Pemetrexed is an antifolate cytostatic agent targeting several folate-dependent enzymatic pathways, widely used in the treatment of locally advanced or metastatic stage non-small cell lung cancer. Aside from the non-squamous histology, there is still no available molecular biomarker predicting treatment efficacy of pemetrexed-based chemotherapy. The aim of our retrospective study was to evaluate the association of thyroid transcription factor 1 expression with outcome of a large cohort of patients with non-squamous non-small cell lung cancer treated with pemetrexed. We retrospectively analysed clinical data of 463 patients with advanced-stage non-small cell lung cancer (IIIB or IV) treated with pemetrexed-based chemotherapy. Thyroid transcription factor 1 expression was assessed using indirect immunohistochemical detection in formalin-fixed paraffin-embedded tumour tissue at the time of diagnosis. Thyroid transcription factor 1 expression was detected in the tumour tissue from 76.0% of patients, and tumours from 24.0% of patients were thyroid transcription factor 1 negative. The median progression-free survival and overall survival for patients with thyroid transcription factor 1 positive tumours were 4.8 and 11.8 months compared to 2.8 and 8.3 months for those with thyroid transcription factor 1 negative tumours (p = 0.001 and p < 0.001). The multivariable Cox proportional hazards model revealed that thyroid transcription factor 1 expression was significantly associated with progression-free survival (hazard ratio = 1.57, p < 0.001) and also with overall survival (hazard ratio = 1.73, p < 0.001). In conclusion, the results of the conducted retrospective study suggest that the thyroid transcription factor 1 expression was independently associated with progression-free survival and overall survival in patients with advanced-stage non-squamous non-small cell lung cancer treated with pemetrexed-based chemotherapy.
Keywords: Thyroid transcription factor 1; biomarker; expression; non-small cell lung cancer; prognosis; survival.