point response scale ranging from much improved (+ 3) to much worse (- 3). The total score ranges from + 3 to - 3, with a higher score indicating best outcome.
| score on a scale | DTX401 (Japan Cohort) |
|---|---|
| Japan Cohort: PGIC Assessment Score at Week 48 | 1.7 ± 1.2 |
The LS mean and SE are based on MMRM analysis.
| hours | Placebo Followed by DTX401 | DTX401 Followed by Placebo |
|---|---|---|
| Change at Week 36 | 0.46 ± 0.84 | 2.02 ± 0.94 |
| Change at Week 48 | 0.50 ± 0.80 | 1.12 ± 0.91 |
| hours | DTX401 (Japan Cohort) |
|---|---|
| Change at Week 36 | 2.43 ± 2.50 |
| Change at Week 48 | 2.73 ± 2.97 |
The LS mean and SE are based on MMRM analysis.
| percentage of glucose values | Placebo Followed by DTX401 | DTX401 Followed by Placebo |
|---|---|---|
| Change at Week 24 | -12.66 ± 2.60 | -1.97 ± 2.93 |
| Change at Week 30 | -7.78 ± 2.64 | -0.18 ± 2.93 |
| Change at Week 36 | -6.34 ± 2.64 | 0.28 ± 2.93 |
| Change at Week 42 | -5.20 ± 2.64 | 2.05 ± 2.93 |
| Change at Week 48 | -6.54 ± 2.64 | -0.52 ± 2.93 |
| percentage of glucose values | DTX401 (Japan Cohort) |
|---|---|
| Change at Week 24 | 1.97 ± 12.82 |
| Change at Week 30 | -6.35 ± 7.14 |
| Change at Week 36 | 5.35 ± 7.57 |
| Change at Week 42 | -9.45 ± 14.07 |
| Change at Week 48 | 11.55 ± 1.06 |
Adverse event (AE) is defined as any untoward medical occurrence associated with use of a drug in humans, whether or not considered drug related. TEAE is defined as any AE not present prior to initiation of drug treatment or any AE already present that worsens in either intensity or frequency following exposure to drug treatment. SAE is an AE that meets any of following criteria in view of either Investigator or Ultragenyx: death; life-threatening; inpatient hospitalization or prolongation of existing hospitalization; disability/incapacity; congenital anomaly/birth defect not present at screening; other important medical events. AESIs are events of scientific or medical interest specific to drug treatment requiring further investigation and close monitoring to further characterize them. Hepatic reactions (vector-induced hepatic effects) were AESIs for this study and were defined as clinically significant increases in aminotransferase levels (AST/ALT) in the judgment of Investigator.
| participants | PEAP: Placebo | PEAP: DTX401 | Crossover and Follow-up: Placebo to DTX401 | Crossover and Follow-up: DTX401 |
|---|---|---|---|---|
| TEAEs | 22 | 21 | 19 | 20 |
| Important Potential Risk and AESIs for DTX401 (Vector-induced Hepatic Effect) | 6 | 15 | 15 | 14 |
| Important Potential Risk and AESIs for DTX401 (Infusion Related Reactions) | 2 | 2 | 0 | 0 |
| AESI Associated with Corticosteroids/Placebo (Adrenal Insufficiency) | 0 | 5 | 1 | 1 |
| Serious TEAEs | 3 | 8 | 10 | 9 |
| DTX401/Placebo Related TEAEs | 8 | 16 | 14 | 6 |
| Fatal AEs | 0 | 0 | 0 | 0 |
| Discontinuation From Study due to AE | 0 | 0 | 0 | 0 |
| Discontinuation From Investigational Product Due to AEs | 0 | 2 | 0 | 0 |
AE is defined as any untoward medical occurrence associated with use of a drug in humans, whether or not considered drug related. TEAE is defined as any AE not present prior to initiation of drug treatment or any AE already present that worsens in either intensity or frequency following exposure to drug treatment. SAE is an AE that meets any of following criteria in view of either Investigator or Ultragenyx: death; life-threatening; inpatient hospitalization or prolongation of existing hospitalization; disability/incapacity; congenital anomaly/birth defect not present at screening; other important medical events. AESIs are events of scientific or medical interest specific to drug treatment requiring further investigation and close monitoring to further characterize them. Hepatic reactions were considered to be important identified risk for this study and were defined as clinically significant increases in aminotransferase levels (AST/ALT) in the judgment of Investigator.
