Relationship Between TTF-1 Expression and PFS of Pemetrexed-containing Chemotherapy in Non-squamous-NSCLC Patients With and Without Driver Genes

Background/Aim: We performed a retrospective study too clarify whether the presence or absence of driver genes affects the relationship between thyroid transcription factor-1 (TTF-1) expression and response to pemetrexed (PEM) in non-squamous non-small cell lung cancer (non-sq-NSCLC) patients. Patients and Methods: We reviewed the medical charts of patients treated with PEM-containing chemotherapy during the period from February 2016 to February 2022 at Mito Medical Center-University of Tsukuba, Ryugasaki Saiseikai General Hospital, and University of Tsukuba Hospital. Results: During the period of the study, 185 driver gene-negative patients negative, and 65 driver gene-positive patients were evaluated. Among the 165 driver gene-negative patients, progression free survival (PFS) of TTF-1-expressing patients treated with PEM-containing chemotherapy was significantly longer compared to that of TTF-1-negative patients. In the analysis of 65 driver gene-positive patients, the PFS of TTF-1-positive patients treated with PEM-containing chemotherapy did not differ significantly from that of TTF-1-negative patients. There was no significant difference in PFS between driver gene-negative and driver gene-positive patients treated with PEM-containing chemotherapy. Comparison between four groups defined according to the presence of driver gene and TTF-1 expression indicated shorter PFS only in ‘driver gene-negative and TTF-1-negative’ patients. Conclusion: In driver gene-positive non-sq NSCLC patients, expression of TTF does not affect the survival outcome of PEM-containing-chemotherapy. In other words, in these patients, second-line or later-line PEM-containing chemotherapy after development of resistance for specific-tyrosine kinase inhibitor could be expected to have the same level of efficacy as first-line PEM containing chemotherapy in driver gene-negative, TTF-1-positive non-sq NSCLC patients.