The Role of Irreversible EGFR Inhibitors in the Treatment of Non-Small Cell Lung Cancer: Overcoming Resistance to Reversible EGFR Inhibitors

Discovery of BLU-945, a Reversible, Potent, and Wild-Type-Sparing Next-Generation EGFR Mutant Inhibitor for Treatment-Resistant Non-Small-Cell Lung Cancer

While epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have changed the treatment landscape for EGFR mutant (L858R and ex19del)-driven non-small-cell lung cancer (NSCLC), most patients will eventually develop resistance to TKIs. In the case of first- and second-generation TKIs, up to 60% of patients will develop an EGFR T790M mutation, while third-generation irreversible TKIs, like osimertinib, lead to C797S as the primary on-target resistance mutation. The development of reversible inhibitors of these resistance mutants is often hampered by poor selectivity against wild-type EGFR, resulting in potentially dose-limiting toxicities and a sub-optimal profile for use in combinations. BLU-945 (compound 30) is a potent, reversible, wild-type-sparing inhibitor of EGFR+/T790M and EGFR+/T790M/C797S resistance mutants that maintains activity against the sensitizing mutations, especially L858R. Pre-clinical efficacy and safety studies supported progression of BLU-945 into clinical studies, and it is currently in phase 1/2 clinical trials for treatment-resistant EGFR-driven NSCLC.

CD146-mediated acquisition of stemness phenotype enhances tumour invasion and metastasis after EGFR-TKI resistance in lung cancer

INTRODUCTION

Tumours are more likely to metastasize after the development of resistance to EGFR-TKIs. CD146 is a multifunctional molecule and is implicated in tumour invasion and metastasis; however, its role in lung cancer has not been clearly established.

OBJECTIVE

Here, we aimed to explore the relationship between CD146 pathway and stem cell phenotype after EGFR-TKI resistance in lung cancer.

METHODS

EGFR-TKI-resistant cell lines were established by exposing parental cells to erlotinib/gefitinib. The CD146 level was measured by a western blot, RT-PCR and immunocytochemistry fluorescent. Cell migration was examined by the transwell assay and the scratch assay. Stemness phenotype genes were evaluated by RT-PCR and stem cell phenotype was observed by the microsphere formation assay.

RESULTS

CD146 and stemness phenotype genes increased while β-catenin decreased in acquired EGFR-TKI-resistant cell lines. CD146's over-expression induced the up-regulation of stemness-related genes and was inversely correlated with the β-catenin expression, which further increased the migration capability of resistant cancer cells. CD146's knockdown suppressed cell migration and stemness phenotype.

CONCLUSIONS

CD146 molecule contributes to the stemness phenotype and migration in EGFR-TKI-resistant cells. CD146 might be a potential therapeutic target for EGFR-TKI-resistant lung cancer or metastasis prevention.

KRAS driven expression signature has prognostic power superior to mutation status in non-small cell lung cancer

KRAS is the most frequently mutated oncogene in non‐small cell lung cancer (NSCLC). However, the prognostic role of KRAS mutation status in NSCLC still remains controversial. We hypothesize that the expression changes of genes affected by KRAS mutation status will have the most prominent effect and could be used as a prognostic signature in lung cancer.

We divided NSCLC patients with mutation and RNA‐seq data into KRAS mutated and wild type groups. Mann‐Whitney test was used to identify genes showing altered expression between these cohorts. Mean expression of the top five genes was designated as a “transcriptomic fingerprint” of the mutation. We evaluated the effect of this signature on clinical outcome in 2,437 NSCLC patients using univariate and multivariate Cox regression analysis.

Mutation of KRAS was most common in adenocarcinoma. Mutation status and KRAS expression were not correlated to prognosis. The transcriptomic fingerprint of KRAS include FOXRED2, KRAS, TOP1, PEX3 and ABL2. The KRAS signature had a high prognostic power. Similar results were achieved when using the second and third set of strongest genes. Moreover, all cutoff values delivered significant prognostic power (p < 0.01). The KRAS signature also remained significant (p < 0.01) in a multivariate analysis including age, gender, smoking history and tumor stage.