| participants | DTX401 (Japan Cohort) |
|---|---|
| TEAEs | 3 |
| Important Identified Risk of DTX401: Hepatic Reactions | 3 |
| Important Identified Risk of DTX401: Infusion Related Reaction | 0 |
| Serious TEAEs | 0 |
| DTX401 Related TEAEs | 3 |
| Fatal AEs | 0 |
| Potential Risk Related to Corticosteroids: Adrenal Insufficiency | 0 |
| Discontinuation From Study due to AE | 0 |
| Discontinuation From Investigational Product Due to AEs | 0 |
| percent change | Placebo Followed by DTX401 | DTX401 Followed by Placebo |
|---|---|---|
| Main Study: Percent Change From Baseline to Week 96 in Daily Cornstarch Intake (Grams) | -61.32 ± 26.84 | -60.81 ± 19.68 |
| number of total daily doses | Placebo Followed by DTX401 | DTX401 Followed by Placebo |
|---|---|---|
| Main Study: Change From Baseline to Week 96 in Number of Total Daily Doses of Cornstarch | -1.6 ± 1.9 | -1.9 ± 1.5 |
| percentage of glucose values | Placebo Followed by DTX401 | DTX401 Followed by Placebo |
|---|---|---|
| Main Study: Change From Baseline to Week 96 in Percentage of Glucose Values in Hypoglycemic Range (Less Than (<) 70 Milligrams Per Deciliter (mg/dL) [3.9 Millimoles Per Liter (mmol/L)]) | 2.44 ± 3.36 | 5.19 ± 6.32 |
The PGIC captures the participants' perspective on changes in their glycogen storage disease type Ia (GSDIa) since the start of the study using a 7-point response scale ranging from much improved (+ 3) to much worse (- 3). The total score ranges from + 3 to - 3, with a higher score indicating best outcome.
| score on a scale | Placebo Followed by DTX401 | DTX401 Followed by Placebo |
|---|---|---|
| Main Study: Patient Global Impression of Change (PGIC) Assessment Score at Week 96 | 2.1 ± 1.0 | 1.4 ± 1.2 |
| hours | Placebo Followed by DTX401 | DTX401 Followed by Placebo |
|---|---|---|
| Main Study: Change From Baseline to Week 96 in Time to Hypoglycemia (< 54 mg/dL [3.0 mmol/L]) During the Controlled Fasting Challenge (CFC) | 1.34 ± 3.44 | 1.13 ± 3.69 |
| percentage of glucose values | Placebo Followed by DTX401 | DTX401 Followed by Placebo |
|---|---|---|
| Main Study: Change From Baseline to Week 96 in Percentage of Glucose Values in the Range of 70-120 mg/dL (3.9- 6.7 mmol/L) | 11.47 ± 15.88 | 8.90 ± 14.72 |
Collected over PEAP Arms and Japan Cohort - AEs with onset from Day 1 to Week 48; Crossover and Follow-up - Placebo to DTX401 Arm: AEs with onset after Week 48 dosing with DTX401 to Week 144; Crossover and Follow-up DTX401 Arm: AEs from Week 48 to Week 144. Non-serious events are listed at a 5% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| PEAP: Placebo | 0/25 (0%) | 3/25 (12%) | 23/25 (92%) |
| PEAP: DTX401 | 0/21 (0%) | 8/21 (38.1%) | 20/21 (95.2%) |
| Crossover and Follow-up: Placebo to DTX401 | 0/19 (0%) | 10/19 (52.6%) | 19/19 (100%) |
| Crossover and Follow-up: DTX401 | 0/21 (0%) | 9/21 (42.9%) | 20/21 (95.2%) |
| DTX401 (Japan Cohort) | 0/3 (0%) | 0/3 (0%) | 3/3 (100%) |
| Event | PEAP: Placebo | PEAP: DTX401 | Crossover and Follow-up: Placebo to DTX401 | Crossover and Follow-up: DTX401 | DTX401 (Japan Cohort) |
|---|---|---|---|---|---|
| Gastroenteritis ViralInfections and infestations | 1/25 | 0/21 | 3/19 | 3/21 | 0/3 |
| HypertriglyceridaemiaMetabolism and nutrition disorders | 0/25 | 0/21 | 3/19 | 0/21 | 0/3 |
| Lactic AcidosisMetabolism and nutrition disorders | 0/25 | 1/21 | 0/19 | 3/21 | 0/3 |
| Adrenal InsufficiencyEndocrine disorders | 0/25 | 2/21 | 0/19 | 0/21 | 0/3 |
| Anaphylactic ReactionImmune system disorders | 0/25 | 2/21 | 0/19 | 0/21 | 0/3 |
| GastroenteritisInfections and infestations | 0/25 | 2/21 | 0/19 | 2/21 | 0/3 |
