Study of the Efficacy and Safety of RPH-104 in Adult Subjects With Schnitzler Syndrome

Inclusion Criteria: * 1\. Able to read, understand and willing to sign the ICF and abide with study procedures. The ICF must be signed and dated prior to performing any Screening assessment. * 2\. Confirmed diagnosis of SchS based on diagnostic criteria adapted by Lipsker as an urticarial skin rash (chronic), monoclonal IgM component (ie, IgM \< 10 g/L), or IgG (variant type), and at least of 2 of the following: * Fever (intermittent) * Arthralgia or arthritis * Bone pain * Lymphadenopathy * Hepato and/or splenomegaly * Elevated erythrocyte sedimentation rate (ESR) and/or leukocytosis * Bone abnormalities (on radiological or histological investigation) * 3\. Subjects with symptomatic SchS (as defined by SDAS with a score of 2 or more with a CRP \[local laboratory\] levels \> 10 mg/L) on the day of randomization. * 4\. Willing, committed, and able to return for all clinic visits and complete all study related procedures, including willingness to have SC injections administered by a qualified person. * 5\. Males, female partners of sexually active male subjects, and women of childbearing potential (WOCBP) (defined as all female subjects with physiological potential to conceive) must agree to use highly effective contraceptive methods throughout the study starting from Screening (signing informed consent) through at least 8 weeks after the final dose of study drug. Highly effective contraceptive method is defined as follows: 1. Complete abstinence: if it corresponds to the preferred and conventional lifestyle of the female subject. Periodic abstinence (eg, calendar, ovulation, symptothermal, postovulation method) and interrupted coitus are not considered acceptable contraceptive methods. 2. Sterilization: surgical bilateral ovariectomy (with/without hysterectomy) or tubal ligation at least 6 weeks prior to the study therapy initiation. In case of ovariectomy only the female reproductive status should be verified by further hormonal test. 3. Sterilization of male partner with documented absence of sperm in ejaculate post vasectomy for at least 6 months (vasectomized male partner should be the only partner of the participating female subject). 4. Combination of 2 of the following methods (i + ii, i + iii, or ii + iii): i. Oral, injectable, or implanted hormonal contraceptives; in case of oral contraceptives the female subjects should administer the same product for at least 3 months prior to the study therapy. ii. Intrauterine device or contraceptive system. iii. Barrier methods: condom or occlusive cap (diaphragm or cervical cap/vaginal fornix cap) with spermicidal foam/gel/film/cream/vaginal suppository. * 6\. WOCBP must have negative pregnancy tests at Screening (serum chorionic gonadotropin test), and all subsequent visits (urine). Exclusion Criteria: * 1\. Hypersensitivity to the study drug (RPH 104) and/or its components/excipients and/or the products of the same chemical class. * 2\. Concurrent/on going treatment with anakinra (Kineret) or recent treatment within 5 days prior to Day 0. * 3\. Concurrent/on going treatment with other biologics or recent treatment within 4 weeks or 5 × t½ prior to Day 0, whichever is longer. * 4\. Concurrent/on going treatment with immunosuppressive agents (eg, cyclosporine, methotrexate, dapsone, colchicine, or others) within 4 weeks or 5 × t½ prior to Day 0, whichever is longer. * 5\. Concurrent/on going treatment with high doses of systemic steroids (\> 0.2 mg/kg/day prednisolone equivalent). Intra articular, peri articular, intravenous, or intramuscular corticosteroid injections within 4 weeks prior to the Day 0 visit. * 6\. Administration of live (attenuated) vaccine within 3 months prior to Day 0 and necessity of live vaccine administration for 3 months after Day 70. * 7\. 1. History of active tuberculosis (TB), evidence of active or latent M. tuberculosis infection as defined by local guidelines/local medical practice at Screening. 2. Positive QuantiFERON Gold Plus (TB) test at Screening. 3. Chest X ray findings confirming pulmonary TB at Screening. * 8\. Active bacterial, fungal, or viral infection(s) within 4 weeks prior to Day 0. * 9\. A history of persistent chronic bacterial, fungal, or viral infection(s) requiring treatment with parenteral antibiotics, parenteral antivirals, or parenteral antifungals within 4 weeks prior to Day 0. * 10\. Opportunistic infections and/or Kaposi's sarcoma at the time of Screening. * 11\. Any other relevant concomitant diseases (infectious, cardiovascular, nervous, endocrine, urinary, gastrointestinal, hepatic disorders, coagulation disorders, and other autoimmune/autoinflammatory diseases, etc) or conditions which, according to the investigator's judgment, may affect the subject's participation or well being in the study and/or distort assessment of the study results. * 12\. History of malignancies within 5 years prior to screening other than successfully treated non metastatic, basal, or squamous cell carcinoma of the skin and/or in situ cancer. * 13\. Evidence of lymphoproliferative diseases (except SchS associated monoclonal gammopathy). * 14\. Presence of any of the following laboratory abnormalities at screening visit: white blood cell count (WBC) \< 3000/µL; platelet count \< 75,000/µL; alanine aminotransferase (ALT) or aspartate aminotransferase (AST) \> 3.0 × upper limit of normal (ULN), TBil \> 2 × ULN unless due to Gilbert's syndrome. * 15\. Severe renal failure: Cockcroft Gault creatinine clearance \< 30 mL/min. * 16\. Women who are either pregnant or lactating. * 17\. Subjects for whom there is concern about compliance with the protocol procedures. * 18\. Psychiatric disorders which, according to the investigator's judgment, may affect the subject participation in the study and his/her ability to follow the protocol procedures. * 19\. History of organ transplantation or transplantation is anticipated during the study. * 20\. Concomitant participation in other clinical studies at the start of Screening or administration of any unauthorized (investigational) products less than 4 weeks or 5 × t½ periods (whichever is longer) before Day 0 (treatment initiation).