FIH Study to Evaluate Safety, Tolerability, PK, PD & Preliminary Efficacy of AT03-65 With Advanced Solid Tumors

NCT06809114 | Recruiting Phase 1 FDA Drug

• 1 other identifier: AT0365-P1-01
• Study Type: interventional
• Target: 83
• Locations: 1 country
• Sites: 1

Brief Summary

A Phase I, First-in-Human Study to Evaluate the Safety, Tolerability, Pharmacokinetics, Pharmacodynamics, and Preliminary Efficacy of AT03-65 in Adults with Advanced Solid Tumors

Conditions

Solid Tumor

Outcome Measures

Primary Outcomes (2)

• Maximum tolerated dose (MTD) of AT03-65

  The MTD is defined as the highest dose with an observed incidence of DLT in no more than one out of six patients treated at a particular dose level.

  Up to 21 days

• Dose-limiting toxicity (DLT)

  DLT refers to AEs that occurred during DLT observation period in dose escalation study, excluding toxicities clearly due to the underlying disease or extraneous causes.

  Up to 21 days

Secondary Outcomes (10)

• Determine levels of AT03-65 and its constituents over time in plasma

  Maximum 2 years

• Evaluate changes in circulating tumor DNA in plasma

  Maximum 2 years

• Determine the presence of antibodies to AT03-65 at different times in plasma

  Maximum 2 years

• Assessment of Overall Response Rate (ORR) in subjects with advanced / metastatic solid tumors

  Maximum 2 years

• Determine the expression level of CLDN6 in tumor samples

  Maximum 2 years

Study Arms (1)

AT03-65 Dose Escalation and Dose Expansion

EXPERIMENTAL

Subjects will receive AT03-65 via intravenous (IV) infusion on Day 1 of a 21-Day treatment cycle.

Drug: AT03-65

Interventions

AT03-65 DRUG

Treatment will continue until disease progression, unacceptable toxicity, subject withdrawal of consent or death.

Also known as: AT03-65 Antibody Drug Conjugate

AT03-65 Dose Escalation and Dose Expansion

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• At least 18 years old at the time of signing written informed consent form (ICF).
• Eastern cooperative oncology group (ECOG) Performance Status score of 0 or 1 at screening and on C1D1.
• Pathologically documented, definitively diagnosed, advanced/metastatic solid tumor that is resistant or refractory to standard treatment, for which no further standard treatment is available, or the subject refuses or cannot tolerate standard therapy. Subjects must have measurable lesion according to response evaluation criteria in solid tumors (RECIST) v1.1.
• a) Monotherapy dose escalation study (Phase 1a):
• Subjects (with documented CLDN6 expression after the lower three dose levels) will be enrolled, including but not limited to the following histological subtypes: serous or endometrioid ovarian cancer, primary peritoneal cancer or fallopian tube cancer, endometrial cancer, NSCLC, breast cancer, esophageal cancer, and gastric/GEJ cancer. There is no upper limit on the number of prior treatment regimens the subject may have received.
• b) Monotherapy cohort expansion study (Phase 1b)
• Subjects must meet the minimum requirement of CLDN6-expressing by IHC (cutoff value to be determined based on Phase Ia data and/or clinical studies of other CLDN6-targeting drugs), to be confirmed prior to enrollment.
• Three cohorts will be involved:
• Cohort 1: 24-30 subjects with advanced/metastatic CLDN6-expressing ovarian cancer, platinum resistant, refractory, or non-tolerant. Patients must have had one (or more) prior platinum-based chemotherapeutic regimen for management of primary disease containing carboplatin, cisplatin, or another organoplatinum compound, which may have included intraperitoneal therapy, high-dose therapy, consolidation, or extended therapy administered after completion of initial chemotherapy; patients must be considered platinum resistant or refractory according to standard Gynecologic Oncology Group (GOG) criteria, i.e., have had a treatment-free interval following platinum of 6 months or less, have persistent disease at the completion of primary platinum-based therapy or have progressed during platinum-based therapy, or be determined to be nontolerant after a recognized desensitization regimen.
• Cohort 2: 24-30 subjects with advanced/metastatic CLDN6-expressing NSCLC. Subjects must have received at least one checkpoint inhibitor combination regimen (or platinum doublet where contraindicated). Patients with established driver mutations (epidermal growth factor receptor \[EGFR\], anaplastic lymphoma kinase \[ALK\], ROS proto-oncogene \[ROS\], mesenchymal epithelial transition factor \[MET\], rearranged during transfection \[RET\], B-Raf proto-oncogene, serine/threonine kinase \[BRAF\], and/or rat sarcoma \[RAS\]) must have progressed on standard of care for said mutation.
• Cohort 3: 12 subjects with other advanced/metastatic CLDN6-expressing solid tumors who have exhausted options for standard of care therapies. There is no upper limit on the number of prior treatment regimens the subject may have received.
• \) Subjects have fresh tumor sample or available archival block for CLDN6 IHC (except for the lower three dose levels of Phase Ia). If archival block samples from multiple timepoints are available, the most recent one is preferred.
• \) Subjects with good organ function
• \) Has a left ventricular ejection fraction (LVEF) ≥50% as determined by either an echocardiogram (ECHO) or multi-gated acquisition scan (MUGA) within 28 days before the start of study treatment.
• \) Life expectancy ≥3 months.

