Study Comparing Short Term Efficacy of Dysport and Dysport NG to Placebo, and to Assess Efficacy and Safety of Dysport NG of Subjects With Cervical Dystonia

The purpose of this study is to evaluate how well a new drug called Dysport NG works and how safe it is, when it is used for the treatment of cervical dystonia. Dysport NG will be compared to an approved drug called Dysport.

The primary study objectives will be assessed in terms of improvement of the subject's CD at a pre-defined time point after treatment. The primary study objectives are to demonstrate the superiority of Dysport NG to placebo in terms of efficacy and to test the non-inferior efficacy of Dysport NG, when compared to Dysport, in CD subjects. In addition to testing for the primary study objectives, the superiority in terms of efficacy of Dysport versus placebo, will be assessed.

This clinical study was designed and implemented and reported in accordance with the International Conference on Harmonization (ICH) Harmonized Tripartite Guidelines for Good Clinical Practice (GCP), with applicable local regulations (including European Directive 2001/20/EC, US Code of Federal Regulations Title 21, and with the ethical principles laid down in the Declaration of Helsinki.

A large body of evidence demonstrates the safety and efficacy of Dysport across several clinical indications. This study was the first use of Dysport NG in humans with CD. The active substance (BTX-A-HAC) in Dysport NG was the same as in the currently marketed Dysport product and had the same mechanism of action. Dysport NG was, therefore, expected to have the same efficacy and safety profile in humans as Dysport, with the advantage of eliminating the potential risk of transmission of infective agents, by the substitution of plant and synthetic products for human and animal-derived products. However, due to the change of excipient, thorough assessment of the safety and efficacy of Dysport NG is necessary. Previous clinical studies indicate that the maximum effect of Dysport and maximum improvements in CD are observed approximately 4 weeks post treatment, after which there is a gradual return to baseline disease status. The Week 4 follow up visit after the first treatment cycle was therefore, chosen as the primary time point of interest. Retreatment is necessary in order to maintain the beneficial effect and the long term treatment of CD. Previously conducted long term studies demonstrate the maintenance of the therapeutic effect of Dysport following repeated treatments, with a favourable short and long term safety and immunogenicity profile.

Eligibility Criteria:
Inclusion Criteria:

* Dystonia with at least 18 months duration since onset.
* Previously untreated with Botulinum toxin-A (BTX-A) or -B or a minimum of 14 weeks since the last injection.
* TWSTRS score at baseline of: Total score ≥ 30, Severity Sub-Scale score ≥ 15, Disability Sub-Scale score ≥ 3, Pain Sub-Scale score ≥ 2.

Exclusion Criteria:

* Known hypersensitivity to Botulinum toxin (BTX) or related compounds or any component in the study drug formulation (including cow milk protein).
* Pure anterocollis or pure retrocollis.
* In apparent remission from Cervical Dystonia.
* Known clinically significant underlying swallowing or respiratory abnormality which might be exacerbated by BTX treatment.
* Previous poor response to BTX treatment or known presence of BTX neutralising antibodies.
* Previous phenol or alcohol injections into the neck muscles.
* Previous myotomy or denervation surgery involving the neck or shoulder region.