This study aims to assess the safety and tolerability of ABCL575 in healthy participants following single ascending dose (SAD), in comparison to a placebo

This is a phase I randomized, double-blind, placebo-controlled, single ascending dose (SAD) study. The study will consist of 5 planned cohorts (A1 to A5), each comprised of 8 healthy participants. Doses of ABCL575 are intended to escalate through cohorts A1 to A5.

Inclusion Criteria:

• Healthy male or female ≥ 18 and ≤ 65 years of age at the time of screening

• Good general health as determined through medical history and general physical examination

• Body weight ≥ 50 and ≤ 100 Kg

• Body mass index (BMI) between 18.5 kg/m2 and 30.0 kg/m2

• Non- or ex-smoker (an ex-smoker defined as someone who has completely stopped using nicotine products for at least 180 days prior to study drug administration)

• Meeting 1 of the following:

  1. Is of childbearing potential or able to procreate and agrees to use an acceptable contraceptive method from the time of signing the ICF through the EOS visit.
  2. Is of nonchildbearing potential or unable to procreate

• If male, agrees not to donate sperm from the study drug administration through EOS visit; If female, agrees not to donate or retrieve eggs from the study drug administration through EOS visit

Exclusion Criteria:

• Pregnancy and/or lactation.
• Seated pulse rate less than 50 beats per minute (bpm) or more than 100 bpm or a seated blood pressure < 90/50 mmHg or > 140/90 mmHg
• eGFR < 60 mL/min/1.73 m2
• Severe hypersensitivity reactions (like angioedema) to any drugs.
• Presence or history of significant gastrointestinal, liver disease, kidney disease, or surgery that may affect drug bioavailability.
• History of significant cardiovascular, pulmonary, hematologic, neurological, psychiatric, endocrine, immunologic, or dermatologic disease.
• History or presence of multiple or severe drug allergies.
• Evidence of any active bacterial, viral, or fungal infection
• Disrupted skin integrity (apparent burn or dermatitis).
• History of syncope, palpitations, or unexplained dizziness.
• Use of prescription drugs (except for hormonal contraceptives or hormone replacement therapy) in the 28 days prior to study drug administration, that in the opinion of an investigator would put into question the participant's healthy status.
• Use of any over-the-counter products in the 7 days or 5 half-lives (whichever is longer) prior to study drug administration.
• Receipt of live vaccines within 5 weeks prior to screening or plans to receive live vaccines within 180 days after study drug administration.
• History of latent or active tuberculosis.
• History of herpes zoster (shingles) or RZV (eg, Shingrix) vaccination within 28 days prior to screening or scheduled during the study period