An Open-label, Single-arm Study of Prophylaxis for Datopotamab Deruxtecan (Dato-DXd) -Related Stomatitis in Eligible Patients With Metastatic or Inoperable Locally Recurrent Breast Cancer or Locally Advanced or Metastatic Epidermal Growth Factor Receptor-Mutated Non-small Cell Lung Cancer.

Study summary

This is a multicenter, open-label, single-arm study of prophylaxis for Dato-DXd-related stomatitis in eligible patients with metastatic or inoperable locally recurrent breast cancer or locally advanced or metastatic Epidermal Growth Factor Receptor-Mutated (EGFRm) non-small cell lung cancer

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Key things to know

Main goalPrevention

This describes the study’s primary purpose.

What is being studiedDexamethasone mouthwash and Datopotamab Deruxtecan (Dato-DXd)

The study team can explain what participation involves.

Who it may be forNon-small cell lung cancer (NSCLC) · Early-stage or resectable · Locally advanced

These are broad labels—not an eligibility decision.

Checked against the public recordLast updated Sep 30, 2026 · Source: ClinicalTrials.gov

Is enrollment open?Recruiting

The study is currently accepting participants.

What kind of study?Phase 4

Interventional

Where is it offered?40 U.S. locations

Locations may change over time.

Who runs it?AstraZeneca

Study sponsor

Study overview

What this study is about

Purpose: Prevention
Study type: Interventional
Phase: Phase 4
Sponsor: AstraZeneca
Interventions being studied: Drug: Dexamethasone mouthwash; Drug: Datopotamab Deruxtecan (Dato-DXd)

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How this study is categorized

These labels come from structured fields and exact terms in the public record.

Cancer type

Non-small cell lung cancer (NSCLC)→

Disease setting

Early-stage or resectable→Locally advanced→Metastatic or stage IV→Recurrent or relapsed→

Public criteria

Who may be able to participate

The sponsor separates these requirements into two groups. You do not need to interpret them alone—use them to guide a conversation with the study team.

Requirements people may need to meetInclusion criteria

Patients are eligible to be included in the study only if all the following criteria apply: Disease Characteristics 1. Patients with any of the following disease characteristics are eligible (specific population subject to FDA Dato-DXd label):
Patients with unresectable or metastatic HR+/HER2- (IHC 0, IHC 1+, or IHC 2+/ISH-) breast cancer who have received prior ET and chemotherapy for unresectable or metastatic disease. OR
Adult patients with unresectable or metastatic TNBC who are not candidates for PD-1/PD-L1 inhibitor therapy. Participants will be enrolled upon FDA approval on use of Dato-DXd for this indication. OR
Patients with locally advanced or metastatic EGFRm NSCLC who have received prior EGFR-directed therapy and platinum-based chemotherapy. Age 2. Patient must be ≥ 18 years, at the time of signing the informed consent. Type of Patient and Disease Characteristics- 3. Has documentation that Dato-DXd will be prescribed for the labelled indication and has not received any dose of Dato-DXd prior to enrollment. 4. Is willing to comply with use of prophylactic dexamethasone mouthwash at the start of first infusion and throughout Dato-DXd administration. 5. ECOG performance status 0 or 1. 6. Has adequate bone marrow function (hemoglobin ≥ 9 g/dL; red blood cell/plasma transfusion is not allowed within 1 week prior to screening assessment). 7. All women of childbearing potential must have a negative serum pregnancy test result at screening. Informed Consent 8. Capable of giving signed informed consent as described in the protocol which includes compliance with the requirements and restrictions listed in the ICF and the protocol.

Reasons someone may not be able to joinExclusion criteria

Patients are excluded from the study if any of the following criteria apply: 1. Has received Dato-DXd prior to enrollment. Medical Conditions 2. As judged by the investigator, any evidence of cardiac, pulmonary, vascular, and other renal conditions which in the investigator's opinion makes it undesirable for the patient to participate in the study. 3. Has any-grade active and uncontrolled stomatitis or mouth ulcers at baseline (participants with prior medical history of stomatitis or mouth ulcers are eligible). 4. Use of steroid-containing mouthwash is contraindicated in, including but not limited to:
Active oral infections (eg, viral, bacterial, or fungal), where the use of a steroid-containing mouthwash may impair local immune response and delay healing
Known hypersensitivity or allergy to corticosteroids or any excipients contained in the mouthwash formulation 5. Uncontrolled infection requiring IV antibiotics, antivirals, or antifungals; suspected infections (eg, prodromal symptoms); or inability to rule out infections (participants with localized fungal infections of skin or nails are eligible). 6. Has clinically significant corneal disease. 7. Has a history of severe hypersensitivity reactions to either the drug or inactive ingredients of Dato-DXd (including, but not limited to, polysorbate 80). 8. Has a history of severe hypersensitivity reactions to other monoclonal antibodies. 9. Is pregnant, or breastfeeding, or planning to become pregnant. Other Exclusions 10. Involvement in the planning and/or conduct of the study (applies to both AstraZeneca staff and/or staff at the study site). 11. Judgment by the investigator that the patient should not participate in the study if the patient is unlikely to comply with study procedures, restrictions, and requirements. 12. Previous enrollment in the present study.

Important: This is the sponsor’s public criteria, not a determination of eligibility. The study team must review your individual situation.

Study sites

U.S. locations

Research SiteTucson, Arizona
Research SiteHot Springs, Arkansas
Research SiteLittle Rock, Arkansas
Research SiteDuarte, California
Research SiteGlendale, California
Research SiteLakewood, California
Research SiteLong Beach, California
Research SiteTorrance, California
Research SiteWashington D.C., District of Columbia
Research SitePlantation, Florida
Research SiteAthens, Georgia
Research SiteBoise, Idaho

Source and freshness
Processed from ClinicalTrials.gov. Last public update: Sep 30, 2026. Always confirm current availability with the study team.

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