No abstract

RET rearrangement has been proven as an oncogenic driver in patients with lung cancer. However, the prevalence, clinical characteristics, molecular features and therapeutic options in RET-rearranged patients remain unclear, especially in Chinese lung cancers. We retrospectively collected 6125 Chinese lung cancer patients who have been profiled using next-generation sequencing (NGS). The clinical demographics and molecular features of RET rearrangement-positive patients were analyzed. RET rearrangements were identified in 84 patients with proportion of 1.4% in our cohort. The median age at diagnosis was 58 years and it mainly occurred in females with adenocarcinoma histology. KIF5B-RET was the most frequently fusion type and accounted for 53.8% (57/106) of all RET fusions identified, with K15-R12 as the most frequent variant (71.9%). Among 47 RET-positive patients profiled with larger panels, 72.3% (34/47) harbored concurrent alterations. TP53 ranked as the most common concurrent alteration and concomitant EGFR oncogenic alterations were identified in 7 patients. Moreover, we presented an adenocarcinoma patient harboring concurrent RET fusion and EGFR L858R responded to combinatorial treatment of cabozantinib and osimertinib, with a progression-free survival of 5 months. Our study improved knowledge of clinical characteristics and molecular features of RET-rearranged Chinese lung cancers. It might be helpful for guiding clinicians for more effective personalized diagnostic and therapeutic approaches.

Background: Leptomeningeal metastases (LM), associated with poor prognosis, are frequent complications of advanced non-small cell lung cancer (NSCLC) patients, especially in patients with epidermal growth factor receptor (EGFR) mutations. Due to limited access to leptomeningeal lesions, the mutational landscape of LM has not been comprehensively investigated in large cohorts and the underlining biology of LM remains elusive. Some studies have explored the potential of cerebrospinal fluid (CSF) in reflecting the molecular profile of LM but with limited number of patients enrolled. Methods: In this study, we performed capture-based targeted sequencing using a panel consisting of 168 lung cancer-related genes on matched CSF and plasma samples from 72 advanced NSCLC patients with confirmed LM to interrogate the potential of CSF as a source of liquid biopsy. Results: We revealed a rate of detection of 81.5% and 62.5% for CSF and plasma, respectively (p = 0.008). The maximum allelic fraction (MaxAF) was also significantly higher in CSF (43.6% vs. 4.6%) (p < 0.001). CSF, harboring a unique genomic profile by having a significant number of CSF-specific mutations, primarily copy number variations, is superior to plasma in reflecting the mutational profile of LM. Further pathway enrichment analysis revealed that most of CSF-specific mutations participated in pathways relevant to the tumorigenesis and the development of metastases. Moreover, our data also revealed that TP53 loss of heterozygosity (LOH) predominantly existed in CSF (p < 0.001). Conclusions: Collectively, we demonstrated that CSF provides a more comprehensive profile of LM than plasma in a large cohort, thus can be used as an alternative source of liquid biopsy for LM patients.

Defective neurogenesis in the postnatal brain can lead to many neurological and psychiatric disorders, yet the mechanism behind postnatal neurogenesis remains to be investigated. Huntingtin-associated protein 1 (HAP1) participates in intracellular trafficking in neurons, and its absence leads to postnatal death in mice. Here, we used tamoxifen-induced (TM-induced) Cre recombination to deplete HAP1 in mice at different ages. We found that HAP1 reduction selectively affects survival and growth of postnatal mice, but not adults. Neurogenesis, but not gliogenesis, was affected in HAP1-null neurospheres and mouse brain. In the absence of HAP1, postnatal hypothalamic neurons exhibited reduced receptor tropomyosin-related kinase B (TRKB) levels and decreased survival. HAP1 stabilized the association of TRKB with the intracellular sorting protein sortilin, prevented TRKB degradation, and promoted its anterograde transport. Our findings indicate that intracellular sorting of neurotrophin receptors is critical for postnatal neurogenesis and could provide a therapeutic target for defective postnatal neurogenesis.

PurposeERBB2 exon 20 insertions (20ins) have been identified as oncogenic drivers in lung cancers. Lung cancer patients with 20ins benefit from afatinib. However, response heterogeneity was observed in patients harboring different 20ins subtypes. In this study, we interrogated clinical characteristics in ERBB2-mutated Chinese lung cancer and investigated the clinical outcomes of specific ERBB2 20ins in response to afatinib.Experimental designIn this study, we retrospectively collected genomic profiling data of 7,520 lung cancer patients sequenced using next-generation sequencing in a Clinical Laboratory Improvement Amendments-certified laboratory. We analyzed the clinical and molecular features of patients harboring ERBB2 20ins and evaluated clinical outcomes of 19 patients with clinical records after afatinib treatment.ResultsERBB2 20ins were identified in 2.27% (171/7,520) of this lung cancer cohort. It occurred with a high proportion in females with adenocarcinoma histology. ERBB2 20ins was mutually exclusive with other well-established lung cancer oncogenic driver mutations. The most frequently appearing subtype was Y772_A775dup (69.6%) and several novel insertion subtypes were also identified. The correlations of specific 20ins subtypes and survival were investigated. The presence of a glycine at position 778 in ERBB2 was suggested to be a common feature of drug sensitivity mutations. Patients harboring G778_P780dup (G778) subtype achieved longer median progression-free survival and median overall survival than other 20ins (non-G778) subtypes (median progression-free survival, 10 vs 3.3 months, P=0.32; median overall survival, 19.7 vs 7 months, P=0.16). Moreover, we presented the first clinical case of a lung squamous cell carcinoma patient harboring ERBB2 20ins who achieved partial response to afatinib.ConclusionThis study interrogated the characteristics of ERBB2 20ins in a large cohort from single ethnicity and demonstrated the response heterogeneity to afatinib among different ERBB2 20ins subtypes. Further studies in a larger cohort are needed to investigate the underlying molecular mechanisms and clinical response of different ERBB2 20ins subtypes.