Proton Spatially Fractionated Radiotherapy or Photon Stereotactic Body Radiotherapy in Combination With Pembrolizumab Before Surgery for the Treatment of Locally Advanced and Radiation-Naive Locoregionally Recurrent Oral Cavity Cancer, OSPRI Trial
August 20, 2026 updated by: Mayo Clinic
Phase II: Randomized Neoadjuvant Treatment of Oral Cavity Cancer With Spatially Fractionated Proton Radiotherapy and Immunotherapy (OSPRI)
This phase II trial compares the effect of adding proton spatially fractionated radiotherapy (SFRT) or photon stereotactic body radiotherapy (SBRT) to standard immunotherapy pembrolizumab before surgery (neoadjuvant) in treating patients with oral cavity squamous cell cancer that has spread to nearby tissue or lymph nodes (locally advanced) or that has come back where it first started (primary site) or near it (locoregionally recurrent) and have not had (naive) prior radiation.
Radiation therapy uses high energy x-rays, particles, or radioactive seeds to kill tumor cells and shrink tumors.
Proton SFRT is a type of external beam radiation treatment that uses streams of protons (tiny particles with a positive charge) to deliver different doses of radiation to different parts of the tumor in a grid like pattern.
This type of radiation kills tumor cells but does not damage nearby tissues.
SBRT is a type of external radiation therapy that uses special equipment to position a patient and precisely deliver radiation to tumors in the body (except the brain).
The total dose of radiation is divided into smaller doses given over several days.
This type of radiation therapy helps spare normal tissue.
Immunotherapy with monoclonal antibodies, such as pembrolizumab, may help the body's immune system attack the tumor, and may interfere with the ability of tumor cells to grow and spread.
Giving neoadjuvant proton SFRT or SBRT in combination with pembrolizumab may be safe and tolerable and may be an effective approach to shrink the tumor, reduce the extent of surgery and/or the need for further treatment in patients with locally advanced or locoregionally recurrent oral cavity squamous cell cancer.
Study Overview
Status
Not yet recruiting
Conditions
Intervention / Treatment
- Biological: Pembrolizumab
- Procedure: Biospecimen Collection
- Procedure: Magnetic Resonance Imaging
- Procedure: Surgical Procedure
- Procedure: Computed Tomography
- Procedure: Positron Emission Tomography
- Procedure: Biopsy Procedure
- Radiation: Spatially-fractionated Radiation Therapy
- Radiation: Photon Stereotactic Body Radiation Therapy
Study Type
Interventional
Enrollment (Estimated)
30
Phase
- Phase 2
Contacts and Locations
This section provides the contact details for those conducting the study, and information on where this study is being conducted.
Study Contact
- Name: Clinical Trials Referral Office
- Phone Number: 855-776-0015
- Email: mayocliniccancerstudies@mayo.edu
Study Locations
-
-
Minnesota
-
Rochester, Minnesota, United States, 55905
- Mayo Clinic in Rochester
-
Contact:
- Clinical Trials Referral Office
- Phone Number: 855-776-0015
- Email: mayocliniccancerstudies@mayo.edu
-
Principal Investigator:
- Daniel K. Ebner, MD, MPH
-
-
Participation Criteria
Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.
Eligibility Criteria
Ages Eligible for Study
- Adult
- Older Adult
Accepts Healthy Volunteers
No
Description
Inclusion Criteria:
Patients with histologically confirmed human papillomavirus (HPV)/p16-unrelated squamous cell carcinoma of the oral cavity and:
- Either locally advanced (T3-T4) non-metastatic disease, or
- Radiation-naïve locoregionally recurrent disease (prior radiation to a site outside of the treatment fields is permitted)
- Age ≥ 18 years old
- Eastern Cooperative Oncology Group (ECOG) performance status (PS) ≤ 2
- Eligible to receive immunotherapy on multidisciplinary evaluation
- Ability to complete questionnaire(s) by themselves or with assistance
- Provide signed written informed consent in accordance with ethical, regulatory, and institutional requirements
- Willing to return to enrolling institution for follow-up (during the active monitoring phase of the study)
- Willing to consent to and provide tissue and blood samples for correlative research purposes (not the optional Riskguard and OncoExtra testing)
- PD-L1 combined positive score ≥ 1
Exclusion Criteria:
Participation in another clinical study with an investigational product during the last 3 months (12 weeks)
- Exception: Unless it is an observational (non-interventional) clinical study during the follow-up period of the study
- Contraindications to pembrolizumab
- Prior radiation therapy to the head and neck
- Previous anticancer therapeutic received ≤ 30 days prior to registration, or adequate washout period on a per-agent basis, or concurrent anti-cancer therapeutic not specified by this protocol
- Uncontrolled pre-existing condition(s), such as infection, congestive heart failure, hypertension, angina, arrhythmia, chronic diarrhea, psychiatric conditions, or others, that in the opinion of the treating investigator limits the ability to provide consent or longitudinal participation in this study
- Inability to place 2 or more SFRT spheres within the tumor target
- Prophylactic placement of feeding tubes is not allowed
Study Plan
This section provides details of the study plan, including how the study is designed and what the study is measuring.
How is the study designed?
Design Details
- Primary Purpose: Treatment
- Allocation: Randomized
- Interventional Model: Parallel Assignment
- Masking: None (Open Label)
Arms and Interventions
Participant Group / Arm |
Intervention / Treatment |
|---|---|
|
Experimental: Arm A (proton SFRT, pembrolizumab, surgery)
Patients receive proton SFRT QOD for up to 3 treatment fractions over 1 week.
