Correlation of a four gene set with H-ARS severity in irradiated minipigs treated with Myelo001.

PURPOSE: Early prediction of hematological acute radiation syndrome (H-ARS) saves lives. For H-ARS severity prediction, we established a four-gene panel (FDXR, DDB2, POU2AF1, WNT3) using leukemia patients and non-human primates. Further confirmation in 12 minipigs failed, due to a weak response of these genes after irradiation. MATERIALS AND METHODS: Here, we intended to confirm previous findings using a larger cohort (n = 19) and assess the impact of Myelo001 on clinical progression and gene expression. All minipigs received 2.1 Gy total-body irradiation (LD ≈ 40/30). The study included an irradiated control group and two irradiated groups treated with Myelo001 (11 or 15 days). Peripheral blood was collected six days before and on days 1-, 3-, and 10 after irradiation. RNA was isolated, reverse-transcribed, and analyzed by qRT-PCR using TaqMan assays. Differential gene expression (DGE) was calculated relative to pre-irradiation samples. RESULTS: WNT3 was undetectable in most animals. No significant difference in gene expression, survival, or clinical progression were found between Myelo001-treated and untreated animals, so treatment groups were pooled for DGE analyses. Across all time points, no significant changes in DGE were observed, except for slight DDB2 upregulation on day 3 (DGE = 2.3). The expected pattern of upregulated (DGE >2) FDXR/DDB2 with simultaneous downregulation (DGE <0.5) of POU2AF1, was absent (except on day one in one minipig). This missing pattern contrasted with an on average 5.5-fold reduction in lymphocyte counts, indicative of severe H-ARS. Also, no age or sex related changes were observed. CONCLUSION: This independent minipig study confirms previous work showing that these genes do not exhibit statistically significant radiation-responsiveness in this animal model. Under the experimental conditions applied, no significant age or sex related changes nor treatment-related effects of Myelo001 were observed, which may reflect model-specific limitations or a lack of efficacy in this setting, or a combination of both.