A Phase 4 interventional study of Dexamethasone mouthwash and Datopotamab Deruxtecan (Dato-DXd) in Stomatitis, sponsored by AstraZeneca. Recruiting at 41 sites in United States. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-10-28.
Sponsored by AstraZeneca · Phase 4, Interventional, and Prevention
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
The purpose of this Phase IV study is to describe the incidence and severity of Dato-DXd treatment-emergent grade ≥ 2 stomatitis in participants receiving prophylactic dexamethasone mouthwash within the first 12 weeks of study treatment (ie, Dato-DXd dosing).
The study will enroll an estimated 100 participants across approximately 35 sites in the U.S. Enrollment of participants is planned to occur over approximately 18 months, with a minimum of 12 weeks of follow-up for each participant after the first Dato-DXd dose.
This study has one arm, and the study population will consist of 2 independent cohorts (approximately 50 participants in each cohort):
Participants will receive the study intervention, dexamethasone mouthwash, throughout the duration of their standard of care treatment with Dato-DXd.
306 studies on the registry are indexed under Stomatitis; 75 are open to participants now.
This study's planned enrollment of 100 is above the median of 60 across 276 interventional studies indexed under Stomatitis.
Browse Stomatitis studies →AstraZeneca is the lead sponsor of 3,499 studies on the registry; 270 are open to participants now.
Of its 368 completed or terminated interventional studies of FDA-regulated products, 178 (48%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Patients are eligible to be included in the study only if all the following criteria apply:
Disease Characteristics
Patients with any of the following disease characteristics are eligible (specific population subject to FDA Dato-DXd label):
OR
OR
Age
Patient must be ≥ 18 years, at the time of signing the .
Type of Patient and Disease Characteristics-
All women of must have a negative serum pregnancy test result at screening.
Informed Consent
Exclusion Criteria:
Patients are excluded from the study if any of the following criteria apply:
Has received Dato-DXd prior to enrollment.
Medical Conditions
Use of -containing mouthwash is in, including but not limited to:
Is pregnant, or breastfeeding, or planning to become pregnant.
Other Exclusions
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
HER2 is a protein, made from the ERBB2 gene, that drives the growth of some cancers. A study may look for a level of the protein, extra copies of the gene, or a particular change in it.
In breast cancer, protein tests are read as HER2-positive, HER2-low or HER2-negative; other cancers use their own rules. Check which test result the study requires.
PD-1, PD-L1 and CTLA-4 are proteins that act as brakes on the immune system. Checkpoint inhibitors, such as pembrolizumab or nivolumab, block them so the immune system can attack a cancer.
PD-L1 can also be measured in a tumour sample. Some scores count stained tumour cells only (TPS); others also count certain immune cells (CPS). The study names the score and the minimum it uses.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Metastases
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HER2
HER2 is a protein, made from the ERBB2 gene, that drives the growth of some cancers. A study may look for a level of the protein, extra copies of the gene, or a particular change in it.
In breast cancer, protein tests are read as HER2-positive, HER2-low or HER2-negative; other cancers use their own rules. Check which test result the study requires.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
PD-1, PD-L1 and checkpoint inhibitors
PD-1, PD-L1 and CTLA-4 are proteins that act as brakes on the immune system. Checkpoint inhibitors, such as pembrolizumab or nivolumab, block them so the immune system can attack a cancer.
PD-L1 can also be measured in a tumour sample. Some scores count stained tumour cells only (TPS); others also count certain immune cells (CPS). The study names the score and the minimum it uses.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECOG performance status
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hemoglobin (Hb)
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Excipients
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will use dexamethasone 0.5 mg/5 mL alcohol-free mouthwash (10 mL, 4 times daily, swish for approximately 2 minutes, then spit out without swallowing). Participants will remain without food or drink for at least 30 minutes after use of dexamethasone
Drug: Dexamethasone mouthwash · Drug: Datopotamab Deruxtecan (Dato-DXd)
Dexamethasone steroid-based oral solution, comprised of 0.5 milligrams per 5mL of alcohol-free dexamethasone.
