A Study to Assess the Analgesic Efficacy and Safety of ASP0819 in Patients With Fibromyalgia

Inclusion Criteria

• Subject has a body mass index (BMI) ≤ 45 kg/m2.
• Female subject must either:
• Be of nonchildbearing potential: postmenopausal (defined as at least 1 year without any menses) prior to Screening, or documented surgically sterile (e.g., hysterectomy, bilateral salpingectomy, bilateral oophorectomy).
• Or, if of childbearing potential: agree not to try to become pregnant during the study and for 28 days after the final study drug administration, have a negative blood pregnancy test at Screening and negative urine test on Day 1, and if heterosexually active, agree to consistently use 1 form of highly effective birth control starting at Screening and throughout the study period and for 28 days after the final study drug administration.
• Female subject must agree not to breastfeed at Screening and throughout the study period, and for 28 days after the final study drug administration.
• Female subject must not donate ova starting at Screening, throughout the study period, and for 28 days after the final study drug administration
• Male subject must not donate sperm starting at Screening and throughout the study period, and for 28 days after the final study drug administration.
• Male subject with a partner of child-bearing potential, or a pregnant or breastfeeding partner(s) must agree to remain abstinent or use a condom throughout the study period and for 28 days after the final study drug administration.
• Subject meets the American College of Rheumatology (ACR) 1990 fibromyalgia diagnostic criteria at Screening:
• Widespread pain for at least 3 months, defined as the presence of all of the following: pain on right and left sides of the body, pain above and below the waist, and pain in the axial skeleton (cervical spine or anterior chest or thoracic spine or low back) must be present.
• Pain in at least 11 of 18 tender point sites on digital palpation. Digital palpation should be performed with an approximate force of 4 kg.
• Subject meets the ACR 2010 fibromyalgia diagnostic criteria at Screening:
• Widespread pain index (WPI) ≥ 7 and Symptom severity (SS) scale score ≥ 5 or WPI 3-6 and SS scale score ≥ 9.
• Symptoms have been present at a similar level for at least 3 months.
• The subject does not have a disorder that would otherwise explain the pain.
• Subject has a pain score ≥ 4 on the revised fibromyalgia impact questionnaire revised (FIQR) pain item at Screening.
• Subject is compliant with daily pain recordings during the Baseline Diary Run-In period, as defined by the completion of a minimum of 5 of 7 daily average pain ratings and agrees to complete daily diaries throughout the duration of the study.
• Subject has a mean daily average pain score ≥ 4 and ≤ 9 on an 11-point 0 to 10 NRS as recorded in the subject e-diary during the Baseline Diary Run-In period, and meeting pre-specified criteria for daily average pain scores.
• Subject agrees to use only acetaminophen as rescue medication for fibromyalgia pain throughout the course of the trial (up to 1000 mg per dose and not to exceed 3000 mg/day).
• Subject agrees not to initiate or change any non-pharmacologic interventions (including normal daily exercise routines, chiropractic care, physical therapy, psychotherapy, and massage therapy) during the course of the study. Non-pharmacologic interventions must be stable for a minimum of 30 days prior to Screening. The subject agrees to maintain usual level of activity for the duration of the study.
• Subject is capable of completing study assessments and procedures.
• Subject agrees not to participate in another interventional study from Screening through the End of Study (EOS) visit.

Exclusion Criteria

• Subject has received an investigational therapy within 28 days or 5 half-lives, whichever is longer, prior to Screening.
• Subject has had no meaningful improvement, from 2 or more prior treatments (commercially available) for fibromyalgia (in at least 2 pharmacologic classes).
• Subject has had