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

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
30

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • 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

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • United States
    • Minnesota
      • Rochester, Minnesota, United States, 55905
        • Mayo Clinic in Rochester
        • Contact:
        • 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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

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

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
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.
Biological: Pembrolizumab
Given IV
Other Names:
  • Keytruda
  • MK-3475
  • Lambrolizumab
  • SCH 900475
  • MK3475
  • SCH-900475
  • BCD-201
  • Pembrolizumab Biosimilar BCD-201
  • Pembrolizumab Biosimilar QL2107
  • QL2107
  • GME 751
  • GME751
  • Pembrolizumab Biosimilar GME751
  • MK 3475
  • SCH900475
  • Pembrolizumab Biosimilar RPH-075
  • RPH 075
  • RPH-075
  • RPH075
  • Pembrolizumab Biosimilar SB27
  • SB 27
  • SB-27
  • SB27
Procedure: Biospecimen Collection
Undergo blood sample collection
Other Names:
  • Biological Sample Collection
  • Biospecimen Collected
  • Specimen Collection
  • Sample Collection
Procedure: Magnetic Resonance Imaging
Undergo PET/MRI
Other Names:
  • MRI
  • Magnetic Resonance
  • Magnetic Resonance Imaging Scan
  • Medical Imaging, Magnetic Resonance / Nuclear Magnetic Resonance
  • MR
  • MR Imaging
  • MRI Scan
  • NMR Imaging
  • NMRI
  • Nuclear Magnetic Resonance Imaging
  • Magnetic Resonance Imaging (MRI)
  • sMRI
  • Magnetic resonance imaging (procedure)
  • MRIs
  • Structural MRI
Procedure: Surgical Procedure
Undergo surgical resection
Other Names:
  • Operation
  • Surgery
  • Surgery Type
  • Surgical
  • Surgical Intervention
  • Surgical Interventions
  • Surgical Procedures
  • Type of Surgery
  • Surgery, NOS
Procedure: Computed Tomography
Undergo CT or PET/CT
Other Names:
  • CT
  • CAT
  • CAT Scan
  • Computed Axial Tomography
  • Computerized Axial Tomography
  • Computerized Tomography
  • CT Scan
  • tomography
  • Computerized axial tomography (procedure)
  • Computerized Tomography (CT) scan
  • Diagnostic CAT Scan
  • Diagnostic CAT Scan Service Type
Procedure: Positron Emission Tomography
Undergo PET/CT or PET/MRI
Other Names:
  • Medical Imaging, Positron Emission Tomography
  • PET
  • PET Scan
  • Positron Emission Tomography Scan
  • Positron-Emission Tomography
  • PT
  • Positron emission tomography (procedure)
Procedure: Biopsy Procedure
Undergo tissue biopsy
Other Names:
  • Bx
  • BIOPSY_TYPE
  • Biopsy
Radiation: Spatially-fractionated Radiation Therapy
Receive proton SFRT
Other Names:
  • SFRT
  • GRID Therapy
  • Spatially Fractionated Radiation Therapy
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.
Biological: Pembrolizumab
Given IV
Other Names:
  • Keytruda
  • MK-3475
  • Lambrolizumab
  • SCH 900475
  • MK3475
  • SCH-900475
  • BCD-201
  • Pembrolizumab Biosimilar BCD-201
  • Pembrolizumab Biosimilar QL2107
  • QL2107
  • GME 751
  • GME751
  • Pembrolizumab Biosimilar GME751
  • MK 3475
  • SCH900475
  • Pembrolizumab Biosimilar RPH-075
  • RPH 075
  • RPH-075
  • RPH075
  • Pembrolizumab Biosimilar SB27
  • SB 27
  • SB-27
  • SB27
Procedure: Biospecimen Collection
Undergo blood sample collection
Other Names:
  • Biological Sample Collection
  • Biospecimen Collected
  • Specimen Collection
  • Sample Collection
Procedure: Magnetic Resonance Imaging
Undergo PET/MRI
Other Names:
  • MRI
  • Magnetic Resonance
  • Magnetic Resonance Imaging Scan
  • Medical Imaging, Magnetic Resonance / Nuclear Magnetic Resonance
  • MR
  • MR Imaging
  • MRI Scan
  • NMR Imaging
  • NMRI
  • Nuclear Magnetic Resonance Imaging
  • Magnetic Resonance Imaging (MRI)
  • sMRI
  • Magnetic resonance imaging (procedure)
  • MRIs
  • Structural MRI
Procedure: Surgical Procedure
Undergo surgical resection
Other Names:
  • Operation
  • Surgery
  • Surgery Type
  • Surgical
  • Surgical Intervention
  • Surgical Interventions
  • Surgical Procedures
  • Type of Surgery
  • Surgery, NOS
Procedure: Computed Tomography
Undergo CT or PET/CT
Other Names:
  • CT
  • CAT
  • CAT Scan
  • Computed Axial Tomography
  • Computerized Axial Tomography
  • Computerized Tomography
  • CT Scan
  • tomography
  • Computerized axial tomography (procedure)
  • Computerized Tomography (CT) scan
  • Diagnostic CAT Scan
  • Diagnostic CAT Scan Service Type
Procedure: Positron Emission Tomography
Undergo PET/CT or PET/MRI
Other Names:
  • Medical Imaging, Positron Emission Tomography
  • PET
  • PET Scan
  • Positron Emission Tomography Scan
  • Positron-Emission Tomography
  • PT
  • Positron emission tomography (procedure)
Procedure: Biopsy Procedure
Undergo tissue biopsy
Other Names:
  • Bx
  • BIOPSY_TYPE
  • Biopsy
Radiation: Photon Stereotactic Body Radiation Therapy
Receive photon SBRT
Other Names:
  • Photon SBRT

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
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

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
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

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Mayo Clinic

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • 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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
September 7, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
April 1, 2030

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
April 1, 2030

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
August 20, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
August 20, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
August 25, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
August 25, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
August 20, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
August 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant 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.

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