Amifostine Prophylaxis in Irradiated Breast Reconstruction: A Study of Oncologic Safety In Vitro.

Background: Indications for adjuvant radiation therapy (XRT) in breast cancer have expanded. Although highly effective, XRT damages surrounding tissues and vasculature, often resulting in delayed or compromised breast reconstruction. Thus, effective yet safe methods of radiation injury prophylaxis would be desirable. Amifostine is a Food and Drug Administration-approved radioprotectant; however, concerns about its potential to also protect cancer remain. The purpose of this study was to evaluate the oncologic safety of amifostine (AMF) in vitro and determine its effect on human breast cancer cells in the setting of XRT.

Methods: One ER+/PR+/Her2- (MCF-7) and two ER-/PR-Her2- (MDA-MB-231, MDA-MB-468) breast cancer cell lines were investigated. Female fibroblasts were used as controls. Cells were treated with WR-1065, the active metabolite of AMF, 20 minutes before 0Gy, 10Gy, or 20Gy XRT. Live and dead cells were quantified; percent cell death was calculated.

Results: WR-1065 treatment significantly preserved viability and reduced healthy female fibroblasts death after XRT compared with untreated controls. All three breast cancer cells lines exhibited radiosensitivity with substantial cell death. Cancer cells retained their radiosensitivity despite WR-1065 pretreatment, achieving the same degree of cell death as untreated controls.

Conclusions: This study demonstrated the proficiency of AMF to selectively protect healthy cells from XRT while breast cancer cells remained radiosensitive. These results support the oncologic safety of AMF in breast cancer in vitro. Further investigation is now warranted in vivo to ascertain the translational potential of using AMF as a radioprotectant to improve breast reconstruction after radiation treatment.