A pilot study of preoperative gefitinib for early-stage lung cancer to assess intratumor drug concentration and pathways mediating primary resistance

68Ga labeled Olmutinib: Design, synthesis, and evaluation of a novel PET EGFR probe

Radiolabeled tyrosine kinase inhibitors (TKIs) offer a promising approach for molecular imaging of EGFR-positive cancers. Despite the development of various EGFR small-molecule probes, none of the 68Ga-labeled small-molecule probes based on the chelator DOTA have shown tumor-specific uptake. To address this challenge, we selected Olmutinib, a third-generation EGFR covalent inhibitor, as a PET imaging tracer for EGFR-positive tumors. We synthesized the precursor DOTA-Olmutinib through a five-step process and subsequently radiolabeled it with 68Ga to prepare 68Ga-DOTA-Olmutinib. 68Ga-DOTA-Olmutinib displayed moderate lipophilicity (log P = 0.85) and exhibited high stability in vitro and in vivo. Western blot analysis was used to detect the level of EGFR in multiple tumor cells. In cell uptake experiments, 68Ga-DOTA-Olmutinib exhibited enhanced uptake specifically in tumor cells with a higher level of EGFR supporting it as an EGFR-specific tracer. Additionally, PET/CT imaging with 68Ga-DOTA-Olmutinib showed significant tumor uptake at 60 min with 4 % ID/g post-injection, marking a breakthrough, though the uptake is not yet ideal. Overall, our results suggest that 68Ga-labeled Olmutinib holds promise as a potential PET tracer for detecting EGFR-positive cancers.

HOXB8 mediates resistance to cetuximab in colorectal cancer cells through activation of the STAT3 pathway

Homeobox B8 (HOXB8) belongs to the HOX family and was essential to the development of colorectal carcinoma. Among the prevalent monoclonal antibodies for treating RAS/BRAF wild-type metastatic colorectal cancer (mCRC) patients, cetuximab stands out, but resistance to cetuximab frequently arises in targeted treatments. Currently, the role of HOXB8 in cetuximab-resistant mCRC remains unclear. By comparing drug-sensitive cell lines (SW48) with drug-resistant cell lines (HCT116, CACO2), we discovered that HOXB8 was substantially expressed in cetuximab-resistant cell lines, and furthermore, in drug-resistant cell lines (HCT116, CACO2), HOXB8 knockdown increased the cytotoxicity of cetuximab via blocking the signal transducer and activator of transcription 3 (STAT3) signaling pathway. Conversely, the excessive expression of HOXB8 reduced the growth suppression in SW48 cells caused by cetuximab by triggering the STAT3 signaling pathway. Conclusively, we conclude that HOXB8 has played an essential role in cetuximab-resistant mCRC and that treating HOXB8 specifically may be a useful treatment approach for certain cetuximab-resistant mCRC patients.

Measuring Tumour Imatinib Concentrations in Gastrointestinal Stromal Tumours: Relevant or Redundant?

Imatinib plasma trough concentrations are associated with efficacy for patients treated for advanced or metastatic KIT-positive gastrointestinal stromal tumours (GISTs). This relationship has not been studied for patients treated in the neoadjuvant setting, let alone its correlation with tumour drug concentrations. In this exploratory study we aimed to determine the correlation between plasma and tumour imatinib concentrations in the neoadjuvant setting, investigate tumour imatinib distribution patterns within GISTs, and analyse its correlation with pathological response. Imatinib concentrations were measured in both plasma and in three regions of the resected primary tumour: the core, middle part, and periphery. Twenty-four tumour samples derived from the primary tumours of eight patients were included in the analyses. Imatinib tumour concentrations were higher compared to plasma concentrations. No correlation was observed between plasma and tumour concentrations. Interpatient variability in tumour concentrations was high compared to interindividual variability in plasma concentrations. Although imatinib accumulates in tumour tissue, no distribution pattern of imatinib in tumour tissue could be identified. There was no correlation between imatinib concentrations in tumour tissue and pathological treatment response.

Opportunities and challenges of neoadjuvant targeted therapy in nonsmall cell lung cancer

PURPOSE OF REVIEW

The aim of this study is to summarize the completed and ongoing clinical trials of neoadjuvant targeted therapy, discuss tolerability and efficacy, and explain the role of neoadjuvant targeted therapy in patients with resectable nonsmall cell lung cancer (NSCLC). At the same time, the existing challenges are presented, including assessment methods, biomarkers, surrogate endpoints and so on. We also put forward our views on possible ways to make improvements and establish neoadjuvant therapy a standard treatment in resectable NSCLC.

RECENT FINDINGS

The mortality of lung cancer has decreased in the last 10 years, which can partly be attributed to advancement of targeted therapy. Targeted therapy has become the first-line treatment for patients with advanced mutation gene positive NSCLC, achieving the effect of prolonging overall survival (OS). Compared with chemotherapy, targeted therapy is associated with good tolerability and high response rate. Neoadjuvant targeted therapy has emerged in recent years and attracted attention of researchers. Early findings proved that neoadjuvant targeted therapy alone can improve patients' disease-free survival (DFS) and the efficacy of combining with other forms of neoadjuvant therapy is also being explored by researchers.

SUMMARY

Neoadjuvant targeted therapy is playing an important role in NSCLC and worth more in-depth research.

Intra-Tumoral Pharmacokinetics of Pazopanib in Combination with Radiotherapy in Patients with Non-Metastatic Soft-Tissue Sarcoma

There is a lack of understanding whether plasma levels of anticancer drugs (such as pazopanib) correlate with intra-tumoral levels and whether the plasma compartment is the best surrogate for pharmacokinetic and pharmacodynamic evaluation. Therefore, we aimed to quantify pazopanib concentrations in tumor tissue, to assess the correlation between tumor concentrations and plasma concentrations and between tumor concentrations and efficacy. In this clinical trial, non-metastatic STS patients were treated with neo-adjuvant concurrent radiotherapy and pazopanib. Plasma samples and tumor biopsies were collected, and pazopanib concentrations were measured using liquid chromatography-tandem mass spectrometry. Twenty-four evaluable patients were included. The median pazopanib tumor concentration was 19.2 µg/g (range 0.149-200 µg/g). A modest correlation was found between tumor concentrations and plasma levels of pazopanib (ρ = 0.41, p = 0.049). No correlation was found between tumor concentrations and percentage of viable tumor cells (p > 0.05); however, a trend towards less viable tumor cells in patients with high pazopanib concentrations in tumor tissue was observed in a categorical analysis. Possible explanations for the lack of correlation might be heterogeneity of the tumors and timing of the biopsy procedure.

Dual inhibition of EGFR and IL-6-STAT3 signalling by miR-146b: a potential targeted therapy for epithelial ovarian cancer

Epidermal growth factor receptor (EGFR) signalling and the interleukin-6 (IL-6)/signal transducer and activator of transcription 3 (STAT3) are aberrantly activated in ovarian cancer. However, inhibition of EGFR signalling in ovarian cancer patients resulted in a disappointing clinical benefit. In this study, we found that EGFR could activate IL-6-STAT3 pathway in ovarian cancer cells. However, we also demonstrated that EGFR knockdown could increase STAT3 phosphorylation in HO8910 and OVCAR-3 ovarian cancer cells. Interestingly, we further demonstrated that the non-coding RNA miR-146b could simultaneously block both the EGFR and IL-6-STAT3 pathways. Finally, our data demonstrated that miR-146b overexpression resulted in a greater suppression of cell migration than STAT3 pathway inhibition alone.These results suggest a complex and heterogeneous role of EGFR in ovarian cancer. Combined blockade of EGFR and IL-6-STAT3 pathways by miR-146b might be a strategy for improving the clinical benefit of targeting the EGFR pathway in ovarian cancer patients in the future.

