Targeted therapies in small cell lung cancer

Drug-Eluting Beads Bronchial Arterial Chemoembolization in Treating Relapsed/Refractory Small Cell Lung Cancer Patients: Results from a Pilot Study

Background

We aimed to explore the efficacy and tolerance of drug-eluting beads bronchial arterial chemoembolization (DEB-BACE) treatment in relapsed/refractory small cell lung cancer (SCLC) patients.

Methods

Eleven relapsed/refractory SCLC patients were enrolled and treated with DEB-BACE. Then, treatment response and tumor marker levels were assessed at the first, second and sixth month post treatment. Quality of life was assessed by the EORTC QLQ-C30 scale. Progression-free survival (PFS) and overall survival (OS) were also evaluated.

Results

At the first, second and sixth month post treatment, the objective response rates were 63.6%, 54.5%, and 36.4%, respectively; and the disease control rates were 90.9%, 90.9% and 54.5%, respectively. In addition, the neuron-specific enolase (NSE) and progastrin-releasing peptide levels were reduced at the second and sixth month. Quality of life assessed by EORTC QLQ-C30 scale, which included subscales of general health status, functional domains, symptom domains, and single domains except for financial difficulty, was markedly improved at second month post treatment. Median values of PFS and OS were 5.1 (95% CI: 4.1–5.9) months and 9.0 (95% CI: 6.0–12.0) months, respectively. The ECOG score and preoperative NSE level were independent predictive factors for PFS, and age as well as lesion location were independent predictive factors for OS. Adverse events were all mild and manageable with chest pain and chest stuffiness the most common ones.

Conclusion

DEB-BACE could be a therapeutic option for relapsed/refractory SCLC patients regarding its favorable treatment response, quality of life, survival benefit and safety profile.

EGFR Inhibitor Gefitinib Induces Cardiotoxicity through the Modulation of Cardiac PTEN/Akt/FoxO3a Pathway and Reactive Metabolites Formation: In Vivo and in Vitro Rat Studies

Gefitinib (GEF) is a selective inhibitor of the epidermal growth factor receptor (EGFR) used to treat non-small cell lung cancer. Yet, few cases of cardiotoxicity have been reported. However, the role of the PTEN/Akt/FoxO3a pathway, which mediates GEF anticancer activity, in GEF cardiotoxicity remains unclear. For this purpose, in vitro H9c2 cells and in vivo rat cardiomyocytes were utilized as study models. Treatment of H9c2 cells and Sprague-Dawley rats with GEF significantly induced the expression of hypertrophic and apoptotic markers at mRNA and protein levels with an increased plasma level of troponin. This was accompanied by induction of autophagy and mitochondrial dysfunction in H9c2 cells. Inhibition of cardiac EGFR activity and Akt cellular content of in vitro and in vivo rat cardiomyocytes by GEF increased PTEN and FoxO3a gene expression and cellular content. Importantly, treatment of H9c2 cells with PI3K/Akt inhibitor increased PTEN and FoxO3a mRNA expression associated with potentiation of GEF cardiotoxicity. In addition, by using LC-MS/MS, we showed that GEF is metabolized in the rat heart microsomes into one cyanide- and two methoxylamine-adduct reactive metabolites, where their formation was entirely blocked by CYP1A1 inhibitor, α-naphthoflavone. The current study concludes that GEF induces cardiotoxicity through modulating the expression and function of the cardiac PTEN/AKT/FoxO3a pathway and the formation of CYP1A1-mediated reactive metabolites.

