First in Man Study to Evaluate Initial Safety

The goal of this clinical trial is to learn about the safety and tolerability of drug ZP6590 and to learn how the body processes the drug ZP6590 in adults. The main questions it aims to answer are: * Is the drug ZP6590 safe and well tolerated when administered as escalating single and multiple doses of the ZP6590? * How quickly and to what extent the administered investigational drug is absorbed and distributed, and how long it takes to be eliminated from the body? In the first Part of the study: Participants will: • Get a single ascending dose of the drug ZP6590 or placebo and will have an observation period of 4 weeks. In the second Part of the study: Participants will: • Get multiple dosages of the drug ZP6590 or placebo for 6 or 12 weeks followed by an observation period of 6 weeks after last dosing.

The purpose of this first-in-human (FIH) study is to evaluate the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of GL-0719 following single intravenous (IV) and subcutaneous injection (SC) doses in healthy adult male and female subjects. In addition, safety, tolerability, PK, and pilot efficacy biomarkers will be evaluated in subjects with cold agglutinin disease (CAD).