Current Evidence of the Efficacy and Safety of Neoadjuvant EGFR-TKIs for Patients With Non-small Cell Lung Cancer

Purpose

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have been indicated to be an effective treatment for advanced EGFR-mutant NSCLC. However, the neoadjuvant application of EGFR-TKIs in resectable NSCLC needs further investigation. Here, we aimed to evaluate the efficacy and safety of neoadjuvant EGFR-TKIs for lung cancer.

Methods

Published studies on neoadjuvant EGFR-TKIs in NSCLC were identified in PubMed, Web of Science, and EMBASE until June 1, 2020. Data on surgical rates, objective response rates (ORRs), pathologic responses, and adverse event (AE) rates were retrieved for proportional meta-analysis.

Results

In total, 7 enrolled studies involving 129 EGFR-TKI-sensitive NSCLC patients were included in this analysis. The overall surgical rate in these studies was 95% (95% CI: 83% to 100%), with an ORR of 48% (95% CI: 39% to 57%) in the population with EGFR-TKI-sensitive mutations, whereas the ORR including wild-type EGFR patients was 28% (95% CI: 14% to 44%). The rate of grade 1-2 AEs was 69% (95% CI: 41% to 91%) but with an acceptable rate of grade 3-4 AEs of 0% (95% CI: 0% to 5%). The pooled rates of rash and diarrhea were 56% (95% CI: 31% to 79%) and 25% (95% CI: 6% to 51%), respectively. The impact of neoadjuvant EGFR-TKIs on survival remains inconclusive.

Conclusions

Neoadjuvant EGFR-TKIs showed objective responses in approximately half of EGFR-sensitive NSCLC patients with a tolerable adverse effect profile. The favorable impact of neoadjuvant EGFR-TKIs on NSCLC needs more evidence for validation, such as the comparison of survival improvement between EGFR-TKIs and chemotherapy. The efficacy of neoadjuvant next-generation EGFR-TKIs in clinical trials remains unclear.

Overcoming Resistance to Targeted Therapies in Gastrointestinal Cancers: Progress to Date and Progress to Come

Targeted therapies have transformed the treatment paradigm in diseases such as non-small cell lung cancer and melanoma but have shown relatively modest clinical benefit in gastrointestinal malignancies. Anti-EGFR therapy in RAS wild-type colorectal cancer, anti-HER2 therapy in HER2- amplified esophagogastric cancer, and FGFR and isocitrate dehydrogenase 1 (IDH1) inhibitors in FGFR2 fusion-positive and IDH1-mutant biliary tract cancers offer antitumor efficacy, but the clinical benefit and durability of response in each case are typically limited. We review targeted therapies in each of these therapeutic areas and discuss their clinical efficacy, mechanisms of primary and acquired resistance, and strategies to overcome this resistance. We discuss lessons learned that we hope will lead to an expanded role for molecularly targeted therapy options for patients with gastrointestinal cancers.

A novel STAT3 inhibitor W2014-S regresses human non-small cell lung cancer xenografts and sensitizes EGFR-TKI acquired resistance

Constitutive activation of signal transducer and activator of transcription 3 (STAT3) is a common feature in human non-small cell lung cancer (NSCLC). STAT3 plays an important role in cancer progression as a driver oncogene and acquired resistance of targeted therapies as an alternatively activated pathway. W2014-S with pharmacophore structure of imidazopyridine, which was firstly reported to be utilized in STAT3 inhibitor discovery, was screened out as a potent STAT3 inhibitor from a library of small molecules. The aim of this study is to investigate the antitumor activities and mechanisms of W2014-S in NSCLC and effect on epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) resistance in vitro and in vivo. Methods: SPR analysis, Co-immunoprecipitation, confocal microscope imaging, and luciferase report gene assays were utilized to determine the mechanisms. Cell viability, colonial survival, wound healing, cell invasion assay, human cancer cell xenografts and PDX tumor xenografts were used to determine antitumor activities. Results: W2014-S disrupted STAT3 dimerization and selectively inhibited aberrant STAT3 signaling in NSCLC cell line. W2014-S strongly suppressed proliferation, survival, migration and invasion of lung cancer cells with aberrant STAT3 activation and inhibited the growth of human NSCLC cell xenografts and PDX tumor xenografts in mouse model. Furthermore, W2014-S significantly sensitized resistant NSCLC cell line to gefitinib and erlotinib in vitro and enhances the anti-tumor effect of gefitinib in TKI-resistant lung cancer xenografts in vivo. Conclusions: Our study has provided a novel STAT3 inhibitor with significant anti-tumor activities in NSCLC and suggests that combination of STAT3 inhibitor such as W2014-S with gefitinib could serve as a promising strategy to overcome EGFR-TKIs acquired resistance in NSCLC patients.

Analyses of putative anti-cancer potential of three STAT3 signaling inhibitory compounds derived from Salvia officinalis

The extract of Salvia officinalis (Common Sage) exhibited inhibitory activity of STAT3 signal after screening of several plants extracts using the STAT3-responsive reporter system. Cirsiliol, luteolin, and carnosol were identified from the methanol extract of Silvia officinalis as inhibitors of STAT3 signaling and the effects of these three compounds on STAT3 protein or growth inhibition on cancer cells was compared. Luteolin at the dose of 90 μM clearly suppressed the phosphorylation of STAT3 induced by IL-6, while carnosol was prone to decrease total STAT3 proteins at high doses (>90 μM). Cirsiliol had almost no effect. Since the three compounds exhibited similar concentration-dependent suppression patterns in the reporter assay except for cirsiliol became plateau beyond 30 μM, these compounds appeared to function as STAT3 inhibitory factors in different ways. The direct anti-proliferative activity of three compounds was examined with or without the anti-cancer drug gefitinib using HepG2 and A549 cells. The anti-proliferative effect of the three compounds was additively enhanced by gefitinib. At the doses of 3.6 μM, statistically significant suppression of proliferation was observed in HepG2 cells only by cirsiliol among the three compounds in the absence of gefitinib but all three compounds were prone to suppress the proliferation of HepG2 cells and A549 cells dose-dependently although cirsiliol showed a modest dose-dependency and this suppression of proliferation was enhanced by the addition of gefitinib. Cirsiliol, a dimethyoxylated flavone, activated the natural killer activity of KHYG-1 cells against erythroleukemia K562 cells like a hexamethoxylated flavone, nobiletin, suggesting that it may also have an indirect anti-cancer potential through activation of NK cells. These results shed light on the putative anti-cancer potential of Salvia officinalis.

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Carnosol, luteolin and cirsiliol were identified as STAT3 signal inhibitors in S. officinalis.

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Cirsiliol inhibited the STAT3-responsive reporter expression at 7.5 μM but showed low dose-dependency at higher doses.

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Cirsiliol at 90 μM showed almost no effect on phosphorylation of STAT3 and weakly suppressed total STAT3.

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Cirsiliol exhibited anti-proliferative activity at 3.6 μM against HepG2 cells and A549 cells but showed low dose-dependency.

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Cirsiliol activated NK cells by stimulating exocytosis of granules for cytolysis.

