Nomacopan Therapy in Adult Patients With Bullous Pemphigoid Receiving Adjunct Oral Corticosteroid Therapy (ARREST-BP)

Inclusion Criteria: 1. Male or female between 18 and 89 years of age inclusive at the time of consent with Karnofsky score of 50% or more at screening 2. Male or female ≥90 years of age at the time of consent with Karnofsky score of 70% or more at screening 3. Diagnosis of Bullous Pemphigoid either newly diagnosed or relapsing 4. Patients with confirmed atypical Bullous Pemphigoid 5. Bullous Pemphigoid classified as either moderate or severe on the basis of the Investigator Global Assessment (IGA) at randomisation 6. Willing to receive immunisation against Neisseria meningitidis and/or antibiotic prophylaxis 7. Provision of voluntary written informed consent Exclusion Criteria: 1. Patients with recalcitrant BP that have never achieved CDA or who have never been in complete disease remission despite long term treatment with super potent topical steroid or oral cotricosteroid 2. Epidermolysis bullosa acquisita, mucous membrane pemphigoid, or anti p200 pemphigoid 3. Mucosal lesions BPDAI score accounts for ≥30% of total BPDAI activity score at randomisation 4. BP considered to be drug induced, in particular diagnosis of BP made within two months of starting a drug well known to induce BP 5. Treatment with BP-directed biologics including: a) Any cell-depleting agents including, but not limited to, rituximab within 12 months prior to baseline, b) Other biologics within five half-lives (if known) or 16 weeks prior to the baseline, whichever is longer, or c) Intravenous immunoglobulin within 16 weeks prior to the baseline. 6. Taking \> 0.3 mg/kg/day OCS at screening 7. Treatment with systemic immunomodulators such as dapsone or doxycycline within four half-lives of the drugs prior to baseline Day 1 8. Treatment with immunosuppressants within the last two weeks prior to baseline 9. Treatment with an anti-complement therapy or with Zileuton within the last three months prior to baseline 10. OCS dose no more than 0.3mg/kg/day in the 7 days before screening visit 11. Taking super-potent topical corticosteroids and unable to discontinue them at or before the screening assessment 12. Active systemic or organ system bacterial or fungal infection or progressive severe infection 13. Known congenital immunodeficiency or a history of acquired immunodeficiency including a positive human immunodeficiency virus (HIV) test 14. Active infection with hepatitis B or C 15. Positive nasal throat swab for Neisseria species 16. Known hypersensitivity to nomacopan and any of its excipients 17. Receipt of live attenuated vaccines within 2 weeks of Day 1