Afatinib increases sensitivity to radiation in non-small cell lung cancer cells with acquired EGFR T790M mutation

T790M mutation sensitizes non-small cell lung cancer cells to radiation via suppressing SPOCK1

Background

Approximately 50% of patients harbor the T790M mutation after developing first-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) resistance. Evidence has showed the major treatment failure is local relapses and limited metastases. Several studies have demonstrated the value of radiotherapy in metastatic non-small cell lung cancer (NSCLC) with the EGFR T790M mutation after the development of TKI resistance. The aim of this study was to explore the role of radiation in T790M-mutant NSCLC and the value of early radiotherapy for NSCLC with T790M-mediated EGFR-TKI resistance.

Methods

Gefitinib-resistant NSCLC cell lines were established via stepwise exposure to increasing concentrations of gefitinib (PC-9-GR). Droplet digital PCR was used to determine the relative T790M subclone abundance. In vitro and in vivo models were established using different mixtures of PC-9-GR and PC-9 cells. Differentially expressed genes were identified using RNA sequencing. Two research models were constructed (salvage and prophylactic radiotherapy) to determine the effects of early radiotherapy on gefitinib-resistant cells.

Results

PC-9-GR cells exhibited higher radiosensitivity than PC-9 cells (sensitivity enhancement ratio = 1.5). Salvage radiation reduced the number of T790M-mutant subclones, and the relative T790M abundance was significantly lower than that without radiation at 90 days (10.94% vs. 21.54%). Prophylactic radiation prevented the development of T790M subclones. These results were also confirmed in vivo. qRT-PCR revealed threefold elevation of miR-1243 in PC-9-GR cells, and the increased radiosensitivity of PC-9-GR cells was inhibited when miR-1243 was knocked down. RNA sequencing revealed that SPOCK1 was downregulated in PC-9-GR cells. Interestingly, bioinformatic analysis showed that SPOCK1 was a target gene of miR-1243. SPOCK1 knockdown markedly increased the radiosensitivity of PC-9 cells.

Conclusion

Gefitinib-resistant NSCLC with the T790M mutation had higher radiosensitivity than that without the mutation, possibly mediated by SPOCK1. Early radiotherapy can eliminate T790M subclones, providing evidence for the benefit of early local treatment in patients with TKI-resistant NSCLC.

Oncoprotein SET dynamically regulates cellular stress response through nucleocytoplasmic transport in breast cancer

SETβ is the predominant isoform of oncoprotein SE translocation (SET) in various breast cancer cell lines. Interactome-transcriptome analysis has shown that SETβ is intimately associated with cellular stress response. Among various exogenous stimuli, formaldehyde (FA) causes distinct biological effects in a dose-dependent manner. In response to FA at different concentrations, SET dynamically shuttles between the nucleus and cytoplasm, performing diverse biofunctions to restore homeostasis. At a low concentration, FA acts as an epidermal growth factor (EGF) and activates the HER2 receptor and downstream signaling pathways in HER2+ breast cancer cells, resulting in enhanced cell proliferation. Nucleocytoplasmic transport of SETβ is controlled by the PI3K/PKCα/CK2α axis and depletion or blockade of the transport of SETβ suppresses EGF-induced activation of AKT and ERK. SETβ also inhibits not only stress-induced activation of p38 MAPK signaling pathway, but also assembly of stress granules by hindering formation of the G3BP1-RNA complex. Our findings suggest that SET functions as an important regulator which modulates cellular stress signaling pathways dynamically.

Combined PARP inhibitors and small molecular inhibitors in solid tumor treatment (Review)

With the development of precision medicine, targeted therapy has attracted extensive attention. Poly(ADP‑ribose) polymerase inhibitors (PARPi) are critical clinical drugs designed to induce cell death and are major antitumor targeted agents. However, preclinical and clinical data have revealed the limitations of PARPi monotherapy. Therefore, their combination with other targeted drugs has become a research hotspot in tumor treatment. Recent studies have demonstrated the critical role of small molecular inhibitors in multiple haematological cancers and solid tumors via cellular signalling modulation, exhibiting potential as a combined pharmacotherapy. In the present review, studies focused on small molecular inhibitors targeting the homologous recombination pathway were summarized and clinical trials evaluating the safety and efficacy of combined treatment were discussed.

Efficacy and Failure Patterns of Early SBRT to the Primary Tumor in Advanced EGFR-Mutation-Positive Lung Cancer with EFGR-TKI Treatment: A Prospective, Single Arm, Phase II Study

Early stereotactic body radiation therapy (SBRT) to the primary tumor combined with epidermal growth factor receptor tyrosine kinase inhibitor (EFGR-TKI) treatment may increase progression-free survival (PFS) by delaying resistance in patients with advanced EGFR-mutant non-small cell lung cancer (NSCLC). In this prospective, single arm, phase II study, patients with advanced NSCLC were treated with EGFR-TKI (icotinib 125 mg tid or gefitinib 250 mg qd) for one month followed by SBRT (40-60 Gy/5-8 F/5-10 d) to the primary tumor with concurrent EGFR-TKI until disease progression. The primary endpoint was PFS and the patterns of failure. Overall survival (OS) and adverse effects (AEs) were secondary endpoints. Overall, 41 advanced NSCLC patients with EGFR mutations received treatment with 24.42 months of median follow-up time. On average, SBRT was initiated 1.49 months after EGFR-TKI administration. Tumors were found to have an average shrinkage rate of 42.50%. Median PFS was 15.23 months (95% CI 13.10-17.36), while median OS was 27.57 months (95% CI 23.05-32.09). Thirty-three patients were found to have disease progression, of which new site failure (NF) (22 patients, 66.66%) was the most common pattern, followed by original site failure (OF) (7 patients, 21.21%) and simultaneous OF/NF (ONF) (4 patients, 12.12%). There were no Aes equal to or greater than grade 3, with the most frequent AE being radiation pneumonitis. Therefore, administering therapy targeted at the primary tumor using early SBRT after EGFR-TKI initiation is a new potentially safe and effective approach to treat EGFR-mutant advanced NSCLC.