Tyrosine Kinase Inhibitors Reduce Glucose Uptake by Binding to an Exofacial Site on hGLUT-1: Influence on 18 F-FDG PET Uptake

Positron emission tomography (PET) using 2‐deoxy‐2‐[¹⁸F]fluoro‐d‐glucose ([¹⁸F]FDG), a marker of energy metabolism and cell proliferation, is routinely used in the clinic to assess patient response to chemotherapy and to monitor tumor growth. Treatment with some tyrosine kinase inhibitors (TKIs) causes changes in blood glucose levels in both nondiabetic and diabetic patients. We evaluated the interaction of several classes of TKIs with human glucose transporter‐1 (hGLUT‐1) in FaDu and GIST‐1 cells by measuring [³H]2‐deoxy‐d‐glucose ([³H]2‐DG) and [³H]FDG uptake. Uptake of both was inhibited to varying extents by the TKIs, and representative TKIs from each class showed competitive inhibition of [³H]2‐DG uptake. In GIST‐1 cells, [³H]FDG uptake inhibition by temsirolimus and nilotinib was irreversible, whereas inhibition by imatinib, gefitinib, and pazopanib was reversible. Molecular modeling studies showed that TKIs form multiple hydrogen bonds with polar residues of the sugar binding site (i.e., Q161, Q282, Q283, N288, N317, and W388), and van der Waals interactions with the H‐pocket site. Our results showed interaction of TKIs with amino acid residues at the glucose binding site to inhibit glucose uptake by hGLUT‐1. We hypothesize that inhibition of hGLUT‐1 by TKIs could alter glucose levels in patients treated with TKIs, leading to hypoglycemia and fatigue, although further studies are required to evaluate roles of other SLC2 and SLC5 members. In addition, TKIs could affect tumor [¹⁸F]FDG uptake, increasingly used as a marker of tumor response. The hGLUT‐1 inhibition by TKIs may have implications for routine [¹⁸F]FDG‐PET monitoring of tumor response in patients.

Lapatinib‑induced inhibition of ovarian function is counteracted by the STAT3 pathway both in vivo and in vitro

The present study was designed to ascertain whether lapatinib, a tyrosine kinase inhibitor of epidermal growth factor receptor (EGFR), affects ovarian reserve and fertility potential in a mouse model. Female C57BL/6 mice were treated with either vehicle or lapatinib (100 or 200 mg/kg/day orally) for 4 weeks, after which body weight, vaginal smears, follicle numbers, serum anti‑Müllerian hormone (AMH) levels and mating outcomes were analyzed to assess the ovarian reserve and reproductive function. Slices from the ovaries of 4‑week‑old mice were cultured with lapatinib (0, 5 or 10 µM) for 24 and 48 h, and protein expression levels were assessed to validate the changes in signaling pathways. The results indicated that mice treated with 200 mg/kg lapatinib showed a slight decrease in body weight compared to those treated with vehicle or 100 mg/kg lapatinib. There was no statistical difference in estrous cyclicity among the three groups. No significant difference was observed in follicle numbers, AMH levels, histological morphologies of the ovaries or mating outcomes in the three groups of mice. Western blotting and immunohistochemical staining of the EGF receptor and its main downstream signaling pathways showed decreased phosphorylation of EGFR and mitogen‑activated protein kinase (MAPK)3/1 and increased phosphorylation of signal transducers and activators of transcription (STAT)3 in the lapatinib‑treated groups compared to the control group. Our study suggests that lapatinib has little effect on ovarian reserve and reproductive function in a mouse model. This lack of effect of lapatinib on ovarian function may be due to the activation of the STAT3 signaling pathway that counteracts the inhibitory effects of lapatinib on EGF receptors.

The analysis of pharmacokinetic and pharmacogenomic impact on gefitinib efficacy in advanced non-small cell lung cancer patients: results from a prospective cohort study

Background

The current study is aimed to examine the impact of pharmacokinetics and gene polymorphisms of enzymes involving in absorption, distribution, metabolism and excretion (ADME) on the efficacy of gefitinib in non-small cell lung cancer (NSCLC) patients.

Methods

Eligible patients with indication of gefitinib treatment were prospectively enrolled in this study. Two peripheral blood samples at baseline and before cycle 2 day 1 were collected for the detection of single nucleotide polymorphisms (SNPs) of drug ADME enzymes and trough drug concentration (C_trough) at steady state. Thirteen SNPs were genotyped using the Sequenom Massarray system. C_trough was determined by validated high-performance liquid chromatographic method with tandem mass spectrometric (LC-MS/MS).

Results

Fifty-eight NSCLC patients were enrolled in this study. The median of C_trough was 175ng/mL (range from 47.8 to 470 ng/mL). The trough concentration was not associated with either objective response or progression free survival (PFS). C_trough was significantly lower in CYP3A4 rs2242480 CC + CT genotype than in TT genotype (P=0.019) and in ABCG2 rs2231142 AA genotype than in AC + CC genotype (P=0.031). ABCB1 rs2032582 dominant model was significantly correlated with overall response rate (ORR) and patients with GG phenotype respond better than patients with GT + TT phenotypes (84.6% vs. 51.2%, P=0.032). ABCB1 rs10256836 recessive model was significantly correlated with PFS and patients with GG phenotype achieved longer PFS than patients with GC + CC phenotypes (17.40 vs. 10.33 months, P=0.040).

Conclusions

The C_trough of gefitinib was significantly different between CYP3A4 and ABCG2 genotypes, but not with the efficacy of gefitinib treatment. ABCB1 rs2032582 and rs10256836 polymorphisms were correlated treatment outcome. Polymorphisms analysis of ABCB1 could be a predictive biomarker for gefitinib treatment.

An Autocrine IL-6/IGF-1R Loop Mediates EMT and Promotes Tumor Growth in Non-small Cell Lung Cancer

Epithelial-to-mesenchymal transition (EMT) is a key process in EGFR-TKI resistance but the detailed mechanism is largely unknown. We aim to evaluate the role of interleukin-6 (IL-6) and insulin-like growth factor-1 receptor (IGR-1R) in EMT in non-small cell lung cancer (NSCLC). We used IL-6 to induce EMT in EGFR-TKI sensitive NSCLC cells. We found that both STAT3 and IGF-1R were activated. Interestingly activation of STAT3 and JAK1 was blocked by inhibiting IGF-1R, suggesting that IGF-1R might signal via JAK/STAT3. Activation of IGF-1R and AKT was inhibited by blocking STAT3, suggesting that STAT3 blockade might provide negative feedback signal to inhibiting IGF-1R. Reporter assay further confirmed that STAT3 activated gene transcription of IGF-1R. RT-PCR analyses showed that IL-6 induced the expression of IL-6 per se as well as IGF-1 and IGF-2. Expression of IL-6 and IGF-1R ligands was suppressed by inhibiting either STAT3 or IGF-1R. Meanwhile IL-6 induced gefitinib resistance and increased migration. We elucidated an autocrine loop of IL-6/IGF-1R/STAT3 in EMT-mediated resistance and tumor growth in NSCLC.

ABCC10 Plays a Significant Role in the Transport of Gefitinib and Contributes to Acquired Resistance to Gefitinib in NSCLC

Gefitinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (EGFR-TKI), is used clinically as first-line therapy in patients with advanced non-small cell lung cancer (NSCLC) with EGFR activating mutations, but the inevitable development of acquired resistance limits its efficacy. In up to 30–40% of NSCLC cases, the mechanism underlying acquired resistance remains unknown. ATP-binding cassette (ABC) transporters are a family of membrane proteins that can significantly influence the bioavailability of numerous drugs, and have confirmed to play an essential role in multidrug resistance (MDR) in cancer chemotherapy. However, their role in acquired resistance to gefitnib in NSCLC has not been well studied. Here, through RNA sequencing (RNA-Seq) technology we assessed the differentially expressed ABC transporters in gefitinib-sensitive (PC9 and H292) and gefitinib-resistant (PC9/GR and H292/GR) NSCLC cells, with ABCC10 identified as a transporter of interest. Both ABCC10 mRNA and protein were significantly increased in acquired gefitinib-resistant NSCLC cells, independent of EGFR mutation status. In vitro transport assay showed that ABCC10 could actively efflux gefitinib, with an efflux ratio (ER) of 7.8. Further results from in vitro cell line models and in vivo xenograft models showed that overexpression of ABCC10 led to a reduction in gefitinib sensitivity through decreasing the intracellular gefitinib accumulation. Our data suggest that ABCC10 has an important role in acquired resistance to gefitinib in NSCLC, which can serve as a novel predictive marker and a potential therapeutic target in gefitinib treatment.