You may not qualify if:

• Subjects previously received or is currently receiving any systemic anti-cancer therapy within 4 weeks or 5xT(1/2) if 5xT(1/2) of the drug/therapy used by the subject is confirmed to be \< 4 weeks, 5xT(1/2) shall prevail\] - prior to first dose of IMP
• Not yet recovered to Grade 1 or baseline for treatment-related toxicities related to previous treatment with the exception of alopecia. The recovery time after surgery was less than 28 days
• Subjects with clinically significant congenital or acquired cardiovascular diseases.
• Presence of other active invasive cancers other than the one treated in this study within 5 years prior to screening, except appropriately treated BCC of the skin or in situ carcinoma of uterine cervix, or other local tumors considered cured by local treatment
• Subjects with severe or uncontrolled systemic disease, including uncontrolled hypertension, uncontrolled diabetes mellitus, active bleeding diatheses, or active infection requiring intravenous injection (IV) of antibiotics, antivirals or antifungals
• Subjects with medical history of clinically significant lung disease or who are suspected to have these disease by imagining at screening
• Live vaccine within 4 weeks prior to first dose of IMP
• Presence of active or untreated metastases to central nervous system or meninges or other evidence showing that metastatic lesions in central nervous system or meninges that have not yet been controlled at screening. Note: Subjects with central nervous system or meningeal metastases who are free of neurological symptoms not managed with steroids and stable by imagining 28 days after treatment prior to the first dose may be considered for enrollment
• Presence of leptomeningeal disease.
• Prior treatment with any ADC targeting CLDN6. Note: Prior treatment with immune engagers targeting CLDN6 is permitted.
• Subjects who have received prior allogeneic or autologous bone marrow transplants.
• Subjects who are pregnant (as confirmed by pregnancy tests performed within 7 days before enrollment) or planning to become pregnant.
• Subjects who have received moderate or strong cytochrome P450 (CYP) 2C8 or CYP3A inhibitors or inducers, or P-glycoprotein (P-gp) inhibitors within 14 days prior to the first dose or cannot be discontinued during the study.
• The investigator considers that the patient is not suitable for participating in this study (e.g.,IMP is not in the best interest of patient, patients with mental disorder, patients with poor compliance, etc.).

Sponsors & Collaborators

• Axcynsis Therapeutics Pte Ltd: lead

Study Sites (1)

Oregon Health & Science University (OHSU)

Portland, Oregon, 97239, United States

RECRUITING

Central Study Contacts

Humphrey Gardner

CONTACT

7813756856; h.gardner@axcynsis.com

Maria DeAssis

CONTACT

6178208329; maria.deassis@axcynsis.com

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SEQUENTIAL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Model Details: Dose escalation (Phase 1a) followed by Dose Expansion (Phase 1b)

Study Record Dates

• First Submitted: January 24, 2025
• First Posted: February 5, 2025
• Study Start: January 14, 2026
• Primary Completion (Estimated): December 1, 2027
• Study Completion (Estimated): August 1, 2028
• Last Updated: January 30, 2026

Record last verified: 2026-01

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)