Transformation of NSCLC to SCLC after 1st- and 3rd-generation EGFR-TKI resistance and response to EP regimen and erlotinib: 2 CARE-compliant case reports

RATIONALE

Genotypic and histological evolution of non-small-cell lung cancer (NSCLC) into small-cell lung cancer (SCLC) has been described as a mechanism of acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) therapy. However, the number of clinical cases is rare.

PATIENT CONCERNS

Two lung adenocarcinoma patients with EGFR mutations who recurred after radical resection transformed into SCLC under treatment with the sequential first- and third-generation EGFR-TKIs.

DIAGNOSIS

The 2 cases were both confirmed as SCLC by pathological rebiopsy after EGFR-TKIs resistance.

INTERVENTIONS

Case 1 was treated with etoposide plus cisplatin (EP) regimen and erlotinib, while case 2 was treated with erlotinib and EP followed by oral etoposide.

OUTCOMES

Case 1 treated with EP only achieved 3-month progression-free survival (PFS), which is the first case that reported T790 M/C797S cis-mutation for osimertinib resistance before the SCLC transformation. However, case 2 treated with erlotinib and EP followed by oral etoposide, PFS lasted for 8 months.

LESSONS

The cases highlighted the importance of rebiopsy that identified pathologically SCLC transformation after EGFR-TKI resistance, and suggested the treatment of erlotinib plus EP followed by etoposide, which could provide a reference for such phenotype.

An observational study of the epidermal growth factor receptor-tyrosine kinase inhibitor resistance mechanism in epidermal growth factor receptor gene mutation-positive non-small cell lung cancer

Non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutation show a high response to EGFR-tyrosine kinase inhibitor (EGFR-TKI). Clinically, EGFR-positive NSCLC acquires several resistance mechanisms during EGFR-TKI treatment, such as the emergence of a secondary mutation (T790M), MET gene amplification, and transformation to small cell lung cancer. However, the mechanism of resistance to afatinib, a second-generation EGFR-TKI, remains unclear. In this study, we prospectively investigate the mechanism of resistance to afatinib using proteomic analyses.In total, 35 EGFR-positive NSCLC patients of both sexes and ≥20 years old will be included. NSCLC patients with major obstacles in major organs, such as bone marrow, heart, lung, liver, and kidney, will be excluded. Eligible patients will be administered afatinib or gefitinib until disease progression and proteomic analysis will be performed with biopsy samples before treatment and at disease progression.The primary outcome is to detect the potential predictive anomalies in proteins that can be candidates for the resistance factor of afatinib. The secondary outcome is to detect gene and protein abnormalities affecting progression-free survival, response rate, and rate of disease control in afatinib therapy.The protocol was approved by the institutional review boards of Kyoto Prefectural University of Medicine and all the participating hospitals. Written informed consent was obtained from all patients before registration, in accordance with the Declaration of Helsinki. The results of the study will be disseminated via publications in peer-reviewed journals.Trial registration number is UMIN000031013.