Phase III Study To Compare The Effect of Panzyga Versus Placebo in Patients With Pediatric Acute-onset Neuropsychiatric Syndrome (PANS/PANDAS)

Inclusion Criteria

• Patients ≥6 to ≤17 years of age.
• Confirmed diagnosis of moderate to severe PANS with prominent and stable obsessive-compulsive disorder (OCD) symptoms (i.e. Clinical Global Impression (CGI)-Severity-OCD rating of ≥ 4 or higher on 2 ratings without a change of more than 1 unit between measurements) based on the following criteria:
• Abrupt dramatic onset of OCD meeting DSM-5 diagnostic criteria for OCD as confirmed by the MINI-KID-7
• Concurrent presence of additional neuropsychiatric symptoms, with similarly severe and acute onset, from at least two of the following seven categories, that are not better explained by a known neurologic or medical disorder, such as Sydenham chorea (SC), systemic lupus erythematosus, Tourette disorder, or other:
• Anxiety (particularly, separation anxiety)
• Emotional lability (extreme mood swings) and/or depression
• Irritability, aggression and/or severely oppositional behaviors
• Behavioral (developmental) regression (examples, talking baby talk,throwing temper tantrums, etc.)
• Deterioration in school performance
• Sensory or motor abnormalities
• Somatic signs and symptoms, including sleep disturbances, bed wetting or urinary frequency
• Signed informed consent of patient's legal representative(s)/guardians(s). If patients are old enough to understand the risks and benefits of the study (as determined by each institution), they should provide written assent/consent.
• Legal representative(s)/guardians(s) must be capable of understanding and complying with the relevant aspects of the study protocol.

Patients who will additionally meet the following optional inclusion criteria will be identified as patients with Pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (PANDAS):

• An episodic (relapsing-remitting) course of symptom severity
• Temporal association between symptoms onset or exacerbation and infections with group A streptococcal infection (GAS, positive throat culture and/or anti-GAS antibody titers)

Exclusion Criteria

• Onset of current PANS episode more than 12 months prior to first investigational medicinal product (IMP) treatment.
• a. In patients with relapsing episodes: Onset of initial PANS episode more than 24 months prior to first IMP treatment.

b. In patients with relapsing episodes: Absence of significant improvement and stabilization between the episodes according to investigator's judgment.

• Contraindication to receiving intravenous immunoglobulin (IVIG), including:
• History of severe hypersensitivity, e.g. anaphylaxis or severe systemic response, to immunoglobulin, blood or plasma derived products, or any component of Panzyga.
• Immunoglobulin (Ig) A deficiency with antibodies to IgA ( 120 µmol/L or 1.36 mg/dL), history of renal dysfunction, or known risk factor for renal dysfunction (chronic renal insufficiency, diabetes mellitus, taking known nephrotoxic medication). For Italy, estimated glomerular filtration rate (eGFR) needs to be calculated with the 2009 Schwartz equation (eGFR = k * height/Serum creatinine (Scr), where k is 0.413) [2]. eGFR must not be below 30.
• Severely restricted food intake likely to require parenteral nutrition, and <5th percentile BMI-for-age (BMI Percentile Calculator for Child and Teen based on Centers for Disease Control and Prevention growth charts for children and teens ages 2 through 19 years)
• Body mass index ≥ 40 kg/m2
• Presence of symptoms consistent with autism or schizophrenia, bipolar disorder, or other psychotic disorder (unless psychotic symptoms have onset coincident with PANS).
• Presence of serious or unstable medical illness, psychiatric (e.g. high suicide risk) or behavioral symptoms that would make participation unsafe or study procedures too difficult to tolerate.
• Treatment with systemic corticosteroids within eight weeks before randomization.
• Treatment with NSAIDs within five days before randomization.
• Treatment with melat