Mechanisms of resistance to anti-EGFR therapy in colorectal cancer

Targeting the epidermal growth factor receptor (EGFR) either alone or in combination with chemotherapy is effective for patients with RAS wild type metastatic colorectal cancer (mCRC). However, only a small percentage of mCRC patients are sensitive to anti-EGFR therapy and even the best cases finally become refractory to this therapy. It has become apparent that the RAS mutations correlate with resistance to anti-EGFR therapy. However, these resistance mechanisms only account for nearly 35% to 50% of nonresponsive patients, suggesting that there might be additional mechanisms. In fact, several novel pathways leading to escape from anti-EGFR therapy have been reported in recent years. In this review, we provide an overview of known and novel mechanisms that contribute to both primary and acquired anti-EGFR therapy resistance, and enlist possible treatment strategies to overcome or reverse this resistance.

Heterogeneous drug penetrance of veliparib and carboplatin measured in triple negative breast tumors

BACKGROUND

Poly(ADP-ribose) polymerase inhibitors (PARPi), coupled to a DNA damaging agent is a promising approach to treating triple negative breast cancer (TNBC). However, not all patients respond; we hypothesize that non-response in some patients may be due to insufficient drug penetration. As a first step to testing this hypothesis, we quantified and visualized veliparib and carboplatin penetration in mouse xenograft TNBCs and patient blood samples.

METHODS

MDA-MB-231, HCC70 or MDA-MB-436 human TNBC cells were implanted in 41 beige SCID mice. Low dose (20 mg/kg) or high dose (60 mg/kg) veliparib was given three times daily for three days, with carboplatin (60 mg/kg) administered twice. In addition, blood samples were analyzed from 19 patients from a phase 1 study of carboplatin + PARPi talazoparib. Veliparib and carboplatin was quantified using liquid chromatography-mass spectrometry (LC-MS). Veliparib tissue penetration was visualized using matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI) and platinum adducts (covalent nuclear DNA-binding) were quantified using inductively coupled plasma-mass spectrometry (ICP-MS). Pharmacokinetic modeling and Pearson's correlation were used to explore associations between concentrations in plasma, tumor cells and peripheral blood mononuclear cells (PBMCs).

RESULTS

Veliparib penetration in xenograft tumors was highly heterogeneous between and within tumors. Only 35% (CI 95% 26-44%), 74% (40-97%) and 46% (9-37%) of veliparib observed in plasma penetrated into MDA-MB-231, HCC70 and MDA-MB-436 cell-based xenografts, respectively. Within tumors, penetration heterogeneity was larger with the 60 mg/kg compared to the 20 mg/kg dose (RSD 155% versus 255%, P = 0.001). These tumor concentrations were predicted similar to clinical dosing levels, but predicted tumor concentrations were below half maximal concentration values as threshold of response. Xenograft veliparib concentrations correlated positively with platinum adduct formation (R 2 = 0.657), but no PARPi-platinum interaction was observed in patients' PBMCs. Platinum adduct formation was significantly higher in five gBRCA carriers (ratio of platinum in DNA in PBMCs/plasma 0.64% (IQR 0.60-1.16%) compared to nine non-carriers (ratio 0.29% (IQR 0.21-0.66%, P < 0.0001).

CONCLUSIONS

PARPi/platinum tumor penetration can be measured by MALDI-MSI and ICP-MS in PBMCs and fresh frozen, OCT embedded core needle biopsies. Large variability in platinum adduct formation and spatial heterogeneity in veliparib distribution may lead to insufficient drug exposure in select cell populations.

EGFR and KRAS mutations do not enrich for the activation of IL-6, JAK1 or phosphorylated STAT3 in resected lung adenocarcinoma

Resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) against EGFR mutant lung adenocarcinoma develops after a median of nine to thirteen months. Upregulation of the interleukin-6 (IL-6)/Janus kinase (JAK)/signal transducers and activators of transcription (STAT) pathway may be a potential source of resistance to EGFR TKIs. We undertook a detailed assessment of the IL-6/JAK1/phosphorylated STAT3 (pSTAT3) pathway in resected lung adenocarcinoma specimens, with special interest in whether the presence of an EGFR mutation enriched for pSTAT3 positivity. Tumours from 143 patients with resected lung adenocarcinoma were assessed. EGFR and KRAS mutation status were scanned for with high-resolution melting and confirmed by polymerase chain reaction. Immunohistochemisty (IHC) was performed for IL-6, gp130, JAK1 and pSTAT3. Two methods for assigning IHC positivity were assessed (the presence of any positivity, and the presence of positivity at an H score >40). We found statistically significant associations between IL-6, JAK1 and pSTAT3 measured by IHC, consistent with the activation of the pathway in clinical specimens. No relationship was demonstrated between members of this pathway and oncogenic mutations in EGFR or KRAS. However, a proportion of tumours with EGFR mutations showed staining for IL-6, JAK1 and pSTAT3. No correlations with clinicopathologic features or survival outcomes were found for IL-6, JAK1 or pSTAT3 staining. The presence of EGFR or KRAS mutations did not enrich for the activation of IL-6, JAK1 or pSTAT3. pSTAT3 may still play a role in resistance to EGFR TKIs in clinical practice.

STAT3 signaling mediates tumour resistance to EGFR targeted therapeutics

Several EGFR inhibitors are currently undergoing clinical assessment or are approved for the clinical management of patients with varying tumour types. However, treatment often results in a lack of response in many patients. The majority of patients that initially respond eventually present with tumours that display acquired resistance to the original therapy. A large number of receptor tyrosine and intracellular kinases have been implicated in driving signaling that mediates this tumour resistance to anti-EGFR targeted therapy, and in a few cases these discoveries have led to overall changes in prospective tumour screening and clinical practice (K-RAS in mCRC and EGFR T790M in NSCLC). In this mini-review, we specifically focus on the role of the STAT3 signaling axis in providing both intrinsic and acquired resistance to inhibitors of the EGFR. We also focus on STAT3 pathway targeting in an attempt to overcome resistance to anti-EGFR therapeutics.

Proteome-wide Profiling of Clinical PARP Inhibitors Reveals Compound-Specific Secondary Targets

Poly(ADP-ribose) polymerase (PARP) inhibitors (PARPi) are a promising class of targeted cancer drugs, but their individual target profiles beyond the PARP family, which could result in differential clinical use or toxicity, are unknown. Using an unbiased, mass spectrometry-based chemical proteomics approach, we generated a comparative proteome-wide target map of the four clinical PARPi, olaparib, veliparib, niraparib, and rucaparib. PARPi as a class displayed high target selectivity. However, in addition to the canonical targets PARP1, PARP2, and several of their binding partners, we also identified hexose-6-phosphate dehydrogenase (H6PD) and deoxycytidine kinase (DCK) as previously unrecognized targets of rucaparib and niraparib, respectively. Subsequent functional validation suggested that inhibition of DCK by niraparib could have detrimental effects when combined with nucleoside analog pro-drugs. H6PD silencing can cause apoptosis and further sensitize cells to PARPi, suggesting that H6PD may be, in addition to its established role in metabolic disorders, a new anticancer target.

