Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors Gefitinib Research Articles

Transtinib, a potent tyrosine kinase inhibitor inhibits L858R/T790M mutant NSCLC cell lines and xenografts

Non-small cell lung cancer (NSCLC) patients with activating epidermal growth factor receptor (EGFR) mutations initially respond well to the EGFR tyrosine kinase inhibitors (TKIs) erlotinib and gefitinib. However, clinical efficacy is limited by the development of resistance. In most cases, this resistance is in the form of the T790M mutation. Here, we report the design, synthesis and biochemical evaluation of a novel series of irreversible EGFR tyrosine kinase inhibitors (EGFR-TKIs) that are derived from the anilinoquinazoline scaffold. Guided by molecular modeling, this series of analogs was evolved to target a cysteine residue in the ATP binding site via covalent bond formation and to achieve high levels of anti-tumor activity in cell cultures and in xenografts. The most promising compound 13c ((E) –N - (4 - (4 - (3-fluorobenzyloxy) -3- chlorophenylamino) -7-ethoxyquinazolin-6-yl) -3- ((S) -pyrrolidin-2-yl)acrylamide, which we named Transtinib) displayed strong anti-proliferative activity against the H1975 and A431 cell lines with IC50 values of 34 nM and 62 nM, respectively. In xenograft models, Transtinib significantly decreases tumor size for a prolonged period of time. These results suggest that Transtinib is a potential cancer therapeutic drug lead for the inhibition of mutant EGFR to overcome the development of resistance.

The P21-activated kinase expression pattern is different in non-small cell lung cancer and affects lung cancer cell sensitivity to epidermal growth factor receptor tyrosine kinase inhibitors.

Exploring methods for increasing epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) sensitivity has become a major focus in non-small cell lung cancer (NSCLC). Major downstream effectors of the Rho family small guanosine triphosphatases, P21-activated kinases (PAKs) activate the main signaling pathways downstream of EGFR and thus promote tumor cell proliferation. In this study, we explored the expression pattern of phosphorylated PAKs in NSCLC and their potential value as drug targets for treating cancer. The expression and prognostic significance of phosphorylated group I and II PAKs were evaluated in 182 patients with NSCLC. Immunohistochemical analysis revealed low group I PAK expression in normal lung tissues and increased expressed in the cytoplasm, particularly in lung squamous cell carcinoma. Abnormal group I PAK expression was associated with lymph node metastases and high tumor-node-metastases (TNM) stage in NSCLC patients and correlated with poor prognosis. We used group I PAK inhibitor (IPA3) to specifically decrease group I PAK activity in human lung cancer cell lines. Decreased group I PAK activity inhibited cell proliferation and combined IPA3 and EGFR-TKI (gefitinib) treatment inhibited cell proliferation in an obvious manner. Together, our results revealed the PAK expression pattern in NSCLC, and a role for group I PAK in cell proliferation, which provides evidence that decreased PAK activity may have a potential application as a molecular targeted therapy in advanced NSCLC.

Treatment and prognosis after progression in long-term responders to EGFR-tyrosine kinase inhibitor in advanced non-small cell lung cancer.

IntroductionThe aim of this study was to investigate the treatment and prognosis of advanced non-small cell lung cancer (NSCLC) patients after failure of long-term treatment with epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI).Material and methodsWe retrospectively analyzed all NSCLC patients with EGFR-TKI (gefitinib or erlotinib) treatment at our institution between 2011 and 2013 who progressed after at least stable disease on erlotinib or gefitinib for more than 6 months. Survival curves were plotted using the Kaplan-Meier method. The Cox proportional hazard model was used for multivariate analysis.ResultsIn total, 521 patients were administered EGFR-TKI. Of these, 298 patients received EGFR-TKI with progression-free survival less than 6 months (group A), and the other 223 patients more than 6 months (group B). There was a significant difference in overall survival (OS) between group A and group B (7.2 months vs. 5.0 months, p < 0.0001). The median OS for group B patients was 5.0 months. Among the 223 patients in group B, 38 patients received chemotherapy with continued EGFR-TKI after failure of prior gefitinib or erlotinib treatment, 92 with chemotherapy alone and 93 with best supportive care. Patients who continued gefitinib or erlotinib had a significantly longer OS (median: 7.5 months), followed by chemotherapy (5.5 months) and best supportive care (4.0 months) (p < 0.001).ConclusionsThe prognosis of advanced NSCLC patients after failure of long-term treatment with EGFR-TKI was poor. Chemotherapy with continued EGFR-TKI beyond progression of long-term responders was feasible and led to prolonged OS in advanced NSCLC patients.

