DrugMap: A quantitative pan-cancer analysis of cysteine ligandability

Cysteine-focused chemical proteomic platforms have accelerated the clinical development of covalent inhibitors for a wide range of targets in cancer. However, how different oncogenic contexts influence cysteine targeting remains unknown. To address this question, we have developed "DrugMap," an atlas of cysteine ligandability compiled across 416 cancer cell lines. We unexpectedly find that cysteine ligandability varies across cancer cell lines, and we attribute this to differences in cellular redox states, protein conformational changes, and genetic mutations. Leveraging these findings, we identify actionable cysteines in NF-κB1 and SOX10 and develop corresponding covalent ligands that block the activity of these transcription factors. We demonstrate that the NF-κB1 probe blocks DNA binding, whereas the SOX10 ligand increases SOX10-SOX10 interactions and disrupts melanoma transcriptional signaling. Our findings reveal heterogeneity in cysteine ligandability across cancers, pinpoint cell-intrinsic features driving cysteine targeting, and illustrate the use of covalent probes to disrupt oncogenic transcription-factor activity.

DrugMap: A quantitative pan-cancer analysis of cysteine ligandability

Cysteine-focused chemical proteomic platforms have accelerated the clinical development of covalent inhibitors of a wide-range of targets in cancer. However, how different oncogenic contexts influence cysteine targeting remains unknown. To address this question, we have developed DrugMap , an atlas of cysteine ligandability compiled across 416 cancer cell lines. We unexpectedly find that cysteine ligandability varies across cancer cell lines, and we attribute this to differences in cellular redox states, protein conformational changes, and genetic mutations. Leveraging these findings, we identify actionable cysteines in NFκB1 and SOX10 and develop corresponding covalent ligands that block the activity of these transcription factors. We demonstrate that the NFκB1 probe blocks DNA binding, whereas the SOX10 ligand increases SOX10-SOX10 interactions and disrupts melanoma transcriptional signaling. Our findings reveal heterogeneity in cysteine ligandability across cancers, pinpoint cell-intrinsic features driving cysteine targeting, and illustrate the use of covalent probes to disrupt oncogenic transcription factor activity.

Abstract 1156: GUK1 is a novel metabolic liability in oncogene-driven lung cancer

There is a longstanding desire to take therapeutic advantage of dysregulated metabolic states in cancer. While it has been appreciated that lung tumors rewire their cellular metabolic networks to support unrestrained proliferation, metabolic vulnerabilities have largely not been explored in the context of specific onco-genotypes. This represents a major gap in our understanding of how different oncogenic drivers in non-small cell lung cancer (NSCLC) confer reliance on discrete metabolic networks to sustain tumor growth. The goals of this project are (1) to investigate metabolic dependencies in distinct molecular subtypes of lung cancer and (2) to elucidate how metabolic reprogramming drives resistance to targeted therapy. Using patient-derived cell culture models and tumor specimens collected from patients with ALK-positive (ALK+) NSCLC, we identified that lung tumors with ALK rearrangements harbor a unique metabolic signature marked by reliance on anabolic nucleotide pathways. A phosphoproteomic screen in ALK+ patient-derived cells identified a novel metabolic target of ALK signaling, GUK1, the only known enzyme responsible for GDP synthesis. We show that ALK binds to and phosphorylates GUK1 and that ALK-mediated GUK1 phosphorylation augments GDP/GTP nucleotide biosynthesis. Steady-state and tracing metabolomic studies demonstrate that ALK inhibition and GUK1 phosphomutant are epistatic in guanine nucleotide production. Molecular dynamic modeling suggests that phosphorylation of GUK1 alters the dynamics of active site closure to enhance substrate processivity and protects GUK1 from a non-catalytic confirmation. Introduction of phosphomutant GUK1 into ALK+ patient-derived cell lines results in decreased tumor proliferation in vitro and in vivo in xenograft models. Spatially resolved mass spectrometry imaging of tumor specimens from ALK+ patients demonstrates significant enrichment of guanine nucleotides in ALK+ and phospho-GUK1+ tumor cells. We identified that other oncogenic fusion proteins regulate GUK1 phosphorylation, highlighting the need to further characterize GUK1 as a metabolic liability in NSCLC. Furthermore, a subset of patient-derived cell lines with resistance to ALK tyrosine kinase inhibitors (TKIs) exhibits increased expression and phosphorylation of GUK1, indicating that regulation of this metabolic enzyme may play a role in mediating acquired resistance. We anticipate these studies will pave the way for the development of new therapeutic approaches by exploiting metabolic vulnerabilities in oncogene-driven lung cancers.

Citation Format: Jaime Laurel Schneider, Kiran Kurmi, Ishita Dhiman, Roberta Colapietro, Shakchhi Joshi, Christian Johnson, Satoshi Yoda, Joao Paulo, Daniela Ruiz, Sylwia Stopka, Gerard Baquer, Jessica Lin, Kevin Haigis, Nathalie Agar, Steven Gygi, Aaron Hata, Marcia Haigis. GUK1 is a novel metabolic liability in oncogene-driven lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1156.

NVL-520 Is a Selective, TRK-Sparing, and Brain-Penetrant Inhibitor of ROS1 Fusions and Secondary Resistance Mutations

SIGNIFICANCE

The combined preclinical features of NVL-520 that include potent targeting of ROS1 and diverse ROS1 resistance mutations, high selectivity for ROS1 G2032R over TRK, and brain penetration mark the development of a distinct ROS1 TKI with the potential to surpass the limitations of earlier-generation TKIs for ROS1 fusion-positive patients. This article is highlighted in the In This Issue feature, p. 517.

