A First-in-Human Phase 1 Single-Ascending Dose Study of ABCL575 in Healthy Participants

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 physicalexamination

• 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 usingnicotine 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 anacceptable contraceptive method from at least 28 days prior to the screeningvisit through EOS visit

2. Is of nonchildbearing potential or unable to procreate

• If male, agrees not to donate sperm from the study drug administration through EOSvisit; If female, agrees not to donate or retrieve eggs from the study drugadministration 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 aseated 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 replacementtherapy) in the 28 days prior to study drug administration.

• Use of any over-the-counter products in the 7 days prior to study drugadministration.

• Receipt of live vaccines within 5 weeks prior to screening or plans to receive livevaccines within 180 days after study drug administration.

• History of latent or active tuberculosis.