Eventual role of EGFR-tyrosine kinase inhibitors in early-stage non-small-cell lung cancer

Nonadvanced non-small-cell lung cancer (NSCLC) has a poor long-term survival from surgery or definitive radiation that is minimally improved with induction/adjuvant conventional chemotherapy. EGFR-tyrosine kinase inhibitors (TKIs), which provide a significant benefit for molecularly selected EGFR-mutant patients with advanced NSCLC, have been infrequently explored in nonadvanced NSCLC to date. Current published studies reported no significant benefit from adding EGFR-TKI to the induction/adjuvant setting. However, many of them present eventual biases such as unpowered statistics, lack of molecular selection, recruitment of low-risk NSCLC, low sample size or unsuitable control arms. Results, strengths and deficiencies of completed and ongoing trials were fully discussed. Similarly, the selection of patients and control arms, the duration and risks of EGFR-TKI therapies in early-stage NSCLC, the evaluation of response and the diagnosis of EGFR status were considered and analyzed.

Management Strategies for Adverse Events Associated With EGFR TKIs in Non-Small Cell Lung Cancer

New advances in the treatment of non-small cell lung cancer (NSCLC) have afforded patients longer progression-free survival times, but these therapies are also associated with specific side effects that may not be seen with chemotherapy or radiotherapy. One class of agents includes the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), which have been shown to be efficacious in patients whose tumors harbor EGFR-activating mutations. Certain adverse effects, particularly rash and diarrhea, as well as mucositis/stomatitis, paronychia, ocular disorders, and interstitial lung disease, are seen with this class as a function of their mechanism of action. This review presents the suggested pathogenesis of these toxicities as well as specific management strategies to assist advanced practitioners in helping patients receive the full benefit of treatment with EGFR TKIs.

The STAT3 pathway as a therapeutic target in head and neck cancer: Barriers and innovations

Proteins of the signal transducer and activator of transcription (STAT) family mediate cellular responses to cytokines and growth factors. Aberrant regulation of the STAT3 oncogene contributes to tumor formation and progression in many cancers, including head and neck squamous cell carcinoma (HNSCC), where hyperactivation of STAT3 is implicated in both treatment resistance and immune escape. There are no oncogenic gain-of-function mutations in HNSCC. Rather, aberrant STAT3 signaling is primarily driven by upstream growth factor receptors, such as Janus kinase (JAK) and epidermal growth factor receptor (EGFR). Moreover, genomic silencing of select protein tyrosine phosphatase receptors (PTPRs), tumor suppressors that dephosphorylate STAT3, may lead to prolonged phosphorylation and activation of STAT3. This review will summarize current knowledge of the STAT3 pathway and its contribution to HNSCC growth, survival, and resistance to standard therapies, and discuss STAT3-targeting agents in various phases of clinical development.

Nuclear PKM2 contributes to gefitinib resistance via upregulation of STAT3 activation in colorectal cancer

Gefitinib (Iressa, ZD-1839), a small molecule tyrosine kinase inhibitor (TKI) of the epidermal growth factor receptor (EGFR) pathway, is currently under investigation in clinical trials for the treatment of colorectal cancer (CRC). However, as known, some patients develop resistance to TKIs, and the mechanisms mediating intrinsic resistance to EGFR-TKIs in CRC have not been fully characterized. Resistance to EGFR inhibitors reportedly involves activation of signal transducer and activator of transcription 3 (STAT3) in glioma and lung cancer. Here, we demonstrated that the nuclear pyruvate kinase isoform M2 (PKM2) levels were positively correlated with gefitinib resistance in CRC cells. The overexpression of nuclear PKM2 in HT29 cells decreased the effect of gefitinib therapy, whereas PKM2 knockdown increased gefitinib efficacy. Furthermore, the activation of STAT3 by nuclear PKM2 was associated with gefitinib resistance. Inhibition of STAT3 by Stattic, a STAT3-specific inhibitor, or STAT3-specific siRNA sensitized resistant cells to gefitinib. These results suggest that nuclear PKM2 modulates the sensitivity of CRC cells to gefitinib and indicate that small molecule pharmacological disruption of nuclear PKM2 association with STAT3 is a potential avenue for overcoming EGFR-TKI resistance in CRC patients.

Epidermal growth factor receptor tyrosine kinase inhibitors in early-stage nonsmall cell lung cancer

PURPOSE OF REVIEW

Targeted molecular therapy is playing an increasingly important role in the treatment of nonsmall cell lung cancer (NSCLC). Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have demonstrated efficacy in the advanced disease setting. Preliminary findings suggest that EGFR-TKIs may also be beneficial as adjuvant therapy following complete resection in patients with EGFR-mutation-positive early-stage I-III NSCLC; however, many questions remain unanswered.

RECENT FINDINGS

Single-arm trials of adjuvant EGFR-TKI therapy in patients with tumors harboring activating EGFR mutations show impressive 2-year disease-free survival (DFS). Phase III randomized trial data do not support adjuvant EGFR-TKI therapy in unselected completely resected stage I-III NSCLC, but show improved DFS in patients with completely resected EGFR-mutated NSCLC. Adverse events leading to treatment withdrawal and dose reductions are frequent with adjuvant EGFR-TKI therapy, and relapse following treatment withdrawal is common. Adjuvant EGFR-TKIs have not yet been shown to improve the overall survival (OS) in patients with tumors harboring activating EGFR mutations.

SUMMARY

There are no data to support the use of adjuvant EGFR-TKIs in unselected early-stage NSCLC. Although EGFR-TKIs hold promise as adjuvant therapy in patients whose tumors harbor EGFR mutations, in the absence of definitive data confirming an OS benefit eligible patients should continue to receive adjuvant chemotherapy following complete resection.

The Dissociation of Gefitinib Trough Concentration and Clinical Outcome in NSCLC Patients with EGFR Sensitive Mutations

Gefitinib is an essential drug for NSCLC patients harboring EGFR sensitive mutations. The approved dose 250 mg/day is based on limited clinical trials, this research aims to explore the relationship between drug exposure and gefitinib response. C trough of 87 NSCLC patients harboring EGFR sensitive mutations were determined by LC-MS/MS. The median of C trough was 173.9 ng/ml (P25-P75, 130.5-231.2 ng/ml), and cutoff value 200 ng/ml was determined by X-Tile. The PFS between C trough < 200 ng/ml and C trough ≥ 200 ng/ml groups were not significantly different (17.3 VS 14.8 months; p = 0.258). C trough was not significantly associated with rash, diarrhea and hepatotoxicity. Non-smokers enjoyed longer PFS than smokers (18.7 VS 9.3 months; p = 0.025). The results showed that, for NSCLC patients with EGFR sensitive mutations, the PFS in lower trough concentration group were not inferior to that in higher trough concentration group and dose reduction is a rational suggestion for adjustment of dose regimen for aforementioned patients. More clinical trials are warranted to explore the precision dose schedule of gefitinib.

Synergistic anti-tumor effect of combined inhibition of EGFR and JAK/STAT3 pathways in human ovarian cancer

Background

The EGFR signaling pathway is frequently activated in human ovarian cancer and associated with poor prognosis. However, inhibition of EGFR signaling in patients with recurrent ovarian cancer has been disappointing. It remains to be addressed whether ovarian cancer patients could benefit from targeting EGFR signaling. Here we investigated the mechanisms underlying the resistance to EGFR inhibition in ovarian cancer and developed a strategy to overcome it.

