Table 3. Overview of ongoing clinical trials involving FLASH radiotherapy

NCT identifier	Cancer	Design	Population	Estimated enrollment	Radiation source	Treatment	Primary endpoint	Status1) (study start date)
NCT04986696	Malignant melanoma	Phase INon-randomizedDose escalation	Multiple skin metastasesPD after systemic treatment	46	Electrons	7 dose levels (22, 24, 26, 28, 30, 32, and 34 Gy in a single fraction)	MTD or RP2D	Recruiting (July 1, 2021)
NCT05524064	Bone metastasis	Phase ISingle arm	1–3 symptomatic bone metastasis in the thorax	10	Protons	8 Gy in a single fraction	ToxicityPatient-reported pain reliefPain medication use	Recruiting (March 8, 2023)
NCT05724875	Skin cancer	Phase IIRandomized	T1-2N0M0 cutaneous squamous cell carcinoma or basal cell carcinoma	60	Electrons	FLASH-RTvs.Conventional RT (T1, 22 Gy in a single fraction; T2, 30 Gy in 5 fractions)	Skin toxicity (≥grade 3)Local control rate	Recruiting (June 22, 2023)

NCT, National Clinical Trial; PD, progressive disease; MTD, maximum tolerated dose; RP2D, recommended phase II dose; RT, radiotherapy.
From https://clinicaltrials.gov/ (accessed on July 26, 2024).