MDIG promotes cisplatin resistance of lung adenocarcinoma by regulating ABC transporter expression via activation of the WNT/β-catenin signaling pathway

Mineral dust-induced gene (MDIG) is a proto- oncogene associated with lung cancer that serves a key role in the biological processes of tumorigenesis. The aim of the present study was to determine whether MDIG is involved in cisplatin (DDP) resistance in lung adenocarcinoma, and to investigate the associated molecular mechanism. In the present study, MDIG-knockdown and MDIG-overexpressing A549 cells and DDP-resistant A549/DDP cells were initially constructed, and then the mRNA and protein expression levels of MDIG and ATP-binding cassette (ABC) transporters (ABCB1, ABCC1, ABCG2), and the expression levels of the major associated proteins in the WNT/β-catenin pathway were determined by reverse transcription-quantitative PCR and Western blotting experiments. The results revealed that the mRNA and protein expression levels of MDIG in A549/DDP cells were significantly higher compared with those in A549 cells, and that the protein expression levels of MDIG increased in a dose-dependent manner with increasing DDP concentrations. Overexpression of MDIG in A549 and A549/DDP cells led to an increase in the IC₅₀ value, whereas silencing of MDIG led to a clear reduction in the IC₅₀ value. The overexpression of MDIG in the A549 and A549/DDP cells markedly upregulated the mRNA and protein expression levels of ABCB1, ABCC1, ABCG2, WNT family member 5A, WNT family member 3A and active β-catenin, and these were markedly decreased following MDIG silencing. Taken together, these results demonstrated that the DDP resistance of lung adenocarcinoma may be associated with an upregulation of MDIG expression, and that the expression levels of MDIG are positively associated with the degree of DDP resistance. Furthermore, MDIG promoted the expression of ABC transporters in tumor cells by activating the WNT/β-catenin signaling pathway, which may, in turn, lead to DDP resistance in lung adenocarcinoma.

Application of computed tomography-based radiomics signature analysis in the prediction of the response of small cell lung cancer patients to first-line chemotherapy

The aim of the present study was to investigate the utility of a computed tomography (CT)-based radiomics signature for the early prediction of the tumor response of small cell lung cancer (SCLC) patients to chemotherapy. A dataset including 92 patients from a clinical trial was retrospectively assembled. All of the patients received the standard first-line regimen of etoposide and cisplatin. According to the Response Evaluation Criteria in Solid Tumors 1.1, the patients were divided into two groups: Response and no response groups. A total of 21 radiomics features were extracted from CT images prior to and after two cycles of chemotherapy and a radiomics signature was constructed via a binary logistic regression model. The area under the receiver operating characteristics curve (AUC) was determined to evaluate the performance of the radiomics signature to predict the response to chemotherapy. The clinicopathological factors associated with chemotherapy in patients with SCLC were also evaluated, and a predictive model was established using a binary logistic regression analysis. The 21 radiological features were used to establish a radiomics signature that was significantly associated with the efficacy of SCLC chemotherapy (P<0.05). The performance of the radiomics signature to predict the chemotherapy efficacy (AUC=0.797) was better than that of the model using clinicopathological parameters (AUC=0.670). Therefore, the present study demonstrated that radiomics features may be promising prognostic imaging biomarkers to predict the response of SCLC patients to chemotherapy and may thus be utilized to guide appropriate treatment planning.

Functional Gene Knockout of NRF2 Increases Chemosensitivity of Human Lung Cancer A549 Cells In Vitro and in a Xenograft Mouse Model

Recent studies point to the evolution of drug resistance in lung cancer as being centered, at least in part, on the upregulation of various genes involved in controlling efflux or drug inactivation. Among the most important of these genes is Nuclear Factor Erythroid 2-Related Factor (NRF2), considered the master regulator of 100–200 target genes involved in cellular responses to oxidative and/or electrophilic stress. With increased focus on the development of combinatorial approaches for cancer treatment, we utilized CRISPR/Cas9 to disable the NRF2 gene in lung cancer cells by disrupting the NRF2 nuclear export signal (NES) domain; phenotypically, the protein is largely blocked from transiting into the nucleus after translation. In tissue culture, cells with this gene knockout were found to have a reduced proliferation phenotype and are more sensitive to chemotherapeutic agents, such as cisplatin and carboplatin. These observations were confirmed in xenograft mouse models wherein the homozygous knockout cells proliferate at a slower rate than the wild-type cells, even in the absence of drug treatment. Tumor growth was arrested for a period of 16 days, with a dramatic decrease in tumor volume being observed in samples receiving the combined action of CRISPR-directed gene editing and chemotherapy.