Abstract A171: Targeting tumor metabolism by novel EGFR inhibitor in head and neck cancer

Abstract Cellular metabolism is substantially altered during tumor progression, and associated with poor prognosis and therapeutic resistance of human cancers. Therefore, the metabolic rewiring of cancer cells has been viewed as a promising source for novel drug targets, and being actively pursued in the development of selective antineoplastic agents. EGFR targeted agents currently approved or under investigation for head and neck squamous cell carcinoma (HNSCC) include EGFR monoclonal antibodies or EGFR tyrosine kinase inhibitors (EGFR-TKI). However, HNSCC patients failing to these agents treatment, due to the development of acquired tumor resistance, will have a compromised survival. We have identified a novel EGFR-TKI, BPR3K007S0. Based on the EC50 in enzyme-based assay of wild-type EGFR &amp; EGFR mutant L858R protein, BPR3K007S0 is more effective than that of clinical used EGFR-TKI gefitinib (Iressa). We further evaluated the drug effects on EGFR phosphorylation in HNSCC cells, and found that BPR3K007S0 inhibited phosphorylation of EGFR in a time-dependent manner. Further study demonstrated that BPR3K007S0 decreased HNSCC cell proliferation and colony formation by causing G1-phase arrest, which was strongly associated with a marked decrease of the level of cyclin E and cdk2 with concomitant induction of p21 and p27. Notably, BPR3K007S0 showed much potent effect toward cell growth in vitro and in vivo than that of gefitinib in HNSCC cells, implicating that the anticancer effect of BPR3K007S0 is not limited to EGFR inhibition. More importantly, we found that BPR3K007S0 significantly suppressed the expression of a wide range of metabolic genes. Among them, the levels of c-Myc and hexokinase 2 were significantly decreased in a time-dependent manner by treatment with BPR3K007S0. Gene manipulation study demonstrated that knockdown of c-Myc leads to a decreased level of hexokinase 2. In this system, silence of EGFR did not affect c-Myc expression, suggesting that c-Myc may not be the EGFR downstream target in used HNSCC cells. Taken together, these results revealed that BPR3K007S0 has added benefits by targeting of EGFR and cancer metabolism, and are likely to be superior to gefitinib in HNSCC models. Thus, development of multi-kinase and metabolic inhibitors holds promises for overcoming treatment resistance of HNSCC. (Grant support: DOH102-TD-M-111-102001) Citation Format: Ching-Chuan Kuo, Hsing-Pang Hsieh, Hsing-Jien Kung. Targeting tumor metabolism by novel EGFR inhibitor in head and neck cancer. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr A171.

LXR ligands sensitize EGFR-TKI-resistant human lung cancer cells in vitro by inhibiting Akt activation

Lung adenocarcinoma cells harboring epidermal growth factor receptor (EGFR) mutations are sensitive to EGFR tyrosine kinase inhibitors (TKIs). Prolonged cancer treatment will induce the development of acquired resistance to EGFR TKI. Here we investigate the effects of two novel liver x receptor (LXR) ligands (T0901317 or GW3965) on the development of acquired resistance to an EGFR TKI gefitinib. We observed known mechanisms of acquired resistance to EGFR TKI, including the EGFR T790M mutation, MET gene amplification and loss of PTEN in the gefitinib-resistant HCC827-8-1 cells. However, we found expression of MET was lower in HCC827-8-1 cells than in HCC827 cells. T0901317 or GW3965 inhibited Akt activation and sensitized HCC827-8-1 cells to gefitinib-induced cytotoxicity. In contrast, LXR ligands alone had no significant effect on HCC827-8-1 cells. In conclusion, this combined treatment may be of interest for treatment of lung adenocarcinomas harboring EGFR mutations and acquired resistance to gefitinib.

RECIST progression patterns during EGFR tyrosine kinase inhibitor treatment of advanced non-small cell lung cancer patients harboring an EGFR mutation.

