The Role of Pharmacoethnicity in the Development of Cytotoxic and Molecular Targeted Drugs in Oncology

The effective and toxic ranges of anticancer drugs are very narrow and, in some cases, inverted. Thus determination of the most appropriate dosage and schedule of administration is crucial for optimal chemotherapy. In common arm trials conducted in Japan and by Southwest Oncology Group (SWOG) that used the same doses and schedules for the administration of carboplatin plus paclitaxel, the frequency of hematological toxicity was significantly higher in the Japanese trials than in the SWOG trial, despite demonstrating similar response rates. The frequency of epidermal growth factor receptor (EGFR) mutations in tumors was significantly higher among East Asian populations, and these populations are also reported to demonstrate a higher response rates to epidermal growth factor receptor tyrosine-kinase inhibitors (EGFR-TKIs). The prevalence of interstitial lung disease induced by treatment with EGFR-TKIs has been shown to be quite high in the Japanese population. Clinical trials of cetuximab against non-small cell lung cancer and of bevacizumab against stomach cancer have shown that these agents are only active in Caucasians. In a trial examining the use of sorafenib after transarterial chemoembolization in Korean and Japanese patients with advanced hepatocellular carcinoma, the compliance and dose intensity of the drug were quite low compared with other trials. Although not only identified pharmacogenomics differences but also differences in social environment, and regional medical care, including pharmacoeconomics strongly influence ethnic differences in treatment response, further identification and understanding of the pharmacogenomics underlying ethnic differences will be essential to timely and reliable global development of new anticancer drugs.

Present Status and Problems on Molecular Targeted Therapy of Cancer / Journal of the Korean Cancer Association, 대한암학회지

Numerous clinical trials of molecular targeted drugs for cancer have been conducted, with remarkable results for certain drugs and accumulation of "negative data" causing a hitch in the development plan for some other compounds. Five recent issues and problems of molecular targeted therapies were discussed critically. Drug discovery and effects against driver mutations (activating mutations) and problems: possibility for circumventing inherent and acquired resistance with the aim of achieving radical cure. Synthetic lethality: reasonable patient selection in individualized treatment strategy. Response rate and progression-free survival improvement with or without overall survival benefit and enhancement of toxicity in bevacizumab therapy: best endpoints for the evaluation of effect of antiangiogenic therapy. Negative data on small-molecule targeted therapy, primarily vascular endothelial growth factor tyrosine kinase inhibitors: loose GO or NO-GO decision criteria for further development of new compounds in early clinical trials. Effect of immunotherapy: difficulty to verify by proof of principle study. We are faced to many questions for the development of efficient personalized therapy. Accumulation of scientific global preclinical and clinical evidences is essential to use these new therapeutic modalities for the improvement of oncologic health care.

Molecularly Targeted Therapy for Lung Cancer : Recent Topics

Many clinical trials of molecular target drugs have been done against advanced lung cancer, however, majority did not meet the primary endpoint. Positive studies of EGFR-TKI such as BR21 and Interest used unselected populations of non-small cell lung cancer. It was quite difficult to explain why they were positive. In the present review, the difficulties of clinical trial design in molecular target drugs were discussed based on the differences of the magnitude of antitumor activity and the target tumor cell population between cytotoxic drugs and molecular target therapy

Treatment of Small Cell Lung Cancer / Journal of the Korean Cancer Association, 대한암학회지

Among patients with lung cancer, approximately 15% have small cell lung cancer (SCLC), SCLC is usually staged as either limited and extensive. Extensive-stage SCLC is treated primarily with chemotherapy. A recent Japanese randomized trial compared cisplatin and irinotecan (IP) with cisplatin and etoposide (EP). Patients in the IP arm did significantly better than patients in the EP arm. In the IP arm, the response rate was 84%, and the median overall survival period was 12.8 months. Limited- stage SCLC is usually treated with concurrent chemotherapy and accelerated radiation therapy, and approximately 20% of patients are cured. Future research should focus on optimizing chemotherapy regimens and radiation therapy schedules. The role of molecular targeted drugs in the treatment of SCLC must also be evaluated.

Antitumor Activity of Oxaliplatin, 5-FU and Paclitaxel Given Alone or in Combination with ZD1839 in Human Gastric Carcinoma Cells in vitro / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Oxaliplatin (LOHP), 5-FU, and paclitaxel (PTX) are considered highly active against advanced gastric carcinomas, and the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, ZD1839 is considered as a good candidate for the treatment of gastric cancers when given alone or in combination with cytotoxic agents. The present study evaluated the antitumor effects of these agents in SNU-1 human gastric cancer cells either alone or when given as a doublet (i.e., as a cytotoxic-cytostatic combination). MATERIALS AND METHODS: We selected SNU-1 cells that showed DNA mismatch repair (MMR) deficiency and EGFR overexpression. Growth inhibition was measured by MTT and by direct cell counting and cell cycle distribution by flow cytometry. The combination index (CI) was used to describe synergistic interaction. RESULTS: The four drugs showed IC50s ranging from 1.81 nM to 13.2microM. MTT assay appeared to underestimate the cytotoxicity of PTX, which was attributed to a significant resistant fraction (32%). LOHP and PTX induced G2/M arrest, 5-FU increased in S phase, and ZD1839 in-creased in G1 in a concentration dependent manner. PTX ZD1839 showed the greatest synergism and LOHP ZD1839 showed a similar result. The cell cycle effect of PTX was potentiated by the coadministration of ZD1839. A previously developed cytostatic TPi model was used to assess the contribution of cell cycle arrest to overall growth inhibition, and 64% and 80% of the overall growth inhibition was attributed to cell cycle arrest for LOHP and PTX, when exposed to 7.55microM and 10 nM for 72 hr, respectively. CONCLUSION: This study demonstrates the antitumor activity and significant cell cycle arrest effect of ZD1839 against human gastric carcinoma cells and its synergistic interaction with LOHP and PTX. These results provide a preclinical rationale for the clinical development of ZD1839 and its use in combination with LOHP or PTX against human gastric cancers that express EGFR.