EGFR, KRAS, BRAF, PTEN, and PIK3CA mutation in plasma of small cell lung cancer patients

Background

Small cell lung cancer (SCLC) is an aggressive and deadly neuroendocrine tumor derived from bronchial epithelial cells. Although it results in a 95% mortality rate, the development of targeted therapies for SCLCs has lagged behind. The aim of this study is to better research mutation characteristics of SCLC and identify potential biomarkers for target therapy.

Methods

We utilized high-resolution melting analysis to identify the mutations in epidermal growth factor receptor (EGFR), Kirsten rat sarcoma viral oncogene (KRAS), v-raf murine sarcoma viral oncogene homolog B1 (BRAF), phosphatase and tensin homolog (PTEN), and phosphatidylinositol-3-kinase catalytic (PIK3CA) from the blood. A cohort of 99 SCLC patients including 44 limited-stage disease patients and 55 extensive-stage disease patients were prospectively collected.

Results

EGFR 18 (G719X) mutation was found in 5 patients, EGFR 19 (del) mutation in 2, EGFR 20 (T790M) in 3, EGFR 21 (L858R) in 2, KRAS 2 (G13D) in 5, BRAF 15 (V600E) in 1, PIK3CA 9 (E542K) in 1, and no mutations in PTEN 5 (R130G), PTEN 6 (R173C), PTEN 8 (T319fs*1), and PIK3CA 20 (H1047R) were identified. Among these patients, two harbored EGFR double mutation, one patient with EGFR double mutation and KRAS 2 (G13D) mutation.

Conclusion

The mutation form of EGFR may differ from lung adenocarcinoma, and mutations of KRAS, BRAF, and PIK3CA were rare in SCLC. These results aided us in comprehensively analyzing genetic features and laid the foundation for exploring the possibility of target therapy.

Friend leukemia virus integration 1 promotes tumorigenesis of small cell lung cancer cells by activating the miR-17-92 pathway

Small cell lung cancer (SCLC) is regarded as the most devastative type of human lung malignancies. The rapid and disseminated growth pattern remains the primary cause of poor clinical prognosis in patients with SCLC. However, the molecular factors that drive rapid progression of SCLC remain unclear. Friend leukemia virus integration 1 (FLI1), an Ets transcription factor family member, has been previously reported to act as a major driver of hematological malignancies. In this study, we explored the potential role of FLI1 in SCLC. Using immunohistochemical staining, we found that FLI1 was significantly upregulated in SCLC tissues, compared to that in non-small cell lung cancer (NSCLC) and normal lung tissues (p < 0.01). The expression score of FLI1 oncoprotein was associated with the extensive stage of SCLC and the overexpressed Ki67. Knockdown of FLI1 with small interfering RNA (siRNA) or short hairpin RNA (shRNA) promoted apoptosis and induced repression of cell proliferation, tumor colony formation and in vivo tumorigenicity in highly aggressive SCLC cell lines. Importantly, we discovered that FLI1 promoted tumorigenesis by activating the miR-17-92 cluster family. This study uncovers FLI1 as an important driving factor that promotes tumor growth in SCLC through the miR-17-92 pathway. FLI1 may serve as an attractive target for therapeutic intervention of SCLC.

Evaluation of factors associated with platinum-sensitivity status and survival in limited-stage small cell lung cancer patients treated with chemoradiotherapy

In this retrospective study, we analyzed the association of clinicopathological factors and therapeutic plans with platinum-sensitivity status and survival of limited-stage small cell lung cancer (LS-SCLC) patients. We enrolled 452 LS-SCLC patients with 279 platinum sensitive and 173 platinum refractory patients. The low serum neuro-specific enolase levels (NSE; p = 0.011), neutrophil-to-lymphocyte ratios (NLR; p = 0.013) and higher objective response rates (p = 0.003) were associated with sensitive group but not the refractory group. Multivariate analysis showed that treatment modality (HR = 0.267, p < 0.001), serum lactate dehydrogenase (LDH; HR = 1.894, p = 0.016), NLR (HR = 2.043, p = 0.043) and platinum-sensitivity status (HR = 0.561, p = 0.036) were independent prognostic factors for survival. We further showed that the numbers of chemotherapy cycles and response to first-line therapy were independent prognostic factors for refractory patients only. Our study demonstrates that platinum-sensitivity status is of prognostic importance, as it is strongly associated with survival in LS-SCLC patients.