Abstract P249: Preclinical antitumor activity of NVL-520 in patient-derived models harboring ROS1 fusions, including G2032R solvent front mutation

ROS1 is a proto-oncogene that encodes the receptor tyrosine kinase ROS1, which can be aberrantly activated by gene rearrangement to drive tumor cell proliferation, survival, and metastasis. In non-small cell lung cancer (NSCLC), ROS1 rearrangements are detected in up to 3% of patients with up to 40% of these patients also presenting with accompanying central nervous system (CNS) metastases. Although various tyrosine kinase inhibitors (TKI) have been approved or are under development for treating ROS1-positive patients, these therapies are associated with one or more of the following significant challenges: 1. emergence of ROS1 mutations that confer disease resistance, including the G2032R solvent front mutation, 2. disease progression into the CNS, and 3. treatment-related adverse events (AEs) associated with off-target kinase inhibition, notably TRKB in the CNS. NVL-520 was developed to address the challenges listed above. Preclinical studies have shown that NVL-520 inhibits wild-type and drug resistance mutants of the ROS1 kinase and demonstrated activity against CNS disease with minimal kinase off-target activity, suggesting an opportunity for durable responses for patients with ROS1-positive disease. Here we report detailed characterization of cellular and antitumor activity of NVL-520 in patient-derived models of ROS1-driven NSCLC. Methods: Cellular and antitumor activity of NVL-520 were evaluated in patient-derived models of NSCLC representing ROS1 and ROS1-G2032R driven disease. For in vivo studies, treatments were administered orally. Western blotting, immunohistochemistry, and gene expression analyses were used to measure pharmacodynamic (PD) effects in tumor tissue. Pharmacokinetic (PK) analyses were also performed. Results: In patient-derived cell (PDC) models of EZR-ROS1 and CD74-ROS1 G2032R, NVL-520 treatment resulted in antiproliferative activity, with IC50 values < 10 nM, and reduced levels of phospho-ROS1 and markers of downstream signaling. Studies in patient-derived xenograft (PDX) models demonstrated that NVL-520 was well-tolerated and resulted in dose-dependent antitumor activity, including tumor regression in all models. Analysis of PD biomarkers showed that NVL-520 suppressed ROS1 phosphorylation and significantly impacted ROS1-dependent signaling pathways. PK analysis demonstrated dose-dependent differences in NVL-520 exposure. PD-Efficacy correlation analysis showed that changes in PD were consistent with dose-dependent antitumor activity of NVL-520 with distinct changes observed at doses that induce tumor stasis versus tumor regression. Conclusion: NVL-520 exhibits antiproliferative and antitumor activity in NSCLC models driven by ROS1 and ROS1-G2032R solvent front mutation. We believe the findings presented here support evaluation of NVL-520 for the treatment of patients with ROS1-driven disease.

Citation Format: Amit M. Deshpande, Satoshi Yoda, Anupong Tangpeerachaikul, Nancy E. Kohl, Joshua C. Horan, Aaron N. Hata, Henry E. Pelish. Preclinical antitumor activity of NVL-520 in patient-derived models harboring ROS1 fusions, including G2032R solvent front mutation [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P249.

Alginate-based 3D cancer cell culture for therapeutic response modeling

Two-dimensional (2D) culture of tumor cells fails to recapitulate some important aspects of cellular organization seen in in vivo experiments. In addition, cell cultures traditionally use non-physiological concentration of nutrients. Here, we describe a protocol for a facile three-dimensional (3D) culture format for cancer cells. This 3D platform helps overcome the 2D culture limitations. In addition, it allows for longitudinal modeling of responses to cancer therapeutics.

For complete details on the use and execution of this protocol, please refer to Lhuissier et al. (2017), Lehmann et al. (2016), Liu et al. (2016), and Duval et al. (2011).

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A detailed protocol on hydrogel-based 3D culture of patient-derived tumor cell lines

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No binding sites for cells in hydrogel polymers allowing for pure interaction of cells

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Longitudinal 3D proliferation assays and drug-response assessments

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Quick and easy recovery of 3D-cultured cells for downstream experiments

Spectrum of Mechanisms of Resistance to Crizotinib and Lorlatinib in ROS1 Fusion-Positive Lung Cancer

PURPOSE

Current standard initial therapy for advanced, ROS proto-oncogene 1, receptor tyrosine kinase fusion (ROS1)-positive (ROS1⁺) non-small cell lung cancer (NSCLC) is crizotinib or entrectinib. Lorlatinib, a next-generation anaplastic lymphoma kinase/ROS1 inhibitor, recently demonstrated efficacy in ROS1⁺ NSCLC, including in crizotinib-pretreated patients. However, mechanisms of lorlatinib resistance in ROS1⁺ disease remain poorly understood. Here, we assessed mechanisms of resistance to crizotinib and lorlatinib.

EXPERIMENTAL DESIGN

Biopsies from patients with ROS1 ⁺ NSCLC progressing on crizotinib or lorlatinib were profiled by genetic sequencing.

