Precision medicine approaches to lung adenocarcinoma with concomitant MET and HER2 amplification

IRS2 Amplification as a Predictive Biomarker in Response to Ceritinib in Small Cell Lung Cancer

Small cell lung cancer (SCLC) is a fast-growing and malignant cancer that responds well to chemotherapy; however, the survival rate is less than 15% after 2 years of diagnosis. Therefore, novel therapeutic agents for treating SCLC patients need to be evaluated. This study aims to identify the therapeutic targets based on the comprehensive genomic profiling of SCLC patients. Among the molecular-profiled SCLC samples obtained using targeted sequencing, the array-based comparative genomic hybridization (array CGH) identified focal insulin receptor substrate 2 (IRS2) amplification in the SCLC patients. IRS2 amplification was confirmed in 5% of 73 SCLC patients. To determine whether IRS2 amplification could act as a therapeutic target, we generated a patient-derived xenograft (PDX) model and subsequently screened 43 targeted agents using the PDX-derived cells (PDCs). Ceritinib significantly inhibited the cell growth and impaired the tumor sphere formation in IRS2-expressing PDCs. Its effects were confirmed in various in vitro assays and were further validated in the mouse xenograft models. In this study, we present that IRS2 amplification and/or expression serve as preclinical implications for a novel therapeutic target in SCLC progression. Furthermore, we suggest that insulin-like growth factor-1 (IGF-1) receptor inhibitor-based therapy could be used for treating SCLC with IRS2 amplification.

The fidelity of cancer cells in PDX models: Characteristics, mechanism and clinical significance

Patient-derived xenograft (PDX) models are widely used as preclinical cancer models and are considered better than cell culture models in recapitulating the histological features, molecular characteristics and intratumoral heterogeneity (ITH) of human tumors. While the PDX model is commonly accepted for use in drug discovery and other translational studies, a growing body of evidence has suggested its limitations. Recently, the fidelity of cancer cells within a PDX has been questioned, which may impede the future application of these models. In this review, we will focus the variable phenotypes of xenograft tumors and the genomic instability and molecular inconsistency of PDX tumors after serial transplantation. Next, we will discuss the underlying mechanism of ITH and its clinical relevance. Stochastic selection bias in the sampling process and/or deterministic clonal dynamics due to murine selective pressure may have detrimental effects on the results of personalized medicine and drug screening studies. In addition, we aim to identify a possible solution for the issue of fidelity in current PDX models and to discuss emerging next-generation preclinical models.

Unique profiles of targetable genomic alterations and prognosis in young Chinese patients with lung adenocarcinoma

OBJECTIVE

Lung adenocarcinoma in young patients is a rare entity, and the targetable genomic alterations (GAs) are poorly studied. In other cancers, it has been demonstrated that young age defines unique disease biology. Here, the association of young age with GAs and prognosis is studied in a large cohort of Chinese patients.

METHODS

We retrospectively screened 1000 consecutive patients, and identified 181 patients aged 40 years or younger. GAs were identified by next-generation sequencing (NGS) assay. The clinical and genetic characteristics were analyzed.

RESULTS

Among younger group, 167(92.3%) patients were diagnosed with advanced-stage adenocarcinoma, 98(54.1%) were female, 27(14.9%) were smokers, and the median age was 35 years. Targetable GAs which were significantly more common in the younger population (P <  0.001), were associated with young age (P < 0.05). The frequency of ALK translocations, EGFR and KRAS mutations was 37.6%, 34.3% and 6.1%, respectively. Younger patients had a higher prevalence of rare GAs including HER2, ROS1 and MET (P < 0.05). Prognosis for younger patients was similar (median OS of patients with GAs, 23.91 vs 23.67 months, P >  0.05) or better than that for older population (median OS of patients without GAs, 44.28 vs 41.88 months, P <  0.05) according to GAs. Therapy modality was an independent prognostic factor (P <  0.05), and 83% of death rate decreased if given preferred therapy.

CONCLUSION

Younger patients with lung adenocarcinoma had unique prevalence of targetable GAs. Comprehensive genotyping including NGS is recommended for personalized therapy and prognosis evaluation in this population.