This is a Phase 1, Randomized, Single-blind, Placebo-controlled Study to Assess the Safety, Pharmacokinetics (PK), and Pharmacodynamics (PD) of BEAM-103 in Healthy Subjects

A Randomized, Single-Blind, Placebo-Controlled, Phase 1 Single Ascending Dose Study to Assess the Safety, Pharmacokinetics, and Pharmacodynamics of BEAM-103 in Healthy Subjects

The purpose of this Phase I single ascending dose study is to evaluate the safety, pharmacokinetics (PK), and pharmacodynamics (PD) of BEAM-103 in healthy subjects between the ages of 18 and 55. The main questions the study aims to answer are:

• Safety and tolerability of BEAM-103
• The pharmacokinetic (PK) profile and pharmacodynamic (PD) characteristics of EAM-103
• The effect of BEAM-103 on hematologic parameters
• To assess the immunogenicity of BEAM-103

Researchers will determine and establish the therapeutic window of the antibody and select optimal doses for future trials in patients.

Subjects will:

• Be asked to participate in the study for a duration of 4-5 months total
• Be asked to sign informed consent
• Be assessed for eligibility
• Provide medical and medication history
• Receive a single intravenous infusion of BEAM-103 or placebo on study Day 1 according to their assigned cohort
• Be followed up to 4 months after infusion

Study Overview

• Status: Recruiting
• Conditions: Healthy Subjects; Healthy Participant Study
• Intervention / Treatment: Drug: BEAM-103; Drug: Placebo Comparator

• Study Type: Interventional
• Enrollment (Estimated): 30
• Phase: Phase 1

Contacts and Locations

Study Locations

• United Kingdom
  • London, United Kingdom
    • Recruiting
    • Clinical Study Site
    • Contact: Medical Information; Phone Number: +1 857-327-8641; Email: clinicalinfo@beamtx.com

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Ages 18 to ≤55 years
• Body mass index (BMI) of 18.5 to 25 kg/m2
• Morning neutrophil count ≥2.6 × 109 cells/L for Black/African American subjects or ≥3.5 ×109 cells/L for Caucasian/Other subjects
• Baseline hemoglobin value of ≥14 g/dL for males and ≥12 g/dL for females
• Baseline platelet count of >150 × 109/L.
• Subjects must be in general good health without significant medical conditions (based on physical exam, electrocardiogram (ECG), and laboratory test results with no clinically significant deviations), per the investigator's assessment

Exclusion Criteria:

• Known hypersensitivity to any component of the investigational medicinal product (IMP).
• Participation in another clinical trial involving treatment with an investigational agent within 90 days of informed consent is prohibited.
• Positive serum pregnancy test or breastfeeding at screening (female participants).
• Live virus vaccination within 4 weeks prior to signing informed consent.
• Any severe or uncontrolled medical condition (eg. severe asthma or severe peanut allergy) that in the opinion of the investigator would put the subject at undue medical risk or impair the ability to interpret study results.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Sequential Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: BEAM-103 Drug Product; BEAM-103 is a monoclonal antibody that will be administered in single dose ascending dose cohorts as an intravenous infusion through the arm.	Drug: BEAM-103; • BEAM-103 is a monoclonal antibody administered as a single intravenous dose
Placebo Comparator: Placebo; Normal Saline Solution will be administered as a matching place in single dose ascending dose cohorts as an intravenous infusion through the arm.	Drug: Placebo Comparator; • The matching placebo comparator is administered as a single intravenous dose

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
To determine the safety and tolerability of single ascending doses of BEAM-103	Incidence of treatment-emergent AEs, serious AEs, severe AEs, AEs related to BEAM-103	from enrollment to the end of study at 5 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Free Stem Cell Factor (SCF) in Peripheral Blood Over Time	Concentration of SCF in peripheral blood measured in nanograms per milliliter (mL)	from the start of treatment to the end of study at 5 months
Change in Tryptase Level in Peripheral Blood Over Time	Serum tryptase concentration measured in nanograms per milliliter (ng/mL)	from the start of treatment to the end of study at 5 months
Change in Reticulocyte Count in Peripheral Blood Over Time	Absolute reticulocyte count measured in cells per microliter (cells/µL)	From enrollment to end of study at 5 months
Change in Neutrophil Count in Peripheral Blood Over Time	Absolute neutrophil count measured in cells per microliter (cells/µL)	From enrollment to end of study at 5 months
Maximum Observed Plasma Concentration (Cmax)	Cmax will be calculated as the highest observed plasma/blood/serum concentration following drug administration	From enrollment to end of study at 5 months
Area Under the Plasma Concentration-Time Curve to Last Quantifiable Concentration (AUClast)	AUClast will be calculated from time zero to the time of the last quantifiable concentration	From enrollment to end of study at 5 months
Area Under the Plasma Concentration-Time Curve to Infinity (AUC∞)	AUC∞ will be calculated as AUClast plus Clast divided by λz	From enrollment to end of study at 5 months
Terminal Elimination Half-Life (t½)	t½ will be estimated from the terminal elimination phase of the plasma concentration-time curve	From enrollment to end of study at 5 months

Collaborators and Investigators

• Sponsor: Beam Therapeutics Inc.

Study record dates

Study Major Dates

• Study Start (Actual): October 27, 2025
• Primary Completion (Estimated): January 29, 2026
• Study Completion (Estimated): May 29, 2026

Study Registration Dates

• First Submitted: September 29, 2025
• First Submitted That Met QC Criteria: December 12, 2025
• First Posted (Actual): December 26, 2025

Study Record Updates

• Last Update Posted (Actual): December 26, 2025
• Last Update Submitted That Met QC Criteria: December 12, 2025
• Last Verified: November 1, 2025

More Information

Terms related to this study

• Keywords: ESCAPE; BEAM-103
• Other Study ID Numbers: BTX-103-001

Drug and device information, study documents

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