Safety and efficacy of combining afatinib and whole-brain radiation therapy in treating brain metastases from EGFR-mutated NSCLC: a case report and literature review

Combining EGFR-tyrosine kinase inhibitors (TKIs) to whole brain radiation therapy (WBRT) has been shown to be more effective than EGFR-TKIs or WBRT alone in treating brain metastases (BMs) from EGFR-mutated Non Small-Cell Lung Cancer (NSCLC). However, despite the combination results well tolerated, EGFR-TKIs are often discontinued before WBRT, to reduce the risk of possible side effects, potentially resulting in reduced treatment efficacy and possible progression of intra- and extra-cranial disease. Afatinib, an irreversible inhibitor of EGFR-TK, has been shown to radiosensitize NSCLC in pre-clinical models and, compared to the other EGFR-TKIs, more efficiently penetrates the blood-brain barrier. However, nowadays, only two case reports describe the therapeutic efficiency and safety of combining afatinib with WBRT. Herein, we report on a 58-year-old woman patient with symptomatic BMs from NSLCL, treated with afatinib and concomitant WBRT, 30 Gy in 10 fractions. Treatment induced a remarkable and persistent radiological regression of BMs and the disappearance of neurological symptoms. However, the patient experienced severe skin toxicity of G3, corresponding to the irradiation area. Toxicity was successfully treated pharmacologically, and the patient did not experience any BMs-related symptoms for the next 10 months. She died of COVID-19-related respiratory failure. The association of afatinib with WBRT appears to be a successful strategy in the control of BMs from EGFR-mutated NSCLC. However, it should be considered that the combination could be responsible for serious dermatological toxicity.

Afatinib-loaded inhalable PLGA nanoparticles for localized therapy of non-small cell lung cancer (NSCLC)-development and in-vitro efficacy

Afatinib (AFA) is a potent aniline-quinazoline derivative, approved by the Food and Drug Administration (FDA) in 2013, as a first-line treatment for metastatic non-small cell lung cancer (NSCLC). However, its clinical application is highly limited by its poor solubility, and consequently low bioavailability. We hypothesize that loading of AFA into biodegradable PLGA nanoparticles for localized inhalational drug delivery will be instrumental in improving therapeutic outcomes in NSCLC patients. Formulated AFA nanoparticles (AFA-NP) were evaluated for physicochemical properties (particle size: 180.2 ± 15.6 nm, zeta potential: - 23.1 ± 0.2 mV, % entrapment efficiency: 34.4 ± 2.3%), formulation stability, in-vitro aerosol deposition behavior, and anticancer efficacy. Stability studies revealed the physicochemical stability of AFA-NP. Moreover, AFA-NP exhibited excellent inhalable properties (mass median aerodynamic diameter (MMAD): 4.7 ± 0.1 μm; fine particle fraction (FPF): 77.8 ± 4.3%), indicating efficient particle deposition in deep lung regions. With respect to in-vitro drug release, AFA-NP showed sustained drug release with cumulative release of 56.8 ± 6.4% after 48 h. Cytotoxic studies revealed that encapsulation of AFA into PLGA nanoparticles significantly enhanced its cytotoxic potential in KRAS-mutated NSCLC cell lines (A549, H460). Cellular uptake studies revealed enhanced internalization of coumarin-loaded nanoparticles compared to plain coumarin in A549. In addition, 3D tumor spheroid studies demonstrated superior efficacy of AFA-NP in tumor penetration and growth inhibition. To conclude, we have established in-vitro efficacy of afatinib-loaded PLGA nanoparticles as inhalable NSCLC therapy, which will be of great significance when designing preclinical and clinical studies. Graphical abstract.

Osimertinib versus afatinib in patients with T790M-positive, non-small-cell lung cancer and multiple central nervous system metastases after failure of initial EGFR-TKI treatment

Background

The purpose of this study was to compare the efficacy of osimertinib (OSI) versus afatinib (AFA) in patients with T790M-positive, non-small-cell lung cancer (NSCLC) and multiple central nervous system (CNS) metastases after failure of initial epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) treatment.

Methods

Consecutive patients with T790M-positive NSCLC and multiple CNS metastases after failure of initial EGFR-TKI treatment were retrospectively identified from our medical institution during 2016–2018 and underwent either oral 80 daily OSI or oral 40 daily AFA every 3 weeks for up to 6 cycles, until disease progression, intolerable adverse events (AEs), or death. The co-primary endpoints were overall survival (OS) and progression-free survival (PFS).

Results

The cohort consisted of 124 patients (OSI: n = 60, mean age = 64.24 years [SD: 12.33]; AFA: n = 64, mean age = 64.13 years [SD: 13.72]). After a median follow-up of 24 months (range, 3 to 28), a significant improvement in OS was detected (hazard ratio [HR] 0.59, 95% confidence interval [CI], 0.39–0.91; p = 0.0160; median, 13.7 months [95% CI, 11.1–14.8] for OSI vs 9.6 months [95% CI, 8.4–10.2] for AFA). The median duration of PFS was significantly longer with OSI than with AFA (HR 0.62; 95% CI, 0.41–0.91; p = 0.014; median, 4.5 months [95% CI, 3.5–5.7] vs 3.9 months [95% CI, 3.1–4.8]). The proportion of grade 3 or higher adverse events (AEs) was lower with OSI (22.4%) than with AFA (39.4%).

Conclusions

In patients with T790M-positive NSCLC and multiple CNS metastases after failure of initial EGFR-TKI treatment, OSI may be associated with significantly improved survival benefit compared with AFA, with a controllable tolerability profile.