RESULTS

From 55 patients, 47 post-crizotinib and 32 post-lorlatinib biopsies were assessed. Among 42 post-crizotinib and 28 post-lorlatinib biopsies analyzed at distinct timepoints, ROS1 mutations were identified in 38% and 46%, respectively. ROS1 G2032R was the most commonly occurring mutation in approximately one third of cases. Additional ROS1 mutations included D2033N (2.4%) and S1986F (2.4%) post-crizotinib and L2086F (3.6%), G2032R/L2086F (3.6%), G2032R/S1986F/L2086F (3.6%), and S1986F/L2000V (3.6%) post-lorlatinib. Structural modeling predicted ROS1^L2086F causes steric interference to lorlatinib, crizotinib, and entrectinib, while it may accommodate cabozantinib. In Ba/F3 models, ROS1^L2086F, ROS1^{G2032R/L2086F}, and ROS1^{S1986F/G2032R/L2086F} were refractory to lorlatinib but sensitive to cabozantinib. A patient with disease progression on crizotinib and lorlatinib and ROS1 L2086F received cabozantinib for nearly 11 months with disease control. Among lorlatinib-resistant biopsies, we also identified MET amplification (4%), KRAS G12C (4%), KRAS amplification (4%), NRAS mutation (4%), and MAP2K1 mutation (4%).

CONCLUSIONS

ROS1 mutations mediate resistance to crizotinib and lorlatinib in more than one third of cases, underscoring the importance of developing next-generation ROS1 inhibitors with potency against these mutations, including G2032R and L2086F. Continued efforts are needed to elucidate ROS1-independent resistance mechanisms.

Small cell transformation of ROS1 fusion-positive lung cancer resistant to ROS1 inhibition

Histologic transformation from non-small cell to small cell lung cancer has been reported as a resistance mechanism to targeted therapy in EGFR-mutant and ALK fusion-positive lung cancers. Whether small cell transformation occurs in other oncogene-driven lung cancers remains unknown. Here we analyzed the genomic landscape of two pre-mortem and 11 post-mortem metastatic tumors collected from an advanced, ROS1 fusion-positive lung cancer patient, who had received sequential ROS1 inhibitors. Evidence of small cell transformation was observed in all metastatic sites at autopsy, with inactivation of RB1 and TP53, and loss of ROS1 fusion expression. Whole-exome sequencing revealed minimal mutational and copy number heterogeneity, suggestive of "hard" clonal sweep. Patient-derived models generated from autopsy retained features consistent with small cell lung cancer and demonstrated resistance to ROS1 inhibitors. This case supports small cell transformation as a recurring resistance mechanism, and underscores the importance of elucidating its biology to expand therapeutic opportunities.

RET Solvent Front Mutations Mediate Acquired Resistance to Selective RET Inhibition in RET-Driven Malignancies

INTRODUCTION

Novel rearranged in transfection (RET)-specific tyrosine kinase inhibitors (TKIs) such as selpercatinib (LOXO-292) have shown unprecedented efficacy in tumors positive for RET fusions or mutations, notably RET fusion-positive NSCLC and RET-mutated medullary thyroid cancer (MTC). However, the mechanisms of resistance to these agents have not yet been described.

METHODS

Analysis was performed of circulating tumor DNA and tissue in patients with RET fusion-positive NSCLC and RET-mutation positive MTC who developed disease progression after an initial response to selpercatinib. Acquired resistance was modeled preclinically using a CCDC6-RET fusion-positive NSCLC patient-derived xenograft. The inhibitory activity of anti-RET multikinase inhibitors and selective RET TKIs was evaluated in enzyme and cell-based assays.

RESULTS

After a dramatic initial response to selpercatinib in a patient with KIF5B-RET NSCLC, analysis of circulating tumor DNA revealed emergence of RET G810R, G810S, and G810C mutations in the RET solvent front before the emergence of clinical resistance. Postmortem biopsy studies reported intratumor and intertumor heterogeneity with distinct disease subclones containing G810S, G810R, and G810C mutations in multiple disease sites indicative of convergent evolution on the G810 residue resulting in a common mechanism of resistance. Acquired mutations in RET G810 were identified in tumor tissue from a second patient with CCDC6-RET fusion-positive NSCLC and in plasma from patients with additional RET fusion-positive NSCLC and RET-mutant MTC progressing on an ongoing phase 1 and 2 trial of selpercatinib. Preclinical studies reported the presence of RET G810R mutations in a CCDC6-RET patient-derived xenograft (from a patient with NSCLC) model of acquired resistance to selpercatinib. Structural modeling predicted that these mutations sterically hinder the binding of selpercatinib, and in vitro assays confirmed loss of activity for both anti-RET multikinase inhibitors and selective RET TKIs.

CONCLUSIONS

RET G810 solvent front mutations represent the first described recurrent mechanism of resistance to selective RET inhibition with selpercatinib. Development of potent inhibitor of these mutations and maintaining activity against RET gatekeeper mutations could be an effective strategy to target resistance to selective RET inhibitors.

MET Alterations Are a Recurring and Actionable Resistance Mechanism in ALK-Positive Lung Cancer

PURPOSE

Most ALK-positive lung cancers will develop ALK-independent resistance after treatment with next-generation ALK inhibitors. MET amplification has been described in patients progressing on ALK inhibitors, but frequency of this event has not been comprehensively assessed.

EXPERIMENTAL DESIGN

We performed FISH and/or next-generation sequencing on 207 posttreatment tissue (n = 101) or plasma (n = 106) specimens from patients with ALK-positive lung cancer to detect MET genetic alterations. We evaluated ALK inhibitor sensitivity in cell lines with MET alterations and assessed antitumor activity of ALK/MET blockade in ALK-positive cell lines and 2 patients with MET-driven resistance.

