Clinical Trial for Safety and Effectiveness Evaluation of Tarlatamab (AMG757) With Etoposide, Carboplatin and Atezolizumab in Transformed Small Cell Lung Cancer Patients From Adenocarcinoma After EGFR TKI Treatment

The primary treatment option for non-small cell lung cancer (NSCLC) adenocarcinoma (ADC) with activating epidermal growth factor receptor (EGFR) mutation is EGFR tyrosine kinase inhibitor (TKI). After a certain period of treatment with EGFR TKI, acquired resistance emerges most frequently with a secondary mutation, p.T790M (36-50%), followed by MET amplification (10-19%). Interestingly, up to 3-5% of patients experience histological transformation into small cell lung cancer (SCLC). As an underlying mechanism, ADC with a predisposed clonally inactivated Rb and p53 mutation and APOBEC mutation signature is known to be associated with SCLC transformation. The transformed SCLC harbors similar morphological and immunohistochemical (IHC) characteristics as those observed in de novo SCLC, including high expression of chromogranin and synaptophysin. However, little is known about the clinical outcomes of transformed SCLC, with limited studies arguing that their outcomes are similar to those of de novo SCLC, where the median overall survival is approximately 9 to 10 months after the transformation. As the first line treatment of SCLC, atezolizumab or durvalumab with four cycles of conventional chemotherapy followed by maintenance therapy demonstrated prolonged overall survival (OS) and placed as the standard treatment option. However, median progression-free survival (PFS) of both study was only 5.2 months and 5.1 months, despite the objective response rate showing 60.2% and 79%. This finding suggest further development of maintenance treatment strategy to prolonged longer duration of response to the treatment. In addition to the conventional treatment, Tarlatamab (AMG757), bispecific t-cell engager (BiTE), designed to engage DLL3 on SCLC and CD3 on T-cell has been tested in SCLC. DLL3 is expressed in more than 80% of patients with SCLC, regardless of disease stage and researched for the potential target protein for the antibody based treatment in SCLC. By targeting DLL3