Predictive factors for a long-term response duration in non-squamous cell lung cancer patients treated with pemetrexed.

BACKGROUND

Pemetrexed is widely used for the treatment of advanced non-squamous non-small-cell lung cancer (NSCLC). However, factors that can predict the benefits of pemetrexed therapy have not yet been defined.

METHODS

We compared the clinical and molecule pathological characteristics of good and poor responders among a cohort of 1,848 non-squamous NSCLC patients who had received at least two cycles of pemetrexed therapy between November 2006 and February 2015. Among these cases, 92 good responders who were the top 5 % in terms of progression-free survival (PFS) and 222 poor responders who had progressive disease after only 2 cycles of therapy were selected for the analysis.

RESULTS

The median PFS of the good responders was 29.9 months (range; 20.9-90.0) and the median number of cycle was 37 (range; 18-129). Although 53.5 % of patients showed stable disease (SD), this response was sustained (median PFS in SD, 29.6 months). A never-smoking status was related to better survival outcome, whereas EGFR mutation, two or more metastatic sites, and intra-abdominal metastasis were each associated with a poor PFS. ALK translocation showed a tendency for a positive impact on response to pemetrexed, whereas metastatic lesion to liver, adrenal gland or bone showed a tendency for a negative impact despite not reaching our threshold for statistical significance.

CONCLUSIONS

Predictive factors, such as smoking status, the status of genetic alteration and tumor burden, should be considered when administering pemetrexed therapy for non-squamous NSCLC.