Progression patterns at the response evaluation criteria in solid tumors-progressive disease (RECIST-PD) during treatment with epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) for advanced non-small cell lung cancer (NSCLC) in patients harboring an EGFR mutation are clinically heterogeneous. We evaluated the association between progression patterns during EGFR-TKI treatment and prognosis after treatment in such patients. From 2008 to 2012, 160 consecutive patients with advanced NSCLC harboring an EGFR mutation were treated with EGFR-TKIs (erlotinib or gefitinib). Among these, 104 who experienced RECIST-PD were retrospectively evaluated for initial response to EGFR-TKIs, progression sites, focus of progression (solitary lesion or multiple lesions), symptom status at RECIST-PD evaluation, and post-progression survival (PPS). Of 104 patients, 96 (92%) had an EGFR major mutation, and 50 (48%) received EGFR-TKIs as first-line treatment. Overall response rate and median time to RECIST-PD on EGFR-TKIs were 68% and 8.2 months, respectively. At the time of attaining RECIST-PD status, 44 (42%) patients were symptomatic, and 60 (58%) were asymptomatic. Progression sites at RECIST-PD were isolated brain in 17 (16%) patients and systemic in 87 (84%): 24 (23%) had a solitary lesion, and 80 (77%) had multiple lesions. After RECIST-PD assessment, 40 (38%) patients continued EGFR-TKIs, and 25 (24%) switched to cytotoxic agents; 10 (10%) received local radiotherapy for an isolated progression site (brain 6; bone 3; lung 1). Median PPS was 10.8 months. Multivariate analysis revealed that asymptomatic or solitary lesion status was associated with significantly longer PPS (asymptomatic: HR 0.36, 95% CI 0.21-0.62, P<0.01; solitary progression lesion: HR 0.45, 95% CI 0.18-99, P=0.04). Progression patterns at the RECIST-PD during EGFR-TKI treatment of advanced NSCLC in patients harboring an EGFR mutation are widely diverse, and might be associated with clinical outcome after treatment failure.

Contrasting Effects of the Cytotoxic Anticancer Drug Gemcitabine and the EGFR Tyrosine Kinase Inhibitor Gefitinib on NK Cell-Mediated Cytotoxicity via Regulation of NKG2D Ligand in Non-Small-Cell Lung Cancer Cells.

IntroductionSeveral cytotoxic anticancer drugs inhibit DNA replication and/or mitosis, while EGFR tyrosine kinase inhibitors inactivate EGFR signalling in cancer cell. Both types of anticancer drugs improve the overall survival of the patients with non-small-cell lung cancer (NSCLC), although tumors often become refractory to this treatment. Despite several mechanisms by which the tumors become resistant having been described the effect of these compounds on anti-tumor immunity remains largely unknown.MethodsThis study examines the effect of the cytotoxic drug Gemcitabine and the EGFR tyrosine kinase inhibitor Gefitinib on the expression of NK group 2 member D (NKG2D) ligands as well as the sensitivity of NSCLC cells to the NK-mediated lysis.ResultsWe demonstrate that Gemcitabine treatment leads to an enhanced expression, while Gefitinib downregulated the expression of molecules that act as key ligands for the activating receptor NKG2D and promote NK cell-mediated recognition and cytolysis. Gemcitabine activated ATM and ATM- and Rad-3-related protein kinase (ATR) pathways. The Gemcitabine-induced phosphorylation of ATM as well as the upregulation of the NKG2D ligand expression could be blocked by an ATM-ATR inhibitor. In contrast, Gefitinib attenuated NKG2D ligand expression. Silencing EGFR using siRNA or addition of the PI3K inhibitor resulted in downregulation of NKG2D ligands. The observations suggest that the EGFR/PI3K pathway also regulates the expression of NKG2D ligands. Additionally, we showed that both ATM-ATR and EGFR regulate MICA/B via miR20a.ConclusionIn keeping with the effect on NKG2D expression, Gemcitabine enhanced NK cell-mediated cytotoxicity while Gefitinib attenuated NK cell killing in NSCLC cells.

Lysophosphatidic acid induces both EGFR-dependent and EGFR-independent effects on DNA synthesis and migration in pancreatic and colorectal carcinoma cells.

Lysophosphatidic acid (LPA) is a small glycerophospholipid ubiquitously present in tissues and plasma. It acts through receptors belonging to the G-protein-coupled receptor (GPCR) family, is involved in several biological processes, and is strongly implicated in different cancers. In this paper, we have investigated the effects of LPA on DNA synthesis and migration in a panel of pancreatic and colon cancer cells, with particular focus on the involvement of the epidermal growth factor (EGF) receptor (EGFR) in LPA-induced signaling. LPA stimulated DNA synthesis and/or migration in all the cell lines included in this study. In five of the six cell lines, LPA induced phosphorylation of the EGFR, and the effects on EGFR and Akt, and in some of the cells also ERK, were sensitive to the EGFR tyrosine kinase inhibitor gefitinib, strongly suggesting LPA-induced EGFR transactivation in these cells. In contrast, in one of the pancreatic carcinoma cell lines (Panc-1), we found no evidence of transactivation of the EGFR. In the pancreatic carcinoma cell lines where transactivation took place (BxPC3, AsPC1, HPAFII), gefitinib reduced LPA-induced DNA synthesis and/or migration. However, we also found evidence of transactivation in the two colon carcinoma cell lines (HT29, HCT116) although gefitinib did not inhibit LPA-induced DNA synthesis or migration in these cells. Taken together, the data indicate that in many gastrointestinal carcinoma cells, LPA uses EGFR transactivation as a mechanism when exerting such effects as stimulation of cell proliferation and migration, but EGFR-independent pathways may be involved instead of, or in concerted action with, the EGFR transactivation.