RESULTS

MET amplification was detected in 15% of tumor biopsies from patients relapsing on next-generation ALK inhibitors, including 12% and 22% of biopsies from patients progressing on second-generation inhibitors or lorlatinib, respectively. Patients treated with a second-generation ALK inhibitor in the first-line setting were more likely to develop MET amplification than those who had received next-generation ALK inhibitors after crizotinib (P = 0.019). Two tumor specimens harbored an identical ST7-MET rearrangement, one of which had concurrent MET amplification. Expressing ST7-MET in the sensitive H3122 ALK-positive cell line induced resistance to ALK inhibitors that was reversed with dual ALK/MET inhibition. MET inhibition resensitized a patient-derived cell line harboring both ST7-MET and MET amplification to ALK inhibitors. Two patients with ALK-positive lung cancer and acquired MET alterations achieved rapid responses to ALK/MET combination therapy.

CONCLUSIONS

Treatment with next-generation ALK inhibitors, particularly in the first-line setting, may lead to MET-driven resistance. Patients with acquired MET alterations may derive clinical benefit from therapies that target both ALK and MET.

Formation of Nanofibrous Structure in Biopolymer Aerogel during Supercritical CO2 Processing: The Case of Chitosan Aerogel

Supercritical drying is widely considered as the gold standard to produce aerogels that preserve the microstructure of the gels, but we have found this is not always the case. Chitosan aerogel, one of the emerging biopolymer aerogels, was prepared by chemical cross-linking gelation, followed by solvent exchange with methanol and supercritical drying using CO₂. Small-angle X-ray scattering analysis shows that the structure of the wet gel, which consists of Gaussian chains of individual molecular strands, converts into a nanofibrous network during CO₂ processing. In situ observation reveals a drastic shrinkage of the gel in CO₂, demonstrating that physical coagulation caused by the low affinity between chitosan and CO₂ is the main structure-forming step. These results challenge the common perception of supercritical drying: it is no longer an inactive drying method, but rather an active nanostructure forming a tool to produce porous biopolymer materials with tailored structure and properties.

Phase Behavior of a Carbon Dioxide/Methyl Trimethoxy Silane/Polystyrene Ternary System

Recently, polymeric foams filled with a silica aerogel have been developed. The phase behavior of CO₂/silicon alkoxide binary systems and CO₂/silicon alkoxide/polymer ternary systems is an important factor that affects the design of novel processes. The phase behavior of a carbon dioxide (CO₂)/methyl trimethoxy silane (MTMS)/polystyrene (PS) ternary system was measured using a synthetic method involving the observation of the bubble and cloud point. The phase boundaries were measured at temperatures ranging from 313.2 to 393.2 K and CO₂ weight fractions between 0.01 and 0.08. The CO₂/MTMS/PS system showed a similar CO₂ mass fraction dependence of the phase behavior to that observed for the CO₂/tetramethyl orthosilicate (TMOS)/PS system. When the phase boundaries of these systems were compared, the vapor-liquid (VL) and vapor-liquid-liquid (VLL) lines were found to be nearly identical, while the liquid-liquid (LL) lines were different. These results indicate that the affinity between the silicon alkoxide and polymer greatly influences the liquid-liquid phase separation.

Landscape of Acquired Resistance to Osimertinib in EGFR-Mutant NSCLC and Clinical Validation of Combined EGFR and RET Inhibition with Osimertinib and BLU-667 for Acquired RET Fusion

We present a cohort of 41 patients with osimertinib resistance biopsies, including 2 with an acquired CCDC6-RET fusion. Although RET fusions have been identified in resistant EGFR-mutant non-small cell lung cancer (NSCLC), their role in acquired resistance to EGFR inhibitors is not well described. To assess the biological implications of RET fusions in an EGFR-mutant cancer, we expressed CCDC6-RET in PC9 (EGFR del19) and MGH134 (EGFR L858R/T790M) cells and found that CCDC6-RET was sufficient to confer resistance to EGFR tyrosine kinase inhibitors (TKI). The selective RET inhibitors BLU-667 and cabozantinib resensitized CCDC6-RET-expressing cells to EGFR inhibition. Finally, we treated 2 patients with EGFR-mutant NSCLC and RET-mediated resistance with osimertinib and BLU-667. The combination was well tolerated and led to rapid radiographic response in both patients. This study provides proof of concept that RET fusions can mediate acquired resistance to EGFR TKIs and that combined EGFR and RET inhibition with osimertinib/BLU-667 may be a well-tolerated and effective treatment strategy for such patients. SIGNIFICANCE: The role of RET fusions in resistant EGFR-mutant cancers is unknown. We report that RET fusions mediate resistance to EGFR inhibitors and demonstrate that this bypass track can be effectively targeted with a selective RET inhibitor (BLU-667) in the clinic.This article is highlighted in the In This Issue feature, p. 1494.

First report of hepatobiliary Mycobacterium avium infection developing obstructive jaundice in a patient with neutralizing anti-interferon-gamma autoantibodies

This study describes a patient who experienced hepatobiliary Mycobacterium avium infection associated with neutralizing anti–interferon gamma (IFN-γ) autoantibodies during treatment for disseminated M. avium disease. Hepatobiliary M. avium infection should be considered in jaundiced patients with neutralizing anti–IFN-γ autoantibodies, including those receiving antimycobacterial therapy for disseminated M. avium disease.

