Subclonal architecture and genomic evolution of small-cell lung cancer (SCLC) under treatment has not been well studied primarily due to lack of tumor specimens, particularly longitudinal samples acquired during treatment. SCLC is characterized by early hematogenous spread, which makes circulating cell-free tumor DNA (ctDNA) sequencing a promising modality for genomic profiling. Here, we perform targeted deep sequencing of 430 cancer genes on pre-treatment tumor biopsies, as well as on plasma samples collected prior to and during treatment from 22 SCLC patients. Similar subclonal architecture is observed between pre-treatment ctDNA and paired tumor DNA. Mean variant allele frequency of clonal mutations from pre-treatment ctDNA is associated with progression-free survival and overall survival. Pre- and post-treatment ctDNA mutational analysis demonstrate that mutations of DNA repair andNOTCHsignaling pathways are enriched in post-treatment samples. These data suggest that ctDNA sequencing is promising to delineate genomic landscape, subclonal architecture, and genomic evolution of SCLC.

Mechanisms of resistance to irreversible epidermal growth factor receptor tyrosine kinase inhibitors and therapeutic strategies in non-small cell lung cancer Mechanisms of resistance to irreversible epidermal growth factor receptor tyrosine kinase inhibitors and therapeutic strategies in non-small cell lung cancer

Kinase domain duplications of the epidermal growth factor receptor (EGFR‐KDD) have been identified and implicated to be oncogenic in nonsmall cell lung cancers (NSCLCs). However, its prevalence and clinical contributions in lung cancer are largely unknown. Here, we conducted a multicenter record review of 10,759 NSCLC patients who underwent genetic testing using next‐generation sequencing (NGS) targeting EGFR exons and the introns involved in EGFR‐KDD rearrangements. EGFR‐KDDs were identified in a total of 13 patients, which is approximately 0.12% of the total population reviewed, and also consisted of 0.24% (13/5394) of EGFR mutation‐positive patients. A total of 85% of patients (11/13) were identified with the canonical EGFR‐KDD duplication of exons 18–25, while the remaining two cases harbored duplications of EGFR exons 14–26 and exons 17–25, which have not been previously described. Importantly, none of the 13 patients had other coexisting driver mutations, highlighting the potential oncogenic role of this type of alteration. Three out of five patients who had exon 18–25 duplications showed partial antitumor responses to targeted therapies, while the other two patients demonstrated no clinical improvement. Furthermore, our data suggested that the EGFR T790 M mutation and EGFR amplification may represent the major resistance mechanisms against targeted therapies in tumors bearing EGFR‐KDD. In summary, our findings provide valuable insight into the prevalence of EGFR‐KDDs in NSCLCs and their clinical outcomes to targeted therapies.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) secreted by tumors was reported as a deleterious factor that led to the reduction of lymphocyte infiltration and the poorer efficacy of ICIs in vivo. This study aimed to explore whether PCSK9 expression in tumor tissue could predict the response of advanced non-small cell lung cancer (NSCLC) to anti-PD-1 immunotherapy and the synergistic antitumor effect of the combination of the PCSK9 inhibitor with the anti-CD137 agonist. One hundred fifteen advanced NSCLC patients who received anti-PD-1 immunotherapy were retrospectively studied with PCSK9 expression in baseline NSCLC tissues detected by immunohistochemistry (IHC). The mPFS of the PCSK9^lo group was significantly longer than that of the PCSK9^hi group [8.1 vs. 3.6 months, hazard ratio (HR): 3.450; 95% confidence interval (CI), 2.166-5.496]. A higher objective response rate (ORR) and a higher disease control rate (DCR) were observed in the PCSK9^lo group than in the PCSK9^hi group (54.4% vs. 34.5%, 94.7% vs. 65.5%). Reduction and marginal distribution of CD8⁺ T cells were observed in PCSK9^hi NSCLC tissues. Tumor growth was retarded by the PCSK9 inhibitor and the anti-CD137 agonist alone in the Lewis lung carcinoma (LLC) mice model and further retarded by the PCSK9 inhibitor in combination with the CD137 agonist with long-term survival of the host mice with noticeable increases of CD8⁺ and GzmB⁺ CD8⁺ T cells and reduction of Tregs. Together, these results suggested that high PCSK9 expression in baseline tumor tissue was a deleterious factor for the efficacy of anti-PD-1 immunotherapy in advanced NSCLC patients. The PCSK9 inhibitor in combination with the anti-CD137 agonist could not only enhance the recruitment of CD8⁺ and GzmB⁺ CD8⁺ T cells but also deplete Tregs, which may be a novel therapeutic strategy for future research and clinical practice.

