Short versus continuous gemcitabine treatment of non-small cell lung cancer in an in vitro cell culture bioreactor system.

Five-year survival for non-small cell lung cancer is 15%. Gemcitabine is a nucleoside analogue that inhibits ribonucleotide reductase and interferes with DNA replication. In this study, we sought to compare short versus continuous infusion gemcitabine in an in vitro bioreactor system using pharmacokinetic-guided dosing. Gemcitabine was infused over either 0.5 or 2.5h to produce concentration-time profiles that mimic those measured in biological samples (i.e., patient plasma). The effects of gemcitabine on the growth and survival of H2009 cells were examined using trypan blue staining, cell cycle analysis, TUNEL assay, and clonogenic assay. Data were analyzed with two ways analysis of variance. Maximum gemcitabine (Cmax) concentrations during the short infusion were 51.2+/-10.4 microM and for the continuous, 14.8+/-2.93 microM. Steady-state concentrations during the continuous infusions were 14.9+/-2.90 microM. Gemcitabine treatment resulted in a decrease for G1 fraction relative to controls. G2/M, subG1 and TUNEL were higher following gemcitabine relative to controls. Survival was approximately 20-fold higher following the short infusion compared with the continuous infusion (p = 0.0085). In conclusion, gemcitabine infused by this novel method induced apoptosis after both the short and continuous infusions, and long-term survival was significantly diminished following continuous compared with the short infusion.

Exposure-response relationships for oxaliplatin-treated colon cancer cells.

Data are lacking for an optimal infusion length for oxaliplatin administered intraperitoneally. Our objectives were to establish the roles of hyperthermia and an effective length of oxaliplatin treatment in maximizing antitumor activity. SW620 cells were treated for 0.5 vs. 2 h and at 37 vs. 42 degrees C. Cytotoxicity, cell cycle analysis, subG1 and survival were assessed with the MTT assay, flow cytometry and the clonogenic assay. The IC50 for cells treated at 37 degrees C was 2.90+/-0.83 microg/ml and at 42 degrees C, 1.99+/-0.66 microg/ml (P=0.14). The Emax for 37 degrees C was 93.9+/-2.57% and for 42 degrees C, 97.8+/-1.59% (P=0.05). The subG1 fraction did not differ between cells treated at 37 and 42 degrees C (P=0.12). The IC50 for the cells treated for 0.5 h was 10.6+/-0.60 microg/ml and for 2 h, 2.80+/-1.70 microg/ml (P=0.02). The Emax for 0.5 h was 87.9+/-5.13% and for 2 h, 96.6+/-3.35% (P=0.09). SubG1 for 0.5 h was 8.24+/-1.33% and for 2 h, 15.8+/-2.45% (P=0.02). Clonogenic assays demonstrated diminished survival when treated with low concentrations (10 microg/ml) of oxaliplatin combined with heat treatment (P=0.017) for 2 h, but not 0.5 h. Similar clonogenic assay experiments were performed with the oxaliplatin-resistant WiDr cell line, and differences in survival following oxaliplatin and heat treatment were again observed for 2 h, but not for 0.5 h (P=0.002). Drug treatment for 2 h of both SW620 and WiDr cell lines is superior to treatment for 0.5 h. Cell kill effects are reliant on treatment length; hence, the choice of time exposure must be made with a view to maintaining a balance between the cell kill effects and the clinical feasibility of treating the patient.