Targeting human epidermal growth factor receptor 2 enhances radiosensitivity and reduces the metastatic potential of Lewis lung carcinoma cells

BACKGROUND

Sublethal radiation induces matrix metalloproteinase 9 (MMP-9)-mediated radioresistance in Lewis lung carcinoma (LLC) cells and their metastatic dissemination. We aim to determine if EGFR/HER2 activation associates with MMP-9-mediated radioresistance and invasiveness in irradiated LLC cells.

METHODS

LLC cells were treated with erlotinib or afatinib followed by sublethal radiation. After irradiation, we examined the phosphorylation of EGFR/HER2 and MMP-9 expression. Colony formation assay determined if the kinase inhibitors sensitize LLC cells to radiation. Matrigel-coated Boyden chamber assay assessed cellular invasiveness. Resulting tumors of wild-type LLC cells or HER2 knock-down mutant cells were irradiated to induce pulmonary metastases.

RESULTS

Afatinib more effectively sensitized LLC cells to radiation and decreased invasiveness by inhibiting phosphorylation of EGFR, HER2, Akt, ERK, and p38, and down-regulating MMP-9 when compared to erlotinib. Afatinib abolished radiation-induced lung metastases in vivo. Furthermore, LLC HER2 knock-down cells treated with radiation had growth inhibition.

CONCLUSION

Dual inhibition of radiation-activated EGFR and HER2 signaling by afatinib suppressed the proliferation and invasion of irradiated LLC cells. Increased radiosensitivity and decreased metastatic dissemination were observed by pharmacological or genetic HER2 inhibition in vivo. These findings indicate that HER2 plays a pivotal role in enhancing radioresistance and reducing metastatic potential of LLC cells.

Timing in combination with radiotherapy and patterns of disease progression in non-small cell lung cancer treated with EGFR-TKI

OBJECTIVES

Tyrosine kinase inhibitor (TKI) has been the standard of care for advanced non-small cell lung cancers (NSCLC) harboring epidermal growth factor receptor (EGFR) mutation, but these tumors invariably develop drug resistance. As progression most frequently advances in sites of original disease, our study sought to explore the time to response for NSCLC to TKI therapy and the patterns of disease progression, to provide evidence for timing and candidates for local therapy intervention.

MATERIALS AND METHODS

A cohort of 105 EGFR-mutated IIIB or IV NSCLC patients treated with EGFR-TKI were retrospectively analyzed. The disease progression patterns were divided into 3 categories: progression in sites of original disease, progression in new distant sites, and combined progression.

RESULTS

Before cut-off date, 80 patients had disease progression. Thirty-three (41.25 %) patients had progression in sites of original disease, 34 (42.5 %) patients had progression in new sites and 13 (16.25 %) patients had combined progression, respectively. The median time to response for responders was 2.00 months (95 %CI 1.28-2.92 months), and the median time to maximal tumor shrinkage for SD patients was 2.00 months (95 %CI 1.42-2.58 months). Multivariate logistic regression model showed that the 21 exon mutation is related to the incidence of original site failure.

CONCLUSION

Over 1/3 of the patients progress at the original sites, which indicated that this subset of patients may benefit from local therapy. Moreover, as the results indicate that considerable shrinkage for TKI therapy occurs in first two months after TKI initiation, local therapy can be adopted after this timepoint, before disease progression. We also propose EGFR gene mutation type as potential inclusion criteria to identify candidates for combined local therapy.

Osimertinib (AZD9291) increases radio‑sensitivity in EGFR T790M non‑small cell lung cancer

Osimertinib (AZD9291) is a third generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor that has demonstrated significant clinical benefits in patients with EGFR‑sensitizing mutations or the T790M mutation. However, the potential therapeutic effect of osimertinib combined with ionizing irradiation (IR) is not well understood. The present study investigated treatment with osimertinib combined with IR in EGFR T790M non‑small cell lung cancer (NCI‑H1975) in vitro and in vivo. The results revealed that osimertinib inhibited proliferation and clonogenic survival following irradiation, decreased G2/M phase arrest in irradiated cells, and delayed DNA damage repair in a concentration‑ and time‑dependent manner. Furthermore, osimertinib alone or in combination with IR, blocked the phosphorylation of EGFR (Tyr1068/Tyr1173), protein kinase B and extracellular signal‑regulated kinase. Osimertinib also enhanced the antitumor activity of IR in tumor‑bearing nude mice. The results of the present study indicated that osimertinib has therapeutic potential as a radiation‑sensitizer in lung cancer cells harboring the EGFR T790M mutation, providing a rationale for clinically combining osimertinib with irradiation in EGFR T790M non‑small cell lung cancer.

Efatutazone and T0901317 exert synergistically therapeutic effects in acquired gefitinib-resistant lung adenocarcinoma cells

The development of acquired EGFR‐TKI therapeutic resistance is still a serious clinical problem in the management of lung adenocarcinoma. Peroxisome proliferator activated receptor gamma (PPARγ) agonists may exhibit anti‐tumor activity by transactivating genes which are closely associated with cell proliferation, apoptosis, and differentiation. However, it remains not clear whether efatutazone has similar roles in lung adenocarcinoma cells of gefitinib resistant such as HCC827‐GR and PC9‐GR. It has been demonstrated by us that efatutazone prominently increased the mRNA and protein expression of PPARγ, liver X receptor alpha (LXRα),as well as ATP binding cassette subfamily A member 1 (ABCA1). In the presence of GW9662 (a specific antagonist of PPARγ) or GGPP (a specific antagonist of LXRα), efatutazone (40 μmol/L) restored the proliferation of both HCC827‐GR and PC9‐GR cells and obviously inhibited the increased protein and mRNA expression of PPAR‐gamma, LXR‐alpha, and ABCA1 induced by efatutazone. LXRα knockdown by siRNA (si‐LXRα) significantly promoted the HCC827‐GR and PC9‐GR cells proliferation, whereas incubation efatutazone with si‐LXRα restored the proliferation ability compared with the control group. In addition, combination of efatutazone and LXRα agonist T0901317 showed a synergistic therapeutic effect on lung adenocarcinoma cell proliferation and PPAR gamma, LXR A and ABCA1 protein expression. These results indicate that efatutazone could inhibit the cells proliferation of HCC827‐GR and PC9‐GR through PPARγ/LXRα/ABCA1 pathway, and synergistic therapeutic effect is achieved when combined with T0901317.

