Phase I/II Trial of Docetaxel and Carboplatin as a First-Line Therapy in Patients with Stage IV Non-Small-Cell Lung Cancer

Different treatment efficacies and side effects of cytotoxic chemotherapy

Differences in efficacy and toxicity between Asian and Caucasian patients with lung cancer treated with systemic chemotherapy is increasingly recognised. This is a major concern in the clinical setting as it influences outcomes and affect international harmonization of drug development. Interindividual variability of pharmacokinetics, where different genetic polymorphisms affect drug metabolism, transport, and receptor binding may account for the ethnic differences. Treatment efficacy and outcomes may also be explained by differences in diet and lifestyle, access to healthcare, cultural barriers and environmental exposure. Efforts made to design prospective studies investigating ethnic specific determinants to systemic therapy and individualise lung cancer treatment based on genetic makeup of patient are important.

Inhibition of proliferation and induction of G1-phase cell-cycle arrest by dFMGEN, a novel genistein derivative, in lung carcinoma A549 cells

Genistein (GEN) is a molecule of great interest as a potent chemopreventive agent against atherosclerosis and cancer. However, the bioavailability of GEN is very low in vivo. Our previous study showed that a GEN derivative, 7-difluoromethyl-5,4'-dimethoxygenistein (dFMGEN) has a better bioavailability than GEN in vivo. In this study, we further evaluated the efficacy of dFMGEN as a candidate for cancer therapy. We demonstrated that dFMGEN treatment decreased the viability of A549 cells in a concentration- and time-dependent manner and induced cell-cycle arrest at the G(1) phase. G(1) phase arrest was correlated with a significant reduction of Cdk4 and cyclin D1 protein level. Further studies showed that cyclin-dependent kinase (Cdk)4 and cyclin D1 protein-level decrease was caused by Cdk inhibitors p15, p21, and p27 level increase, and decreased protein level directly suppressed Rb protein phosphorylation and E2F-1 expression, then cell-cycle progression was arrested. Finally, we also found that dFMGEN has a dosage effect in suppressing tumor growth in vivo, and that dFMGEN was well tolerated by animals. In summary, our results suggest that dFMGEN has therapeutic potential for the treatment of human lung cancer.

Melding a New 3-Dimensional Agarose Colony Assay with the E(max) Model to Determine the Effects of Drug Combinations on Cancer Cells

The goal of our study was two-fold: (i) develop a robust 3D colony assay methodology to interrogate drug combinations using GelCount and (ii) to develop 2-drug combinations that might be useful in the clinic for the treatment of high-grade gliomas. We used three glioma cell lines (U251MG, SNB19, and LNZ308) and two adenocarcinoma cell lines (MiaPaCa and SW480) grown as colonies in a two-tiered agarose cultures. We evaluated two-drug combinations of difluoromethylornithine (DFMO), carboplatin, vorinostat (SAHA), and docetaxel. To analyze for antitumor efficacy we used GelCount to measure the area under the curve for tumor colony volumes (microm(2) x OD) in each plate. The non-linear dose-response E(max) model and the interaction index based on the Loewe additivity are applied to calculate two-drug synergy, additive, and antagonistic interactions. For glioblastoma cell lines, (i) carboplatin followed by DFMO was synergistic or additive in 2/3 cell lines, (ii) carboplatin before SAHA was synergistic in 1 cell line, (iii) carboplatin before docetaxel was synergistic in 2/3 cell lines and partially additive in the third, (iv) SAHA before docetaxel was synergistic in 1/3 cell lines, (v) docetaxel before DFMO was additive or partially active in 3/3 cell lines, and (vi) DFMO plus SAHA was inactive regardless of order. In the MiaPaCA cell line, synergy occurred when DFMO followed carboplatin and, at short exposure times, when SAHA was combined with carboplatin (regardless of order). In the SW480 cell line synergy occurred only in short exposures for carboplatin followed by docetaxel; additive and mixed partial effects were also seen with DFMO plus carboplatin or docetaxel (regardless of order), carboplatin before DFMO, carboplatin before SAHA, and docetaxel before carboplatin. In conclusion, by applying the Gelcount automated counting and sizing of colonies and the use of E(max) and Loewe models to define drug interactions, we can reliably define drug combination efficacy as a function of log dose and duration of drug exposure.