A Study of Intravenous CPTX2309 in Healthy Participants and Participants With Moderate to Severe Rheumatoid Arthritis (RA) or Systemic Lupus Erythematosus (SLE)

A First-in-Human, Phase 1, Open-Label, Single and Multiple Ascending Dose Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of CPTX2309 by Intravenous Administration in Healthy Volunteers and Subjects With Moderate to Severe Rheumatoid Arthritis (RA) or Systemic Lupus Erythematosus (SLE)

The purpose of this study is to assess the safety and tolerability of CPTX2309 in healthy adult participants and adult participants with moderate to severe rheumatoid arthritis or systemic lupus erythematosus.

Study Overview

• Status: Recruiting
• Conditions: Rheumatoid Arthritis; Systemic Lupus Erythematosus; Healthy Volunteers
• Intervention / Treatment: Drug: CPTX2309

Detailed Description

A first-in-human Phase 1, open label study to evaluate safety and tolerability of a single ascending dose (SAD) and multiple ascending dose (MAD) of CPTX2309 intravenously administered to healthy adult participants and adult participants with moderate to severe rheumatoid arthritis or systemic lupus erythematosus.

• Study Type: Interventional
• Enrollment (Estimated): 64
• Phase: Phase 1

Contacts and Locations

• Study Contact: Name: ABBVIE CALL CENTER; Phone Number: 844-663-3742; Email: abbvieclinicaltrials@abbvie.com

Study Locations

• Australia
  • Queensland
    • Herston, Queensland, Australia, 4006
      • Completed
      • Nucleus Network Brisbane
  • Victoria
    • Bayswater, Victoria, Australia, 3153
      • Recruiting
      • Veritus Research
  • Western Australia
    • Nedlands, Western Australia, Australia, 6009
      • Recruiting
      • Linear Clinical Research

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Male and female participants who are healthy as determined by the investigator based on review of medical history, physical examination, and clinical laboratory tests obtained during the screening period.
• Participant is willing and able to adhere to the study visit schedule and other protocol requirements.

RA Only:

• Clinical diagnosis of RA and fulfilling the 2010 ACR/EULAR classification criteria for RA
• Presence of rheumatoid factor or ACPA above the ULN
• Confirmation of at least moderate active disease at screening with the presence of at least 6 swollen and 6 tender joints at screening using the 68 (tender)/66 (swollen) joint count OR the presence of at least 3 joints with active synovitis via MRI assessment.

SLE Only:

• Clinical diagnosis of SLE and fulfilling the 2019 EULAR/ACR classification criteria for SLE
• Positive ANA>=1:80 and the presence of at least one of the following autoantibodies above the upper limit of normal (ULN): anti-double standard DNA (dsDNA) or anti-Smith (Sm).

Exclusion Criteria:

• Evidence of organ dysfunction or any clinically significant deviation from normal in physical examination, vital signs, or clinical laboratory tests beyond what is consistent with a healthy population in the region in which the study is conducted.
• Use of any investigational medical device or investigational drug within 30 days or 5 half-lives of the investigational drug (whichever is longer) prior to the first administration of CPTX2309.

RA Only:

- Participants diagnosed with Felty's syndrome

SLE Only:

• Active neuropsychiatric SLE, as defined by the CNS portion of SLEDAI at Screening, or signs of symptoms of neuropsychiatric SLE within 6 months prior to Screening (lupus headache permissible)
• Note: Other protocol-defined inclusion/exclusion criteria apply

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Non-Randomized
• Interventional Model: Sequential Assignment
• Masking: None (Open Label)

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Part A: SAD Cohorts; Escalating single doses of CPTX2309 on a specified day to healthy adult participants.	Drug: CPTX2309; Intravenous Infusion
Experimental: Part B: MAD Cohorts; Escalating multiple doses of CPTX2309 on specified days to healthy adult participants.	Drug: CPTX2309; Intravenous Infusion
Experimental: Part C: SAD Cohorts; Escalating single doses of CPTX2309 on a specified day to adult participants with moderate to severe RA or SLE.	Drug: CPTX2309; Intravenous Infusion
Experimental: Part D: MAD Cohorts; Escalating multiple doses of CPTX2309 on specified days to adult participants with moderate to severe RA or SLE.	Drug: CPTX2309; Intravenous Infusion

