New hope for Hard-to-Treat cancers? first human trial launches
NCT ID NCT06809114
First seen Jun 25, 2026 · Last updated Jun 27, 2026 · Updated 1 time
Summary
This early-stage study is testing a new drug called AT03-65 in 83 adults with advanced solid tumors that have not responded to standard treatments. The main goal is to check safety and find the right dose, while also looking for early signs that the drug might shrink tumors. Participants will receive the drug until their disease gets worse or side effects become too severe.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- AT03-65 (an antibody drug conjugate)
- What this could lead to
- If it works, this could point toward a new treatment option for people with advanced solid tumors that have stopped responding to standard therapies.
- What could go wrong
- This is a very early Phase 1 trial with only 83 participants, so it is primarily checking safety. The drug may not shrink tumors or could cause serious side effects.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Phase
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Phase 1
The first testing in people. Mainly checks safety and dose, usually in a small group.
- Participants
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About 83 people
The number the study aims to enrol. It can still change while the study runs.
- Started
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Jan 2026
- Expected to finish
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Aug 2028
An estimate. End dates often move.
- Lead sponsor
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A company
The lead sponsor is a pharmaceutical, biotech, or medical-device company.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
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18 years and older
- Sex
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Anyone
- Healthy volunteers
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Not accepted
This study is not open to healthy volunteers. The entry requirements below say who it is open to.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion Criteria: 1. At least 18 years old at the time of signing written informed consent form (ICF). 2. Eastern cooperative oncology group (ECOG) Performance Status score of 0 or 1 at screening and on C1D1. 3. 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. 3a) 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. 3b) 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. 4\) 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. 5\) Subjects with good organ function 6\) 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. 7\) Life expectancy ≥3 months. 8\) Male subjects with female partners of childbearing potential and female subjects of childbearing potential must agree to use a highly effective form of contraception or avoid intercourse throughout the study period and for at least 6 months after the final administration of IMP. Males must agree not to freeze or donate sperm throughout the study period and for at least 6 months after final administration of IMP. Investigators will advise male subjects on the conservation of sperm prior to study treatment. Females must agree not to donate or retrieve ova for own use throughout the study period and for at least 6 months after final administration of IMP. Exclusion Criteria: 1. 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 2. 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 3. Subjects with clinically significant congenital or acquired cardiovascular diseases. 4. 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 5. 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 6. Subjects with medical history of clinically significant lung disease or who are suspected to have these disease by imagining at screening 7. Live vaccine within 4 weeks prior to first dose of IMP 8. 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 9. Presence of leptomeningeal disease. 10. Prior treatment with any ADC targeting CLDN6. Note: Prior treatment with immune engagers targeting CLDN6 is permitted. 11. Subjects who have received prior allogeneic or autologous bone marrow transplants. 12. Subjects who are pregnant (as confirmed by pregnancy tests performed within 7 days before enrollment) or planning to become pregnant. 13. 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. 14. 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.).
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Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
How to take part
Only the study team decides who joins. These are the ways to reach them.
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The places running it
1 site. The list below names each one and where it is.
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The official record
ClinicalTrials.gov lists the study team's own contact details, including names and phone numbers. We don't republish those.
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A doctor treating you
A doctor who knows your case can contact a study site on your behalf, and can tell you whether this study is worth pursuing at all.
Contacts and locations
Locations
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Oregon Health & Science University (OHSU)
RECRUITINGPortland, Oregon, 97239, United States
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