This is a Phase 1a, randomized, double-blind, single ascending dose study, designed to assess the safety, tolerability, and PK of a single CSX-1004 injection, administered by IV infusion across a range of doses in healthy adult subjects. The study will have 3 phases: Screening, Inpatient Treatment, and Outpatient Follow-up.

The primary objective of the study is to determine the safety and tolerability of CSX-1004 Injection administered by intravenous (IV) infusion across a range of doses in healthy adult subjects.

The secondary objective of the study is to determine the pharmacokinetics (PK) of CSX-1004 Injection administered by IV infusion across a range of doses in healthy adult subjects.

Major Inclusion Criteria:

• Healthy male or female subjects, aged 18 to 50 years, inclusive,
• Minimum weight of 50.0 kg and maximum weight of 100.0 kg
• Body mass index (BMI) within the range of 18.0 to 32.0 kg/m2, inclusive

Major Exclusion Criteria:

• Positive UDS for substances of abuse (including alcohol) at Screening or admission to the Treatment Phase
• Current daily cigarette smoker within 3 months of Screening. Social smoking, as defined by non-daily use of nicotine-containing products, is permitted.
• History or presence of any clinically significant cardiac, psychiatric, endocrine, hematologic, hepatic, immunologic, metabolic, urologic, pulmonary, neurologic, dermatologic, renal, or other major disease or illness at Screening, which in the opinion of the Investigator, might jeopardize the safety of the subject or the validity of the study results.