Purpose: Our primary purpose is to explore safety and efficacy of high-dose icotinib in comparison with routine-dose icotinib in patients with non–small cell lung cancer (NSCLC) harboring 21-L858R mutation. Patients and Methods: Patients with treatment-naïve, EGFR-mutant (21-L858R or exon 19 deletion at 2:1) NSCLC were enrolled. Patients with 21-L858R mutation were randomized to receive routine-dose icotinib (125 mg, thrice daily; L858R-RD) or high-dose icotinib (250 mg, thrice daily; L858R-HD), whereas patients with exon 19 deletion received only routine-dose icotinib (19-Del-RD) until progression, death, or unacceptable toxicity. The primary endpoint was median progression-free survival (mPFS), assessed by an independent review committee. Results: From May 2015 to November 2017, 253 patients (86 in L858R-RD; 90 in L858R-HD; and 77 in 19-Del-RD) were enrolled. The mPFS in L858R-HD group was similar to that in 19-Del-RD group (12.9 months and 12.5 months, respectively) and was significantly longer than that in L858R-RD group [12.9 months vs. 9.2 months, hazard ratio (HR): 0.75; 95% confidence interval (CI), 0.53–1.05]. A longer but statistically nonsignificant mPFS was observed between 19-Del-RD and L858R-RD groups (12.5 months vs. 9.2 months, HR: 0.80; 95% CI, 0.57–1.13). A higher objective response rate (ORR) was observed in L858R-HD group compared with L858R-RD group (73% vs. 48%), also between 19-Del-RD and L858R-RD groups (75% vs. 48%). Similar incidences of grade 3/4 toxicities were observed among the three treatment groups. Conclusions: High-dose icotinib improved mPFS and ORR in patients with NSCLC harboring 21-L858R mutation with acceptable tolerability, which could be a new therapeutic option for this patient population.

Background: ALK rearrangement is a very rare subset of squamous cell carcinoma (SCC) and one of the clinical features in patients is lack of data. Here, we report eight patients diagnosed with SCC of the lung harboring ALK rearrangement.Methods: We collected primary NSCLC samples at the Beijing Chest Hospital between January 2012 and December 2018 for Ventana (D5F3) immunohistochemical detection. Among the 148 patients was diagnosed ALK‐rearranged non small cell lung cancer (NSCLC), only eight cases was SCC. We collected patients information from electronic patent records (EPRs).Results: The eight cases of SCC were diagnosed by immunohistochemistry (IHC). Two were given crizotinib as second‐line therapy. One patient had stable disease (SD) and progression‐free survival (PFS) of six months. The other patient had progressive disease (PD) but PFS was only one month. The side effects were tolerable. This report identified 31 cases of ALK rearrangement in SCC patients from a literature search (including the eight patients in this study). These fusion genes are often seen in a younger age group (mean age: 55.6 years) and non‐smokers (18/31, 58.1%). A total of 20 cases received an ALK inhibitor as first‐ or second‐line treatment which included 11 with a partial response (PR), four with SD, and five with PD. The DCR and ORR was 75.0% (15/20) and 55.0% (11/20), respectively. The median duration time of therapy was 6.4 ± 4.4 months.Conclusions: Patients with ALK‐rearranged SCC obtained clinical benefit from ALK‐inhibitor therapy, especially those who were non‐smokers and whose tumors had been identified by IHC+/FISH+.