This is a Study to Evaluate the Long-term Safety, Tolerability and Efficacy of Bimekizumab in Adult Patients With Chronic Plaque Psoriasis.

Inclusion Criteria:

- Subject must have completed all dosing requirements in PS0016 without meeting any
withdrawal criteria

- Female subjects must be postmenopausal, permanently sterilized or, if of childbearing
potential, must be willing to use a highly effective method of contraception up till
20 weeks after last administration of study drug, and have a negative pregnancy test
at Visit 1 (Screening) and immediately prior to first dose

- Male subjects with a partner of childbearing potential must be willing to use a condom
when sexually active, up till 20 weeks after the last administration of study
medication (anticipated 5 half-lives)

Exclusion Criteria:

- Subjects previously participating in this study

- Subject has any medical or psychiatric condition that, in the opinion of the
Investigator, could jeopardize or would compromise the subject's ability to
participate in this study. Note: For any subject with an ongoing serious adverse event
(SAE), or a history of serious infections (including herpes zoster or
hospitalizations) in PS0016, the Medical Monitor must be consulted prior to the
subject's entry into PS0018

- Subject has any current sign or symptom that may indicate a medically significant
infection

- Subject has current clinically active infection with Histoplasma, Coccidiodes,
Paracoccidioides, Pneumocystis, tuberculosis (TB), nontuberculous mycobacteria
(NTMB),Blastomyces, Aspergillus, or Candidiasis (systemic). Any subject diagnosed with
Histoplasmosis, Coccidiodes, Paracoccidiodes, Pneumocystis, TB, NTMB, Blastomyces,
Aspergillus, or Candidiasis (systemic) during PS0016 is excluded from PS0018 even if
treatment has been completed.

- Any subject who meets any withdrawal criteria in the feeder study (PS0016) is excluded
from participating in the open-label extension study (PS0018)