This Phase 2 trial will evaluate the safety and efficacy of ABP-450 for the treatment of cervical dystonia in adults. The study will enroll 60 patients across approximately 30 sites in the United States. Study subjects will be divided evenly across a low dose group, a medium dose group, a high dose group, and a placebo group for one treatment cycle.

This Phase 2 trial will evaluate the safety and efficacy of ABP-450 for the treatment of cervical dystonia in adults. The study will enroll 60 patients across approximately 30 sites in the United States. Study subjects will be divided evenly across a low dose, a medium dose group, a high dose and placebo group for one treatment cycle.

Inclusion Criteria:

1. Male or female patients between 18 and 75 years of age (inclusive)

2. A clinical diagnosis of cervical dystonia (ie, spasmodic torticollis) defined by:

   • TWSTRS total score ≥20
   • TWSTRS severity score ≥10
   • TWSTRS disability score ≥3
   • TWSTRS pain score ≥1

3. On a stable dose of medications (if any) used for focal dystonia treatment (eg, anticholinergics and benzodiazepines) for at least 3 months prior to and expected throughout the study duration

4. For pre-treated patients only: Source documentation (eg, patient history) of the last 2 consecutive injection sessions with a botulinum toxin type A

5. For pre-treated patients only: At least 16 weeks must have passed between the last injection with botulinum toxin for cervical dystonia and baseline treatment (patients can be screened at Week 15 but cannot be enrolled until 16 weeks [for Day 0 injection])

6. Provided written informed consent to being treated for cervical dystonia with ABP-450

7. Stated willingness to comply with all study procedures, including attendance at the study center for all study visits as scheduled and have technological capabilities to have televisits

Exclusion Criteria:

1. Traumatic torticollis or tardive torticollis

2. Predominant retrocollis or anterocollis

3. Myotomy or denervation surgery in the affected muscles (eg, peripheral denervation and/or spinal cord stimulation)

4. Hypersensitivity to human serum albumin, sucrose, or botulinum toxin type A

5. Previous treatment for cervical dystonia with rimabotulinumtoxin B

6. Diagnosis of myasthenia gravis, Lambert-Eaton syndrome, amyotrophic lateral sclerosis, or any other significant neuromuscular disease that might interfere with the trial

7. Current swallowing disorder of any origin (dysphagia scale ≥3, ie, severe, with swallowing difficulties and requiring a change in diet)

8. Marked limitation on passive range of motion that suggests contractures or other structural abnormality, eg, cervical contractures or cervical spine syndrome

9. Treatment with botulinum toxins of any type for any indication other than cervical dystonia within 16 weeks prior to baseline and during the study

10. Medical or psychiatric conditions that may increase the risk associated with study participation or may interfere with the interpretation of study results and, in the judgment of the investigator, would make the patient inappropriate for entry into this study

11. Participation in another interventional study during participation in this study

12. Pregnant or lactating females, or females of child-bearing potential not willing to use an acceptable method of contraception (ie, intrauterine device, barrier methods with spermicide, or abstinence)

13. For pre-treated patients only: The patient's most recent injection with botulinum toxin exceeding the number of units specified as follows:

    • OnabotulinumtoxinA (BOTOX®): >300 units
    • IncobotulinumtoxinA (Xeomin®): >300 units
    • AbobotulinumtoxinA (Dysport®): >750 units

Individual Participant Data collected during the trial, after deidentification may be shared following review of the clinical study report by the FDA review division and if a decision is made to publish the results in a publication outside posting the results in clinicaltrials.gov.

The investigator, study nurse/other study personnel, and patients will be blinded to the treatment group. An appropriately trained person will reconstitute investigational product, fill masked syringes and provide them to the blinded investigator, but will not perform any assessments with the patient.