Targeting oncogenic drivers in lung cancer: Recent progress, current challenges and future opportunities

Targeted therapies have changed the landscape of treatments for non-small cell lung cancer (NSCLC). Specific targeted therapies have been approved for NSCLC patients harboring genetic alterations in four oncogenes, and agents targeting additional oncogenic drivers are under investigation. Standard first-line chemotherapy has been supplanted by these targeted therapies due to superior efficacy and lower toxicity. Despite excellent response rates and durable responses in some cases, most patients experience relapse within a few years due to the development of acquired drug resistance. Next generation targeted therapies are being developed to overcome drug resistance and extend the duration of therapy. In this review, we summarize the current treatment strategies for the major targetable oncogenic mutations/alterations in NSCLC and discuss the mechanisms leading to acquired drug resistance.

Abstract 4795: Potency of a new ALK/ROS1 inhibitor TPX-0005 to ALK G1202R mutation and ROS1 G2032R mutation

ALK rearrangements and ROS1 rearrangements are important therapeutic targets in non-small cell lung cancer (NSCLC). ALK-positive NSCLC is currently treated with the first-generation ALK inhibitor crizotinib followed by more potent, second-generation ALK inhibitors, such as ceritinib, alectinib, or brigatinib, and ROS1-positve NSCLC is currently treated with crizotinib. Even though these drugs produce responses in most patients, drug resistance eventually develops. Notable mechanisms of resistance are kinase domain solvent front mutations, such as ALK G1202R and ROS1 G2032R. Genomic analysis of relapsed cases show ALK G1202R in 21%, 29%, or 43% of ceritinib-, alectinib-, or brigarinib-resistant cases, and ROS1 G2032R in 41% of crizotinib-resistant cases.

The novel ALK/ROS1 inhibitor TPX-0005 was designed to overcome clinical resistance mutations, especially solvent front mutations, and is currently being evaluated in a phase 1/2 study. Engineered preclinical models have demonstrated the potency of TPX-0005 against ALK G1202R and ROS1 G2032R. For example, Ba/F3 cells expressing EML4-ALK G1202R or CD74-ROS1 G2032R resistant to second-generation ALK inhibitors or crizotinib, respectively, but were sensitive to TPX-0005. Here we investigate the potency of TPX-0005 to overcome solvent front mutations in resistant patient-derived models. We generated cell lines and patient-derived xenograft mouse models from ALK G1202R and ROS1 G2032R tumors at the time of relapse on second-generation ALK inhibitors or crizotinib, respectively. As expected, these models were resistant to second-generation ALK inhibitors or crizotinib. In contrast, TPX-0005 suppressed ALK or ROS1 phosphorylation, and led to decreased cell viability and tumor regression in vivo. These data demonstrate that TPX-0005 overcomes solvent front mutations in clinically relevant models and provides rationale for the clinical development of TPX-0005 for patients harboring ALK G1202R or ROS1 G2032R resistance mutations.

Citation Format: Satoshi Yoda, Leila Dardaei, Kylie Prutisto-Chang, Jean Cui, Alice T. Shaw, Aaron N. Hata. Potency of a new ALK/ROS1 inhibitor TPX-0005 to ALK G1202R mutation and ROS1 G2032R mutation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4795.

Sequential ALK Inhibitors Can Select for Lorlatinib-Resistant Compound ALK Mutations in ALK-Positive Lung Cancer

The cornerstone of treatment for advanced ALK-positive lung cancer is sequential therapy with increasingly potent and selective ALK inhibitors. The third-generation ALK inhibitor lorlatinib has demonstrated clinical activity in patients who failed previous ALK inhibitors. To define the spectrum of ALK mutations that confer lorlatinib resistance, we performed accelerated mutagenesis screening of Ba/F3 cells expressing EML4-ALK. Under comparable conditions, N-ethyl-N-nitrosourea (ENU) mutagenesis generated numerous crizotinib-resistant but no lorlatinib-resistant clones harboring single ALK mutations. In similar screens with EML4-ALK containing single ALK resistance mutations, numerous lorlatinib-resistant clones emerged harboring compound ALK mutations. To determine the clinical relevance of these mutations, we analyzed repeat biopsies from lorlatinib-resistant patients. Seven of 20 samples (35%) harbored compound ALK mutations, including two identified in the ENU screen. Whole-exome sequencing in three cases confirmed the stepwise accumulation of ALK mutations during sequential treatment. These results suggest that sequential ALK inhibitors can foster the emergence of compound ALK mutations, identification of which is critical to informing drug design and developing effective therapeutic strategies.Significance: Treatment with sequential first-, second-, and third-generation ALK inhibitors can select for compound ALK mutations that confer high-level resistance to ALK-targeted therapies. A more efficacious long-term strategy may be up-front treatment with a third-generation ALK inhibitor to prevent the emergence of on-target resistance. Cancer Discov; 8(6); 714-29. ©2018 AACR.This article is highlighted in the In This Issue feature, p. 663.