Starting within 7 days of initiating SFRT, patients receive pembrolizumab IV on day 1 of each cycle.
Cycles repeat every 3 weeks for up to 2 cycles in the absence of disease progression or unacceptable toxicity.
Within 8 weeks of completing pembrolizumab, patients undergo surgical resection per standard of care.
Patients also undergo blood sample collection, CT, and PET/MRI or PET/CT throughout the study.
Additionally, patients may also undergo tissue biopsy at baseline and/or on study.
|
Given IV
Other Names:
Undergo blood sample collection
Other Names:
Undergo PET/MRI
Other Names:
Undergo surgical resection
Other Names:
Undergo CT or PET/CT
Other Names:
Undergo PET/CT or PET/MRI
Other Names:
Undergo tissue biopsy
Other Names:
Receive proton SFRT
Other Names:
|
|
Experimental: Arm B (photon SBRT, pembrolizumab, surgery)
Patients receive photon SBRT QOD for up to 3 treatment fractions over 1 week.
Starting within 7 days of initiating SBRT, patients receive pembrolizumab IV on day 1 of each cycle.
Cycles repeat every 3 weeks for up to 2 cycles in the absence of disease progression or unacceptable toxicity.
Within 8 weeks of completing pembrolizumab, patients undergo surgical resection per standard of care.
Patients also undergo blood sample collection, CT, and PET/MRI or PET/CT throughout the study.
Additionally, patients may also undergo tissue biopsy at baseline and/or on study.
|
Given IV
Other Names:
Undergo blood sample collection
Other Names:
Undergo PET/MRI
Other Names:
Undergo surgical resection
Other Names:
Undergo CT or PET/CT
Other Names:
Undergo PET/CT or PET/MRI
Other Names:
Undergo tissue biopsy
Other Names:
Receive photon SBRT
Other Names:
|
What is the study measuring?
Primary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
|
Improvement in major pathologic response rate (MPR)
Time Frame: At the time of surgical resection
|
MPR is defined from pathologic evaluation of the surgically resected tumor, demonstrating less than 10% of residual tumor in the resection sample (≥90% disease reduction).
Will be assessed using a Bayesian pick-the-winner randomized phase-II clinical trial design.
|
At the time of surgical resection
|
Secondary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
|
Pathologic complete response rate
Time Frame: At the time of surgical resection
|
Pathologic complete response rate is defined from pathologic evaluation of the surgically resected tumor, demonstrating no signs of residual disease following immuno-radiation.
This will be calculated separately for Arm A and for Arm B.
|
At the time of surgical resection
|
|
Percent of patients receiving the prescribed therapy
Time Frame: Up to 1 year
|
Will be defined as the number of patients who received the prescribed therapy divided by the number of evaluable patients who signed a consent form and began treatment.
This will be calculated separately for Arm A and Arm B.
|
Up to 1 year
|
|
Incidence of Adverse Events (AEs) Prior to Surgery:
Time Frame: From the time of registration until surgery
|
Overall AEs, overall toxicities, and by maximum grade per type of AE per patient of the AEs that occur before surgery will be explored and summarized descriptively, mainly through the use of frequency tables.
Toxicity is defined as an adverse event that is classified as possibly, probably, or definitely related to study treatment.
AEs are graded per National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) version 6.0.
|
From the time of registration until surgery
|
Collaborators and Investigators
This is where you will find people and organizations involved with this study.
Sponsor
Investigators
- Principal Investigator: Daniel K. Ebner, MD, MPH, Mayo Clinic in Rochester
Publications and helpful links
The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.
Helpful Links
Study record dates
These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.
Study Major Dates
Study Start (Estimated)
September 7, 2026
Primary Completion (Estimated)
April 1, 2030
Study Completion (Estimated)
April 1, 2030
Study Registration Dates
First Submitted
August 20, 2026
First Submitted That Met QC Criteria
August 20, 2026
First Posted (Actual)
August 25, 2026
Study Record Updates
Last Update Posted (Actual)
August 25, 2026
Last Update Submitted That Met QC Criteria
August 20, 2026
Last Verified
August 1, 2026
More Information
Terms related to this study
Additional Relevant MeSH Terms
- Neoplasms by Site
- Neoplasms
- Neoplasms by Histologic Type
- Head and Neck Neoplasms
- Neoplasms, Glandular and Epithelial
- Carcinoma
- Carcinoma, Squamous Cell
- Squamous Cell Carcinoma of Head and Neck
- Investigative Techniques
- Clinical Laboratory Techniques
- Diagnostic Techniques and Procedures
- Diagnosis
- Cytological Techniques
- Cytodiagnosis
- Diagnostic Techniques, Surgical
- Chemistry Techniques, Analytical
- Spectrum Analysis
- Biopsy
- Specimen Handling
- pembrolizumab
- Magnetic Resonance Spectroscopy
- Surgical Procedures, Operative
Other Study ID Numbers
- GMROR2472
- NCI-2026-05918 (Registry Identifier: CTRP (Clinical Trial Reporting Program))
- 24-011038 (Other Identifier: Mayo Clinic Institutional Review Board)
Drug and device information, study documents
Studies a U.S. FDA-regulated drug product
Yes
Studies a U.S. FDA-regulated device product
No
This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.