Optimal Methods to Characterize ADC Resistance in Solid Tumors and Identify Clinically Useful Biomarkers (OASIS)

International Multicenter Multicohort Open-label Phase II Trial Aiming to Define Optimal Methods for Predicting Response/Resistance to Antibody-drug Conjugates in Patients With Solid Tumors Treated According to Current Standard Indications.

International study that will evaluate the association of prespecified biomarkers with resistance to Antibody-drug conjugates (ADCs), a type of targeted cancer treatment currently used in clinical practice for treating different tumor types.

Study Overview

• Status: Recruiting
• Conditions: Advanced Breast Cancer; Advanced Gastric Cancer; Advanced Urothelial Cancer; Advanced Non Small Cell Lung Cancer (NSCLC)
• Intervention / Treatment: Procedure: Biological samples collection; Behavioral: questionnaires to collect patient reported outcomes

Detailed Description

Over the past five years, antibody-drug conjugates (ADCs) have dramatically improved survival in solid and hematologic malignancies. Among 14 ADCs approved worldwide, nine are now available in Europe, and over 370 others are in clinical development. This expanding landscape indicates that ADCs could soon replace conventional chemotherapy across multiple tumor types. Given this rapid evolution, clinicians will need to select the most suitable ADC for each patient, considering tumor biology, microenvironment (TME) and patient-specific factors. Yet, despite remarkable efficacy, resistance to ADCs eventually arises. Understanding resistance mechanisms is therefore essential to guide therapeutic sequencing and optimize next-generation ADCs.

ADCs are complex molecules combining an antibody, a linker, and a cytotoxic payload. Their activity depends on factors such as antigen expression, internalization, linker stability, and payload sensitivity. Resistance can result from altered vascular perfusion, antigen downregulation, defective internalization or trafficking, impaired linker cleavage, drug efflux, or payload target modifications. These multifactorial processes differ from those driving resistance to traditional chemotherapies. Existing preclinical and clinical tools (Patient-Derived Xenograft(PDX)/Cell-line-Derived Xenograft (CDX) models, standard imaging, Immunohistochemistry (IHC), genomic profiling) fail to capture this complexity or predict ADC efficacy and resistance. Furthermore, ADCs often cause significant toxicities-on-target or off-target-affecting the ocular surface, skin, lungs, and peripheral nerves. Patient factors such as age, comorbidities, and weight influence these events. Understanding the determinants of toxicity is critical to maintain quality of life and treatment adherence.

The OASIS program aims to identify predictive biomarkers of ADC response and toxicity to enable personalized ADC selection and toxicity prevention. This multicenter study will integrate advanced technologies-digital pathology, liquid biopsy, and Patient-derived organoids (PDOs)-to generate comprehensive biological and clinical data. Using these datasets, a multimodal machine-learning model (OASIS Multiparametric Score) will be developed to predict both efficacy and key toxicities of ADCs. The project will prospectively include patients receiving ADCs in standard practice, with longitudinal tumor and blood sampling to investigate biomarkers of resistance and toxicity. In parallel, preclinical models derived from patient tumors will explore resistance mechanisms and screen ADC sensitivity.

A retrospective cohort of patients previously treated with ADCs will first be analyzed to prioritize biomarker candidates based on published data and prior findings. From this, five binary biomarkers will be selected for the primary objective. Combined with prospective data, this retrospective work will expand the translational biobank and support the construction of the OASIS score.

• Study Type: Interventional
• Enrollment (Estimated): 400
• Phase: Phase 2

Contacts and Locations

• Study Contact: Name: Marjorie Mauduit; Phone Number: +33 6 30481792; Email: m-mauduit@unicancer.fr
• Study Contact Backup: Name: Jérôme Lemonnier; Email: j-lemonnier@unicancer.fr

Study Locations

• France
  • Villejuif, France, 94805
    • Recruiting
    • Gustave Roussy Cancer Center
    • Principal Investigator: Barbara PISTILLI, MD
    • Contact: Barbara PISTILLI, MD; Phone Number: +33 (0)1 42 11 61 62; Email: barbara.pistilli@gustaveroussy.fr
    • Contact: Noemie CORCOS, PhD; Phone Number: + 33 (0) 1 42 11 51 58; Email: Noemie.CORCOS@gustaveroussy.fr

