Human normal tissue patient-derived organoids for pre-screening GI radiation countermeasure drugs

PROJECT SUMMARY/ABSTRACT
Exposure to high acute doses of ionizing radiation as a consequence of a radiological or nuclear event can cause
illnesses known collectively as acute radiation syndrome (ARS). No medical radiation countermeasure has been
approved as yet by the FDA to specifically counteract gastrointestinal (GI) ARS.
Radiomitigators efficacy studies cannot be conducted in humans for ethical reasons, thus the FDA requires these
tests in well-controlled animal studies. Two concerns however arise; first, the results obtained from animal
models do not always translate to humans: For instance, they may not reflect the inter-individual variability in the
human response to radiation damage due to factors such as age, sex, and genetic predisposition. Second, in-
vivo animal studies are laborious and expensive, and are not generally consistent with screening a large number
of drugs or drug variants. Thus, there is a need for alternate pre-screening models which are a) based on normal
human GI tissue and b) amenable to high-throughput pre-screening. To fill this gap, our goal is to develop and
validate the use of human normal tissue patient-derived organoids (NT-PDOs) established from healthy normal
tissue biopsies for pre-screening new candidate GI radiation countermeasures, and to assess the significance
of age and sex, in a high-throughput multi-well format.
In the context of GI ARS, NT-PDOs are an excellent extracorporeal model for the personalized screening of
radiomitigators. They stably replicate the morphological characteristics and physiological functions of the original
donor tissue, accurately reproduced the response of the human intestine to known toxic and nontoxic drugs, and
when exposed to ionizing radiation, cognate organoids had similar survival dose responses as small and large
intestinal crypts in mice. With two interrelated Aims, this proof-of-concept study aims at evaluating the feasibility
of using NT-PDOs as proxy of the native organ to test the efficacy/safety of new candidate radiomitigators before
advancing to more complex animal studies. To this end, efficacy of the test radiomitigator CBLB502 will be
evaluated in organoids derived from the small intestine of individuals of different ages and sex. In Aim 1,
effectiveness of the test radiomitigator will be assessed as organoid survival and viability dose-responses.
The mode of action of CBLB502 has been well characterized in animal models; the goal is to evaluate whether
the drug exerts similar functions in irradiated NT-PDOs. In Aim 2 for both sexes, the sample group identified in
Aim 1 with the combination of age, radiation dose, and time of administration of the drug after exposure that
shows the biggest effect on survival compared to respective sham-treated controls, will be analyzed using a
RNAseq approach coupled with RT-PCR of selected genes of interest.
The use of NT-PDOs to pre-screen medical countermeasures in a high-throughput multi-well format can
complement the animal in-vivo based strategy for the assessment of radiation countermeasures for GI ARS.

Grant Number: 1R21AI194022-01
NIH Institute/Center: NIH
Principal Investigator: Manuela Buonanno