Hypermethylation of ATP-binding cassette B1 (ABCB1) multidrug resistance 1 (MDR1) is associated with cisplatin resistance in the A549 lung adenocarcinoma cell line

Development of multiple drug resistance has been attributed to the overexpression of the ATP-binding cassette B1 (ABCB1) gene. In this study, the major purpose was to assess the expression and methylation levels of ABCB1 in human lung adenocarcinoma and to reveal the relationship between these processes and acquisition of cisplatin (DDP) resistance in the human cancer cell line A549. Methylation and expression levels of the ABCB1 gene ABCB1 in clinical human lung tissue were assessed using bisulphite sequencing, reverse transcription real-time PCR (RT² -PCR) and Western blot methods. Cell viability, DDP resistance and apoptosis of A549 cells were evaluated using the Cell Counting Kit-8 and fluorescence-activated cell sorter analysis. Our results showed that the onset of resistance to the cisplatin analogue, DDP, was associated with hypermethylation of the ABCB1 gene. Expression of the ABCB1 gene was enhanced at both mRNA and protein levels. Treatment with 5-Aza-C contributed to the hypomethylation of the ABCB1 gene and decreased ABCB1 protein expression in A549 cells. In conclusion, this in vitro and human tissue study of lung adenocarcinoma cells demonstrated that hypermethylation of the ABCB1 gene correlated with increased gene expression and was associated with the acquisition of resistance to the cisplatin analogue, DDP in human lung adenocarcinoma cells. Taken together, our study highlighted the connection between increased ABCB1 methylation level and upregulated expression of the gene in lung cancer. Moreover, the abnormally high expression of ABCB1 in A549 cells contributed to the development of the DDP resistance.

1p/19q codeletion and RET rearrangements in small-cell lung cancer

The prognosis of small-cell lung cancer (SCLC) is poor despite reports suggesting modest improvement in survival. To date, chemotherapy remains the cornerstone treatment for SCLC patients, and many studies have focused on identifying the molecular characteristics of SCLC, which serve as the basis for precision treatments that improve the prognosis of SCLC. For instance, the therapeutic effect of temozolomide, recommended for patients with relapsed SCLC, is linked to 1p/19q codeletion in anaplastic oligodendroglial tumors. A subpopulation of SCLC patients may derive benefit from tyrosine kinase inhibitors targeting RET. In order to identify 1p/19q codeletion and RET rearrangement in SCLC patients, 32 SCLC resected specimens were retrospectively collected between 2008 and 2014 from the Zhejiang Cancer Hospital in People’s Republic of China. Fluorescence in situ hybridization was used to detect 1p/19q codeletion and RET rearrangement in the specimens. A 1p single deletion was detected in eight specimens, 19q single deletion was detected in three specimens, and only three specimens had a 1p/19q codeletion. None of the specimens had a RET rearrangement. The three patients whose specimens had a 1p/19q codeletion were alive after 58, 50, and 30 months of follow-up care. There was a trend toward prolonged overall survival for the patients with codeletion compared to no codeletion, 1p single deletion, 19q single deletion, and without 1p and 19q deletion (P=0.113, 0.168, 0.116, and 0.122, respectively). Our data showed that RET rearrangement may be not an ideal molecular target for SCLC therapies in People’s Republic of China. Instead, 1p/19q codeletion is a promising marker for a good prognosis and treatment with temozolomide in SCLC.

