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Completed

NCT Number: NCT05823012

Study of XP-8121 For the Treatment of Adult Subjects With Hypothyroidism

This is a non-randomized, open-label, single arm, self-controlled study of XP-8121 (levothyroxine sodium) to determine a target dose conversion factor from stably dosed oral levothyroxine to XP-8121 (levothyroxine sodium) in patients with hypothyroidism and to assess the safety and tolerability of XP-8121(levothyroxine sodium) after once weekly subcutaneous injections. This study includes the following periods: Screening, Titration Period, and Maintenance Period. The study will conclude with an End of Maintenance Visit or Early Termination (ET) Visit.

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Key information

Conditions

Hypothyroidism Endocrine System Diseases Thyroid Diseases

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 2

Primary location

ProSciento, Inc., Chula Vista, California, United States

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About this study

This is a non-randomized, open-label, single arm, self-controlled study of XP-8121 (levothyroxine sodium) to determine a target dose conversion factor from stably dosed oral levothyroxine to XP-8121 (levothyroxine sodium) in patients with hypothyroidism and to assess the safety and tolerability of XP-8121 (levothyroxine sodium) after once weekly subcutaneous injections. This study includes the following periods: Screening, Titration Period (2 to 8 weeks), and Maintenance Period (4 weeks). A pharmacokinetic substudy will be conducted for a subset of participants during the Maintenance Period. The study will conclude with an End of Maintenance Visit or Early Termination (ET) Visit.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Provide written informed consent.
  • Male or female between the ages of 18 and 65 years (inclusive) at Screening, with chronic hypothyroidism and on a stable dose of oral levothyroxine (Synthroid or an FDA-approved generic equivalent to Synthroid) or, if in the pharmacokinetic substudy, Synthroid only for at least 3 months.
  • Thyroid stimulating hormone (TSH) within the normal range at Screening (central laboratory) and at least 3 months prior to Screening (documented by local laboratory).
  • Free thyroxine within the normal range at Screening (central laboratory).

Exclusion criteria

  • History of hypersensitivity to levothyroxine (any formulation).
  • Current dose of oral levothyroxine, based on body weight >2 μg/kg/day.
  • Current levothyroxine total daily dose either <50 μg or >375 μg.
  • Current use of combined thyroid treatment (i.e., Synthroid plus liothyronine or Synthroid plus Armour Thyroid) and/or any other levothyroxine aside from those used in the study.

Treatment and study plan

Levothyroxine Sodium

Drug

Levothyroxine sodium 10 mg/mL

Other names: XP-8121

Primary outcomes

  1. Dose Conversion Factor

    Time frame: Day 29 of the Maintenance Period

    Geometric mean ratio of the weekly dose of XP-8121 to the daily dose of oral levothyroxine (aka dose conversion factor), where the XP-8121 dose corresponds to the administration immediately preceding collection of blood TSH used to determine normalization at the end of Maintenance Period. The dose conversion factor was assessed by comparing the natural log-transformed final XP-8121 dose in μg that maintained normalized TSH throughout the Maintenance Period to the natural log-transformed daily oral levothyroxine dose the participant was taking before the study, using a linear mixed effects model with treatment as the fixed effect and subject as the random effect. Geometric least square means (LSMs) were calculated by exponentiating the LSM from the ANOVA. The geometric mean ratio and the corresponding 90% CI was found by exponentiating the differences of log-transformed LSM and 90% confidence interval (CI) of the difference.

  2. Tolerability Assessment: Modified Draize Scale - Erythema

    Time frame: Week 1 Dosing in Titration Period through Day 22 Dosing in Maintenance Period

    The Modified Draize Scale assessment of erythema and edema was conducted 30 (+/-5) minutes after each dosing. The Modified Draize Scale is a 5-point scale: 0-none, 1-very slight, 2-slight, 3-moderate, 4-severe.

  3. Tolerability Assessment: Modified Draize Scale - Edema

    Time frame: Week 1 Dosing in Titration Period through Day 22 Dosing in Maintenance Period

    The Modified Draize Scale assessment of erythema and edema was conducted 30 (+/-5) minutes after each dosing. The Modified Draize Scale is a 5-point scale: 0-none, 1-very slight, 2-slight, 3-moderate, 4-severe.

  4. Tolerability Assessments: Injection Site Discomfort Evaluation

    Time frame: Week 1 dosing in the Titration Period through Day 22 dosing in the Maintenance Period

    Injection site discomfort was assessed by each participant at 10 (+/-2) minutes post-injection.

Secondary outcomes

  1. Proportion of Participants With Normalized TSH Throughout the Maintenance Period

    Time frame: Day 29 of the Maintenance Period

    Proportion of participants enrolled with normalized TSH throughout the Maintenance Period

  2. Proportion of Participants With Normalized TSH at End of Maintenance Period

    Time frame: Day 29 of the Maintenance Period

    Proportion of participants enrolled with normalized TSH at the end of the Maintenance Period.

  3. Thyroid Hormone Concentrations: Total Thyroxine

    Time frame: Up to Day 29 of the Maintenance Period

    Thyroid hormone concentrations (total thyroxine, free protein-unbound thyroxine (fT4), and TSH) following the first dose of XP-8121 during the Titration Period and Maintenance Periods

  4. Thyroid Hormone Concentrations: Free Thyroxine (fT4)

    Time frame: Up to Day 29 of the Maintenance Period

    Thyroid hormone concentrations (total thyroxine, free protein-unbound thyroxine (fT4), and TSH) following the first dose of XP-8121 during the Titration Period and Maintenance Periods

  5. Thyroid Hormone Concentrations: Thyroid Stimulating Hormone (TSH)

    Time frame: Up to Day 29 of the Maintenance Period

    Thyroid hormone concentrations (total thyroxine, free protein-unbound thyroxine (fT4), and TSH) following the first dose of XP-8121 during the Titration Period and Maintenance Periods

Sponsors and collaborators

Lead sponsor

Xeris Pharmaceuticals

Industry

Registry information

Official study title

A Phase 2, Multicenter, Non-Randomized, Open-Label, Single Arm, Self-controlled Study of XP-8121 For the Treatment of Adult Subjects With Hypothyroidism

Important dates

Study start
2023
Primary completion
2024
Study completion
2024
First posted
Apr 21, 2023
Registry last updated
Jul 3, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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