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Patients must have signed a written informed consent form prior to any trial specific procedures;
2. Patients must be ≥18 years old;
3. Histologically confirmed or radiologically documented unresectable locally advanced or metastatic cancer (Breast, Urothelial, Non small Cell Lung or Gastric) with an indication to receive an Antibody-Drug Conjugate (ADC) approved or accessible through an early access program;
4. Patients must have at least 2 tumor lesions (primary tumor can be included): at least one measurable tumor lesion for tumor evaluation according to response evaluation criteria in solid tumors (RECIST) V1.1 and at least one tumor lesion other than bone and brain for biopsy;
5. Patients must have a metastatic or locally advanced tumor site easily accessible to biopsy (with exception of bone and brain metastasis) and must have agreed to perform pretreatment and post-treatment biopsies; an archival pre-treatment biopsy may be used if it was collected within one month of enrolment, if no anticancer therapy was administered after the biopsy and if sufficient material is available for research;
6. Life expectancy must be ≥12 weeks according to the discretion of the investigator;
7. ECOG performance status ≤ 2;
8. Patients must have adequate hematologic and organ function, compatible with ADC administration, as per drug-specific recommendations;
9. Women of childbearing potential and male patient must agree to use adequate contraception for the duration of trial participation and up to 7 months after completing treatment for women and up to 4 months for men;
10. Patients must be affiliated to a social security system (or equivalent);
11. Patients must be willing and able to comply with the protocol for the duration of the trial;
12. Patients must consent to the use of their collected tumor specimen, as well as, blood samples as detailed in the protocol for future scientific research, which includes but is not limited to DNA, RNA, and protein-based biomarker analysis.

Exclusion Criteria:

1. Patients treated with an antibody drug conjugate in a curative setting;
2. Patients who did not consent to sample use;
3. Presence of another progressive pathology with short-term life-threatening prognosis;
4. Patients undergoing concurrent treatment for a malignancy or hematologic disorder distinct from the indication for which the ADC is being administered.

5. Patients with inadequate washout period prior to Cycle 1 Day 1, defined as:

   • Whole brain radiation therapy <14 days or stereotactic brain radiation therapy <7 days.
   • Any cytotoxic chemotherapy, investigational agents or other anticancer drug(s) (including another ADC) from a previous cancer treatment regimen or clinical study (other than epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKI)), <14 days or 5 half-lives, whichever is longer.
   • Immune checkpoint inhibitor therapy <21 days.
   • Hormonal therapy <21 days.
   • Major surgery (excluding placement of vascular access) <28 days.
   • Radiotherapy treatment to more than 30% of the bone marrow or with a wide field of radiation <28 days or palliative radiation therapy <14 days.
6. Female participant who is pregnant, breastfeeding, or planning to become pregnant while enrolled in this study or within 90 days after the final administration of study treatment;
7. Person deprived of their liberty or under protective custody or guardianship.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Other: T-DXd (trastuzumab deruxtecan); Standard of care T-DXd indication	Procedure: Biological samples collection; Biological samples collection (tumor tissue, blood, sputum) before initiation of treatment, during treatment, and at treatment discontinuation.; Other Names: Blood sample collection; Sputum sample collection; Tumor tissue sample collection; Behavioral: questionnaires to collect patient reported outcomes; QLQ-C30, QLQ-FA12, HADS, EQ-5D 5L
Other: T-DM1 (trastuzumab emtansine); Standard of care T-DM1 indication	Procedure: Biological samples collection; Biological samples collection (tumor tissue, blood, sputum) before initiation of treatment, during treatment, and at treatment discontinuation.; Other Names: Blood sample collection; Sputum sample collection; Tumor tissue sample collection; Behavioral: questionnaires to collect patient reported outcomes; QLQ-C30, QLQ-FA12, HADS, EQ-5D 5L
Other: SG (sacituzumab govitecan); Standard of care SG indication	Procedure: Biological samples collection; Biological samples collection (tumor tissue, blood, sputum) before initiation of treatment, during treatment, and at treatment discontinuation.; Other Names: Blood sample collection; Sputum sample collection; Tumor tissue sample collection; Behavioral: questionnaires to collect patient reported outcomes; QLQ-C30, QLQ-FA12, HADS, EQ-5D 5L
Other: EV (enfortumab vedotin); Standard of care EV indication	Procedure: Biological samples collection; Biological samples collection (tumor tissue, blood, sputum) before initiation of treatment, during treatment, and at treatment discontinuation.; Other Names: Blood sample collection; Sputum sample collection; Tumor tissue sample collection; Behavioral: questionnaires to collect patient reported outcomes; QLQ-C30, QLQ-FA12, HADS, EQ-5D 5L