Focused molecular analysis of small cell lung cancer: feasibility in routine clinical practice

Background

There is an urgent need to identify molecular signatures in small cell lung cancer (SCLC) that may select patients who are likely to respond to molecularly targeted therapies. In this study, we investigate the feasibility of undertaking focused molecular analyses on routine diagnostic biopsies in patients with SCLC.

Methods

A series of histopathologically confirmed formalin-fixed, paraffin-embedded SCLC specimens were analysed for epidermal growth factor receptors (EGFR), KRAS, NRAS and BRAF mutations, ALK gene rearrangements and MET amplification. EGFR and KRAS mutation testing was evaluated using real time polymerase chain reaction (RT-PCR cobas^®), BRAF and NRAS mutations using multiplex PCR and capillary electrophoresis-single strand conformation analysis, and ALK and MET aberrations with fluorescent in situ hybridization. All genetic aberrations detected were validated independently.

Results

A total of 105 patients diagnosed with SCLC between July 1990 and September 2006 were included. 60 (57 %) patients had suitable tumour tissue for molecular testing. 25 patients were successfully evaluated for all six pre-defined molecular aberrations. Eleven patients failed all molecular analysis. No mutations in EGFR, KRAS and NRAS were detected, and no ALK gene rearrangements or MET gene amplifications were identified. A V600E substitution in BRAF was detected in a Caucasian male smoker diagnosed with SCLC with squamoid and glandular features.

Conclusion

The paucity of patients with sufficient tumour tissue, quality of DNA extracted and low frequency of aberrations detected indicate that alternative molecular characterisation approaches are necessary, such as the use of circulating plasma DNA in patients with SCLC.

Origins, genetic landscape, and emerging therapies of small cell lung cancer

Lung cancer is the leading cause of cancer deaths, with small cell lung cancer (SCLC) representing the most aggressive subtype. Standard treatments have not changed in decades, and the 5-year survival rate has remained <7%. Genomic analyses have identified key driver mutations of SCLC that were subsequently validated in animal models of SCLC. To provide better treatment options, a deeper understanding of the cellular and molecular mechanisms underlying SCLC initiation, progression, metastasis, and acquisition of resistance is required. In this review, we describe the genetic landscape of SCLC, features of the cell of origin, and targeted therapeutic approaches.

Next-generation sequencing reveals frequent consistent genomic alterations in small cell undifferentiated lung cancer

Aims

Small cell lung cancer (SCLC) carries a poor prognosis, and the systemic therapies currently used as treatments are only modestly effective, as demonstrated by a low 5-year survival at only ∼5%. In this retrospective collected from March 2013 to study, we performed comprehensive genomic profiling of 98 small cell undifferentiated lung cancer (SCLC) samples to identify potential targets of therapy not currently searched for in routine clinical practice.

Methods

DNA from 98 SCLC was sequenced to high, uniform coverage (Illumina HiSeq 2500) and analysed for all classes of genomic alterations.

Results

A total of 386 alterations were identified for an average of 3.9 alterations per tumour (range 1–10). Fifty-two (53%) of cases harboured at least 1 actionable alteration with the potential to personalise therapy including base substitutions, amplifications or homozygous deletions in RICTOR (10%), KIT (7%), PIK3CA (6%), EGFR (5%), PTEN (5%), KRAS (5%), MCL1 (4%), FGFR1 (4%), BRCA2, (4%), TSC1 (3%), NF1 (3%), EPHA3 (3%) and CCND1. The most common non-actionable genomic alterations were alterations in TP53 (86% of SCLC cases), RB1 (54%) and MLL2 (17%).

Conclusions

Greater than 50% of the SCLC cases harboured at least one actionable alteration. Given the limited treatment options and poor prognosis of patients with SCLC, comprehensive genomic profiling has the potential to identify new treatment paradigms and meet an unmet clinical need for this disease.

