Safety, Tolerability, and Pharmacokinetics of ASCT-83 in Healthy Adults

Seventy-two healthy participants will be randomized to the following groups:

• Part 1, Single Ascending Dose (SAD): Healthy adult participants (age 18-64, inclusive) will be enrolled in 6 dose cohorts: 0.5 mg, 1 mg, 2 mg, 4 mg, 7.5 mg, or 10 mg. Each cohort consists of 8 participants (6 ASCT-83, 2 placebo), totaling 48 participants.
• Part 2, Multiple Ascending Dose (MAD): 3 dose cohorts of 8 participants each (6 ASCT-83, 2 placebo), totaling 24 participants. Dosing and regimens for Part 2 will be determined following review of SAD data by the Data Safety Monitoring Committee (DSMC).

All doses (ASCT-83 or placebo) will be administered as two subcutaneous (SC) injections (arm or thigh), with the second injection occurring within 10 minutes of the first.

The first two participants in every cohort - one administered ASCT-83 and one administered placebo - will be the sentinel participants. In every cohort, the two sentinel participants must be observed for 72 hours before the rest of the cohort is dosed.

The maximum dose escalation increment between any two cohorts will be two-fold. The maximum daily dose will not exceed the maximum tolerated dose established in the SAD study.

Additional cohorts may be recruited based on the emerging safety, tolerability, and PK data.

Inclusion criteria

To participate in the study, you must:

• be medically healthy based on medical history, physical exam, labs, and ECG
• be 18-64 years (inclusive)
• at screening, have a body mass index (BMI) > 19 to < 35 kg/m²
• be willing and able to understand and voluntarily sign an informed consent
• Female participants of childbearing potential (women who can become pregnant) must:

• agree to follow the study contraceptive requirements from screening through 28 days after the final dose of study drug.
• agree to undergo pregnancy testing, including a negative pregnancy test at screening and at admission.
• agree not to donate ova (eggs) from screening through 28 days after the final dose of study drug.
• Male participants must:

• have a vasectomy greater than 6 months prior to screening or be willing to follow the contraceptive requirements from screening through 90 days after final study drug administration
• agree to be willing to abstain from sperm donation from screening through 90 days after final study drug administration

Exclusion criteria

You cannot participate in the study if you:

• are a study site staff, Alcamena employee or immediate family member, or have participated in another clinical trial within 30 days or 5 half-lives of a prior investigational product.
• have evidence of liver disease or abnormal liver tests (ALT/AST, Alk Phos, GGT, or bilirubin > ULN); positive hepatitis B or C serology (people with Gilbert syndrome may be included).
• have a history of kidney disease, protein in the urine or reduced kidney function based on screening blood tests.
• have a history of cancer with active disease, suspected relapse, treatment within 6 months, or ongoing therapy affecting immune, liver, or kidney function.
• have a history of heart disease, including abnormal heart rhythm, heart attack, long QT syndrome, or abnormal heart rhythm findings on screening ECG, or a family history of sudden unexplained death.
• are currently receiving medications that affect or suppress the immune system, including steroids given by any route.
• have a known autoimmune condition (such as lupus, rheumatoid arthritis, sarcoidosis, or vitiligo), even if it is not being treated.
• have a positive HIV test at screening or a history of immune deficiency.
• have abnormal blood tests suggesting ongoing inflammation
• have an active infection or is currently being treated for an infection.
• have a skin condition that could interfere with study skin assessments (such as psoriasis).
• are allergic or sensitive to the study drug or its ingredients.
• have a history of alcohol or drug abuse or addiction within the past five years, have a positive drug or alcohol test at screening, or have smoked within one month before screening.
• have a serious mental health condition, such as major depression, schizophrenia, severe anxiety, eating disorders, severe attention deficit disorder, personality disorders, or suicidal thoughts or behavior within the past five years that could affect safety or study participation.
• have low blood pressure upon standing, defined as a significant drop in blood pressure when moving from lying down to standing during screening or baseline testing.
• have abnormally low white blood cell counts or neutrophil counts, unless this finding is due to a known benign condition such as benign ethnic neutropenia.