Study to Evaluate the Efficacy, Safety and Tolerability of MAS825 in Patients With Monogenic IL-18 Driven Autoinflammatory Diseases, Including NLRC4-GOF, XIAP Deficiency, or CDC42 Mutations

Inclusion Criteria:

For all Patients:

1. Male and female patients weighing at least 3 kg

2. Written informed consent by parent(s)/legal guardian(s) for the pediatric patientsand assent by the pediatric patient (depending on local requirements) must beobtained before any study-specific assessment is performed. For adult patients,written informed consent by patients capable of giving consent, or when the patientis not capable of giving consent, by his/her legal/authorized representative (ifallowed according to local requirements). Cohort 1 specific inclusion criteria:

3. Patients with a genetic diagnosis of either NLRC4-GOF, XIAP deficiency, or CDC42mutation

4. Clinical history and investigations consistent with autoinflammation and infantileenterocolitis (AIFEC/NLRC4-GOF), XIAP or CDC42. XIAP patients must have persistentdisease or be resistant to escalating therapy.

5. At first treatment, evidence of active disease as assessed by inflammatory markersand PGA Cohort 2 specific inclusion criteria:

6. Patients with a genetic diagnosis of NLRC4-GOF, XIAP deficiency, or CDC42 mutationswho are being treated with MAS825 in a Novartis Managed Access Program (MAP).

Exclusion Criteria:

1. History of hypersensitivity to any of the study drugs or to drugs of similarchemical classes or to any of the excipients.

2. Signs and symptoms, in the judgment of the investigator, of clinically significantactive bacterial, fungal, parasitic or viral infections, excluding chronicEpstein-Barr Virus (EBV).

• COVID-19 specific: If in line with health and governmental authority guidance,it is highly recommended that testing to exclude COVID-19 using PCR orcomparable approved methodology be completed within 1 week prior to firstdosing.

3. Any conditions or significant medical problems, which in the opinion of theinvestigator places the patient at unacceptable risk for MAS825 therapy

4. Previous treatment with anti-rejection and/or immunomodulatory drugs within the past 28 days or 5 half-lives (whichever is the longer) for immunomodulatory therapeuticantibodies (or as listed in the prohibited medications section) prior to MAS825treatment with the exceptions of glucocorticoids, cyclosporin and targeted bindingor blocking therapies.

5. A positive HIV test result at Screening. Evidence of prior testing within 3 monthsis sufficient.

6. A positive Hepatitis B surface antigen (HBsAg) or Hepatitis C test result atScreening. Evidence of prior testing within 3 months is sufficient.

7. Presence of tuberculosis infection as defined by a positive TB test at Screening.Evidence of prior testing within 3 months is sufficient.

8. Live vaccinations within 1 month prior to MAS825 treatment, during the trial, and upto 3 months following the last dose.

9. Pregnant or nursing (lactating) females.

10. Female patients of child-bearing potential (or Tanner stage 2 or above) who are ormight become sexually active, agree to use highly effective contraceptive methods toprevent pregnancy while on MAS825 therapy

11. Patients weighing >160 kg at Screening.

12. For CDC42 mutation patients: Takenouchi-Kosaki syndrome - CDC42 mutations associatedwith a diverse syndrome characterized by variable development delays, cardiac, brainand hematological abnormalities.