Src inhibitors act through different mechanisms in Non-Small Cell Lung Cancer models depending on EGFR and RAS mutational status

Resistance to the EGFR tyrosine kinase inhibitors (TKIs) gefitinib and erlotinib, often related to Ras or secondary EGFR mutations, is a relevant clinical issue in Non-Small Cell Lung Cancer (NSCLC). Although Src TK has been involved in such resistance, clinical development of its inhibitors has been so far limited. To better define the molecular targets of the Src TKIs saracatinib, dasatinib and bosutinib, we used a variety of in vitro/in vivo studies. Kinase assays supported by docking analysis demonstrated that all the compounds directly inhibit EGFR TK variants. However, in live cells only saracatinib efficiently reduced EGFR activation, while dasatinib was the most effective agent in inhibiting Src TK. Consistently, a pronounced anti-proliferative effect was achieved with saracatinib, in EGFR mutant cells, or with dasatinib, in wt EGFR/Ras mutant cells, poorly dependent on EGFR and erlotinib-resistant. We then identified the most effective drug combinations to overcome resistance to EGFR inhibitors, both in vitro and in nude mice: in T790M EGFR erlotinib-resistant cells, saracatinib with the anti-EGFR mAb cetuximab; in Ras mutant erlotinib-resistant models, dasatinib with the MEK inhibitor selumetinib. Src inhibitors may act with different mechanisms in NSCLCs, depending on EGFR/Ras mutational profile, and may be integrated with EGFR or MEK inhibitors for different cohorts of NSCLCs.

Abstract 752: Elucidating the mechanisms of acquired resistance in lung adenocarcinomas

Abstract In EGFR mutant lung adenocarcinomas, targeted therapy with the EGFR tyrosine kinase inhibitors (TKIs) erlotinib, gefitinib, and afatinib performs better than standard chemotherapy in terms of progression free survival (PFS) and radiographic response (RR) rates. In the ALK rearranged cases, targeted therapy with crizotinib is associated with PFS of about 9,7 months and RR of 60.8%. Unfortunately, all patients relapse with a median PFS of 7 to 16 months. The mechanisms of acquired resistance to first generation EGFR TKIs include a secondary EGFR mutation (T790M) in about 50% and, with less frequency, MET amplification, HER2 amplification, PTEN loss, transformation to small cell histology, EMT and rare mutations in BRAF and PI3KCA. Resistance to crizotinib is caused by ALK kinase mutations, by ALK or cKIT amplification or by alterations in IGF1R/IRS1, EGFR and KRAS. Here, we made use of next generation sequencing techniques to better understand the mechanisms that drive resistance in lung adenocarcinomas treated with erlotinib or crizotinib. To this aim, we used rebiopsy samples from patients that had either prolonged stable disease or partial response to therapy, and developed radiographic progression under TKI therapy. To model the emergence of resistance mechanisms in vitro, we generated resistant cell lines to a variety of ALK inhibitors. Patient samples and resistant cell lines that were negative for any of the previously reported mechanisms of resistance were analyzed by genome or exome; validation of mutation calls was performed by Sanger sequencing. Sequencing of the erlotinib resistant samples revealed a deletion in the transmembrane domain of ABCD4, an ATP-binding cassette (ABC) transporter. Stable transduction of this mutation in BaF3 cells, showed that neither the expression of ABCD4 nor the mutation resulted in a reduced sensitivity to erlotinib. Results of the functional validation of a mutation found in a Fms-related tyrosine kinase are currently ongoing. Crizotinib resistant samples showed a mutation in the IPT/TIG domain of the RON kinase that, when expressed in sensitive cells, did not confer resistance to crizotinib. However, a mutation in the PSI domain of the semaphorin SEMA3E lead to an prologned Akt activation, thus sustained downstream PI3K signaling in cells treated with crizotinib. The molecular mechanisms behind this finding are being analyzed. Crizotinib resistant samples also showed mutations in SWI/SNF-regulator of chromatin and a GTPase of the Rab family. Cells resistant to different ALK inhibitors harbor mutations in a mitogen activated protein kinase and an ephrin receptor, among others. The functional impact of such mutations and the efficacy of combination therapies in the setting of resistance to these inhibitors are currently being tested. Our results imply a wide range of cellular pathways might be involved in the process of acquired resistance to EGFR and ALK inhibitors in lung adenocarcinomas. Citation Format: Sandra Ortiz-Cuarán, Lynnette Fernandez-Cuesta, Christine M. Lovly, Marc Bos, Matthias Scheffler, Sebastian Michels, Kerstin Albus, Lydia Meyer, Katharina König, Ilona Dahmen, Christian Mueller, Luca Ozretić, Lars Tharun, Philipp Schaub, Alexandra Florin, Berit Pinther, Nike Bahlmann, Sascha Ansén, Martin Peifer, Lukas C. Heukamp, Reinhard Buettner, Martin L. Sos, Jürgen Wolf, William Pao, Roman K. Thomas. Elucidating the mechanisms of acquired resistance in lung adenocarcinomas. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 752. doi:10.1158/1538-7445.AM2015-752