Commercially available Dato-DXd is prescribed and administered to participants according to standard of care
Also known as: Datroway
Incidence and severity of Dato-DXd treatment-emergent grade ≥ 2 stomatitis in patients receiving prophylactic dexamethasone mouthwash within first 12 weeks of study treatment
Incidence is defined as the proportion of participants who develop National Cancer Institute-Common Terminology Criteria for Adverse Events (NCI-CTCAE) v5.0 grade ≥ 2 stomatitis accompanied by either a Normalcy of Diet Subscale score ≤ 50 and/or a Numeric Rating Scale (NRS) oral-pain score of 7 on 2 consecutive days or 8, 9, or 10 on any one day. Severity will be based on the highest NCI-CTCAE v5.0 grade of stomatitis experienced by each participant. CTCAE displays Grades 1-5 with descriptions of severity for each adverse event (AE). Grade 1 for mild symptoms and Grade 5 for death related to AE. The Normalcy of Diet Subscale assesses the degree to which a patient can eat a normal diet and drink liquids. The scale is a ranking of 10 food categories, from easy-to-eat to difficult-to-eat. The Numeric Rating Scale is a scale for self-reporting of pain. Scores range from 0-10, with higher scores meaning the worst pain possible (0=no pain to 10=worst possible pain).
Time frame: From date of first dose of study treatment until 12 weeks after date of first dose of study treatment
Incidence and severity of Dato-DXd treatment-emergent grade ≥ 2 stomatitis
This will be determined using the composite stomatitis definition in the primary outcome. Will be repeated within 6 weeks and within 9 weeks of study treatment.
Time frame: From date of first dose of study treatment until 6 and 9 weeks after date of first dose of study treatment
Incidence and severity of treatment-emergent stomatitis overall, by maximum CTCAE grade, and CTCAE grade ≥ 2
This will be determined using stomatitis CTCAE grade only. Will be analysed at 6, 9 and 12 weeks.
Time frame: From date of first dose of study treatment until 6, 9 and 12 weeks after date of first dose of study treatment
Time to onset of grade ≥ 2 stomatitis
The time (in days) from the date of the first dose of Dato-DXd to the date of first onset to a grade ≥ 2 stomatitis event. The measure of primary interest is median time to onset.
Time frame: From date of first dose until earliest of diagnosis of grade ≥2 stomatitis, Dato-DXD discontinuation and death, whichever occurs first, assessed up to approximately 21 months
Time to resolution of Dato-DXd-related grade ≥ 2 stomatitis
Number of days from the date of onset of stomatitis grade ≥ 2 until the earliest date of event resolved or reduced in severity to grade 1. The measure of primary interest is median time to resolution.
Time frame: From date of diagnosis of grade ≥2 stomatitis until the earliest date of event resolved or reduced in severity to grade 1, assessed up to approximately 21 months
Proportion of participants with a dose modification for Dato-DXd due to stomatitis
Dose modification is defined as dose reduction, delay, or discontinuation due to stomatitis Treatment-Emergent Adverse Event (TEAE).
Time frame: From date of first dose until earliest of Dato-DXD discontinuation and death, assessed up to approximately 21 months
Participant adherence to dexamethasone mouthwash
Adherence to dexamethasone mouthwash will be assessed by cohort using the Daily Activities Diary. The measure of primary interest is the median number of swished mouthwashes per day.
Time frame: From date of first dose of study treatment until 12 weeks after date of first dose of study treatment
Safety and tolerability of Dato-DXd in participants receiving prophylactic dexamethasone mouthwash
Safety and tolerability will be evaluated by cohort in terms of AEs (graded by NCI-CTCAE v5.0) and in terms of the following: * Incidence and severity of TEAEs and Serious Adverse Events (SAEs), including oral infections (such as fungal infections) associated with the use of the dexamethasone mouthwash * Eastern Cooperative Oncology Group (ECOG) performance status * Vital signs and physical examination * Clinical chemistry, hematology, urinalysis, and coagulation assessments * Use of antifungal medication for treating dexamethasone-related fungal infection.
Time frame: From date of first dose of study intervention until 28 days after the last dose (Safety Follow-up), approximately 21 months
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Plan to share: Yes — Qualified researchers can request access to anonymized individual patient-level data from AstraZeneca group of companies sponsored clinical trials via the request portal. All requests will be evaluated as per the AZ disclosure commitment: https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure Yes, indicates that AZ are accepting requests for IPD, but this does not mean all requests will be shared.
Supporting information: Study protocol, Statistical analysis plan
Time frame: AstraZeneca will meet or exceed data availability as per the commitments made to the EFPIA Pharma Data Sharing Principles. For details of our timelines, please rerefer to our disclosure commitment at https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure
Access criteria: When a request has been approved, AstraZeneca will provide access to the anonymized individual patient-level data via secure research environment Vivli.org. A Signed Data Usage Agreement (non-negotiable contract for data accessors) must be in place before accessing requested information.
Data sharing details ↗ · vivli.org
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