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Expertise in Radiation Biology and Evaluation of Medical Countermeasures for Acute Radiation Syndrome (ARS) and Delayed Effects of Acute Radiation Exposure (DEARE)

Epistem has over a decade of experience in evaluating mitigators for ARS and DEARE for the USA's National Institute of Allergy and Infectious Disease (NIAID) and other US Government departments.

An Overview

Expertise and Resources for Comprehensive Evaluation of Radiation Exposure Effects

Acute Radiation Syndrome

ARS occurs when a person is exposed to a high dose of ionizing radiation in a single instance. The damage from radiation primarily affects the haematological, gastrointestinal (GI) and neurovascular systems. Radiation exposure interrupts cell production, and damage to the bone marrow and GI tract is noticeable within days due to the rapid cell turnover. Tissues that regenerate slowly are generally more resistant to radiation and require higher doses to be affected. The key to identifying an effective medical countermeasure for GI-ARS is correlating the proposed mechanism of action and histopathology with the effects on survival. Confounding factors, such as age, strain, concomitant bone marrow damage and medical management must also be characterised.

Epistem has generated a series of radiation dose response curves for both total and partial-body irradiation, with and without medical management. These data are supported by detailed GI histopathology to correlate survival with crypt loss and regeneration. This comprehensive database is now used to screen potential mitigators of GI-ARS.

Delayed Effects of Acute Radiation Exposure

DEARE refers to long-term health consequences that can occur months or years after a person has been exposed to high doses of ionizing radiation. These effects can include the development of cancer, cardiovascular disease and damage to the nervous system. The severity and manifestation of DEARE depend on the dose and duration of radiation exposure, as well as other factors such as age, sex and overall health.


Epistem has worked with the Medical Countermeasures against Radiological Threats (MCART) consortium, which is funded by the USA’s National Institute of Allergy and Infectious Disease (NIAID). MCART was established to protect the USA from weapons of mass destruction as part of Project Bioshield. For over a decade, Epistem has evaluated ARS mitigators for NIAID and other US Government departments.

Epistem’s models incorporate variable levels of bone marrow shielding and medical management to simulate different radiation exposures and clinical support measures. The knowledge and experience gained from these models are also applied to other therapeutic areas, such as the treatment and prevention of oncology therapy side effects and other causes of GI toxicity.


Epistem’s Biodefense Models:

  • Acute Radiation Syndrome
    • Gastrointestinal (GI-ARS)
    • Haematopoietic (H-ARS)
  • Delayed Effects of Acute Radiation Exposure (DEARE)


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