In the current

study, we evaluated the potential of gemcitabine, 5-FU, and sorafenib to radiosensitize HCC to 90Y microspheres. Because the mean dose rate achieved during an administration of 90Y microspheres is 0.05 to 0.5 Gy per hour, we used a novel in vitro LDR model system that could deliver a dose rate in this range. We assessed clonogenic survival, DNA damage repair, and cell cycle distribution in HCC cells in vitro. Additionally, we report our early clinical experience of combining TARE with gemcitabine in patients with primary liver cancer and liver metastases. Human HCC cell lines (Hep3B, HepG2) Paclitaxel were maintained in F-12 or RPMI media supplemented with 10% fetal bovine serum and penicillin/streptomycin. Experiments involving 5-FU were carried out in dialyzed serum with leucovorin. Gemcitabine (Eli Lilly, Indianapolis,

IN), 5-FU/leucovorin (Sigma-Aldrich, St. Louis, MO), and sorafenib (University of Michigan Pharmacy, Ann Arbor, MI) were tested in combination with LDR. Drugs were diluted in PBS to appropriate concentrations which were selected to correspond to clinically achievable levels. LDR was delivered using a custom-built LDR device consisting of an array of cesium-137 sources. This array is shielded by interlocking 6-cm–thick pieces of Cerrobend and resides inside a cell culture incubator at 37°C. Dose homogeneity determined by film was within ± 5%. Cells were irradiated at a dose rate of 0.07, 0.10, or 0.26 Gy/h for 16 hours to a total dose of 1.1, 1.6, or 4.2 Gy. Standard dose rate radiation (SDR) was delivered using a Philips RT250 orthovoltage

unit (Kimtron Medical, Oxford, click here CT) at a dose rate of approximately 2 Gy per minute to a total dose of 2 to 4 Gy. Dosimetry was carried out using an ionization chamber connected to an electrometer system directly traceable to a National Institute of Standards and Technology calibration. After radiation was complete, cells were suspended and counted then plated at set densities based on the dose of radiation received. Cells were incubated until visible colonies were present. Colonies were fixed with methanol/acetic acid (7:1) and stained with crystal violet. The number of colonies containing ≥ 50 cells was determined. Adenosine triphosphate Enhancement ratios were calculated by dividing the surviving fraction without drug by the surviving fraction with drug for each dose of radiation with an adjustment for plating efficiency. Experiments were performed in at least triplicate, and the mean and standard error were calculated. Cell cycle distribution was determined using propidium iodide (PI, 0.018 mg/ml) staining and flow cytometry. Cells were fixed in 70% ethanol at the appropriate time points then incubated with PI before quantification using flow cytometry. Trout erythrocytes were used as the internal standard. Data were analyzed using FlowJo (Tree Star, Ashland, OR).