IL-4, a direct target of miR-340/429, is involved in radiation-induced aggressive tumor behavior in human carcinoma cells

Radiotherapy induces the production of cytokines, thereby increasing aggressive tumor behavior. This radiation effect results in the failure of radiotherapy and increases the mortality rate in patients. We found that interleukin-4 (IL-4) and IL-4Rα (IL-4 receptor) are highly expressed in various human cancer cells subsequent to radiation treatment. In addition, IL-4 is highly overexpressed in metastatic carcinoma tissues compared with infiltrating carcinoma tissues. High expression of IL-4 in patients with cancer is strongly correlated with poor survival. The results of this study suggest that radiation-induced IL-4 contributes to tumor progression and metastasis. Radiation-induced IL-4 was associated with tumorigenicity and metastasis. IL-4 expression was downregulated by miR-340 and miR-429, which were decreased by ionizing radiation (IR). Radiation-regulated miR-340/429-IL4 signaling increased tumorigenesis and metastasis by inducing the production of Sox2, Vimentin, VEGF, Ang2, and MMP-2/9 via activating JAK, JNK, β-catenin, and Stat6 in vitro and in vivo. Our study presents a conceptual advance in our understanding of the modification of tumor microenvironment by radiation and suggests that combining radiotherapy with genetic therapy to inhibit IL-4 may be a promising strategy for preventing post-radiation recurrence and metastasis in patients.

Enhanced efficacy of AZD3759 and radiation on brain metastasis from EGFR mutant non-small cell lung cancer

The prognosis of patients with brain metastasis (BM) is poor. In our study, we demonstrated that AZD3759, an EGFR tyrosine kinase inhibitors (TKIs) with excellent blood-brain barrier (BBB) penetration, combined with radiation enhanced the antitumor efficacy in BM model from EGFR mutant (EGFRm) NSCLC. Besides, the antitumor activity displayed no difference between radiation concurrently with AZD3759 and radiation sequentially with AZD3759. Mechanistically, we found that two factors determined the enhanced efficacy: cells with EGFRm which were sensitive to AZD3759, and a relative high concentration of AZD3759. We have validated mechanisms underlying the radiosensitizing effect of AZD3759, which were involved in decreased cell proliferation and survival, and suppressed repair of DNA damage. Moreover, our study found that AZD3759 inhibited both the non-homologous end joining (NHEJ) and homologous recombination (HR) DNA double-strand breaks (DSBs) repair pathway, and abrogated the G2/M checkpoint to suppress DNA damage repair. We also detected the BBB penetration of AZD3759 when combined with cranial radiation. The results showed the BBB penetration of AZD3759 was decreased within 24 hr after radiation, however, the free concentration of AZD3759 in brain kept at a high level in the context of radiation. In conclusion, our findings suggest that AZD3759 combined with radiation enhances the antitumor activity in BM from EGFRm NSCLC, this combination therapy may be an effective treatment option for BM from EGFRm NSCLC.

AZD9291 Increases Sensitivity to Radiation in PC-9-IR Cells by Delaying DNA Damage Repair after Irradiation and Inducing Apoptosis

AZD9291 is a novel, irreversible epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), which is administered orally. It has been proven effective in non-small cell lung cancer (NSCLC) patients, with both EGFR-sensitizing and EGFR T790M mutations in preclinical models. However, the potential therapeutic effects of AZD9291 combined with other modalities, including ionizing radiation, are not well understood. The presence of AZD9291 significantly increases the cell-killing effects of radiation in PC-9-IR cells with a secondary EGFR mutation (T790M), which was developed from NSCLC PC-9 cells (human lung adenocarcinoma cell with EGFR 19 exon 15 bp deletion) after chronic exposure to increasing doses of gefitinib, and in H1975 cells (human lung adenocarcinoma cell with EGFR exon 20 T790M mutation de novo), but not in PC-9 cells or in H460 cells (human lung adenocarcinoma cell with wild-type EGFR). In PC-9-IR cells, AZD9291 remarkably decreases phosphorylation levels of EGFR, extracellular regulated protein kinase (ERK), and protein kinase B (AKT). AZD9291 increases sensitivity to radiation in PC-9-IR cells by delaying deoxyribonucleic acid (DNA) damage repair after irradiation and inducing apoptosis, and enhances tumor growth inhibition when combined with radiation in PC-9-IR xenografts. Our findings suggest a potential therapeutic effect of AZD9291 as a radiation sensitizer in lung cancer cells with an acquired EGFR T790M mutation, providing a rationale for a clinical trial using the combination of AZD9291 and radiation in NSCLCs harboring acquired T790M mutation.

ALK and ROS1 as targeted therapy paradigms and clinical implications to overcome crizotinib resistance

During the past decade, more than 10 targetable oncogenic driver genes have been validated in non-small cell lung cancer (NSCLC). Anaplastic lymphoma kinase (ALK) and ROS1 kinase are two new driver genes implicated in ALK- and ROS1-rearranged NSCLC. Inhibition of ALK and ROS1 by crizotinib has been reported to be highly effective and well tolerated in these patients. However, resistance to crizotinib emerges years after treatment, and increasing efforts have been made to overcome this issue. Here, we review the biology of ALK and ROS1 and their roles in cancer progression. We also summarize the ongoing and completed clinical trials validating ALK and ROS1 as targets for cancer treatment. In the last section of the review, we will discuss the molecular mechanisms of crizotinib resistance and focus approaches to overcome it. This review describes an exciting new area of research and may provide new insights for targeted cancer therapies.

