A Phase 2/3, Randomized, Double-Blinded, Placebo-Controlled, Parallel-Group Study to Investigate the Efficacy and Safety of Efgartigimod PH20 SC in Adult Participants With Bullous Pemphigoid

Participants are eligible to be included in the study only if all of the
following criteria apply:
1. The participant is willing and able to do the following:
a. understand the requirements of the study
b. provide written informed consent (including consent for the use and
disclosure of research-related health information)
c. comply with the study protocol procedures (including required study visits).
2. The participant is male or female and has reached the local legal age of
consent at the time of signing the informed consent form (ICF).
3. Participants have clinical signs of BP (ie, presence of bullae), with or
without the presence of urticarial/eczematous/erythematous plaques or pruritus
at the screening and baseline visits. The diagnosis of BP must be confirmed by
positive histopathology and DIF before randomization to treatment assignment,
and by positive serology (by IIF, CLEIA, or ELISA, according to local practice)
at screening (Section 8.1.2).
4. The participant has an IGA BP score of 3 or 4 at screening and baseline.
5. The participant has a Karnofsky performance status of at least 60% at
screening.
6. The participant agrees to use contraceptive measures consistent with local
regulations. WOCBP must have a negative serum pregnancy test at screening and a
negative urine pregnancy test at baseline before receiving IMP.

See protocol for the full list of criteria

Participants are excluded from the study if any of the following criteria
apply: 1. Other forms of pemphigoid (including but not limited to pemphigoid
gestationis, drug induced BP that resolves after culprit-drug withdrawal,
anti-p200 pemphigoid, mucous membrane pemphigoid, and cicatricial pemphigoid),
or other AIBDs (including but not limited to epidermolysis bullosa acquisita,
pemphigus vulgaris, and exfoliative erythroderma) 2. Received unstable dose of
treatments known to cause or exacerbate BP (eg, angiotensin converting enzyme
inhibitors, penicillamine, furosemide, phenacetin, dipeptidyl peptidase 4
inhibitor) for at least 4 weeks prior to the baseline visit 3. Use of BP
treatments other than OCS, TCS, conventional immunosuppressants (eg,
azathioprine, cyclophosphamide, methotrexate, mycophenolate mofetil), or
dapsone, including the following: a. sulfasalazine, IVIg, subcutaneous
administration of immunoglobulin (SCIg), immunoadsorption or plasma exchange
within 8 weeks of the baseline visit b. tetracyclines with or without
nicotinamide at doses higher than the recommended daily allowance (RDA)/dietary
reference intake (DRI) within 2 weeks of the baseline visit c. any monoclonal
antibody (including rituximab or another anti-CD20 biologic) within 6 months of
the baseline visit d. complementary therapies*such as traditional Chinese
medicines, herbs, or procedures (eg, acupuncture)*within 4 weeks (or 5
half-lives) of the baseline visit, if the investigator determines that such
therapies may interfere with the study*s efficacy assessments and/or
potentially risk the safety of the participant 4. Known contraindication to OCS
therapy 5. Active, chronic or latent infection at screening 6. Positive
COVID-19 test result at screening (testing performed if required per local
regulations) 7. Any other known autoimmune disease that, in the opinion of the
investigator, would interfere with an accurate assessment of clinical symptoms
of BP or put the participant at undue risk 8. History of malignancy unless
deemed cured by adequate treatment with no evidence of recurrence for >=3 years
before the first administration of the IMP. Participants with the following
cancers can be included at any time, provided they are adequately treated prior
to their participation in the study: a. Basal cell or squamous cell skin cancer
b. Carcinoma in situ of the cervix c. Carcinoma in situ of the breast d.
Incidental histological finding of prostate cancer (tumor-node metastasis [TNM]
stage T1a or T1b) 9. Clinical evidence of other significant serious diseases,
have had a recent surgery, or who have any other condition that, in the opinion
of the investigator, could confound the results of the study or put the patient
at undue risk or prevent participants from complying with protocol
requirements. 10. Use of an investigational product within 3 months or 5
half-lives (whichever is longer) before the first dose of IMP 11. Previously
participated in a clinical study with efgartigimod or currently participating
in another interventional clinical study. 12. Known hypersensitivity to any of
the components of the administered treatments 13. Positive serum test at
screening for an active infection with any of the following conditions: a. HBV
that is indicative of an acute or chronic infection, unless associated with a
negative HBsAg or negative HBV DNA test38 b. HCV based on HCV antibody assay
unless a negative RNA test is available c. HIV based on test results that are
associated with an AIDS-defining condition or a CD4 count <=200 cells/mm3 14.
Primary or secondary hypogammaglobulinemia with total IgG serum levels <4
g/L at screening. [Note: Study candidates with total IgG serum levels of 4 6
g/L at screening may be permitted to participate in the study following
discussion and agreement between the investigator and the sponsor.] 15. Current
or history (ie, within 12 months of screening) of alcohol, drug, or medication
abuse assessed by the investigator 16. Pregnant or lactating females and those
who intend to become pregnant during the study 17. Live or live-attenuated
vaccine received <4 weeks before baseline visit