| HypoglycaemiaMetabolism and nutrition disorders | 0/25 | 2/21 | 0/19 | 2/21 | 0/3 |
| Blood Lactic Acid IncreasedInvestigations | 0/25 | 0/21 | 1/19 | 0/21 | 0/3 |
| EndometriosisReproductive system and breast disorders | 0/25 | 0/21 | 1/19 | 0/21 | 0/3 |
| Hepatic AdenomaNeoplasms benign, malignant and unspecified (incl cysts and polyps) | 0/25 | 0/21 | 1/19 | 0/21 | 0/3 |
| Event | PEAP: Placebo | PEAP: DTX401 | Crossover and Follow-up: Placebo to DTX401 | Crossover and Follow-up: DTX401 | DTX401 (Japan Cohort) |
|---|---|---|---|---|---|
| Alanine Aminotransferase IncreasedInvestigations | 0/25 | 4/21 | 6/19 | 1/21 | 3/3 |
| Aspartate Aminotransferase IncreasedInvestigations | 0/25 | 2/21 | 2/19 | 1/21 | 3/3 |
| Transaminases IncreasedInvestigations | 3/25 | 13/21 | 14/19 | 7/21 | 0/3 |
| Cortisol DecreasedInvestigations | 0/25 | 1/21 | 1/19 | 0/21 | 2/3 |
| DiarrhoeaGastrointestinal disorders | 3/25 | 3/21 | 3/19 | 2/21 | 2/3 |
| NasopharyngitisInfections and infestations | 3/25 | 5/21 | 3/19 | 5/21 | 2/3 |
| Gamma-Glutamyltransferase IncreasedInvestigations | 4/25 | 5/21 | 10/19 | 6/21 | 0/3 |
| NauseaGastrointestinal disorders | 4/25 | 8/21 | 5/19 | 2/21 | 0/3 |
| Upper Respiratory Tract InfectionInfections and infestations | 5/25 | 7/21 | 6/19 | 8/21 | 0/3 |
| HypertriglyceridaemiaMetabolism and nutrition disorders | 1/25 | 3/21 | 7/19 | 6/21 | 0/3 |
For All arms except Japan Cohort: Intention-to-Treat (ITT) analysis set consists of all randomized participants who received any IP (DTX401 or placebo), including participants who received a partial dose of IP. Placebo and DTX401 arms do not include Japanese participants. For Japan Cohort: Full Analysis Set (FAS) included all randomized participants.
| Age, Categorical(Participants) | Placebo Followed by DTX401 | DTX401 Followed by Placebo | DTX401 (Japan Cohort) | Total |
|---|---|---|---|---|
| <=18 years | 10 | 10 | 3 | 23 |
| Between 18 and 65 years | 15 | 11 | 0 | 26 |
| >=65 years | 0 | 0 | 0 | 0 |
| Sex: Female, Male(Participants) | Placebo Followed by DTX401 | DTX401 Followed by Placebo | DTX401 (Japan Cohort) | Total |
|---|---|---|---|---|
| Female | 12 | 7 | 0 | 19 |
| Male | 13 | 14 | 3 | 30 |
| Ethnicity (NIH/OMB)(Participants) | Placebo Followed by DTX401 | DTX401 Followed by Placebo | DTX401 (Japan Cohort) | Total |
|---|---|---|---|---|
| Hispanic or Latino | 3 | 3 | 0 | 6 |
| Not Hispanic or Latino | 17 | 16 | 3 | 36 |
| Unknown or Not Reported | 5 | 2 | 0 | 7 |
| Race (NIH/OMB)(Participants) | Placebo Followed by DTX401 | DTX401 Followed by Placebo | DTX401 (Japan Cohort) | Total |
|---|---|---|---|---|
| American Indian or Alaska Native | 0 | 0 | 0 | 0 |
| Asian | 2 | 0 | 3 | 5 |
| Native Hawaiian or Other Pacific Islander | 0 | 0 | 0 | 0 |
| Black or African American | 0 | 0 | 0 | 0 |
| White | 23 | 18 | 0 | 41 |
| More than one race | 0 | 0 | 0 | 0 |
| Unknown or Not Reported | 0 | 3 | 0 | 3 |
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: No
Ran from Nov 2021 to primary completion in Feb 2024, 27 months.
Results were first posted in Oct 2026, 2 years 7 months after primary completion. A results delay was requested in Feb 2025.
Of 17 phase 3 interventional studies under Glucose Metabolism Disorders, half reached primary completion within 22 months of starting (the median), counting those still running; a quarter within 17 and three quarters within 28. This study's 27 months is above that.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is completed, as verified in Sep 2026. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Prednisolone
Glucose Metabolism Disorders →
Ultragenyx Pharmaceutical Inc →