A meta-analysis of randomized controlled trials comparing early and late concurrent thoracic radiotherapy with etoposide and cisplatin/carboplatin chemotherapy for limited-disease small-cell lung cancer

The aim of the present study was to determine the optimal time for concurrent thoracic radiotherapy (TRT) with etoposide and cisplatin/carboplatin (EP/EC) chemotherapy for the treatment of limited-disease small-cell lung cancer (LD SCLC). Randomized controlled trials comparing early and late concurrent TRT with EP/EC chemotherapy for the treatment of patients with LD SCLC were identified through searching databases such as MEDLINE, the Cochrane Central Register of Controlled Trials and Embase. Early thoracic radiotherapy (ERT) was defined as initiating irradiation within 30 days after chemotherapy initiation. A total of 3 eligible randomized controlled trials were identified. No significant differences in the objective response rate were detected between early and late concurrent TRT [risk ratio (RR)=1.01; 95% confidence interval (CI): 0.86-1.18; P=0.90]. Similar results were observed in the 1-, 2-, 3- and 5-year survival rates between early and late concurrent TRT (RR=1.06, 95% CI: 0.88-1.27, P=0.56; RR=1.15, 95% CI: 0.77-1.71, P=0.49; RR=0.90, 95% CI: 0.66-1.22, P=0.49; and RR=1.18, 95% CI: 0.64-2.16, P=0.60, respectively). The total incidence of grade 3-4 adverse events, including anemia, leukopenia, neutropenia, thrombocytopenia, nausea and vomiting, infection, esophageal toxicity, pulmonary toxicity, alopecia and hemorrhage with early concurrent TRT was significantly higher compared to that with late concurrent TRT (RR=1.21, 95% CI: 1.03-1.43, P=0.02). Thus, the results of our study indicated that the prognosis of LD SCLC treated with late concurrent TRT and EP/EC chemotherapy is similar to that with early concurrent TRT, although the incidence of grade 3-4 adverse events was lower in LD SCLC patients treated with late concurrent TRT combined with EP/EC chemotherapy.

Differential regulation of MMPs by E2F1, Sp1 and NF-kappa B controls the small cell lung cancer invasive phenotype

Background

E2F1 transcription factor plays a vital role in the regulation of diverse cellular processes including cell proliferation, apoptosis, invasion and metastasis. E2F1 overexpression has been demonstrated in small cell lung cancer (SCLC), and extensive metastasis in early phase is the most important feature of SCLC. In this study, we investigated the involvement of E2F1 in the process of invasion and metastasis in SCLC by regulating the expression of matrix metalloproteinases (MMPs).

Methods

Immunohistochemistry was performed to evaluate the expression of E2F1 and MMPs in SCLC samples in a Chinese Han population. The impact of E2F1 on invasion and metastasis was observed by transwell and wound healing experiments with depletion of E2F1 by specific siRNA. The target genes regulated by E2F1 were identified by chromatin immunoprecipitation (ChIP)-to-sequence, and the expressions of target genes were detected by real time PCR and western blotting. The dual luciferase reporter system was performed to analyze the regulatory relationship between E2F1 and MMPs.

Results

E2F1 is an independent and adverse prognosis factor that is highly expressed in SCLC in a Chinese Han population. Knockdown of E2F1 by specific siRNA resulted in the downregulation of migration and invasion in SCLC. The expressions of MMP-9 and −16 in SCLC were higher than other MMPs, and their expressions were most significantly reduced after silencing E2F1. ChIP-to-sequence and promoter-based luciferase analysis demonstrated that E2F1 directly controlled MMP-16 expression via an E2F1 binding motif in the promoter. Although one E2F1 binding site was predicted in the MMP-9 promoter, luciferase analysis indicated that this binding site was not functionally required. Further study demonstrated that E2F1 transcriptionally controlled the expression of Sp1 and p65, which in turn enhanced the MMP-9 promoter activity in SCLC cells. The associations between E2F1, Sp1, p65, and MMP-9 were validated by immunohistochemistry staining in SCLC tumors.

Conclusions

E2F1 acts as a transcriptional activator for MMPs and directly enhances MMP transcription by binding to E2F1 binding sequences in the promoter, or indirectly activates MMPs through enhanced Sp1 and NF-kappa B as a consequence of E2F1 activation in SCLC.