Abstract 2591: Activity of MSC2156119J in non-small cell lung cancer models with activating EGFR mutation

Abstract The therapeutic success of EGFR tyrosine kinase inhibitors (TKIs) in EGFR-mutant non-small cell lung cancer (NSCLC) is hampered in a subset of patients by the development of drug resistance through the EGFR T790M ‘gate keeper’ mutation. Recent investigations suggest that aberrant activation of the c-Met receptor through c-Met amplification and/or HGF upregulation may be an additional mechanism for acquired resistance. Combination of an EGFR TKI with a c-Met inhibitor could, therefore, delay and/or prevent the emergence of c-Met-driven resistance. The aim of our study was to evaluate the efficacy of MSC2156119J, a highly selective small molecule c-Met inhibitor, as monotherapy or in combination with EGFR TKIs (erlotinib, gefitinib and afatinib) in human xenograft models transplanted with two different primary NSCLC explants, LU342 and LU0858. While both tumors express the activated EGFR mutant form, LU342 expresses low levels of c-Met, while LU0858 expresses high levels of c-Met and carries an amplified c-Met locus. Single-agent MSC2156119J was inactive against the low c-Met-expressing LU342 explant and tumors progressed on treatment (median tumor volume [TV] change &amp;gt;73%). Erlotinib treatment resulted in tumor regression, with median TV change of -93% and tumor growth delay (TGD) of 56 days. The combination of MSC2156119J and erlotinib was more active, delaying tumor regrowth by 73 days compared to erlotinib monotherapy. Administration of afatinib at 5mg/kg was highly active in this model, inducing complete tumor regression (median TV change -100%), similar to the combination of afatinib and MSC2156119J. In contrast, the LU0858 explant, which carries an amplified c-Met locus, was sensitive to MSC2156119J at a dose of 100mg/kg 5 days on and 2 days off (5 on/2 off), inducing tumor stasis with a median TV change of 19% and TGD of 34 days. While gefitinib and afatinib alone at doses of 150mg/kg 5 on/2 off and 5mg/kg 5 on/2 off, respectively, were inactive (median TV changes &amp;gt;73%), in combination with MSC2156119J tumor growth inhibition was enhanced, resulting in tumor regression (median TV changes of -64% and -85%, respectively). In comparison, tumors treated with platinum-based doublet chemotherapy (cisplatin 5mg/kg QW/pemetrexed 200mg/kg QW) progressed, with TGD of 16 days. When MSC2156119J was combined with cisplatin/pemetrexed, antitumor activity was not significantly enhanced compared to single-agent MSC2156119J (median TV change -32%, TGD 30 days). Together, these findings are compatible with the hypothesis that inhibition of the c-Met pathway prevents and/or delays the emergence of c-Met-driven resistance in EGFR-mutant NSCLC. Furthermore, the enhancement of antitumor activity in the low c-Met-expressing LU342 model when MSC2156119J was combined with erlotinib suggests that the combination of an EGFR TKI + MSC2156119J may also be active in tumors with low levels of c-Met expression. Citation Format: Friedhelm Bladt, Manja Friese-Hamim, Andree Blaukat. Activity of MSC2156119J in non-small cell lung cancer models with activating EGFR mutation. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2591. doi:10.1158/1538-7445.AM2015-2591

Identifying activating mutations in the EGFR gene: prognostic and therapeutic implications in non-small cell lung cancer.