Current progress and outcomes of clinical trials on using epidermal growth factor receptor-tyrosine kinase inhibitor therapy in non-small cell lung cancer patients with brain metastases

Non-small cell lung cancer (NSCLC) continues to be one of the major causes of cancer-related deaths worldwide, and brain metastases are the major cause of death in NSCLC patients. With recent advances in understanding the underlying molecular mechanism of NSCLC development and progression, mutations in epidermal growth factor receptor (EGFR) have been recognized as a key predictor of therapeutic sensitivity to EGFR tyrosine kinase inhibitors (TKIs). Using EGFR-TKI alone or in combination with standard treatments such as whole-brain radiotherapy and surgery has been an effective strategy for the management of brain metastasis. Particularly, a newer generation of EGFR-TKIs, including osimertinib and AZD3759, has been developed. These new EGFR-TKIs can cross the blood-brain barrier and potentially treat EGFR-TKI resistance and improve prognosis. In this article, current progress and outcomes of clinical trials on the use of EGFR-TKIs for treating NSCLC patients with brain metastasis will be reviewed.

PPARγ agonist efatutazone and gefitinib synergistically inhibit the proliferation of EGFR-TKI-resistant lung adenocarcinoma cells via the PPARγ/PTEN/Akt pathway

Development of acquired resistance to EGFR-TKI therapy continues to be a serious clinical problem in Lung adenocarcinoma management. Peroxisome proliferator-activated receptor gamma (PPARγ) agonists demonstrate anti-tumor activity likely via transactivating genes that regulate cell proliferation, differentiation and apoptosis. Efatutazone, a novel later generation PPARγ agonist, selectively activates PPARγ target genes and has antiproliferative effects in a range of malignancies. However, the exact function and molecular mechanism of PPARγ agonists efatutazone in EGFR-TKI gefitinib-resistance of Lung adenocarcinoma has not been determined. In this study, we studied the development of acquired resistance to an EGFR-TKI gefitinib in lung adenocarcinoma cells and investigated the antiproliferative effects of efatutazone in the acquired resistant cells. The treatment of gefitinib-resistant cells with efatutazone reduced the growth of gefitinib-resistant cells in a dose- and time-dependent manner, and facilitated the anti-proliferative effects of gefitinib. Mechanistic investigations suggested that efatutazone acted by upregulating protein expression of PPARγ, phosphatase and tensin homolog (PTEN), inactivating the Akt pathway, followed by dephosphorylation of p21Cip1 at Thr145 without affecting the transcriptional levels. Our results suggested that efatutazone, alone or in combination with gefitinib, might offer therapeutic effects in lung adenocarcinoma.

Management of non-small cell lung cancer with EGFR mutation: the role of radiotherapy in the era of tyrosine kinase inhibitor therapy-opportunities and challenges

In recent years, the treatment of advanced non-small cell lung cancer (NSCLC) was greatly promoted by the discovery of oncogenic drivers and the development of targeted therapies specific for these drivers. Somatic mutations in epidermal growth factor receptor (EGFR) are the most common type in patients with NSCLC. Small-molecule tyrosine kinase inhibitor (TKI) targeting EGFR produced relatively high response rate and long duration with acceptable toxicity profile. Also, the life expectancy in patients with active EGFR mutation has been significantly prolonged than the past. Additionally, evolution of advanced imaging and radiation techniques has expanded the indications for radiotherapy in complex clinical situation. All of those factors contributed to the widely use of radiotherapy for advanced NSCLC treated with TKI therapy. In this review, we will discuss how to integrate radiotherapy into the comprehensive treatment of patients with TKI therapy in order to maximize the therapeutics effect.

Blocking autophagy improves the anti-tumor activity of afatinib in lung adenocarcinoma with activating EGFR mutations in vitro and in vivo

Afatinib, a second-generation tyrosine kinase inhibitor (TKI), has been approved for the treatment of advanced EGFR-mutant non-small cell lung cancer (NSCLC). However, afatinib’s clinical application is still hampered by acquired resistance. Recently, autophagy is considered as an important mechanism of resistance to TKI. Herein, we investigated the autophagy induction as well as its influence on anti-lung adenocarcinoma activity of afatinib in two activating EGFR-mutants H1975 and H1650 cells. First, Growth inhibition and caspase-dependent apoptosis were observed in afatinib-treated H1975 and H1650 cells. Then we confirmed afatinib-induced autophagy in H1975 and H1650 cells. Importantly, autophagy inhibition using chloroquine (CQ) and 3-MA enhanced the cytotoxicity of afatinib, elucidating the cytoprotective role of autophagy in lung adenocarcinoma therapy with afatinib. Further study suggested that Akt/mTOR and Erk signaling pathways were involved in afatinib-induced autophagy, and reactive oxygen species (ROS) acted as an intracellular transducer regulating both autophagy and apoptosis in afatinib-treated H1975 and H1650 cells. Moreover, the in vivo experiment in xenograft model using H1975 cell line confirmed the enhanced anti-lung adenocarcinoma efficacy of afatinib when combined with autophagy inhibitor CQ. Thus, blocking autophagy may be a promising strategy to overcome resistance and increase sensitivity to afatinib in lung adenocarcinoma harboring activating EGFR mutations.

