OnabotulinumtoxinA Effective for Preventing Chronic Migraine

Emma Hitt, PhD

June 10, 2011

June 10, 2011 (Washington, DC) — Patients treated with onabotulinumtoxinA (Botox, Allergan) for chronic migraine prophylaxis had statistically and clinically meaningful improvements in multiple headache symptoms compared with placebo, according to the results from 2 large phase 3 trials. Beneficial effects on headache symptoms were also noted in a smaller, uncontrolled study.

Sheena Aurora, MD, Director, Swedish Headache Center in Seattle, Washington, and colleagues presented the findings of both studies at the 53rd meeting of the American Headache Society.

Results From Phase 3 Trials

The PREEMPT (Phase 3 REsearch Evaluating Migraine Prophylaxis Therapy) program comprises 2 phase 3 studies: a 24 week, randomized, double blind placebo controlled phase followed by a 32 week open label phase. Patients received injections of onabotulinumtoxinA or placebo every 12 weeks for 2 cycles in the double blind phase followed by onabotulinumtoxinA for 3 cycles.

The secondary analysis of the PREEMPT program presented by Dr. Aurora and colleagues included 1005 patients who had received all 5 treatment cycles and completed the studies (513 received onabotulinumtoxinA only and 492 received placebo followed by active drug). Chronic migraine was defined as headaches lasting at least 4 hours on at least 15 days per month. Demographic characteristics were similar between the treatment groups.

After 56 weeks, when all patients had received onabotulinumtoxinA, significant benefits continued to be shown for the onabotulinumtoxinA vs the placebo/onabotulinumtoxinA group for mean change from baseline in frequency of headache days (-12.0 vs. -11.1; P = .035). In addition, migraine days (-11.6 vs. -10.7; P = .038) and moderate/severe headache days (-11.0 vs. -10.1; P = .042) were also significantly decreased.

At 56 weeks, the percentage of patients showing at least 50% reduction from baseline in headache days was significantly greater in the onabotulinumtoxinA group than in the placebo/onabotulinumtoxinA group (69.6% vs. 62.8%; P = .023). Overall, quality-of-life scores also improved with onabotulinumtoxinA over the 56 weeks of the study.

Treatment-related adverse events were reported by 28.5% and 12.4% of patients in the onabotulinumtoxinA and placebo groups, respectively, over the double blind phase, and by 34.8% of patients treated with active drug over all 5 cycles (56 weeks).

Evaluation of Sumatriptan Response

Additional findings from a small uncontrolled study were also presented by this group. This study evaluated the effects of prophylactic onabotulinumtoxinA (155 to 195 units), given for 2 cycles, on the pain responses to oral sumatriptan for acute headache in 11 patients with chronic migraine.

The primary endpoint was improvement from baseline measured by at least 2 of 3 treated headaches achieving freedom from pain 2 hours after taking sumatriptan, 100 mg. This endpoint was not met because it was achieved in only 1 patient.

However, secondary endpoints improved significantly compared with baseline after 2 cycles of onabotulinumtoxinA: Mean headache frequency decreased from 19.9 to 7.4 days (P < 0.01) and average cumulative headache duration decreased from 257.5 to 62.8 hours (P < 0.01).

After 2 cycles of onabotulinumtoxinA, clinically meaningful improvements from baseline were noted for some headache symptoms. The response to oral sumatriptan was not enhanced or worsened by onabotulinumtoxinA treatment in this small uncontrolled study.

The US Food and Drug Administration has approved onabotulinumtoxinA for headache prophylaxis in adults with chronic migraines.

The studies were supported by Allergan, Inc.

53rd meeting of the American Headache Society. Abstracts P135 and P136. Presented June 3, 2011.

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