An interventional study of Biopsy Procedure and Biospecimen Collection in Metastatic Malignant Skin Neoplasm, Metastatic Malignant Soft Tissue Neoplasm and Recurrent Malignant Skin Neoplasm, sponsored by Mayo Clinic. Recruiting at 1 site in United States. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-09-11.
Sponsored by Mayo Clinic · Not applicable, Interventional, and Treatment
This clinical trial tests the safety and best dose of minibeam radiation therapy (MBRT) with a tungsten slit collimator for treating patients with skin or soft tissue tumors that have come back after a period of improvement (recurrent) or that spread from where they first started (primary site) to other places in the body (metastatic). Radiation therapy uses high energy x-rays, particles, or radioactive seeds to kill tumor cells and shrink tumors. Tungsten is an extremely dense metal and is commonly used for blocking x-rays for minimum radiation exposure. A tungsten slit collimator is a device that separates an initially wide beam of x-rays into several very narrow individual beams of radiation. As radiation passes through the collimator, the radiation hits regions of solid tungsten and is blocked. In the open slit regions, radiation passes through to the intended target/tumor area defined by the physician. The tungsten slit collimator then selectively blocks portions of the radiation to create an alternating pattern of higher "peak" and lower "valley" radiation dose regions. These narrow beams of radiation are referred to as "minibeams" and the general approach referred to as MBRT.
PRIMARY OBJECTIVE:
I. To determine the maximum tolerated dose (MTD) of MBRT and describe the adverse events of treatment.
SECONDARY OBJECTIVE:
I. To assess the ability to maintain a distinct differential between peak and valley doses using film dosimetry.
EXPLORATORY OBJECTIVES:
I. To estimate the rate of freedom from local progression at 6 and 12 months after the start of MBRT.
II. To evaluate pre-treatment and post-treatment differential abundance of peripheral blood immune cell populations and their activation markers.
III. Explore germline and somatic mutations in homologous recombination (HR) genes and their association with freedom from local progression.
IV. Quantify the immune phenotypes and cell signaling in the tumor microenvironment pre-MBRT and post-MBRT using bulk ribonucleic acid (RNA)-sequencing (seq) data.
OUTLINE:
Patients undergo MBRT with a tungsten slit collimator over 2-3 fractions on study. Patients also undergo standard of care CT simulation on study and undergo collection of blood samples and punch or core biopsy throughout the study.
After completion of study treatment, patients are followed up at weeks 2, 4, and 12, and months 6, 9, and 12.
Exclusion Criteria:
Patients undergo MBRT with a tungsten slit collimator over 2-3 fractions on study. Patients also undergo standard of care CT simulation on study and undergo collection of blood samples and punch or core biopsy throughout the study.
Procedure: Biopsy Procedure · Procedure: Biospecimen Collection · Procedure: Computed Tomography · Other: Medical Device Usage and Evaluation · Radiation: Minibeam Radiation Therapy
Undergo biopsy
Also known as: Biopsy, BIOPSY_TYPE, Bx
Undergo collection of blood samples
Also known as: Biological Sample Collection, Biospecimen Collected, Specimen Collection
Undergo CT
Also known as: CAT, CAT Scan, Computed Axial Tomography, Computerized Axial Tomography, Computerized axial tomography (procedure), Computerized Tomography, Computerized Tomography (CT) scan, CT, CT Scan, tomography
Undergo MBRT with tungsten slit collimator
Undergo MBRT with tungsten slit collimator
Also known as: MBRT
Maximum tolerated dose
The maximum tolerated dose is defined as the dose level associated with a dose limiting toxicity (DLT) probability closest to the target toxicity rate (30%), which will be determined based on the time-to-event Bayesian optimal interval procedures. The incidence and proportion of patients experiencing DLTs will be summarized for each dose level and across all dose levels.
Time frame: Up to 28 days
Incidence of adverse events
Safety will be assessed based on reported adverse events (AEs). The severity of AEs will be graded as mild, moderate, severe, or life-threatening according to Common Terminology Criteria for Adverse Events (CTCAE) version 5.0.
Time frame: Up to 12 months
Ability to maintain a distinct differential between peak and valley doses using film dosimetry
Film dosimetry will be obtained for every patient treatment. Radiochromic film will be placed directly on the tumor. Will measure and record peak and valley doses as well as the resulting peak-to-valley dose ratio.
Time frame: Up to 12 months
Incidence of adverse events
Safety will be assessed by CTCAE 5.0 by investigating (1) grade 3 AEs deemed possibly, probably, or definitely related to study treatment and (2) all grade 4-5 AEs regardless of attribution to the study treatment. The proportions of patients with these AEs at months 6, 9, and 12 will be evaluated.
Time frame: At months 6, 9, and 12
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