Introduction: Gaining a higher response rate (RR) has usually been determined as a primary end point in phase II trials evaluating the efficacy of new molecular targeted drugs. However, a relationship between clinical response and survival benefit has not been well studied in the patients treated with molecular targeted agents.
Methods: Prospective trials of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) monotherapy in non-small cell lung cancer were extracted from MEDLINE, EMBASE, and the annual meetings in 2007 of the American Society of Clinical Oncology, European Cancer Conference, and World Conference on Lung Cancer. Correlation between clinical response and survival was examined using linear regression analysis. We also tried to compare the significance of RR as surrogate markers for survival with that of disease control rate (DCR) by calculating the area under their receiver operating characteristic (ROC) curves.
Results: We identified 24 phase II trials and 4 phase III trials with a total of 6171 patients and 30 treatment arms, including 22 arms for the gefitinib group and 8 arms for the erlotinib group. Both RR and DCR strongly correlated with median survival time (MST; p < 0.0001 and p = 0.003, respectively). In an ROC analysis, the area under the ROC curve predicting MST prolongation by RR was 0.918, which was higher than the area under the ROC curve by DCR.
Conclusions: We found a significant relationship between RR and MST in clinical trials with EGFR-TKIs. RR could be an independent surrogate marker for MST in the current response criteria in the clinical trials of EGFR-TKIs.