Methods of use of ultra-high dose rate radiation and therapeutic agent

A method of identifying a subject with cancer as a candidate for a treatment comprising ultra-high-dose-rate radiation (FLASH RT), the method comprising:

• (a) determining an expression level of one or more biomarkers in a tumor sample from the subject, wherein the one or more biomarkers are selected from the group consisting of an immune cell marker, a tumor cell marker, a circulating marker, an imaging marker, and any combination thereof;
• (b) comparing the expression level of the one or more biomarkers in the tumor sample from the subject to an expression level of the one or more biomarkers in a normal tissue sample;
• and
• (c) classifying the subject as a candidate for a treatment comprising FLASH RT if the expression level of the one or more biomarkers in the tumor sample from the subject is modified compared to the expression level of the one or more biomarkers in the normal tissue sample.