Patients with CDH are at the more severe end of the headache/migraine spectrum, and currently available therapies typically provide inadequate relief due to intolerable side effects or other limitations.

CDH isa disabling headache disorder characterized by headaches or migraines that occur on 16 or more days each month.

The purpose of the exploratory trials was to investigate the potential use of Botox (botulinum toxin type A) to treat various forms of headache and levels of headache severity, in an effort to identify a responsive patient population, dose and efficacy endpoints to guide the Phase III program.

Results May Have Been Confounded

Subgroup analyses of patients in the CDH trials revealed that the predetermined primary outcome measure (that is, mean change from baseline in the number of headache-free days at day 180) was met in several subsets of patients receiving Botox, although primary outcomes were not met overall.

Neither were significant between-group differences observed on predetermined outcome measures in studies of patients with episodic migraine.

Additional studies are needed to further examine the possible role of Botox in the treatment of patients with episodic migraine, the researchers suggest.

While primary endpoints were not met in either the CDH or episodic-migraine studies, results may have been confounded by several factors, the researchers point out.

A high proportion of patients took concomitant prophylactic and acute headache pain medications during the studies, which increased the difficulty of differentiating study treatment from placebo.

Well Tolerated

Botox was found to be generally well-tolerated across all Phase II studies, with less than 5% of patients discontinuing participation due to adverse events.

Based on the Phase II findings specific to patients with CDH, Allergan has reached an agreement with the US Food and Drug Administration (FDA) to move forward with a large Phase III clinical trial program, currently scheduled to begin in late 2005, to investigate the safety and efficacy of Botox as a prophylactic therapy in a subset of migraine patients with CDH.

Patients with CDH are at the more severe end of the headache/migraine spectrum, and currently available therapies typically provide inadequate relief due to intolerable side effects or other limitations. Botox currently is not approved by the FDA for the treatment of any headache disorder.

Investigators will present all new and previously reported data from Allergan's Phase II clinical trial program exploring the use of Botox as a treatment for various forms of migraine and headache at the American Headache Society (AHS) 2005 Annual Meeting.