Efficacy of afatinib, an irreversible ErbB family blocker, in the treatment of intracerebral metastases of non-small cell lung cancer in mice

Few effective therapeutic options are currently available for the treatment of non-small cell lung cancer (NSCLC) with brain metastases (BM). Recent evidence shows that NSCLC patients with BMs respond well to afatinib, but little is known about the underlying mechanisms. In this study, we evaluated the efficacy of afatinib in treatment of BMs in mice and investigated whether afatinib could actively penetrate the brain-blood barrier and bind to its target. NSCLC BM model was established in nude mice by intracerebral injection of PC-9.luc cells. The tumors were measured weekly using in vivo quantitative bioluminescence. The mice are administrated afatinib (15, 30 mg·kg^-1·d^-1, ig) for 14 d. The antitumor efficacy of afatinib was determined by tumor growth inhibition (TGI), which was calculated as [1-(change of tumor volume in treatment group/control group)×100]. Pharmacokinetic characteristics were measure in mice receiving a single dose of afatinib (30 mg/kg, ig). Pharmacodynamics of afatinib was also assessed by detecting the expression of pEGFR (Tyr1068) in brain tumor foci using immunohistochemistry. Administration of afatinib (15, 30 mg·kg^-1·d^-1) dose-dependently inhibited PC-9 tumor growth in the brain with a TGI of 90.2% and 105%, respectively, on d 14. After administration of afatinib (30 mg/kg), the plasma concentration of afatinib was 91.4±31.2 nmol/L at 0.5 h, reached a peak (417.1±119.9 nmol/L) at 1 h, and was still detected after 24 h. The cerebrospinal fluid (CSF) concentrations followed a similar pattern. The T_1/2 values of afatinib in plasma and CSF were 5.0 and 3.7 h, respectively. The AUC_{(0-24 h)} values for plasma and CSF were 2375.5 and 29.1 nmol/h, respectively. The plasma and CSF concentrations were correlated (r=0.844, P<0.01). Pharmacodynamics study showed that the expression levels of pEGFR were reduced by 90% 1 h after afatinib administration. The E_max was 86.5%, and the EC₅₀ was 0.26 nmol/L. A positive correlation between CSF concentrations and pEGFR modulation was revealed. Afatinib penetrates the BBB in NSCLC BM mice and contributes to the brain tumor response. The CSF exposure level is correlated with the plasma level, which in turn is correlated with the modulation of pEGFR in the tumor tissues. The results support for the potential application of afatinib in NSCLC patients with BMs.

Capilliposide from Lysimachia capillipes inhibits AKT activation and restores gefitinib sensitivity in human non-small cell lung cancer cells with acquired gefitinib resistance

Most gefitinib-treated patients with non-small cell lung cancer (NSCLC) would eventually develop resistance. Lysimachia capillipes (LC) capilliposide extracts from LC Hemsl. show both in vitro and in vivo anti-cancer effects. In this study we investigated whether LC capilliposide in combination with gefitinib could overcome the resistance of NSCLC cells to gefitinib and identified the signaling pathways involved. Treatment with LC capilliposide alone inhibited the growth of a panel of NSCLC cell lines (PC-9, H460, H1975, H1299 and PC-9-GR) sensitive or resistant to gefitinib with IC₅₀ values in the range of μg/mL. In the gefitinib-resistant PC-9-GR cells (which have a T790M EGFR mutation), LC capilliposide (at the IC30, i.e.1.2 μg/mL) markedly enhanced the inhibitory effects of gefitinib with its IC50 value being decreased from 6.80±1.00 to 0.77±0.12 μmol/L. By using the median effect analysis we showed that combination treatment of LC capilliposide and gefitinib could restore gefitinib sensitivity in PC-9-GR cells. Furthermore, LC capilliposide (1.2 μg/mL) significantly increased the apoptotic responses to gefitinib (0.77 μmol/L) in PC-9-GR cells, but did not affect gefitinib-induced G₀/G₁ arrest. Moreover, LC capilliposide (1.2 μg/mL) in combination with gefitinib (0.77, 1.0 μmol/L) markedly decreased the phosphorylation of the EGFR downstream signaling molecule AKT, which neither LC capilliposide nor gefitinib alone affected. In PC-9-GR cells with siRNA knockdown of AKT, addition of LC capilliposide was unable to increase gefitinib sensitivity. In a PC-9-GR xenograft mouse model, combination treatment with LC capilliposide (15 mg·kg^-1·d^-1, ip) and gefitinib (50 mg·kg^-1·d^-1, ip) dramatically enhanced tumor growth suppression (with a TGI of 109.3%), compared with TGIs of 22.6% and 56.6%, respectively, in mice were treated with LC capilliposide or gefitinib alone. LC capilliposide can restore the cells' sensitivity to gefitinib through modulation of pAKT levels, suggesting that a combination of LC capilliposide and gefitinib may be a promising therapeutic strategy to overcome gefitinib resistance in NSCLCs with a T790M mutation.

Brain Metastases from NSCLC: Radiation Therapy in the Era of Targeted Therapies

Brain metastases (BMs) will develop in a large proportion of patients with NSCLC throughout the course of their disease. Among patients with NSCLC with oncogenic drivers, mainly EGFR activating mutations and anaplastic lymphoma receptor tyrosine kinase gene (ALK) rearrangements, the presence of BM is a common secondary localization of disease both at the time of diagnosis and at relapse. Because of the limited penetration of a wide range of drugs across the blood-brain barrier, radiotherapy is considered the cornerstone of treatment of BMs. However, evidence of dramatic intracranial response rates has been reported in recent years with targeted therapies such as tyrosine kinase inhibitors and has been supported by new insights into pharmacokinetics to increase rates of tyrosine kinase inhibitors' penetration of the cerebrospinal fluid (CSF). In this context, the combination of brain radiotherapy and targeted therapies seems relevant, and there is a strong radiobiological rationale to harness the radiosentizing effect of the drugs. Nevertheless, to date, there is a paucity of high-level clinical evidence supporting the combination of brain radiotherapy and targeted therapies in patients with NSCLC and BMs, and there are often methodological biases in reported studies, such as the lack of stratification by mutation status. Moreover, among asymptomatic patients not suitable for ablative treatment, this strategy is challenged by the promising results associated with the administration of targeted therapies alone. Herein, we review the biological rationale to combine targeted therapies and brain radiotherapy for patients with NSCLC and BMs, report the clinical data available to date, and discuss future directions to improve outcome in this group of patients.

