Patient description: The patient is a 60 year old man complaining of frequent headaches, generalized bone pain and difficulty chewing that started 6 years ago and is worsening. Examination shows bilateral swellings around the molars. The swellings have increased since his last examination. Several extraoral lesions are detected in the head and face. The swellings are non-tender and attached to the underlying bone. Further evaluation shows increased uptake of radioactive substance as well as an increase in urinary pyridinoline. His serum alkaline phosphatase is 300 IU/L (the normal range is 44- 147 IU/L). His family history is only significant for hypertension in his mother and DM type 2 in his father. The diagnosis of Paget's Disease of Bone was confirmed and Bisphosphonate will be started as first-line therapy.

Clinical trial eligibility criteria: eligible ages (years): 18.0-999.0,  Hidradenitis Suppurativa Written informed consent provided by the patient Male or female, age 18 years or greater For group A, patients must have received and failed anti-TNF therapy For Group B, patients must not have received any prior treatment with any anti-TNF therapy Patients who have received 200 mg dose of bermekimab in this study (previous version(s)) are eligible to begin receiving 400 mg dose starting with the patient's next scheduled visit for the remainder of his/her treatment plan Diagnosis of HS for at least 1 year prior to screening HS affecting at least two distinct anatomic areas, one of which is Hurley II or III stage A total body count of abscesses and inflammatory nodules (AN) of at least 3 Full understanding of the procedures of the study protocol and willingness to comply with them In case of female patients of childbearing potential, willingness to use one method of contraception of high efficacy during the entire study period. This method can be intake of hormonal contraceptives or the use of one of the following: condoms, diaphragm or an intrauterine device. Women of non-childbearing potential those considered to have a medical history that indicates that pregnancy is not a reasonable risk, including post-menopausal women and those with a history of hysterectomy  Age below 18 years Receipt of oral antibiotic treatment for HS within 28 days prior to screening Receipt of prescription topical therapies for the treatment of HS within 14 days prior to screening, and/or systemic therapies for HS (immunosuppressants, corticosteroids, retinoids, or hormonal therapies) within 28 days prior to screening History of treatment with bermekimab for any reason, patients previously treated with 200 mg bermekimab dose in the previous version(s) of this study History of severe allergic or anaphylactic reactions to human, humanized, chimeric, or murine monoclonal antibodies Has received a live (attenuated) vaccine over the 4 weeks prior to screening New intake of opioid analgesics starting within 14 days prior to screening Major surgery (requiring general anesthesia or respiratory assistance) within 28 days prior to Visit 1, Day 0 of start of study drug Hepatic dysfunction defined as any value of transaminases or of γ-glutamyl transpeptidase (γGT), or of total bilirubin > 3 x upper normal limit Stage C Child-Pugh liver cirrhosis