A Study to Evaluate the Efficacy and Safety of Gefapixant (MK-7264) in Women With Endometriosis-Related Pain (MK-7264-034)

Study Overview
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Brief Summary
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The purpose of this study is to evaluate the efficacy, safety, and tolerability of gefapixant (MK-7264) in premenopausal female participants with moderate to severe endometriosis-related pain. The primary hypothesis: gefapixant is superior to placebo in reducing the average daily pelvic pain score (cyclic and non-cyclic, combined) during Treatment Cycle 2.

Official Title
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A Phase 2a, Proof of Concept, Randomized, Double-Blind, Placebo-Controlled Clinical Trial, to Evaluate the Efficacy and Safety of MK-7264 in Women With Moderate to Severe Endometriosis-Related Pain

Conditions
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Endometriosis-related Pain

Intervention / Treatment
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* Drug: Gefapixant
* Drug: Placebo
* Drug: Naproxen


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: has been surgically (laparoscopy or laparotomy) diagnosed with endometriosis. has cyclic AND non-cyclic, moderate to severe endometriosis-related pelvic pain (overall pelvic pain score ≥5 using a 0-10 NRS, with 0 representing no pain and 10 representing extremely severe pain). has had spontaneous menstrual cycles before Visit 1. has body mass index (BMI) between 18 kg/m^2 to 40 kg/m^2 at Visit 1. is not pregnant, not breastfeeding, and agrees to follow the contraceptive guidance. must agree to switch from her usual analgesic medication to only that which is permitted in the study. Exclusion Criteria: history of hysterectomy and/or bilateral oophorectomy. has undiagnosed vaginal bleeding. has chronic, non-pelvic pain not caused by endometriosis that requires chronic analgesic. has a clinically significant gynecologic condition identified in the screening evaluation. has a history of anaphylaxis or cutaneous adverse drug reaction (with or without systemic symptoms) to sulfonamide antibiotics or other sulfonamide-containing drugs. has a known allergy/sensitivity or contraindication to gefapixant or its excipients. has an allergy/sensitivity/intolerance to naproxen sodium (rescue medication) or any contraindication to its use, or has experienced asthma, urticaria, or allergic-type reactions after taking aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs). has a history of endometriosis-related pain that was non-responsive to treatment with combined hormonal contraceptives (CHCs), gonadotropin-releasing hormone (GnRH) antagonists, GnRH agonists, progestins, or aromatase inhibitors. has a positive urine pregnancy test at any time before randomization. has required more than 2 weeks of continuous use of narcotics for treatment of endometriosis-related pain within 6 months of Visit 1.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 49 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Gefapixant<br>Participants will receive a gefapixant 45 mg tablet twice a day for approximately 8 weeks (2 menstrual cycles). Naproxen sodium 275 mg tablets will also be provided to participants for use as rescue medication for endometriosis-related pain. | Drug: Gefapixant<br>* Gefapixant tablet 45 mg taken orally<br>* Other names: MK-7264;Drug: Placebo<br>* Placebo matching gefapixant tablet taken orally<br>Drug: Naproxen<br>* Naproxen sodium 275 mg tablets taken orally as needed, at dose prescribed by sites' principal investigator<br>|
| Placebo Comparator: Placebo<br>Participants will receive a placebo matching gefapixant tablet twice a day for approximately 8 weeks (2 menstrual cycles). Naproxen sodium 275 mg tablets will also be provided to participants for use as rescue medication for endometriosis-related pain. | Drug: Placebo<br>* Placebo matching gefapixant tablet taken orally<br>Drug: Naproxen<br>* Naproxen sodium 275 mg tablets taken orally as needed, at dose prescribed by sites' principal investigator<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change From Baseline in Average Daily Pelvic Pain Score During Treatment Cycle 2 | Pelvic pain (cyclic pain associated with menses, and non-cyclic pain not associated with menses) severity score was measured using a 0-10 numeric rating scale (NRS), with 0 representing no pain and 10 representing extremely severe pain. The averages of the daily pelvic pain scores (cyclic and non-cyclic, combined) entered in participants' electronic diaries (eDiaries) were calculated for Baseline and Treatment Cycle 2 (approximately Week 4 to Week 8). A negative change indicates a decrease in pain severity from baseline. | Baseline and Treatment Cycle 2 (Week 4 to Week 8; each cycle is approximately 28 days) | 
| Percentage of Participants Who Experienced an Adverse Event | An adverse event (AE) is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a study intervention. Per protocol, this analysis included AEs reported up to 14 days after end of study intervention. | Up to approximately 10 weeks | 
| Percentage of Participants Who Discontinued Study Drug Due to an Adverse Event | An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a study intervention. | Up to approximately 8 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change From Baseline in Average Daily Cyclic Pelvic Pain Score During Treatment Cycle 2 | Cyclic pelvic pain (associated with menses) severity score was measured using a 0-10 NRS, with 0 representing no pain and 10 representing extremely severe pain. The average of the daily cyclic pelvic pain scores entered in participants' eDiaries was calculated for Baseline and Treatment Cycle 2 (Week 4 to Week 8). A negative change indicates a decrease in pain severity from baseline. | Baseline and Treatment Cycle 2 (Week 4 to Week 8; each cycle is approximately 28 days) | 
| Change From Baseline in Average Daily Non-Cyclic Pelvic Pain Score During Treatment Cycle 2 | Non-cyclic pelvic pain (not associated with menses) severity score was measured using a 0-10 NRS, with 0 representing no pain and 10 representing extremely severe pain. The average of the non-cyclic daily pelvic pain scores entered in participants' eDiaries was calculated for the Baseline and Treatment Cycle 2 (Week 4 to Week 8). A negative change indicates decrease in pain severity from baseline. | Baseline and Treatment Cycle 2 (Week 4 to Week 8; each cycle is approximately 28 days) |