Results

We found that treatment of human ovarian cancer cells with an EGFR inhibitor, gefitinib, resulted in increased STAT3 phosphorylation in a dose- and time-dependent manner. Inhibiting STAT3 activation with a small molecule inhibitor of JAK, an upstream kinase that phosphorylates and activates STAT3, synergistically increased the anti-tumor activity of gefitinib in vitro. Similar results were obtained when STAT3 or JAK1 expression was knocked down. In contrast, inhibiting other signaling pathways, such as AKT/mTOR, MEK or SRC, was relatively less effective. The combined treatment resulted in simultaneous attenuation of multiple survival pathways and increased inhibition of ERK pathway. In addition, the dual inhibition showed a stronger suppression of xenograft tumor growth than either single inhibition.

Conclusions

Our findings demonstrate that feedback activation of STAT3 pathway might contribute to the resistance to EGFR inhibition. Combined blockade of both pathways appears to be more effective against human ovarian cancer than inhibition of each pathway alone both in vitro and in vivo. This study may provide a strategy to improve clinical benefit of targeting EGFR pathway in ovarian cancer patients.

Continuous exposure of non-small cell lung cancer cells with wild-type EGFR to an inhibitor of EGFR tyrosine kinase induces chemoresistance by activating STAT3

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR‑TKIs) have shown promising effects against the growth of non-small cell lung cancer (NSCLC) cells harboring EGFR mutations (EGFR‑mts). However, many patients with NSCLC that are accepted for EGFR‑TKI treatment followed by chemotherapy possess an unknown EGFR status including wild-type EGFR (EGFR‑wt). Little is known about the potential effects of EGFR‑TKI treatment prior to chemotherapy. We investigated the effects and underlying molecular events of 4 weeks of continuous exposure to EGFR‑TKIs in the EGFR‑wt NSCLC line H1299. This treatment dramatically increased the IC50 of several relevant chemotherapeutic agents: cisplatin (DDP) (29.25±6.1 µM for gefitinib, 43.25±14.87 µM for erlotinib, and 6.92±1.15 µM for parental), paclitaxel (11.16±3.36 µM for gefitinib, 9.16±1.41 µM for erlotinib, and 2.09±0.44 µM for parental), gemcitabine (47.18±6.2 µM for gefitinib, 40.36±11.1 µM for erlotinib, and 16.00±3.38 µM for parental) and pemetrexed (11.78±4.07 µM for gefitinib, 15.97±7.23 µM for erlotinib, and 4.72±1.9 µM for parental). This chemoresistance was critically dependent on the activation of the mediator signal transducer and activator of transcription 3 (STAT3). In cells exposed to EGFR‑TKIs for 4 weeks, activation of STAT3 was found to be unrelated to EGFR and to be independent of IL‑6 and ‑22. Treatment with the STAT3 inhibitor NSC 74859 was able to reverse the TKI exposure-induced chemoresistance in EGFR‑wt NSCLC cells. Similar phenomena were observed in H1975 cells harboring EGFR L858R and T790M mutations. Based on the observed molecular events following long exposure of an EGFR‑wt NSCLC cell line to an EGFR‑TKI, this study indicates that such drugs should be not recommended for EGFR‑wt patients who can undergo chemotherapy. This study also suggests that STAT3 inhibitors may aid in the treatment NSCLC patients who exhibit EGFR‑TKI resistance due to an acquired T790M mutation.

Concentrations of Erlotinib in Tumor Tissue and Plasma in Non-Small-Cell Lung Cancer Patients After Neoadjuvant Therapy

INTRODUCTION

Tumors might not optimally respond to systemic therapy if minimal effective levels are not reached within the tumor. Erlotinib has mainly been studied in the adjuvant or palliative setting and, therefore, little is known about erlotinib tumor penetration. The purpose of this exploratory study was to investigate lung tumor tissue erlotinib concentrations after neoadjuvant therapy for non-small-cell lung cancer.

PATIENTS AND METHODS

Patients were treated preoperatively with erlotinib (150 mg once daily for 3 weeks) up to 48 hours before surgery. Plasma samples were collected during treatment. Surgical resection involved radical resection of the lung tumor and tumor biopsies were frozen directly after surgery. Erlotinib and O-desmethyl erlotinib concentrations in lung tumor tissue and predose plasma were determined using high performance liquid chromatography coupled with tandem mass spectrometry.

RESULTS

Thirteen evaluable patients were included. The mean plasma and lung tumor tissue erlotinib levels were 1222 ng/mL (SD, 678) and 149 ng/g (SD, 153), respectively. In 2 individual patients, erlotinib and O-desmethyl erlotinib concentrations in lung tumor tissue were detectable up to 13 days and 7 days after erlotinib intake, respectively. Mean erlotinib tissue concentrations extrapolated to a time point directly after intake of erlotinib were approximated at > 200 ng/g tissue, which is greater than the reported half maximal inhibitory concentration (IC50) of wild type epidermal growth factor receptor (EGFR) (183 ng/mL).

CONCLUSION

No strong accumulation of erlotinib in lung tumor tissue was observed. Nevertheless, extrapolated intratumoral concentrations during erlotinib therapy were greater than the IC50 of wild type EGFR.

Gefitinib resistance resulted from STAT3-mediated Akt activation in lung cancer cells

Hyperactivation of Epidermal Growth Factor Receptor (EGFR) tyrosine kinase is prevalent in human lung cancer and its inhibition by the tyrosine kinase inhibitors (TKIs), including gefitinib and erlotinib, initially controls tumor growth. However, most patients ultimately relapse due to the development of drug resistance. In this study, we have discovered a STAT3-dependent Akt activation that impairs the efficacy of gefitinib. Mechanistically, gefitinib increased association of EGFR with STAT3, which de-repressed STAT3 from SOCS3, an upstream suppressor of STAT3. Such a de-repression of STAT3 in turn fostered Akt activation. Genetic or pharmacological inhibition of STAT3 abrogated Akt activation and combined gefitinib with STAT3 inhibition synergistically reduced the growth of the tumor cells. Taken together, this study suggests that activation of STAT3 is an intrinsic mechanism of drug resistance in response to EGFR TKIs. Combinational targeting on both EGFR and STAT3 may enhance the efficacy of gefitinib or other EGFR TKIs in lung cancer.

Gefitinib targets ZAP-70-expressing chronic lymphocytic leukemia cells and inhibits B-cell receptor signaling

Chronic lymphocytic leukemia (CLL) can be divided into groups based on biomarkers of poor prognosis. The expression of the tyrosine kinase ZAP-70 (member of the Syk tyrosine kinase family) in CLL cells is associated with shorter overall survival in CLL patients. Currently, there is a lack of targeted therapies for patients with ZAP-70 expression in CLL cells. The tyrosine kinase inhibitor gefitinib has been shown to be effective at induce apoptosis in acute myeloid leukemia through inhibition of Syk. In this study, we sought to test the efficacy of gefitinib in primary human ZAP-70+ CLL cells. We demonstrate that gefitinib preferentially induces cell death in ZAP-70-expressing CLL cells with a median IC₅₀ of 4.5 μM. In addition, gefitinib decreases the viability of ZAP-70+ Jurkat T leukemia cells but fails to affect T cells from CLL patients. Western blot analysis shows gefitinib reduces both basal and B-cell receptor (BCR)-stimulated phosphorylation of Syk/ZAP-70, ERK, and Akt in ZAP-70+ CLL cells. Moreover, gefitinib inhibits the pro-survival response from BCR stimulation and decreases pro-survival proteins such as Mcl-1. Finally, ZAP-70 expression sensitizes Raji cells to gefitinib treatment. These results demonstrate that gefitinib specifically targets ZAP-70+ CLL cells and inhibits the BCR cell survival pathway leading to apoptosis. This represents the likelihood of tyrosine kinase inhibitors being effective targeted treatments for ZAP-70+ CLL cells.

