TTF1 and small cell lung carcinoma: However, Wang et al. [47] explored the relationship between the TTF-1 expression status and sensitivity to first-line chemotherapy and prognosis of SCLC patients; analysis of 243 patients revealed that the objective response rate (ORR), median progression-free survival (PFS), and median overall survival (OS) of first-line chemotherapy in patients with positive expression of TTF-1 was higher than that in patients with negative expression of TTF-1, suggesting that TTF-1 may serve as a biomarker for predicting efficacy and prognosis in SCLC.