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
Phase II: Randomized Neoadjuvant Treatment of Oral Cavity Cancer With Spatially Fractionated Proton Radiotherapy and Immunotherapy (OSPRI)
3 other identifiers
interventional
30
1 country
1
Brief Summary
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.
Trial Health
Trial Health Score
Automated assessment based on enrollment pace, timeline, and geographic reach
participants targeted
Target at P25-P50 for phase_2
Started Sep 2026
Typical duration for phase_2
1 active site
Health score is calculated from publicly available data and should be used for screening purposes only.
Trial Relationships
Click on a node to explore related trials.
Study Timeline
Key milestones and dates
First Submitted
Initial submission to the registry
August 20, 2026
CompletedFirst Posted
Study publicly available on registry
August 25, 2026
CompletedStudy Start
First participant enrolled
September 7, 2026
ExpectedPrimary Completion
Last participant's last visit for primary outcome
April 1, 2030
Study Completion
Last participant's last visit for all outcomes
April 1, 2030
August 25, 2026
August 1, 2026
3.6 years
August 20, 2026
August 20, 2026
Conditions
Outcome Measures
Primary Outcomes (1)
Improvement in major pathologic response rate (MPR)
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 Outcomes (3)
Pathologic complete response rate
At the time of surgical resection
Percent of patients receiving the prescribed therapy
Up to 1 year
Incidence of Adverse Events (AEs) Prior to Surgery:
From the time of registration until surgery
Study Arms (2)
Arm A (proton SFRT, pembrolizumab, surgery)
EXPERIMENTALPatients 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.
Arm B (photon SBRT, pembrolizumab, surgery)
EXPERIMENTALPatients 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.
Interventions
Undergo tissue biopsy
Undergo blood sample collection
Undergo CT or PET/CT
Undergo PET/MRI
Given IV
Receive photon SBRT
Undergo PET/CT or PET/MRI
Receive proton SFRT
Undergo surgical resection
Eligibility Criteria
You may qualify if:
- 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
You may not qualify if:
- 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
Contact the study team to confirm eligibility.
Sponsors & Collaborators
- Mayo Cliniclead
Study Sites (1)
Mayo Clinic in Rochester
Rochester, Minnesota, 55905, United States
Related Links
MeSH Terms
Conditions
Interventions
Condition Hierarchy (Ancestors)
Intervention Hierarchy (Ancestors)
Study Officials
- PRINCIPAL INVESTIGATOR
Daniel K. Ebner, MD, MPH
Mayo Clinic in Rochester
Central Study Contacts
Study Design
- Study Type
- interventional
- Phase
- phase 2
- Allocation
- RANDOMIZED
- Masking
- NONE
- Purpose
- TREATMENT
- Intervention Model
- PARALLEL
- Sponsor Type
- OTHER
- Responsible Party
- SPONSOR
Study Record Dates
First Submitted
August 20, 2026
First Posted
August 25, 2026
Study Start (Estimated)
September 7, 2026
Primary Completion (Estimated)
April 1, 2030
Study Completion (Estimated)
April 1, 2030
Last Updated
August 25, 2026
Record last verified: 2026-08