Intratumor heterogeneity and its impact on drug distribution and sensitivity

We provide an overview of the available information on the distribution of chemotherapeutics in human tumors, highlighting the progress made to assess the heterogeneity of drug concentrations in relation to the complex neoplastic tissue using novel analytical methods, e.g., mass spectrometry imaging. The increase in interstitial fluid pressure due to abnormal vascularization and stiffness of tumor stroma explains the variable and heterogeneous drug concentrations. Therapeutic strategies to enhance tumor drug distribution, thus possibly increasing efficacy, are discussed.

Discrepancy between the Clinical Image and Pathological Findings of Non-Small Cell Lung Cancer Harboring an Epidermal Growth Factor Receptor Gene Mutation That Was Surgically Resected after Gefitinib Treatment

We herein describe a discrepancy between the clinical image and pathological findings in a non-small cell lung cancer patient with an epidermal growth factor receptor (EGFR) mutation who underwent surgical resection after gefitinib treatment. The patient was a 66-year-old female with c-stage IIIA lung adenocarcinoma harboring an EGFR gene mutation; she was surgically treated after receiving gefitinib. The pathological examination revealed adenocarcinoma, and the pathologically therapeutic effect was considered to be slight or of no response. EGFR T790M mutation and MET amplification were not present. The pathologically therapeutic effect is generally well correlated with the response rate after induction therapy. In this case, there was a discrepancy between the clinical image and pathological findings. Our findings, therefore, raise questions about the role of surgery after EGFR-tyrosine kinase inhibitor treatment.

Anti-EGFR therapeutic efficacy correlates directly with inhibition of STAT3 activity

Several agents targeting the epidermal growth factor receptor (EGFR) have been FDA-approved to treat cancer patients with varying tumor types including metastatic colorectal cancer. Many patients treated with anti-EGFR therapy however do not respond and those that do initially respond often acquire resistance. Here we show a clear correlation between the efficacy of anti-EGFR inhibitors with their ability to inhibit STAT3 activity in A431 epidermoid carcinoma cells and in a series of wt K-RAS expressing human colon cancer cell lines. Furthermore, the ability of cetuximab to inhibit growth also correlated with its ability to inhibit STAT3 activity in tumor xenograft animal studies. In addition, stable knockdown of the STAT3 phosphatase, protein tyrosine phosphatase receptor delta (PTPRD) resulted in enhanced STAT3 activity and subsequent resistance to cetuximab in DIFI colon carcinoma cells. This resistance could be reversed by STAT3 inhibition. Finally, HN5 cells with acquired resistance to the EGFR tyrosine kinase inhibitor, AG1478 displayed greater STAT3 activity than the HN5 control cell line. These AG1478-refractory HN5 cells were re-sensitized to AG1478, cetuximab and erlotinib when co-treated with a STAT3 inhibitor. Taken together, our current data indicates a key role of STAT3 activity in promoting resistance to anti-EGFR therapy and suggests that anti-EGFR therapy in combination with inhibitors that block STAT3 may provide therapeutic benefit for patients with mCRC and other EGFR driven tumor types.

Erlotinib, gefitinib, and vandetanib inhibit human nucleoside transporters and protect cancer cells from gemcitabine cytotoxicity

PURPOSE

Combinations of tyrosine kinase inhibitors (TKI) with gemcitabine have been attempted with little added benefit to patients. We hypothesized that TKIs designed to bind to ATP-binding pockets of growth factor receptors also bind to transporter proteins that recognize nucleosides.

EXPERIMENTAL DESIGN

TKI inhibition of uridine transport was studied with recombinant human (h) equilibrative (E) and concentrative (C) nucleoside transporters (hENT, hCNT) produced individually in yeast. TKIs effects on uridine transport, gemcitabine accumulation, regulation of hENT1 activity, and cell viability in the presence or absence of gemcitabine were evaluated in human pancreatic and lung cancer cell lines.

RESULTS

Erlotinib, gefitinib and vandetanib inhibited [(3)H]uridine transport in yeast and [(3)H]uridine and [(3)H]gemcitabine uptake in the four cell lines. Treatment of cell lines with erlotinib, gefitinib, or vandetanib for 24 hours reduced hENT1 activity which was reversed by subsequent incubation in drug-free media for 24 hours. Greater cytotoxicity was observed when gemcitabine was administered before erlotinib, gefitinib, or vandetanib than when administered together and synergy, evaluated using the CalcuSyn Software, was observed in three cell lines resulting in combination indices under 0.6 at 50% reduction of cell growth.

CONCLUSIONS

Vandetanib inhibited hENT1, hENT2, hCNT1, hCNT2, and hCNT3, whereas erlotinib inhibited hENT1 and hCNT3 and gefitinib inhibited hENT1 and hCNT1. The potential for reduced accumulation of nucleoside chemotherapy drugs in tumor tissues due to inhibition of hENTs and/or hCNTs by TKIs indicates that pharmacokinetic properties of these agents must be considered when scheduling TKIs and nucleoside chemotherapy in combination.

A pilot study: sequential gemcitabine/cisplatin and icotinib as induction therapy for stage IIB to IIIA non-small-cell lung adenocarcinoma

Background

A phase II clinical trial previously evaluated the sequential administration of erlotinib after chemotherapy for advanced non-small-cell lung cancer (NSCLC). This current pilot study assessed the feasibility of sequential induction therapy in patients with stage IIB to IIIA NSCLC adenocarcinoma.

Methods

Patients received gemcitabine 1,250 mg/m² on days 1 and 8 and cisplatin 75 mg/m² on day 1, followed by oral icotinib (125 mg, three times a day) on days 15 to 28. A repeatcomputed tomography(CT) scan evaluated the response to the induction treatment after two 4-week cycles and eligible patients underwent surgical resection. The primary objective was to assess the objective response rate (ORR), while EGFR and KRAS mutations and mRNA and protein expression levels of ERCC1 and RRM1 were analyzed in tumor tissues and blood samples.

Results

Eleven patients, most with stage IIIA disease, completed preoperative treatment. Five patients achieved partial response according to the Response Evaluation Criteria in Solid Tumors (RECIST) criteria (ORR=45%) and six patients underwent resection. Common toxicities included neutropenia, alanine transaminase (ALT) elevation, fatigue, dry skin, rash, nausea, alopecia and anorexia. No serious complications were recorded perioperatively. Three patients had exon 19 deletions and those with EGFR mutations were more likely to achieve a clinical response (P= 0.083). Furthermore, most cases who achieved a clinical response had low levels of ERCC1 expression and high levels of RRM1.

Conclusions

Two cycles of sequentially administered gemcitabine/cisplatin with icotinib as an induction treatment is a feasible and efficacious approach for stage IIB to IIIA NSCLC adenocarcinoma, which provides evidence for the further investigation of these chemotherapeutic and molecularly targeted therapies.

