Safety, Tolerability, and PK of a Single Intravenous Dose of ETI-204 in Adult Volunteers

To evaluate the safety and tolerability and pharmacokinetics (PK) of a single intravenous (IV) dose of ETI-204 in adult volunteers.

A double-blind, randomized, placebo-controlled study of a single IV dose of 16 mg/kg ETI-204 in adult volunteers (210 subjects ETI-204; 70 subjects placebo).

The total duration of the study for each subject will be approximately 100 days divided as follows:

Screening: Days -28 to -2; In-unit Phase: Day -1, Day 1, and Day 2; Out-of-unit Visits: Day 8 (±2 days); Day 15 (±3 days); Day 29 (±3 days); Day 43 (±3 days); Final Visit: Day 71 (±4 days).

Following completion of a screening visit subjects who qualify for entry into the study will be randomized to receive either ETI-204 or matching placebo on Day 1 in a 3:1 ratio. Subjects will be discharged from the clinic on Day 2 following completion of study assessments and will return for five additional visits on Days 8, 15, 29, 43 and 71.

The first 12 subjects will be dosed in groups of no more than 4 subjects/day. A blinded safety review of the available clinical and laboratory AE data up to and including Day 2 will be completed for the first 12 subjects before any additional subjects are dosed. This review will be conducted by the Investigator in conjunction with the Clinical Trial Steering Committee. If the outcome of this review is satisfactory, dosing of additional subjects will be permitted to continue and subjects may be dosed in group sizes larger than 4.

After Amendment 1, premedication with 50 mg oral diphenhydramine approximately 30 minutes prior to the start of study drug infusion was required.

Eligibility Criteria:
Inclusion Criteria:

1. Females or males ≥ 18 years of age
2. All females, regardless of childbearing potential, must have a negative serum beta human chorionic gonadotropin (β-hCG) pregnancy test at Screening and Day -1
3. Females of childbearing potential (i.e., not postmenopausal or surgically sterile) must agree to practice abstinence or to use a medically accepted method of contraception from the time of Screening through 30 days after final study visit. Acceptable methods of contraception include diaphragm with spermicide; sponge with spermicide; condom with spermicide; or intrauterine device with condom or spermicide. The following contraceptive methods are acceptable only when used with a condom and spermicide: birth control pills, birth control patches, vaginal ring, hormone under the skin, or hormone injections
4. Postmenopausal females, defined as females who have had amenorrhea for at least 12 months either naturally or following cessation of all exogenous hormonal treatments and have a follicle stimulating hormone (FSH) level of \> 40 mIU/mL at Screening
5. Females who have undergone surgical sterilization, including hysterectomy, bilateral oophorectomy, bilateral salpingectomy, tubal ligation, or tubal essure
6. Males must agree to practice abstinence or use a condom with spermicide and refrain from sperm donation during the study and for 30 days after the final study visit
7. Provide written informed consent
8. Willing to comply with study restrictions

Exclusion Criteria:

1. Pregnant or lactating woman
2. Clinically significant comorbidity that would interfere with completion of the study procedures or objectives, or compromise the subject's safety
3. Seated systolic blood pressure (BP) ≥ 150 mmHg or ≤ 90 mmHg or diastolic BP ≥ 95 mmHg
4. Use of H1 receptor antagonists (i.e. antihistamines) within 5 days prior to Day 1
5. Evidence of drug or alcohol abuse as determined by the Investigator within 6 months of Day 1
6. Positive test result for drugs of abuse (with the exception of medically prescribed drugs) at Screening or on Day -1
7. Positive test for alcohol at Screening; exclusion is subject to the Investigator's discretion; subjects who test positive for alcohol at Day -1 are excluded from the study
8. Treatment with an investigational agent within 30 days of Day 1 or within five half-lives of the investigational agent at Day 1 (whichever is longer)
9. Congenital or acquired immunodeficiency syndrome
10. Prior solid organ or bone marrow transplant
11. Positive test for Hepatitis B (surface antigen), Hepatitis C, or human immunodeficiency virus (HIV) at Screening
12. History of prior treatment for anthrax exposure or prior anthrax infection
13. Prior immunization with any approved or investigational anthrax vaccine or prior treatment with an investigational anthrax treatment (i.e., ETI-204, raxibacumab, or anthrax immune globulin)
14. Military personnel deployed in 1990 or after, unless the subject can provide documentation demonstrating they have not previously received any approved or investigational anthrax vaccine
15. Use of systemic steroids, immunosuppressive agents, anticoagulants, or anti-arrhythmics within 1 year prior to Day 1. A single short course (i.e., less than 14 days) of systemic steroid therapy is allowed provided it concluded more than 6 months prior to Day 1
16. Donation or loss of \> 500 mL of blood within 30 days or plasma within 7 days of Day 1
17. Prior stroke, epilepsy, relapsing or degenerative central nervous system disease, or relapsing or degenerative ocular disease
18. Myocardial infarction or acute coronary syndrome in the past 5 years, active angina pectoris, or heart failure (New York Heart Association scale \> 1)
19. History of chronic liver disease
20. Calculated creatinine clearance (CrCl) of \< 30 mL/min using the Cockcroft-Gault equation
21. Any clinically significant abnormality, in the Investigator's opinion, on electrocardiogram (ECG) or clinical laboratory tests (hematology, clinical chemistry, or urinalysis) at Screening; Out of range results may be repeated to confirm.
22. History of allergic or hypersensitivity reactions to other therapeutic antibodies or immunoglobulins
23. History of any malignant neoplasm within the last 5 years, with the exception of adequately treated localized or in situ non-melanoma carcinoma of the skin (i.e., basal cell carcinoma) or the cervix
24. Subjects who, in the opinion of the Investigator, are not suitable candidates for enrollment or who may not comply with the requirements of the study