Impact of EML4-ALK Variant on Resistance Mechanisms and Clinical Outcomes in ALK-Positive Lung Cancer

Purpose Advanced anaplastic lymphoma kinase ( ALK) fusion-positive non-small-cell lung cancers (NSCLCs) are effectively treated with ALK tyrosine kinase inhibitors (TKIs). However, clinical outcomes in these patients vary, and the benefit of TKIs is limited as a result of acquired resistance. Emerging data suggest that the ALK fusion variant may affect clinical outcome, but the molecular basis for this association is unknown. Patients and Methods We identified 129 patients with ALK-positive NSCLC with known ALK variants. ALK resistance mutations and clinical outcomes on ALK TKIs were retrospectively evaluated according to ALK variant. A Foundation Medicine data set of 577 patients with ALK-positive NSCLC was also examined. Results The most frequent ALK variants were EML4-ALK variant 1 in 55 patients (43%) and variant 3 in 51 patients (40%). We analyzed 77 tumor biopsy specimens from patients with variants 1 and 3 who had progressed on an ALK TKI. ALK resistance mutations were significantly more common in variant 3 than in variant 1 (57% v 30%; P = .023). In particular, ALK G1202R was more common in variant 3 than in variant 1 (32% v 0%; P < .001). Analysis of the Foundation Medicine database revealed similar associations of variant 3 with ALK resistance mutation and with G1202R ( P = .010 and .015, respectively). Among patients treated with the third-generation ALK TKI lorlatinib, variant 3 was associated with a significantly longer progression-free survival than variant 1 (hazard ratio, 0.31; 95% CI, 0.12 to 0.79; P = .011). Conclusion Specific ALK variants may be associated with the development of ALK resistance mutations, particularly G1202R, and provide a molecular link between variant and clinical outcome. ALK variant thus represents a potentially important factor in the selection of next-generation ALK inhibitors.

Tracking the Evolution of Resistance to ALK Tyrosine Kinase Inhibitors through Longitudinal Analysis of Circulating Tumor DNA

Purpose

ALK rearrangements predict for sensitivity to ALK tyrosine kinase inhibitors (TKIs). However, responses to ALK TKIs are generally short-lived. Serial molecular analysis is an informative strategy for identifying genetic mediators of resistance. Although multiple studies support the clinical benefits of repeat tissue sampling, the clinical utility of longitudinal circulating tumor DNA analysis has not been established in ALK-positive lung cancer.

Methods

Using a 566-gene hybrid-capture next-generation sequencing (NGS) assay, we performed longitudinal analysis of plasma specimens from 22 ALK-positive patients with acquired resistance to ALK TKIs to track the evolution of resistance during treatment. To determine tissue-plasma concordance, we compared plasma findings to results of repeat biopsies.

Results

At progression, we detected an ALK fusion in plasma from 19 (86%) of 22 patients, and identified ALK resistance mutations in plasma specimens from 11 (50%) patients. There was 100% agreement between tissue- and plasma-detected ALK fusions. Among 16 cases where contemporaneous plasma and tissue specimens were available, we observed 100% concordance between ALK mutation calls. ALK mutations emerged and disappeared during treatment with sequential ALK TKIs, suggesting that plasma mutation profiles were dependent on the specific TKI administered. ALK G1202R, the most frequent plasma mutation detected after progression on a second-generation TKI, was consistently suppressed during treatment with lorlatinib.

Conclusions

Plasma genotyping by NGS is an effective method for detecting ALK fusions and ALK mutations in patients progressing on ALK TKIs. The correlation between plasma ALK mutations and response to distinct ALK TKIs highlights the potential for plasma analysis to guide selection of ALK-directed therapies.

Abstract A145: SHP2 inhibition restores sensitivity to ALK inhibitors in resistant ALK-rearranged NSCLC

Most anaplastic lymphoma kinase (ALK)-rearranged non-small cell lung tumors initially respond to small-molecule ALK inhibitors, but drug resistance often develops. After tumors develop resistance to highly potent 2nd-generation ALK inhibitors, approximately half harbor ALK resistance mutations, while the other half have other mechanisms of resistance. The latter often have activation of at least one of several different tyrosine kinases driving resistance. Such tumors are not expected to respond to the 3rd-generation ALK inhibitor, lorlatinib, which is able to overcome all clinically identified ALK resistance mutations, and further therapeutic options are limited. Herein, we deployed an shRNA screen of 1000 genes in multiple ALK inhibitor-resistant patient-derived cells (PDC) to discover sensitizers to ALK inhibition. This approach identified SHP2, a non-receptor protein tyrosine phosphatase, as a common targetable resistance node in multiple PDCs. SHP2 provides a parallel survival input downstream of multiple tyrosine kinases that promote resistance to ALK inhibitors. The recently discovered small-molecule SHP2 inhibitor, SHP099, in combination with the ALK TKI (tyrosine kinase inhibitor), ceritinib, halted the growth of resistant PDCs by preventing compensatory RAS and ERK1/2 reactivation. These findings suggest that combined ALK and SHP2 inhibition may be a promising therapeutic strategy for resistant cancers driven by several different ALK-independent resistance mechanisms.

Citation Format: Leila Dardaei, Hui Qin Wang, Manrose Singh, Paul Fordjour, Satoshi Yoda, Grainne Kerr, Jinsheng Liang, Yichen Cao, Yan Chen, Justin Gainor, Luc Friboulet, Ibiayi Dagogo-Jack, David Myers, Emma Labrot, David Ruddy, Melissa Parks, Dana Lee, Richard DiCecca, Susan Moody, Huaixiang Hao, Morvarid Mohseni, Matthew LaMarche, Juliet Williams, Keith Hoffmaster, Giordano Caponigro, Alice Shaw, Aaron Hata, Cyril Benes, Fang Li, Jeffrey Engelman. SHP2 inhibition restores sensitivity to ALK inhibitors in resistant ALK-rearranged NSCLC [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A145.

