Efficacy and Safety of LX9211 in Participants With Postherpetic Neuralgia (RELIEF-PHN1)

January 27, 2026 updated by: Lexicon Pharmaceuticals

A Phase 2, Double-blind, Randomized, Placebo-controlled, Parallel-group Study to Evaluate the Efficacy and Safety of LX9211 in the Treatment of Postherpetic Neuralgia (RELIEF-PHN1)

Evaluation of the efficacy of LX9211 compared to placebo in reducing pain related to postherpetic neuralgia over an 11 week assessment period.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
79

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • 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

  • Czechia
      • Choceň, Czechia, 565 01
        • Lexicon Investigational Site (138)
      • Pardubice, Czechia, 53002
        • Lexicon Investigational Site (140)
      • Prague, Czechia, 100 00 00
        • Lexicon Investigational Site (136)
      • Prague, Czechia, 12000
        • Lexicon Investigational Site (137)
      • Prague, Czechia, 13000
        • Lexicon Investigational Site (141)
      • Prague, Czechia, 16000
        • Lexicon Investigational Site (135)
  • Poland
      • Katowice, Poland, 40-282
        • Lexicon Investigational Site (128)
      • Katowice, Poland, 640-748
        • Lexicon Investigational Site (130)
      • Lublin, Poland, 20-064
        • Lexicon Investigational Site (134)
      • Warsaw, Poland, 01-868
        • Lexicon Investigational Site (133)
  • United States
    • Arizona
      • Scottsdale, Arizona, United States, 85258
        • Lexicon Investigational Site
      • Tucson, Arizona, United States, 85741
        • Lexicon Investigational Site
    • California
      • Greenbrae, California, United States, 94904
        • Lexicon Investigational Site
    • Florida
      • Brandon, Florida, United States, 33511
        • Lexicon Investigational Site
      • Miami, Florida, United States, 33032
        • Lexicon Investigational Site (113)
      • Miami, Florida, United States, 33144
        • Lexicon Investigational Site
      • Miami, Florida, United States, 33174
        • Lexicon Investigational Site
      • Ormond Beach, Florida, United States, 32174
        • Lexicon Investigational Site
      • Winter Park, Florida, United States, 32789
        • Lexicon Investigational Site
    • Georgia
      • Marietta, Georgia, United States, 30060
        • Lexicon Investigational Site (147)
    • Illinois
      • Flossmoor, Illinois, United States, 60422
        • Lexicon Investigational Site
      • Wauconda, Illinois, United States, 60084
        • Lexicon Investigational Site
    • Massachusetts
      • Boston, Massachusetts, United States, 02131
        • Lexicon Investigational Site
    • Michigan
      • Canton, Michigan, United States, 48187
        • Lexicon Investigational Site
    • Missouri
      • Hazelwood, Missouri, United States, 63042
        • Lexicon Investigational Site
    • New Mexico
      • Albuquerque, New Mexico, United States, 87102
        • Lexicon Investigational Site
    • North Carolina
      • Cary, North Carolina, United States, 27518
        • Lexicon Investigational Site (148)
    • Pennsylvania
      • Jenkintown, Pennsylvania, United States, 19046
        • Lexicon Investigational Site
    • Texas
      • Baytown, Texas, United States, 77521
        • Lexicon Investigational Site
      • Victoria, Texas, United States, 77901
        • Lexicon Investigational Site
    • Utah
      • Salt Lake City, Utah, United States, 84102
        • Lexicon Investigational Site
    • Wisconsin
      • Kenosha, Wisconsin, United States, 53144
        • Lexicon Investigational Site

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Participant has given written informed consent to participate in the study in accordance with local regulations
  • Adult male and female participants ≥18 years of age at the time of screening
  • Postherpetic neuralgia (PHN) pain that is present for ≥3 months after healing of herpes zoster skin rash affecting a single dermatome (Participants with more than 1 involved dermatome may also be included, provided the affected dermatomes are contiguous)
  • Moderate to severe pain as confirmed by average pain score using scores recorded in the pain diary in the 14 days prior to randomization

Exclusion Criteria:

  • Presence of other painful conditions that may confound assessment or self-evaluation of PHN
  • History of major depressive episode, active, significant psychiatric disorders
  • History of clinically significant drug or alcohol use disorder
  • PHN affecting the face
  • Use of opioid medications for management of PHN within the 2 months prior to Screening Visit
  • Use of Non-steroidal anti-inflammatory drugs (NSAIDs) for the specific treatment of PHN pain