Lung cancer is the leading cause of cancer-related deaths worldwide. Promising new therapies have recently emerged from the development of molecular targeted drugs; particularly promising are those blocking the signal transduction machinery of cancer cells. One of the most widely studied cell signaling pathways is that of EGFR, which leads to uncontrolled cell proliferation, increased cell angiogenesis, and greater cell invasiveness. Activating mutations in the EGFR gene (deletions in exon 19 and mutation L858R in exon 21), first described in 2004, have been detected in approximately 10% of all non-squamous non-small cell lung cancer (NSCLC) patients in Western countries and are the most important predictors of a response to EGFR tyrosine-kinase inhibitors (EGFR-TKIs). Studies of the EGFR-TKIs gefitinib, erlotinib, and afatinib, in comparison with platinum-based regimens, as first-line treatments in chemotherapy-naïve patients have shown that the EGFR-TKIs produce gains in progression-free survival and overall response rates, although only in patients whose tumors harbor activating mutations in the EGFR gene. Clinical trials have also shown EGFR-TKIs to be effective as second- and third-line therapies in advanced NSCLC. Here, we review the main aspects of EGFR pathway activation in NSCLC, underscore the importance of correctly identifying activating mutations in the EGFR gene, and discuss the main outcomes of EGFR-TKI treatment in NSCLC.

T-Darpp Promotes Enhanced EGFR Activation and New Drug Synergies in Her2-Positive Breast Cancer Cells.

Trastuzumab has led to improved survival rates of HER2+ breast cancer patients. However, acquired resistance remains a problem in the majority of cases. t-Darpp is over-expressed in trastuzumab-resistant cell lines and its over-expression is sufficient for conferring the resistance phenotype. Although its mechanism of action is unknown, t-Darpp has been shown to increase cellular proliferation and inhibit apoptosis. We have reported that trastuzumab-resistant BT.HerR cells that over-express endogenous t-Darpp are sensitized to EGFR inhibition in the presence (but not the absence) of trastuzumab. The purpose of the current study was to determine if t-Darpp might modulate sensitivity to EGFR inhibitors in trastuzumab-resistant cells. Using EGFR tyrosine kinase inhibitors AG1478, gefitinib and erlotinib, we found that trastuzumab-resistant SK.HerR cells were sensitized to EGFR inhibition, compared to SK-Br-3 controls, even in the absence of trastuzumab. t-Darpp knock-down in SK.HerR cells reversed their sensitivity to EGFR inhibition. Increased EGFR sensitivity was also noted in SK.tDp cells that stably over-express t-Darpp. High levels of synergy between trastuzumab and the EGFR inhibitors were observed in all cell lines with high t-Darpp expression. These cells also demonstrated more robust activation of EGFR signaling and showed greater EGFR stability than parental cells. The T75A phosphorylation mutant of t-Darpp did not confer sensitivity to EGFR inhibition nor activation of EGFR signaling. The over-expression of t-Darpp might facilitate enhanced EGFR signaling as part of the trastuzumab resistance phenotype. This study suggests that the presence of t-Darpp in HER2+ cancers might predict the enhanced response to dual HER2/EGFR targeting.

A decade of EGFR inhibition in EGFR-mutated non small cell lung cancer (NSCLC): Old successes and future perspectives.

The discovery of Epidermal Growth Factor Receptor (EGFR) mutations in Non Small Cell Lung Cancer (NSCLC) launched the era of personalized medicine in advanced NSCLC, leading to a dramatic shift in the therapeutic landscape of this disease. After ten years from the individuation of activating mutations in the tyrosine kinase domain of the EGFR in NSCLC patients responding to the EGFR tyrosine kinase inhibitor (TKI) Gefitinib, several progresses have been done and first line treatment with EGFR TKIs is a firmly established option in advanced EGFR-mutated NSCLC patients. During the last decade, different EGFR TKIs have been developed and three inhibitors have been approved so far in these selected patients. However, despite great breakthroughs have been made, treatment of these molecularly selected patients poses novel therapeutic challenges, such as emerging of acquired resistance, brain metastases development or the need to translate these treatments in earlier clinical settings, such as adjuvant therapy. The aim of this paper is to provide a comprehensive review of the major progresses reported so far in the EGFR inhibition in this molecularly-selected subgroup of NSCLC patients, from the early successes with first generation EGFR TKIs, Erlotinib and Gefitinib, to the novel irreversible and mutant-selective inhibitors and ultimately the emerging challenges that we, in the next future, are called to deal with.

Whacking a mole-cule: clinical activity and mechanisms of resistance to third generation EGFR inhibitors in EGFR mutated lung cancers with EGFR-T790M.