Translucent, hydrophobic, and mechanically tough aerogels constructed from trimethylsilylated chitosan nanofibers

Cross-linking and trimethylsilylation successfully block off the hydrophilic NH₂ and OH groups in chitosan nanofibers to produce a waterproof nanofibrous aerogel while keeping its nanoscale structural homogeneity intact. The unique microstructure of a three-dimensionally entangled nanofiber network exhibiting a combination of translucency, hydrophobicity, and non-brittleness is described.

Patterns of Metastatic Spread and Mechanisms of Resistance to Crizotinib in ROS1-Positive Non-Small-Cell Lung Cancer

PURPOSE

The ROS1 tyrosine kinase is activated through ROS1 gene rearrangements in 1-2% of non-small cell lung cancer (NSCLC), conferring sensitivity to treatment with the ALK/ROS1/MET inhibitor crizotinib. Currently, insights into patterns of metastatic spread and mechanisms of crizotinib resistance among ROS1-positive patients are limited.

PATIENTS AND METHODS

We reviewed clinical and radiographic imaging data of patients with ROS1- and ALK-positive NSCLC in order to compare patterns of metastatic spread at initial metastatic diagnosis. To determine molecular mechanisms of crizotinib resistance, we also analyzed repeat biopsies from a cohort of ROS1-positive patients progressing on crizotinib.

RESULTS

We identified 39 and 196 patients with advanced ROS1- and ALK-positive NSCLC, respectively. ROS1-positive patients had significantly lower rates of extrathoracic metastases (ROS1 59.0%, ALK 83.2%, P=0.002), including lower rates of brain metastases (ROS1 19.4%, ALK 39.1%; P = 0.033), at initial metastatic diagnosis. Despite similar overall survival between ALK- and ROS1-positive patients treated with crizotinib (median 3.0 versus 2.5 years, respectively; P=0.786), ROS1-positive patients also had a significantly lower cumulative incidence of brain metastases (34% vs. 73% at 5 years; P<0.0001). Additionally, we identified 16 patients who underwent a total of 17 repeat biopsies following progression on crizotinib. ROS1 resistance mutations were identified in 53% of specimens, including 9/14 (64%) non-brain metastasis specimens. ROS1 mutations included: G2032R (41%), D2033N (6%), and S1986F (6%).

CONCLUSIONS

Compared to ALK rearrangements, ROS1 rearrangements are associated with lower rates of extrathoracic metastases, including fewer brain metastases, at initial metastatic diagnosis. ROS1 resistance mutations, particularly G2032R, appear to be the predominant mechanism of resistance to crizotinib, underscoring the need to develop novel ROS1 inhibitors with activity against these resistant mutants.

Abstract 1007: SHP2 inhibition restores sensitivity to ALK inhibition in resistant ALK-rearranged non-small cell lung cancer (NSCLC)

Despite development of highly potent and selective inhibitors (e.g., ceritinib, alectinib, lorlatinib) targeting anaplastic lymphoma kinase (ALK), resistance invariably develops and limits the efficacy of these inhibitors in the clinic. The major classes of resistance are on-target genetic alterations (e.g., secondary ALK kinase domain mutations) and activation of alternative or bypass signaling pathways. While most patients are responsive to sequential treatment with two or more ALK inhibitors, ALK-independent resistance eventually emerges and leads to failure of further ALK-directed monotherapy. We used a synthetic lethal pooled shRNA screen to discover loss-of-function events that could sensitize resistant patient-derived cell lines to ALK inhibition. In addition to identifying known bypass targets such as FGFR, EGFR and SRC, we also identified PTPN11 (which encodes SHP2, a non-receptor protein tyrosine phosphatase that modulates signaling downstream of growth factor receptors) as a common hit shared by cell lines exhibiting different mechanisms of bypass activation. In parallel with the shRNA screen, we also performed a high throughput combination compound screen in the same patient-derived models, and identified activation of the same bypass signaling pathways. We showed that the highly potent and selective small-molecule SHP2 inhibitor SHP099 could sensitize resistant cell lines to ALK inhibition. In biochemical studies, co-targeting of ALK and SHP2 overcame resistance mediated by ALK-independent bypass mechanisms by decreasing RAS-GTP loading potential of cells and inhibiting phospho-ERK rebound. These results suggest that dual ALK and SHP2 inhibition may represent a new therapeutic strategy for ALK-positive patients, whose lung cancers have evolved ALK-independent mechanisms of resistance, including activation of bypass signaling pathways.