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: Quadruple

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Placebo Comparator: Placebo
Following a 2-week Single-blind Run-in period, participants will receive a single loading dose of matching-placebo to LX9211 tablet, orally, on Day 1 and maintenance doses, orally, once daily from Day 2 to Week 6.
Drug: Placebo
LX9211 matching-placebo, tablets will be administered orally.
Experimental: LX9211
Following a 2-week Single-blind Run-in period, participants will receive a single loading dose of 200 milligrams (mg) tablet, orally, on Day 1 and maintenance doses of 20 mg, orally, once daily from Day 2 to Week 6.
Drug: LX9211
LX9211 tablets will be administered orally.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Change From Baseline (Week 2 of the Run-in Period) in Average Daily Pain Score (ADPS)
Time Frame: Baseline (Week 2 of the Run-in period) to Week 6
ADPS is based on question 5 of Zoster Brief Pain Inventory (ZBPI) and assessed on an 11-point numerical rating scale where, 0 = No Pain to 10 = pain as bad as you can imagine. Higher ADPS scores indicates a worse outcome. Negative change from baseline indicates no pain.
Baseline (Week 2 of the Run-in period) to Week 6

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change From Baseline in Pain Interfering With Sleep Based on Question 9F of the ZBPI at Week 6
Time Frame: Baseline to Week 6
Pain interfering with sleep is based on Question 9F of the ZBPI "Indicate the one number that describes how, in the past 24-hours shingles pain has interfered with your: Sleep; 0 = does not interfere to 10 = Completely interferes. Higher the number, the worsening of sleep due to pain interference. Negative change from baseline indicates no interference in sleep. Pain interfering with sleep was based on the daily pain diary data based on Q 9F of the ZBPI.
Baseline to Week 6
Percentage of Participants With ≥30% Reduction in Pain Intensity in ADPS From Baseline at Week 6
Time Frame: Baseline to Week 6
ADPS is based on question 5 of Zoster Brief Pain Inventory (ZBPI) and assessed on an 11-point numerical rating scale where, 0 = No Pain to 10 = pain as bad as you can imagine. Higher ADPS scores indicated a worse outcome.
Baseline to Week 6
Percentage of Participants With ≥50% Reduction in Pain Intensity in ADPS From Baseline at Week 6
Time Frame: Baseline to Week 6
ADPS is based on question 5 of ZBPI and assessed on an 11-point numerical rating scale where, 0 = No Pain to 10 = pain as bad as you can imagine. Higher ADPS scores indicated a worse outcome.
Baseline to Week 6
Change From Baseline in Interference in General Activity, Mood, Walking Ability, Normal Work, Relations With Other People, Sleep, and Enjoyment of Life Interference Based on the Questions 9A-G of the ZBPI
Time Frame: Baseline to Week 6
The ZBPI, a 9-item questionnaire, assesses the severity of pain and its impact on functioning in participants with postherpetic neuralgia (PHN). Each question concerning daily activity (General Activity, Mood, Walking Ability, Normal Work, Relations With Other People, Sleep, and Enjoyment of Life) was scored on a scale from 0 to 10, where 0 indicated no interference and 10 indicated complete interference. Higher ZBPI score indicates a worse outcome. Negative change from baseline indicates no interference in all daily activities. The pain interference at Week 6 in this outcome measure was based on data collected on the ZBPI administered at the Week 6 in-person clinic visit.
Baseline to Week 6
Number of Participants Discontinuing Treatment Due to Lack of Efficacy Defined as Increase in ADPS From Baseline of ≥30% Based on Question 5 of the ZBPI
Time Frame: Baseline to Week 6
ADPS is based on question 5 of ZBPI and assessed on an 11-point numerical rating scale where, 0 = No Pain to 10 = pain as bad as you can imagine.
Baseline to Week 6
Patient Global Impression of Change (PGIC) at Week 6
Time Frame: Baseline to Week 6
PGIC is assessed on a 7-point rating scale where 1= very much improved to 7 = very much worse. Higher scores indicate worse outcomes.
Baseline to Week 6
Time to Loss of Efficacy From Week 6 to Week 11 Among Participants Achieving ≥30% Reduction in Pain Intensity in ADPS Based on Question 5 of the ZBPI.
Time Frame: Week 6 to Week 11
ADPS is based on question 5 of ZBPI and assessed on an 11-point numerical rating scale where, 0 = No Pain to 10 = pain as bad as you can imagine.
Week 6 to Week 11
Number of Participants With Treatment-emergent Adverse Events (TEAEs)
Time Frame: From first dose of study drug up to end of double-blind treatment period (up to Week 6) and end of single-blind treatment period (up to Week 11)
Adverse Events (AEs) are defined as any sign, symptom, or diagnosis/disease that is unfavorable or unintended, that is new, or if pre-existing, worsens in participants administered a pharmaceutical product and that does not necessarily have a causal relationship with this treatment. Treatment-emergent AEs are defined as any AEs reported after the first dose of double-blind study medication on study Day 1.
From first dose of study drug up to end of double-blind treatment period (up to Week 6) and end of single-blind treatment period (up to Week 11)

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Lexicon Pharmaceuticals

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Study Director: Suma Gopinathan, PhD, Lexicon Pharmaceuticals

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
December 10, 2020

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
November 18, 2022

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 28, 2022

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
December 4, 2020

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
December 4, 2020

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
December 10, 2020

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
February 13, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 27, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
January 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • LX9211.1-202-PHN
  • 2020-004639-26 (EudraCT Number)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • CSR

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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