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Biomarkers of resistance to ADC	Resistance is defined by differences in the frequency (higher or lower) of molecular aberrations detected between paired baseline samples and progression samples (i.e., samples collected at the time of disease progression under ADC treatment)	Through study completion, an average of 3 years

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Additional biomarkers of resistance characterised by histology	Differences in the frequency of molecular aberrations characterised by histologic/proteomic/genomic/transcriptomic analysis between samples of patients progressing on ADC and paired pre-treatment samples (beyond biomarkers of primary outcome)	Through study completion, an average of 3 years
Biomarkers of ADC outcome	Progression-Free Survival (PFS) defined as the time from start of treatment and radiological progression or death, whichever occurs first. Tumor assessments are made by local investigators as per standard practice (RECIST 1.1.). Patients still alive at the cut-off time without documented progression (including lost to follow-up) will be censored at the time of latest evaluable efficacy assessment.	From first day of cycle 1 (each cycle is 21 to 28 days) to date of first documented progression or date of death from any cause, whichever came first, assessed up to 60 months
Biomarkers of ADC outcome	Objective Response Rate (ORR) defined as the proportion of patients with a confirmed complete response (CR) or partial response (PR) assessed by investigators after 6 months of treatment.	From first day of cycle 1 (each cycle is 21 to 28 days) to date of 6 months of treatment completion
Biomarkers of ADC outcome	Clinical Benefit Rate (CBR) defined as the proportion of patients who had a CR, PR, or stable disease for 6 months or more.	From first day of cycle 1 (each cycle is 21 to 28 days) to date of first documented progression or date of death from any cause, whichever came first, assessed up to 60 months
Biomarkers of resistance to ADC	Duration of response (DOR) defined as the time from treatment initiation to disease progression or death for patients who achieve CR or PR.	From first day of cycle 1 (each cycle is 21 to 28 days) to date of first documented progression or date of death from any cause, whichever came first, assessed up to 60 months
Biomarkers of ADC outcome	Overall Survival (OS) defined as the time from inclusion to death due to any cause. Patients still alive at the cut-off time (including lost to follow-up) will be censored at the last known alive date.	From first day of cycle 1 (each cycle is 21 to 28 days) to date of death from any cause, assessed up to 60 months
Expression of ADC target measured on CTC and within tumor tissue	Concordance between ADC target expression (HER2, TROP-2, Nectin-4) on pre- and post-treatment tumor biopsy (IHC) and antigen expression on Circulating Tumor Cells (CTCs).	Through study completion, an average of 3 years
Patients' reported outcomes (PROs)	Overall quality of life will be assessed using the EORTC-QLQ-C30 and EQ-5D-5L at Baseline, after 3 months of treatment completion, at treatment discontinuation (for progression or any other reason)	Through study completion, an average of 3 years
Patients' reported outcomes (PROs)	Fatigue will be assessed using QLQ-FA12 at Baseline, after 3 months of treatment completion, at treatment discontinuation (for progression or any other reason).	Through study completion, an average of 3 years
Patients' reported outcomes (PROs)	Anxiety and depression will be assessed using HADS questionnaire at Baseline, after 3 months of treatment completion, at treatment discontinuation (for progression or any other reason)	Through study completion, an average of 3 years
Treatment cost	Number of resources consumed in terms of treatment, hospitalization (for drug administration and toxicity), biological and radiological exams during the ADC treatment, in order to calculated the corresponding management cost.	Through study completion, an average of 3 years
ADC-related specific toxicities	Safety as measured by the frequency and severity of key ADC toxicity (Interstitial Lung Disease, skin toxicity, ocular toxicity, peripheral neuropathy) as measured by NCI-CTCAE v 5.0.	Through study completion, an average of 3 years

Collaborators and Investigators

• Sponsor: UNICANCER
• Investigators: Principal Investigator: Barbara Pistilli, MD, PhD, Gustave Roussy Cancer Center

Study record dates

Study Major Dates

• Study Start (Actual): November 14, 2025
• Primary Completion (Estimated): November 1, 2030
• Study Completion (Estimated): November 1, 2030

Study Registration Dates

• First Submitted: September 26, 2025
• First Submitted That Met QC Criteria: November 20, 2025
• First Posted (Actual): December 2, 2025

Study Record Updates

• Last Update Posted (Actual): December 2, 2025
• Last Update Submitted That Met QC Criteria: November 20, 2025
• Last Verified: August 1, 2025

More Information

Terms related to this study

• Keywords: ADC; resistance
• Other Study ID Numbers: UC-TRA-2507; ID RCB 2025-A01462-47 (Other Identifier: ANSM)

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