We generated a “surrogate signature” of KRAS mutation status in NSCLC patients by computationally linking genotype and gene expression. We show that secondary effects of a mutation can have a higher prognostic relevance than the primary genetic alteration itself.

What's new?

As many as one‐quarter of patients with lung adenocarcinoma (AC), a form of non‐small cell lung cancer (NSCLC), exhibit tumor‐associated mutations in KRAS. Whether KRAS mutation status and expression are correlated to prognosis, however, remains unclear. In this study, a surrogate signature of KRAS mutation status was generated for NSCLC by relating genotype to gene‐expression signature. The approach led to the identification of a significant correlation between overall survival in lung AC and the transcriptomic fingerprint of somatic KRAS mutations. Three genes strongly influenced by KRAS mutation may be relevant to the search for novel NSCLC drug targets.

Pregnane X receptors regulate CYP2C8 and P-glycoprotein to impact on the resistance of NSCLC cells to Taxol

Cytochrome P450 2C8 (CYP2C8) is one of the enzymes that primarily participate in producing metabolisms of medications and P‐glycoprotein (P‐gp) has been regarded as one of the important molecules in chemotherapeutically induced multidrug resistance (MDR). In addition, the pregnane X receptor (PXR) is involved in regulating both CYP2C8 and P‐gp. We aim to research the effect of PXR on Taxol‐resistant non–small‐cell lung cancer (NSCLC cells) via regulating CYP2C8 and P‐gp. NSCLC cells were treated with SR12813, LY335979, or PXR siRNA. Cell counting kit (CCK‐8) assay was used to detect cell vitality. Colony formation assay was used to observe cell proliferation. Western blotting, real‐time polymerase chain reaction (RT‐PCR), and immunofluorescence staining were conducted to analyze the expressions of PXR, CYP2C8, and P‐gp. Taxol and its metabolic products were detected by high‐performance liquid chromatography (HPLC). The expression of PXR in A549 cell line was higher than that in other cell lines. The accumulation of PXR was observed in the nucleus after cells were treated with SR12813. Besides, SR12813 induced higher expressions of CYP2C8 and P‐gp proteins. We also discovered that pretreatment with SR12813 reversed the inhibition of cell viability and proliferation after the Taxol treatment in comparison to the SR12813 untreated group. Furthermore, the hydroxylation products of Taxol analyzed by HPLC were increased in comparison to the SR12813 untreated group, indicating that high expressions of CYP2C8 and P‐gp enhanced the resistance of A549 cells to Taxol. For cells treated with PXR siRNA, cell viability, cell proliferation, and Taxol metabolites were significantly reduced after the Taxol treatment in comparison to the siRNA‐negative group. The cell viability, cell proliferation, and Taxol metabolites were regulated by the expressions of PXR, P‐gp, and CYP2C8. That is, PXR expression has an important effect on the resistance of NSCLC cells to Taxol via upregulating P‐gp and CYP2C8.

The Evolution of Therapies in Non-Small Cell Lung Cancer

The landscape of advanced non-small lung cancer (NSCLC) therapies has rapidly been evolving beyond chemotherapy over the last few years. The discovery of oncogenic driver mutations has led to new ways in classifying NSCLC as well as offered novel therapeutic targets for anticancer therapy. Targets such as epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) gene rearrangements have successfully been targeted with appropriate tyrosine kinase inhibitors (TKIs). Other driver mutations such as ROS, MET, RET, BRAF have also been investigated with targeted agents with some success in the early phase clinical setting. Novel strategies in the field of immune-oncology have also led to the development of inhibitors of cytotoxic T lymphocyte antigen-4 (CTLA-4) and programmed death-1 receptor (PD-1), which are important pathways in allowing cancer cells to escape detection by the immune system. These inhibitors have been successfully tried in NSCLC and also now bring the exciting possibility of long term responses in advanced NSCLC. In this review recent data on novel targets and therapeutic strategies and their future prospects are discussed.

