This Phase 2 Extension trial will evaluate the efficacy and safety of ABP-450 for migraine prevention in adults who suffer from six or more migraine days per month. The study will enroll approximately 666 patients across approximately 65 sites in the United States, Canada and Australia from the Phase 2 trial. Study subjects will be divided evenly across a low dose group and a high dose group. All patients will receive four treatment cycles of ABP-450 utilizing the Company's novel injection paradigm.