This is a first in human (FIH), single-centre, double -blind, randomised, cross-over, SAD followed by a MAD study of IZD334 conducted in healthy adult participants as well as an open-label cohort in adult patients with CAPS. The study is designed to evaluate the safety, tolerability, PK, PD, and food effect of IZD334 in healthy adult participants, and to evaluate the safety, tolerability, PK, PD, and preliminary clinical efficacy of IZD334 in adult patients with CAPS.

Inclusion Criteria: (Healthy Volunteers)

• Healthy male or female volunteers, aged 18 to 65 years (inclusive at the time of informed consent)
• Participants must be in good general health, with no significant medical history, have no clinically significant abnormalities on physical examination at Screening and/or before administration of the initial dose of study drug
• Participants must have a Body Mass Index (BMI) between ≥18.0 and ≤32.0 kg/m2 at Screening
• Participants must have clinical laboratory values within normal range as specified by the testing laboratory, unless deemed not clinically significant by the Investigator or delegate

Inclusion Criteria: (CAPS Patients)

*Patients with a confirmed diagnosis of CAPS (FCAS or MWS) aged 18 to 65 years (inclusive at the time of informed consent)

Exclusion Criteria: (Healthy volunteer)

• Pregnant or lactating at Screening or planning to become pregnant (self or partner) at any time during the study, including the follow-up period
• Prior or ongoing medical conditions, medical history, physical findings, or laboratory abnormality that, in the Investigator's (or delegate's) opinion, could adversely affect the safety of the participant
• Presence of any underlying physical or psychological medical condition that, in the opinion of the Investigator, would make it unlikely that the participant will comply with the protocol or complete the study per protocol
• Blood donation or significant blood loss within 60 days prior to the first study drug administration

Exclusion Criteria: (CAPS Patients)

• Live vaccinations within 3 months prior to Screening, for the duration of the study and for up to 3 months following the last dose of study drug;
• Positive QuantiFERON test at the Screening visit or within 2 months prior to Screening.

Healthy volunteer section is double blind.