Phase 1 Study on the Safety, Tolerability, and Pharmacokinetics of JST-018 in Healthy Adults

Phase 1, Randomized, Double-blind, Placebo-controlled, Single Ascending Dose Study to Assess the Safety, Tolerability, and Pharmacokinetics of JST-018 in Healthy Adults

The goal of this clinical trial is to learn if a single dose of the study drug, JST-018, is safe and tolerable when administered by injection into the arm or thigh muscle of healthy men and women aged 18 to 55. The main questions it aims to answer are:

• Is a single administration of JST-018 safe?
• What is the concentration of the JST-018 in the blood over time?
• Do antibodies to JST-018 develop following a dose of JST-018? Researchers will compare JST-018 to Placebo to see if there are any differences in the safety and tolerability of a single dose at different dose levels.

Participants will be confined to the clinic for the first 3 days. They will receive an injection on the second day, and then return for 9 more visits over the period of 1 year for:

• Physical exam with vital signs
• Electro-cardiogram (ECG)
• Bood collection for clinical labs and research samples
• Urine sample
• Assessment of potential adverse effects and medications taken

Study Overview

• Status: Not yet recruiting
• Conditions: Antiviral Drug
• Intervention / Treatment: Drug: Placebo; Biological: JST-018 combination of 3 monoclonal antibodies

Detailed Description

This is a Phase 1, first-in-human (FIH), randomized, double-blind, placebo-controlled, single ascending dose (SAD) study to assess the safety, tolerability, and PK of a single dose of JST-018 administered IM to healthy participants.

The study will be comprised of a minimum of 3 cohorts (Cohorts A, B, and C, with 12 participants per cohort), each evaluating a single dose of JST-018 administered IM. In each cohort, 2 sentinel participants will be randomized 1:1 such that one participant receives JST-018 and 1 participant receives placebo. Following a favorable blinded safety review committee (SRC) review of sentinel safety data collected through Day 8, the remainder of the cohort (10 non-sentinel participants) will be randomized 4:1 to JST-018 or placebo, and will be dosed.

All safety data for all participants in the current cohort through Day 8 will be reviewed by the SRC in a blinded fashion for each dose cohort before escalating to the next dose cohort (for escalation from Cohort A to Cohort B and escalation from Cohort B to Cohort C); A recommendation on whether to implement Cohort D (along with a recommended dose of JST-018 to be evaluated in Cohort D) may be provided by the SRC following review of blinded safety data from Cohorts A, B, and C.

• Study Type: Interventional
• Enrollment (Estimated): 48
• Phase: Phase 1

Contacts and Locations

• Study Contact: Name: Nels Royer; Phone Number: (206)651-5094; Email: jeb.clinicaltrials@evotec.com

Study Locations

• United States
  • Nevada
    • Las Vegas, Nevada, United States, 89113
      • PPD Las Vegas Clinical Research Unit
      • Contact: Phone Number: (877) 362-2608

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

1. Healthy men or women 18 to 55 years of age
2. BMI between 18 and 32 kg/m2
3. Negative serum pregnancy test
4. Use of highly effective birth control method(s) for a minimum of 60 days prior to consent and is willing to continue use for at least 12 months, or abstinence
5. In good general health as determined by medical history, exams and tests

Exclusion Criteria:

1. Acute illness or fever (≥100.4°F) within 7 days prior to dosing
2. Any history of receiving treatment, vaccine, or monoclonal antibodies (mAbs) against smallpox, monkeypox, or other orthopox viruses.
3. Receipt of any vaccine within 30 days prior to Screening, planned receipt of any vaccine prior to Day 1, or planned receipt of any vaccines before 45 days post-injection.
4. Any medical condition for which IM injections would be contraindicated in the opinion of the investigator (eg, bleeding disorders, anticoagulant therapy, and severe thrombocytopenia)
5. History of congenital or acquired immunodeficiency syndrome, , including positive human immunodeficiency virus (HIV-1/-2) antibody result
6. Prior solid organ or bone marrow transplant

7. Clinically significant corneal or lens abnormality as determined by history, clinical examination, or diagnostic imaging. Including, but not limited to:

   • Corrected vision of less (worse) than 20/40
   • History of any clinically significant history of eye trauma, in the opinion of the investigator
   • History of cataracts or current cataracts
   • Lens opacity greater than NC2, C2, or P0 as determined by the Lens Opacities Classification System (LOCS) III
   • History of uveitis (including acute)
   • Use of ocular or inhaled prescription steroids within 1 year prior to Screening nasal steroids are permissible). A single short course (ie, less than 14 days) of systemic steroid therapy is allowed provided it is concluded more than 6 months prior to Screening.
   • History of diabetes
8. Use of immunosuppressive agents, anticoagulants, or antiarrhythmics within 1 year prior to Screening. Nasal steroid use is permissible.
9. Upper arms and thighs are with insufficient muscular tissue for IM injections or is obscured by tattoos or rash

10. Use of any medications started within 30 days prior to Day -1, including prescription medications, nutritional supplements, and over-the-counter medications