Epidermal growth factor receptor (EGFR) mutations, especially EGFR-exon 19 deletions and EGFR-L858R, are the most frequent actionable genomic events in lung adenocarcinomas. Tumors arise due to constitutively activated EGFR signaling and are susceptible to EGFR tyrosine kinase inhibitors (TKIs). First generation EGFR TKIs (gefitinib and erlotinib) and the second generation EGFR TKI afatinib are approved worldwide. Although targeted therapies against EGFR mutants induce dramatic initial responses, acquired resistance (through multiple biological mechanisms) to erlotinib, gefitinib and afatinib emerges within the first 1-2 years of continued monotherapy. EGFR-T790M accounts for more than half of acquired resistance to first or second generation EGFR TKIs by modifying ATP affinity and drug binding kinetics. Two new studies have shown that two covalent pyrimidine inhibitors-AZD9291 and rociletinib of EGFR-T790M (i.e., third generation EGFR TKIs) shown remarkable clinical activity in patients with acquired resistance to erlotinib, gefitinib and afatinib when the tumor carries EGFR-T790M in conjunction with an activating mutation. However, and regrettably, acquired resistance to these third generation EGFR TKIs has already been reported in preclinical models and clinical specimens; such as a tertiary mutation at EGFR-C797S that prevents covalent binding of EGFR TKIs. The experience with sequential EGFR TKI monotherapy highlights tumor heterogeneity and adaptability (i.e., relentless game of whack-a-mole played between TKIs and cancer), and will help shape future clinical development of novel combinatory approaches to manage EGFR mutated lung adenocarcinomas.

The BIM Deletion Polymorphism and its Clinical Implication in Patients with EGFR-Mutant Non–Small-Cell Lung Cancer Treated with EGFR Tyrosine Kinase Inhibitors

A germline BIM deletion polymorphism has been proposed to predict poor treatment response to certain kinase inhibitors. The purpose of this study was to explore whether the BIM deletion polymorphism predicts treatment efficacy of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in Korean patients with EGFR-mutant non-small-cell lung cancer (NSCLC). Peripheral blood samples from a total of 205 patients with EGFR-mutant NSCLC who were treated with EGFR TKIs between July 2008 and April 2013 were included. The incidence of BIM deletions in these samples was detected by polymerase chain reaction. We compared the clinical outcomes in patients with and without the polymorphism after treatment with EGFR TKIs (gefitinib or erlotinib). The BIM deletion polymorphism was present in 15.6% (32 of 205) of patients. One patient was homozygous for the deletion, and the remaining 31 had heterozygous deletions. The majority of patients were younger than 65 years (74%), female (68%), never smokers (76%), and had stage IV NSCLC (67%). There were no associations between the BIM deletion polymorphism and clinicopathological features including gender, age, smoking status, histology, stage, and number of metastasis sites. Patients with and without the BIM deletion polymorphism had similar objective response rates (91 vs. 84%, p = 0.585). Progression-free survival and overall survival did not differ significantly between patients with and without the BIM deletion polymorphism (median progression-free survival 12 vs. 11 months, p = 0.160; median overall survival 31 vs. 30 months, p = 0.452). Multivariate analysis identified significantly predictive markers for clinical outcomes of EGFR TKIs including Eastern Cooperative Oncology Group performance status 0-1, adenocarcinoma histology, recurrent disease, and EGFR mutation type. The results were validated in an independent cohort of 69 NSCLC patients. It remains to be determined whether the BIM deletion polymorphism provides intrinsic resistance or decreased sensitivity to EGFR TKIs in EGFR-mutant NSCLC patients.

EGFR: The Paradigm of an Oncogene-Driven Lung Cancer.

Somatic, activating mutations in EGFR identify a significant minority of patients with non-small cell lung cancer (NSCLC). Although these mutations are associated with an approximately 70% response rate to some EGFR tyrosine kinase inhibitors (gefitinib, erlotinib, and afatinib), patients develop resistance (i.e., "acquired resistance") after a median of 9 to 12 months. In patients with clinical acquired resistance, repeat biopsy of tumors has identified a number of relevant mechanisms of resistance, but by far the most frequent event is the acquisition of EGFR T790M, a mutation in the "gatekeeper" residue that confers resistance to gefitinib, erlotinib, and afatinib. This emphasizes the critical dependence upon EGFR signaling for some tumors, a property that has been exploited therapeutically. Dual EGFR blockade using afatinib and cetuximab led to a 29% radiographic response rate. More recently, drugs that target EGFR T790M (e.g., rociletinib, AZD9291, and others) have entered clinical trials, with impressive results observed in phase I clinical trials. The development of these newer drugs, with efficacy after resistance to first-line EGFR tyrosine kinase inhibitor, has led to exploration of these strategies in multiple disease settings: at resistance, in the first line, and in adjuvant treatment of those with completely resected early-stage disease who would otherwise die of recurrent/metastatic disease. This example of translational research that identifies mechanisms of resistance to first-generation drugs, and then targets those mechanisms yielding clinical benefit, is a paradigm for how targeted therapies can be developed.

