BACKGROUND We sought to identify the relationship between response to previous systemic treatment and the efficacy of subsequent pemetrexed therapy in advanced non-small cell lung cancer (NSCLC).

PATIENTS AND METHODS Two hundred and fifty clinical stage IIIB or IV NSCLC patients treated with pemetrexed as a second-line or further-line treatment between April 2007 and June 2008 were analyzed retrospectively. Prior therapies were divided into four types (gemcitabine-based [G], paclitaxel-based [P], docetaxel-based [D], and EGFR tyrosine kinase inhibitor [I]). Objective response rates (ORR) and progression-free survivals (PFS) for pemetrexed therapy were analyzed according to the response outcome with each previous treatment.

RESULTS The ORR of pemetrexed therapy was higher for patients who had achieved partial response with previous [G] therapy than others (15.0% vs. 4.3%, p=0.02). In addition, median PFS for pemetrexed therapy was greater for responders to [G] than for nonresponders (3.0 months vs. 1.7 months, p=0.004). The longer PFS for responders to [G] was also shown in the analysis among patients with squamous cell carcinoma (3.2 months vs. 1.7 months, p=0.056). By univariate analyses, the variables of the responder to [G] therapy, female, adenocarcinoma, never smoking status, and ECOG performance status of 0-1 were good predictive factors for pemetrexed therapy in terms of PFS. Multivariate analysis revealed that only response to [G] had statistical significance (hazard ratio=0.62, p=0.006).

CONCLUSION Response outcome to prior [G] therapy might predict the efficacy of subsequent pemetrexed therapy in advanced NSCLC.