Lung cancer genotype-based therapy and predictive biomarkers: present and future

CONTEXT

The advent of genotype-based therapy and predictive biomarkers for lung cancer has thrust the pathologist into the front lines of precision medicine for this deadly disease.

OBJECTIVE

To provide the clinical background, current status, and future perspectives of molecular targeted therapy for lung cancer patients, including the pivotal participation of the pathologist.

DATA SOURCES

Data were obtained from review of the pertinent peer-reviewed literature.

CONCLUSIONS

First-generation tyrosine kinase inhibitors have produced clinical response in a limited number of non-small cell lung cancers demonstrated to have activating mutations of epidermal growth factor receptor or anaplastic lymphoma kinase rearrangements with fusion partners. Patients treated with first-generation tyrosine kinase inhibitors develop acquired resistance to their therapy. Ongoing investigations of second-generation tyrosine kinase inhibitors and new druggable targets as well as the development of next-generation genotyping and new antibodies for immunohistochemistry promise to significantly expand the pathologist's already crucial role in precision medicine of lung cancer.

A phase II trial of dacomitinib, an oral pan-human EGF receptor (HER) inhibitor, as first-line treatment in recurrent and/or metastatic squamous-cell carcinoma of the head and neck

BACKGROUND

An open-label, multicenter, single-arm phase II trial was conducted to investigate the clinical activity of dacomitinib in recurrent/metastatic squamous-cell carcinoma of the head and neck (RM-SCCHN).

PATIENTS AND METHODS

Eligible patients were administered dacomitinib at 45 mg orally daily, in 21-day cycles. Primary end point was objective response rate.

RESULTS

Sixty-nine patients were enrolled with a median age of 62 years. Among response-evaluable patients, 8 [12.7%, 95% confidence interval (CI) 5.6% to 23.5%] achieved a partial response and 36 (57.1%) had stable disease, lasting ≥24 weeks in 9 patients (14.3%). The median progression-free survival (PFS) was 12.1 weeks and the median overall survival (OS) was 34.6 weeks. Most adverse events (AEs) were tolerable. The most common grade 3 or higher treatment-related AEs were diarrhea (15.9%), acneiform dermatitis (8.7%), and fatigue (8.7%). Treatment-related AEs led to at least one dose interruption in 28 (40.6%) patients and dose reductions in 26 (37.7%). Permanent treatment discontinuation occurred in 8 (11.6%) patients due to treatment-related AEs.

CONCLUSIONS

Dacomitinib demonstrated clinical activity in RM-SCCHN, and the primary end point of this study was met. The toxicity profile of this agent was generally manageable with dose interruptions and adjustments.

Personalized medicine in lung cancer: what we need to know

Lung cancer is a complex and often fatal disease. The recent discovery of activating mutations in EGFR and fusion genes involving ALK has set the stage for personalized medicine for lung cancer. Patients selected using biomarkers have benefited from the development of EGFR tyrosine kinase inhibitors and ALK inhibitors with considerable improvement in tumor control and survival. Four key areas of knowledge that are essential to the development of targeted therapy are discussed in this Review: knowing the target, knowing the biomarker, knowing the end point and knowing the mechanisms of resistance.

Switching reversibility to irreversibility in glycogen synthase kinase 3 inhibitors: clues for specific design of new compounds

Development of kinase-targeted therapies for central nervous system (CNS) diseases is a great challenge. Glycogen synthase kinase 3 (GSK-3) offers a great potential for severe CNS unmet diseases, being one of the inhibitors on clinical trials for different tauopathies. Following our hypothesis based on the enhanced reactivity of residue Cys199 in the binding site of GSK-3, we examine here the suitability of phenylhalomethylketones as irreversible inhibitors. Our data confirm that the halomethylketone unit is essential for the inhibitory activity. Moreover, addition of the halomethylketone moiety to reversible inhibitors turned them into irreversible inhibitors with IC(50) values in the nanomolar range. Overall, the results point out that these compounds might be useful pharmacological tools to explore physiological and pathological processes related to signaling pathways regulated by GSK-3 opening new avenues for the discovery of novel GSK-3 inhibitors.