Acquired resistance to EGFR inhibitors is associated with a manifestation of stem cell-like properties in cancer cells

Acquired resistance to EGF receptor (EGFR) tyrosine kinase inhibitor (TKI) is a critical problem in the treatment of lung cancer. Although several mechanisms have been shown to be responsible for acquired resistance, all mechanisms have not been uncovered. In this study, we investigated the molecular and cellular profiles of the acquired resistant cells to EGFR-TKI in EGFR-mutant lung cancers. Four EGFR-mutant cell lines were exposed to gefitinib by stepwise escalation and high-concentration exposure methods, and resistant sublines to gefitinib were established. The molecular profiles and cellular phenotypes of these resistant sublines were characterized. Although previously reported, alterations including secondary EGFR T790M mutation, MET amplification, and appearance of epithelial-to-mesenchymal transition (EMT) features were observed, these 2 drug-exposure methods revealed different resistance mechanisms. The resistant cells with EMT features exhibited downregulation of miRNA-200c by DNA methylation. Furthermore, the HCC827-derived subline characterized by the high-concentration exposure method exhibited not only EMT features but also stem cell-like properties, including aldehyde dehydrogenase isoform 1 (ALDH1A1) overexpression, increase of side-population, and self-renewal capability. Resistant sublines with stem cell-like properties were resistant to conventional chemotherapeutic agents but equally sensitive to histone deacetylase and proteasome inhibitors, compared with their parental cells. ALDH1A1 was upregulated in clinical samples with acquired resistance to gefitinib. In conclusion, our study indicates that the manner of EGFR-TKI exposure influences the mechanism of acquired resistance and the appearance of stem cell-like property with EGFR-TKI treatment.

Targeting Stat3 abrogates EGFR inhibitor resistance in cancer

PURPOSE

EGF receptor (EGFR) is upregulated in most epithelial cancers where signaling through EGFR contributes to cancer cell proliferation and survival. The limited clinical efficacy of EGFR inhibitors suggests that identification of resistance mechanisms may identify new pathways for therapeutic targeting. STAT3 is upregulated in many cancers and activated via both EGFR-dependent and -independent pathways. In the present study, we tested the consequences of STAT3 inhibition in EGFR inhibitor-resistant head and neck squamous cell carcinoma (HNSCC) and bladder cancer models to determine whether STAT3 blockade can enhance responses to EGFR targeting.

EXPERIMENTAL DESIGN

pSTAT3 expression was assessed in human HNSCC tumors that recurred following cetuximab treatment. Cetuximab-sensitive and -resistant cell lines were treated with a STAT3 decoy to determine EC(50) concentrations and the effects on STAT3 target gene expression by Western blotting. In vivo assays included evaluation of antitumor efficacy of STAT3 decoy in cetuximab-sensitive and -resistant models followed by immunoblotting for STAT3 target protein expression.

RESULTS

Targeting STAT3 with a STAT3 decoy reduced cellular viability and the expression of STAT3 target genes in EGFR inhibitor resistance models. The addition of a STAT3 inhibitor to EGFR blocking strategies significantly enhanced antitumor effects in vivo. Biopsies from HNSCC tumors that recurred following cetuximab treatment showed increased STAT3 activation compared with pretreatment biopsies.

CONCLUSIONS

These results suggest that STAT3 activation contributes to EGFR inhibitor resistance both in HNSCC and bladder cancer where concomitant targeting of STAT3 may represent an effective treatment strategy.

The surgeon's role in molecular biology

The biomolecular era is rapidly becoming shaped around the supreme interest in targeted therapy for patients with non-small cell lung cancer. Tissue analysis has become crucial in the definition of biomarkers and genomic signatures able to predict the response to treatment or even survival. Lung screening programs and minimally invasive thoracic surgery are jointly aimed at increasing the quantity and quality of specimens of non-small cell lung cancer caught at the earliest stages with the attendant, significant, effect on patient survival. In addition, biomolecular researchers are disclosing an ever-increasing cohort of patients with specific genetic mutations that make their cancer susceptible to individualized treatment. When needed for immunohistochemical characterization, investigators are ready to request "research biopsies" to consolidate tissue availability for clinical trials, translational research, and in biobanks. With unique and diverse tools in the surgical armamentarium, the thoracic surgeon plays a central role in this new multidisciplinary professional environment, actively participating in creating the foundations of the biomolecular era.

Low-dose gefitinib treatment for patients with advanced non-small cell lung cancer harboring sensitive epidermal growth factor receptor mutations

INTRODUCTION

Although standard schedule of gefitinib was the administration of 250 mg tablet every day, many patients need dose reduction because of toxicities. However, the efficacy of such low-dose gefitinib for patients with epidermal growth factor receptor-mutated non-small cell lung cancer has rarely been evaluated.

METHODS

A post hoc comparison of the efficacy (response rate and survival) in patients treated with gefitinib with or without any dose reduction in NEJ002 study was performed.

RESULTS

Among 114 patients treated with first-line gefitinib in NEJ002, 61 (54%) continued gefitinib without any dose reduction until their diseases progressed, and 53 (46%) reduced their dose of gefitinib because of some toxicities. There was no significant difference of patient characteristics between the two groups. The progression-free survival of low-dose group tended to be better than that of standard-dose group (median progression-free survival, 11.8 versus 9.9 months; p = 0.144), and the overall survival of low-dose group was also better than that of standard-dose group (median survival time, 32.7 versus 25.3 months; p = 0.049).

CONCLUSIONS

The results suggest that low-dose gefitinib may be clinically not inferior to standard-dose gefitinib for non-small cell lung cancer with sensitive epidermal growth factor receptor mutations. Prospective study of low-dose gefitinib is warranted especially for frail patients who need less toxic treatment.

[Inhibitors of the epidermal growth factor receptor (EGFR) tyrosine kinase: similarity and differences]

Tyrosine kinase inhibitors (TKI) of EGFR are used in advanced non-small cell lung cancer (NSCLC) in 2(nd) and 3(rd) line, and for gefitinib in first line in case of EGFR mutations. These drugs are particularly active in presence of these mutations, with response rate around 60-70%. Pharmacological data suggest an equivalent effect of erlotinib and gefitinib. One phase II study has directly compared the two drugs in 2(nd) line, with a non significant advantage for gefitinib in term of response and progression-free survival. However, skin tolerance profile was statistically better with gefitinib. Indirect comparisons between erlotinib and gefitinib in the phase III trials vs chemotherapy 1(st) line have to be interpreted, with caution and take under consideration the impact of the chemotherapy arm on the Hazard Ratio for Progression-free and overall survival. However, response rates seem to be equivalent. Cohort and phase IV studies have shown no significant difference for response and survival, and a similar tolerance profile.

Molecular characteristics predict clinical outcomes: prospective trial correlating response to the EGFR tyrosine kinase inhibitor gefitinib with the presence of sensitizing mutations in the tyrosine binding domain of the EGFR gene

PURPOSE

To determine if tumor regression following treatment with gefitinib correlates with the presence of sensitizing mutations in epidermal growth factor receptor (EGFR).

PATIENTS AND METHODS

Patients with resectable stage I and II non-small cell lung cancer (NSCLC) enriched for the likelihood of EGFR mutation (≤ 15 pack-year cigarette smoking history and/or a component of bronchioloalveolar carcinoma) received preoperative gefitinib for 21 days. Tumor specimens were analyzed for EGFR and KRAS mutations and EGFR protein expression and amplification. Patients with 25% or more reduction in tumor size measured bidimensionally at 3 weeks and/or patients with an EGFR mutation received adjuvant gefitinib for 2 years postoperatively.

RESULTS

Fifty patients with stage I/II NSCLC were treated. After 21 days of preoperative gefitinib a response of 25% or more was observed in 21 of 50 (42%) patients. Seventeen of 21 patients with a response had an EGFR mutation and 4 of 21 patients with a response did not (P = 0.0001). Twenty-five of 50 patients were eligible to receive adjuvant gefitinib. With a median follow-up of 44.1 months, 2-year disease free survival for EGFR mutant patients and for those who received adjuvant gefitinib was not statistically different than those who were EGFR wild-type and those who did not receive adjuvant gefitinib. The median disease free and overall survivals have not been reached.

CONCLUSIONS

The presence of sensitizing EGFR mutations correlates with radiographic response. A short course of preoperative treatment serves a platform for evaluating activity of new agents and assures sufficient tumor availability for correlative analyses.