ILKAP, ILK and PINCH1 control cell survival of p53-wildtype glioblastoma cells after irradiation

The prognosis is generally poor for patients suffering from glioblastoma multiforme (GBM) due to radiation and drug resistance. Prosurvival signaling originating from focal adhesion hubs essentially contributes to therapy resistance and tumor aggressiveness. As the underlying molecular mechanisms remain largely elusive, we addressed whether targeting of the focal adhesion proteins particularly interesting new cysteine-histidine-rich 1 (PINCH1), integrin-linked kinase (ILK) and ILK associated phosphatase (ILKAP) modulates GBM cell radioresistance. Intriguingly, PINCH1, ILK and ILKAP depletion sensitized p53-wildtype, but not p53-mutant, GBM cells to radiotherapy. Concomitantly, these cells showed inactivated Glycogen synthase kinase-3β (GSK3β) and reduced proliferation. For PINCH1 and ILKAP knockdown, elevated levels of radiation-induced γH2AX/53BP1-positive foci, as a marker for DNA double strand breaks, were observed. Mechanistically, we identified radiation-induced phosphorylation of DNA protein kinase (DNAPK), an important DNA repair protein, to be dependent on ILKAP. This interaction was fundamental to radiation survival of p53-wildtype GBM cells. Conclusively, our data suggest an essential role of PINCH1, ILK and ILKAP for the radioresistance of p53-wildtype GBM cells and provide evidence for DNAPK functioning as a central mediator of ILKAP signaling. Strategies for targeting focal adhesion proteins in combination with radiotherapy might be a promising approach for patients with GBM.

Variations in EGFR ctDNA Correlates to the Clinical Efficacy of Afatinib in Non Small Cell Lung Cancer with Acquired Resistance

Monitoring of non small cell lung cancer (NSCLC) patients on afatinib after acquired resistance to 1^st generation tyrosine kinase inhibitors is important. Circulating tumor DNA (ctDNA) offers an attractive means other than conventional tissue biopsy to characterize real time dynamic changes of the disease. In our study, we aim to ascertain the clinical value for ctDNA monitoring of NSCLC patients with acquired resistance for afatinib treatment. 200 patients positive for the activating epithermal growth factor receptor (EGFR) mutations were recruited for the study. Baseline molecular profiling for L858R, Exon 19 deletion and T790M were performed. Thereafter, serial blood samples were taken and patients were assessed by overall survival (OS) to determine the usefulness of ctDNA monitoring. At baseline, matched tumor biopsy and ctDNA analysis had a concordance agreement of 93.5% for L858R and exon 19 deletion. We also determined that a large proportion of patients had the drug resistance mutation T790M prior to starting afatinib and these patients were linked to a worse survival outcome. For patients that registered a drop in ctDNA levels after afatinib was administered, we observed that their survival outcome was more favorable (hazard ratio 1.56, (95% CI 1.04 to 2.43). ctDNA levels were mostly elevated after the 3^rd sampling cycle. Our results suggest that ctDNA can be used to predict the clinical benefits of afatinib treatment. Pre and post blood sampling aids to identify patient groups that may benefit most from the treatment and ctDNA is relatively sensitive to address the dynamic changes of the disease at the molecular level.

AT-101 enhances gefitinib sensitivity in non-small cell lung cancer with EGFR T790M mutations

Background

Although epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs) have become the standard care of patients with advanced EGFR-mutant non-small cell lung cancer (NSCLC), development of acquired resistance is inevitable. A secondary mutation of threonine 790 (T790M) is associated with approximately half of the cases of acquired resistance. Strategies or agents to overcome this type of resistance are still limited. In this study, enhanced antitumor effect of AT-101, a-pan-Bcl-2 inhibitor, on gefitinib was explored in NSCLC with T790M mutation.

Methods

The effect of cotreatment with AT-101 and gefitinib on the viability of NSCLC cell lines harboring acquired T790M mutation was investigated using the MTT assay. The cellular apoptosis of NSCLC cells after cotreatment with AT-101 and gefitinib was assessed by FITC-annexin V/PI assay and Western blots analysis. The potential underlying mechanisms of the enhanced therapeutic effect for AT-101 was also studied using Western blots analysis. The in vivo anti-cancer efficacy of the combination with AT-101 and gefitinib was examined in a mouse xenograft model.

Results

In this study, we found that treatment with AT-101 in combination with gefitinib significantly inhibited cell proliferation, as well as promoted apoptosis of EGFR TKIs resistant lung cancer cells. The apoptotic effects of the use of AT-101 was related to the blocking of antiapoptotic protein: Bcl-2, Bcl-xl, and Mcl-1 and downregrulation of the molecules in EGFR pathway. The observed enhancements of tumor growth suppression in xenografts supported the reverse effect of AT-101 in NSCLC with T790M mutation, which has been found in in vitro studies before.