Combined effects of EGFR tyrosine kinase inhibitors and vATPase inhibitors in NSCLC cells

Despite excellent initial clinical responses of non-small cell lung cancer (NSCLC) patients to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), many patients eventually develop resistance. According to a recent report, vacuolar H+ ATPase (vATPase) is overexpressed and is associated with chemotherapy drug resistance in NSCLC. We investigated the combined effects of EGFR TKIs and vATPase inhibitors and their underlying mechanisms in the regulation of NSCLC cell death. We found that combined treatment with EGFR TKIs (erlotinib, gefitinib, or lapatinib) and vATPase inhibitors (bafilomycin A1 or concanamycin A) enhanced synergistic cell death compared to treatments with each drug alone. Treatment with bafilomycin A1 or concanamycin A led to the induction of Bnip3 expression in an Hif-1α dependent manner. Knock-down of Hif-1α or Bnip3 by siRNA further enhanced cell death induced by bafilomycin A1, suggesting that Hif-1α/Bnip3 induction promoted resistance to cell death induced by the vATPase inhibitors. EGFR TKIs suppressed Hif-1α and Bnip3 expression induced by the vATPase inhibitors, suggesting that they enhanced the sensitivity of the cells to these inhibitors by decreasing Hif-1α/Bnip3 expression. Taken together, we conclude that EGFR TKIs enhance the sensitivity of NSCLC cells to vATPase inhibitors by decreasing Hif-1α/Bnip3 expression. We suggest that combined treatment with EGFR TKIs and vATPase inhibitors is potentially effective for the treatment of NSCLC.

GEFITINIB (IRESSA) IN THE TREATMENT OF BRAIN METASTASES FROM NON-SMALL CELL LUNG CARCINOMA

Since 2006, the N.N. Blokhin Russian Cancer Research Center, Russian Academy of Medical Sciences, has been conducting an investigation of the efficiency of targeted therapy with gefitinib in patients with brain metastasis from non-small cell lung carcinoma (NSCLC). The evaluation of treatment efficiency in 9 patients with tumor EGFR mutation in NSCLC revealed that 1 (11.1 %) and 5 (55.6 %) patients achieved complete and partial regression, respectively; disease stabilization was observed in 3 (33.3 %). The median time to progression was 7 months; the patients did not achieve the median survival. The evaluation of treatment efficiency in a group of 6 patients without tumor EGFR mutation or its evidence showed complete and partial tumor regressions; disease stabilization was noted in 3 (50.0 %); disease progression was in 3 (50 %). The median time to progression was 2 months; the median survival was 5 months. Thus, the high efficiency of treatment with the EGFR inhibitor gefitinib in patients with brain metastases from NSCLS was achieved only in a group of patients with found ECFR mutations in exons 18–21 in the tumor. Determination of the status of ECFR in the tumor is the most important prognostic factor when using therapy with the EGFR tyrosine kinase inhibitor gefitinib in patients with brain metastases. The investigation is being continued.

Fuzheng Kang'ai decoction combined with gefitinib in advanced non-small cell lung cancer patients with epidermal growth factor receptor mutations: study protocol for a randomized controlled trial.

BackgroundPatients with advanced non-small cell lung cancer (NSCLC) harboring mutations of the epidermal growth factor receptor (EGFR) gene respond well to the EGFR tyrosine kinase inhibitor (TKI) gefitinib. Chinese herbal medicine (CHM) has been used as a complementary therapy for cancer for decades in China. CHM was proved to be effective in improving the quality of life (QOL) and reducing the toxicity associated with chemotherapy in patients with NSCLC. The purpose of the present trial is to determine whether CHM (Fuzheng Kang’ai decoction (FZKA), a CHM formula) combined with gefitinib results in longer progression-free survival with less toxicity than gefitinib alone.Methods/DesignThis is a randomized, placebo-controlled, double-blind trial. This trial is designed to determine if CHM (FZKA) combined with gefitinib results in longer progression-free survival with less toxicity than gefitinib alone. A total of 70 NSCLC patients with EGFR mutations will be randomly assigned to treatment group (gefitinib plus FZKA granules) or control group (gefitinib plus placebo). The primary endpoint is progression-free survival. Secondary endpoints are: (1) overall survival; (2) disease control rate; (3) QOL, measured with the questionnaire of Functional Assessment of Cancer Therapy-lung (FACT-L 4.0) and Lung Cancer Symptom Scale and (4) safety.DiscussionIn previous clinical practice, we found that CHM (FZKA) could improve the therapeutic efficacy of gefitinib. This study will provide objective evidence to evaluate the efficiency of CHM combined with gefitinib in NSCLC patients with EGFR mutations, and may provide a novel regimen for patients with NSCLC.Trial registrationChinese Clinical Trial Registry (www.chictr.org): ChiCTR-IOR-14005679, registered 17 December 2014.