Preclinical trials from the standpoint of clinical trials]

The establishment of reliable preclinical test is essential for the reasonable clinical trial. As a methodology for the screening of new active anticancer agents, disease oriented strategy using human tumor cell lines has been proposed in USA. The important questions in DOS are to determine the representative cell lines of specific cancer and it is also extremely important to decide the numbers of cell lines used for the screening. CPT-11, topoisomerase I inhibitor, developed in my country has been demonstrated to be active against lung cancer cell lines compared with mice tumors such as S-180 and P-388. However, no compound is demonstrated to be clinically active so far by this methodology. The criteria for the application of clinical trial are obscure and each drug company decides empirically by themselves. We have proposed to use PEI (predictive efficacy index) for the prediction of antitumor activity of new compounds. The clinical effect of new platinum analogue well correlated with this value. We have conducted phase II trial of 5-FU + LV against NSCLC without no prior chemotherapy. No responder was observed in the trial. Augmentive effect of leucovorin on the cytotoxicity of 5-FU and FdUrd was examined in vitro against NSCLC and colon cancer cell lines. Leucovorin stimulated the cytotoxicity of both drugs only against colon cancer cell lines. We tried to predict the response rate of new platinum derivative based on the data of bioassay of patient's serum administrated with platinum compounds. The predicted response rates of 254-S were 57-67% and 16-27% against SCLC and NSCLC, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

The importance of doing trials right while doing the right trials

Effort is being expended in investigating efficiency measures (i.e., doing trials right) through achievement of accrual and endpoint goals for clinical trials. It is time to assess the impact of such trials on meeting the critical needs of cancer patients by establishing effectiveness measures (i.e., doing the right trials).     

A brief review of the current breast cancer prevention trials and proposals for future trials

The available results from breast cancer chemoprevention trials are reviewed. Four trials using tamoxifen have been performed of which three have reported efficacy results. A fifth trial using raloxifene has also been published. The largest tamoxifen trial shows approximately a 50% reduction in breast cancer incidence in the short term, but the two smaller trials have not found any incidence reduction. Greater agreement exists for side-effects - thromboembolic disease and endometrial cancers are raised about 2 to 3-fold when tamoxifen is used for 5 years. The possible reasons for the discrepancy in breast cancer reduction are explored. A review of trial parameters does not clearly explain this difference, and a meta-analysis indicates that all results are compatible with a 42% reduction in short-term incidence. Several important questions remain about the clinical implication of this result, including the effect on mortality, the appropriate risk groups for chemoprevention and the long-term effects on incidence. Continued follow-up of these trials is crucial for resolving these issues.     

Clinical trials of the subrenal capsule assay

Clinical trials of 4-day subrenal capsule assay (SRC assay) were carried out. One hundred and forty-one cases were investigated in order to evaluate the clinical utility of the assay. A total evaluability rate of 81.0% and a response rate of 36.5% were obtained in the SRC assay. The overall predictive accuracy between the tumor sensitivity of the assay and the clinical response was 82.1%. The percentage inhibition of %DNA/protein content of the implanted tumor, as a new predictor of the tumor growth inhibition, also indicated a good prediction rate for the assay. Correlation between the sensitivity test and the end results after chemotherapy in cases of inoperable gastric cancer classified as stage IV was investigated, retrospectively. Comparison of the survival curves between the patients treated with sensitive agents and those with insensitive agents exhibited a significant advantage for the former (p less than 0.01). These results suggest the utility of the SRC assay for clinical use, but histological studies exhibited certain limitations of this assay due to the existence of early host rejection of the implanted tumor. The utility of the SRC assay should be finally evaluated using more histological assessments and clinical trials.