Conclusions

AT-101 enhances gefitinib sensitivity in NSCLC with EGFR T790M mutations. The addition of AT-101 to gefitinib is a promising strategy to overcome EGFR TKIs resistance in NSCLC with EGFR T790M mutations.

miR-29b attenuates tumorigenicity and stemness maintenance in human glioblastoma multiforme by directly targeting BCL2L2

Glioblastoma multiforme (GBM) is the most common malignant brain tumor and exhibits aggressive and invasive behavior. We previously identified four miRNAs—miR-29b, 494, 193a-3p, and 30e—with enhanced expression in GBM following treatment of ionizing radiation by miRNA microarray analysis. In this study, we found that only miR-29b inhibited tumor cell migration and invasion by reducing MMP-2 activity via phospho-AKT/β-catenin signaling, and stimulated a more epithelial-like morphology. Moreover, miR-29b inhibits angiogenesis by attenuating tube formation and the expression of VEGF and Ang-2, and stemness maintenance in GBM cells, as demonstrated by decreasing neurosphere formation and cancer stem cell marker protein expression. These findings support the anti-tumor properties of miR-29b in human GBM cells. Furthermore, miR-29b expression was inversely proportional to that of BCL2L2 mRNA or protein in various cancer cell types. Interestingly, BCL2L2 mRNA is highly expressed in the mesenchymal type of GBM. To further elucidate the relationship between miR-29b and BCL2L2 in GBM, we performed co-transfection reporter assays and determined that miR-29b downregulates BCL2L2 expression by directly binding its 3′UTR. Finally, we confirmed that BCL2L2 repression is of central importance to miR-29b anti-tumor activity using functional assays to examine cell migration, invasion, angiogenesis, and stemness. From these data, we propose that miR-29b may be a useful therapeutic agent in GBM.

Compound Library Screening Identified Cardiac Glycoside Digitoxin as an Effective Growth Inhibitor of Gefitinib-Resistant Non-Small Cell Lung Cancer via Downregulation of α-Tubulin and Inhibition of Microtubule Formation

Non-small-cell lung cancer (NSCLC) dominates over 85% of all lung cancer cases. Epidermal growth factor receptor (EGFR) activating mutation is a common situation in NSCLC. In the clinic, molecular-targeting with Gefitinib as a tyrosine kinase inhibitor (TKI) for EGFR downstream signaling is initially effective. However, drug resistance frequently happens due to additional mutation on EGFR, such as substitution from threonine to methionine at amino acid position 790 (T790M). In this study, we screened a traditional Chinese medicine (TCM) compound library consisting of 800 single compounds in TKI-resistance NSCLC H1975 cells, which contains substitutions from leucine to arginine at amino acid 858 (L858R) and T790M mutation on EGFR. Attractively, among these compounds there are 24 compounds CC50 of which was less than 2.5 μM were identified. We have further investigated the mechanism of the most effective one, Digitoxin. It showed a significantly cytotoxic effect in H1975 cells by causing G2 phase arrest, also remarkably activated 5' adenosine monophosphate-activated protein kinase (AMPK). Moreover, we first proved that Digitoxin suppressed microtubule formation through decreasing α-tubulin. Therefore, it confirmed that Digitoxin effectively depressed the growth of TKI-resistance NSCLC H1975 cells by inhibiting microtubule polymerization and inducing cell cycle arrest.

Combining genomic and network characteristics for extended capability in predicting synergistic drugs for cancer

The identification of synergistic chemotherapeutic agents from a large pool of candidates is highly challenging. Here, we present a Ranking-system of Anti-Cancer Synergy (RACS) that combines features of targeting networks and transcriptomic profiles, and validate it on three types of cancer. Using data on human β-cell lymphoma from the Dialogue for Reverse Engineering Assessments and Methods consortium we show a probability concordance of 0.78 compared with 0.61 obtained with the previous best algorithm. We confirm 63.6% of our breast cancer predictions through experiment and literature, including four strong synergistic pairs. Further in vivo screening in a zebrafish MCF7 xenograft model confirms one prediction with strong synergy and low toxicity. Validation using A549 lung cancer cells shows similar results. Thus, RACS can significantly improve drug synergy prediction and markedly reduce the experimental prescreening of existing drugs for repurposing to cancer treatment, although the molecular mechanism underlying particular interactions remains unknown.

Predicting combinations of chemotherapeutic drugs that act synergistically is challenging. Here the authors take a computational approach to predict synergistic pairs, validate novel pairs using several cancer cell lines, and assess toxicity in a zebrafish xenograft model.

Phosphatidylinositol 3-kinase/Akt signaling as a key mediator of tumor cell responsiveness to radiation

The phosphatidylinositol 3-kinase (PI3K)/Akt pathway is a key cascade downstream of several protein kinases, especially membrane-bound receptor tyrosine kinases, including epidermal growth factor receptor (EGFR) family members. Hyperactivation of the PI3K/Akt pathway is correlated with tumor development, progression, poor prognosis, and resistance to cancer therapies, such as radiotherapy, in human solid tumors. Akt/PKB (Protein Kinase B) members are the major kinases that act downstream of PI3K, and these are involved in a variety of cellular functions, including growth, proliferation, glucose metabolism, invasion, metastasis, angiogenesis, and survival. Accumulating evidence indicates that activated Akt is one of the major predictive markers for solid tumor responsiveness to chemo/radiotherapy. DNA double-strand breaks (DNA-DSB), are the prime cause of cell death induced by ionizing radiation. Preclinical in vitro and in vivo studies have shown that constitutive activation of Akt and stress-induced activation of the PI3K/Akt pathway accelerate the repair of DNA-DSB and, consequently, lead to therapy resistance. Analyzing dysregulations of Akt, such as point mutations, gene amplification or overexpression, which results in the constitutive activation of Akt, might be of special importance in the context of radiotherapy outcomes. Such studies, as well as studies of the mechanism(s) by which activated Akt1 regulates repair of DNA-DSB, might help to identify combinations using the appropriate molecular targeting strategies with conventional radiotherapy to overcome radioresistance in solid tumors. In this review, we discuss the dysregulation of the components of upstream regulators of Akt as well as specific modifications of Akt isoforms that enhance Akt activity. Likewise, the mechanisms by which Akt interferes with repair of DNA after exposure to ionizing radiation, will be reviewed. Finally, the current status of Akt targeting in combination with radiotherapy will be discussed.