    • Vitamin supplements are allowed
    • Recommended doses of acetaminophen are allowed, except for 24 hours prior to dosing
    • Recommended doses of non-steroidal anti-inflammatory drugs (NSAIDs) (eg, aspirin, ibuprofen) are also allowed, except for 7 days prior to dosing
11. Positive hepatitis B surface antigen, hepatitis B core antigen, or hepatitis C antibody
12. Positive urine drug test or cotinine (indicating active current smoking) at Screening or Day -1, positive alcohol breath test at Screening or on Day -1, or suspected/known drug abuse and/or alcohol use disorder
13. Smoking or has used nicotine or nicotine-containing products (eg, snuff, nicotine patch, nicotine chewing gum, mock cigarettes, or inhalers) within 3 months before study drug dosing
14. Dosing in any clinical research study evaluating another investigational drug or therapy within 30 days or at least 5 half-lives (whichever is longer) of receiving the investigational drug prior to Screening
15. Progressive, unstable, or uncontrolled medical conditions that have required medical attention or changes to medication for medical reasons within 90 days prior to consent
16. History of allergic reactions or hypersensitivity reactions to other therapeutic antibodies or immunoglobulins
17. Receipt of any mAbs in the 12 months prior to Screening
18. High blood pressure
19. Women who are either pregnant or breast-feeding
20. Vulnerable individuals (eg, military recruits, persons in compulsory detention, those with limited legal capacity)
21. Receipt of immunoglobulins or any blood products within 90 days prior to consent or planned receipt during the study period
22. Donation or loss of >500 mL of blood within 30 days or plasma within 7 days of Day 1; any planned donation of blood or plasma during the study period
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 or the cervix
24. Strenuous activity or contact sports within 48 hours before study drug dosing and through Day 8

26. History of relevant drug and/or food allergies

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: JST-018 Investigational Product	Biological: JST-018 combination of 3 monoclonal antibodies; Monoclonal antibodies
Placebo Comparator: JST-017 Placebo	Drug: Placebo; Placebo Comparator

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Safety and tolerability of of JST-018 administered intramuscularly (IM)	Incidence of solicited local (injection site) and systemic AEs post-injection through Day 7 (with the inpatient and outpatient participant diaries being collected on Day 3 and Day 8, respectively)	From injection to Day 7
Safety and tolerability of of JST-018 administered IM	Incidence of unsolicited AEs through end of study (EOS)	From injection to final visit at Week 48
Safety and tolerability of of JST-018 administered IM	Incidence of SAEs, medically attended AEs (MAAEs), and AEs of special interest (AESIs)	From injection to final visit at Week 48
Safety and tolerability of of JST-018 administered IM	Incidence of Clinically Significant Changes in Laboratory Values	From injection to final visit at Week 48
Safety and tolerability of JST-018 administered as IM	Incidence of Clinically Significant Changes in Vital Sign Measurements	From injection to final visit at Week 48
Safety and tolerability of JST-018 administered as IM	Incidence of Clinically Significant Changes in ECG results	From injection to final visit at Week 48

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Pharmacokinetic Cmax of JST-018	Maximum observed concentration (Cmax)	From enrollment to the end of study at 48 weeks
Pharmacokinetic Tmax of JST-018	Time to reach maximum observed concentration (Tmax)	Time Frame: From enrollment to the end of study at 48 weeks
Pharmacokinetic Tlast of JST-018	The timepoint with the last quantifiable concentration (Tlast)	From enrollment to the end of study at 48 weeks
Pharmacokinetic AUC0-t of JST-018	Area under the concentration versus time curve (AUC) from time 0 to the timepoint with the last quantifiable concentration (AUC0-t)	From enrollment to the end of study at 48 weeks
Pharmacokinetic AUC0-inf of JST-018	AUC from time 0 extrapolated to infinity (AUC0-inf)	From enrollment to the end of study at 48 weeks
Pharmacokinetic t1/2 of JST-018	Terminal elimination half-life (t1/2)	From enrollment to the end of study at 48 weeks
Pharmacokinetic CL/F of JST-018	Apparent clearance after IM administration (CL/F)	From enrollment to the end of study at 48 weeks
Pharmacokinetic Vz/F of JST-018	Apparent volume of distribution after IM administration (Vz/F)	From enrollment to the end of study at 48 weeks
Evaluation the effect of anti-drug antibodies (ADA)	Effect of ADAs on pharmacokinetics of JST-018	From enrollment to the end of study at 48 weeks
Evaluate if and to what extent ADAs develop following a single dose of JST-018	Proportion of participants with pre-existing ADAs and those who develop ADAs (treatment boosted and treatment induced) to JST-018	From enrollment to the end of study at 48 weeks

Collaborators and Investigators

• Sponsor: Just-Evotec Biologics

Study record dates

Study Major Dates

• Study Start (Estimated): June 11, 2026
• Primary Completion (Estimated): November 9, 2026
• Study Completion (Estimated): October 4, 2027

Study Registration Dates

• First Submitted: May 7, 2026
• First Submitted That Met QC Criteria: May 14, 2026
• First Posted (Actual): May 19, 2026

Study Record Updates

• Last Update Posted (Actual): May 19, 2026
• Last Update Submitted That Met QC Criteria: May 14, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: DDF4-CL101; MCDC No. W15QKN-16-9-1002 (Other Identifier: US Department of War)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: This is a study in healthy volunteers. Individual participant data is not meaningful.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No