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.
Age ≥ 18 years
Histologically confirmed malignancy
Primary, recurrent, or metastatic skin or superficial soft tissue tumor amenable to palliative orthovoltage radiotherapy
Anticipated life expectancy ≥ 30 days and anticipated capacity for follow up for ≥ 30 days
Hematologic, germ cell, or any other tumor that the investigational team would deem to have a high likelihood of clinical complete response with standard palliative radiotherapy (8 Gy in 1, 30 Gy in 10, etc.)
COHORT A (INTACT SKIN) ONLY: Prior radiotherapy targeting the lesion presenting for treatment or prior adjacent radiotherapy if > 10 Gy overlaps with a portion of the planned target
Treatment with a B-Raf proto-oncogene, serine/threonine kinase (BRAF) inhibitor, monoclonal antibodies targeting vascular endothelial growth factor (VEGF) (bevacizumab or ramucirumab) or small molecule inhibitors inhibiting VEGF within the last 2 weeks or planned treatment with BRAF inhibitor within 4 weeks after radiation
Treatment with an investigational drug therapy within 2 weeks prior to or 4 weeks (the DLT monitoring period) after MBRT
Single group
Biopsy Procedure
Procedure/SurgeryUndergo biopsy
Biospecimen Collection
Procedure/SurgeryUndergo collection of blood samples
Computed Tomography
Procedure/SurgeryUndergo CT
Medical Device Usage and Evaluation
Other interventionUndergo MBRT with tungsten slit collimator
Minibeam Radiation Therapy
RadiationUndergo MBRT with tungsten slit collimator
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.
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.
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.
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.
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