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of participants with changes in the safety parameters	To evaluate the safety and tolerability of CPTX2309 administered to healthy adult participants and participants with moderate to severe RA and SLE.	Up to approximately 1 Year
Number of participants with clinical laboratory assessment abnormalities	To evaluate the safety and tolerability of CPTX2309 administered to healthy adult participants and participants with moderate to severe RA and SLE.	Up to approximately 1 Year
Number of participants with changes in the vital signs	To evaluate the safety and tolerability of CPTX2309 administered to healthy adult participants and participants with moderate to severe RA and SLE.	Up to approximately 1 Year
Number of participants with changes in the ECG	To evaluate the safety and tolerability of CPTX2309 administered to healthy adult participants and participants with moderate to severe RA and SLE.	Up to approximately 1 Year
Number of participants who develop anti-drug antibodies (ADAs) and Circulating Immune Complex (CIC) formation	To evaluate the safety and tolerability of CPTX2309 administered to healthy adult participants and participants with moderate to severe RA and SLE.	Up to approximately 1 Year
Part A and B: Number of participants with change from baseline in vaccine antibody titers	To evaluate the safety and tolerability of CPTX2309 administered to healthy adult participants.	Up to approximately 1 Year
Changes in serum cytokine and chemokine levels that are known to be associated with CAR-T cell therapy related toxicity	To evaluate the safety and tolerability of CPTX2309 administered to healthy adult participants and participants with moderate to severe RA and SLE.	Up to approximately 1 Year
Change from baseline in soluble immunoglobulins (Ig)	To evaluate the safety and tolerability of CPTX2309 administered to healthy adult participants and participants with moderate to severe RA and SLE.	Up to approximately 1 Year
Part C and D: Change from baseline in vaccination-induced antibody titers	To evaluate the safety and tolerability of CPTX2309 administered to participants with moderate to severe RA and SLE.	Up to approximately 1 Year

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Pharmacokinetic Parameters	Levels of CAR+ T cells, levels of CPTX2309 components	Up to approximately 1 Year
Pharmacodynamic Parameters	Levels of circulating B cells expressed as the number of CD19 positive B cells in one microliter of blood by flow cytometry	Up to approximately 1 Year
Part A and B: Pharmacodynamic Parameters	Percentages of naïve and memory B cells in blood by flow cytometry	Up to approximately 1 Year
Part A and B: Pharmacodynamic Parameters	Levels of cytokines and chemokines in nanograms per milliliter of serum by ELISA	Up to approximately 1 Year
Part C and D: Number of Participants who develop ADAs	To evaluate the PK profile of CPTX2309 in participants with moderate to severe RA or SLE.	Up to approximately 1 Year

Collaborators and Investigators

• Sponsor: Capstan Therapeutics
• Investigators: Study Director: Ramin Farzaneh-Far, MD, Capstan Therapeutics, Inc.

Study record dates

Study Major Dates

• Study Start (Actual): April 9, 2025
• Primary Completion (Estimated): November 1, 2027
• Study Completion (Estimated): November 1, 2027

Study Registration Dates

• First Submitted: March 24, 2025
• First Submitted That Met QC Criteria: April 2, 2025
• First Posted (Actual): April 8, 2025

Study Record Updates

• Last Update Posted (Actual): July 16, 2026
• Last Update Submitted That Met QC Criteria: July 14, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Healthy Volunteers; Rheumatoid Arthritis; Systemic Lupus Erythematosus; CPTX2309
• Additional Relevant MeSH Terms: Musculoskeletal Diseases; Arthritis; Joint Diseases; Rheumatic Diseases; Connective Tissue Diseases; Autoimmune Diseases; Immune System Diseases; Skin and Connective Tissue Diseases; Lupus Erythematosus, Systemic; Arthritis, Rheumatoid
• Other Study ID Numbers: CPTX2309-01-01

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No