Citation Format: Leila Dardaei, Hui Qin Wang, Paul Fordjour, Manrose Singh, Grainne Kerr, Satoshi Yoda, Jinsheng Liang, Yichen Cao, Yan Chen, Justin F. Gainor, Luc Friboulet, Ibiayi Dagogo-Jack, David T. Myers, Emma Labrot, David Ruddy, Melissa Parks, Dana Lee, Richard H. DiCecca, Susan Moody, Huaixiang Hao, Morvarid Mohseni, Matthew LaMarche, Juliet Williams, Keith Hoffmaster, Giordano Caponigro, Cyril H. Benes, Alice T. Shaw, Aaron N. Hata, Fang Li, Jeffrey A. Engelman. SHP2 inhibition restores sensitivity to ALK inhibition in resistant ALK-rearranged non-small cell lung cancer (NSCLC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1007. doi:10.1158/1538-7445.AM2017-1007

Abstract 3144: Prediction of ALK mutations associated with acquired resistance to lorlatinib

Anaplastic lymphoma kinase (ALK) rearrangements are important therapeutic targets in non-small cell lung cancer. They are currently treated with the first-generation ALK inhibitor crizotnib followed by more potent, second-generation ALK inhibitors, such as ceritinib, alectinib, or brigatinib. We reported different spectrums of ALK resistance mutations in the biopsies from patients progressing on these drugs. G1202R mutation was found more frequently after treatment with second generation ALK inhibitors. In addition to these drugs, the third-generation ALK inhibitor lorlatinib is currently being evaluated in phase 2 clinical trial. Ba/F3 models indicated that all single ALK mutants are sensitive to lorlatinib and some compound ALK mutations are resistant to lorlatinib. In this study, we performed accelerated mutagenesis screen on Ba/F3 models to predict the resistance mutations which potentially emerge in the patients treated with lorlatinib. Briefly, Ba/F3 cells expressing wild type EML4-ALK or mutant EML4-ALK containing C1156Y, F1174C, L1196M, G1202R, or G1269A were exposed to N-ethyl-N-nitrosourea (ENU). After a 24-hour incubation in normal media, the cells were seeded in 96-well plates and incubated in lorlatinib for 4 weeks. ALK kinase domain was sequenced in clones growing in lorlatinib to identify possible new mutations. As a result, Ba/F3 cells harboring wild type EML4-ALK did not show any mutation on ALK kinase domain. Crizotinib was used as a control to validate the efficiency of mutagenesis. We identified eight different mutations in clones growing in crizotinib, and those were reflecting the spectrum of mutations in the crizotinib-treated patients. Ba/F3 cells with mutant EML4-ALK showed additional compound mutations after incubation with lorlatinib. Those mutations included L1196M + L1198F and G1202R + L1198F which showed high resistance to lorlatinib in Ba/F3 models. Ba/F3 cells with different mutant EML4-ALK showed a distinct spectrum and different frequency of additional mutations. In conclusion, this study predicted that no single mutation would emerge to confer resistance to lorlatinib. Thus, compound mutations and ALK-independent mechanisms become essential mechanisms for lorlatinib resistance.

Citation Format: Satoshi Yoda, Leila Dardaei, Manrose Singh, Jeffrey A. Engelman, Alice T. Shaw, Aaron N. Hata. Prediction of ALK mutations associated with acquired resistance to lorlatinib [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3144. doi:10.1158/1538-7445.AM2017-3144

Erlotinib as second- or third-line treatment in elderly patients with advanced non-small cell lung cancer: Keio Lung Oncology Group Study 001 (KLOG001)

The aim of this study was to assess the efficacy and safety of erlotinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), as second- or third-line treatment for elderly Japanese patients with non-small-cell lung cancer (NSCLC). The patients eligible for this phase II trial were aged ≥70 years, had stage III/IV or recurrent NSCLC, and had previously received 1 or 2 chemotherapy regimens that did not include EGFR-TKIs. The patients received erlotinib at a dose of 150 mg/day. The primary endpoint was overall response rate (ORR), and the secondary endpoints were progression-free survival (PFS), overall survival (OS) and toxicity. A total of 38 patients with a median age of 76 years were enrolled. The majority of the patients were men (66%), had an Eastern Cooperative Oncology Group performance status of 1 (58%), stage IV disease (66%) and adenocarcinoma (74%). Of the 35 patients, 13 (34%) had tumors with EGFR mutations. The ORR was 26.3% (95% confidence interval: 12.1-40.5%) and the disease control rate was 47.4%. The median PFS was 3.7 months and the median OS was 17.3 months. The grade 3 adverse events observed included rash (13%), diarrhea (5%), interstitial pneumonitis (5%), anorexia (3%) and gastrointestinal bleeding (3%). Grade 4 or 5 adverse events were not observed. The median OS did not differ significantly between patients aged <75 years (14.9 months) and those aged ≥75 years (19.0 months; P=0.226). Therefore, erlotinib was found to be effective and well-tolerated in elderly patients with previously treated NSCLC.

Molecular Mechanisms of Resistance to First- and Second-Generation ALK Inhibitors in ALK-Rearranged Lung Cancer

Advanced, anaplastic lymphoma kinase (ALK)-positive lung cancer is currently treated with the first-generation ALK inhibitor crizotinib followed by more potent, second-generation ALK inhibitors (e.g., ceritinib and alectinib) upon progression. Second-generation inhibitors are generally effective even in the absence of crizotinib-resistant ALK mutations, likely reflecting incomplete inhibition of ALK by crizotinib in many cases. Herein, we analyzed 103 repeat biopsies from ALK-positive patients progressing on various ALK inhibitors. We find that each ALK inhibitor is associated with a distinct spectrum of ALK resistance mutations and that the frequency of one mutation, ALK^G1202R, increases significantly after treatment with second-generation agents. To investigate strategies to overcome resistance to second-generation ALK inhibitors, we examine the activity of the third-generation ALK inhibitor lorlatinib in a series of ceritinib-resistant, patient-derived cell lines, and observe that the presence of ALK resistance mutations is highly predictive for sensitivity to lorlatinib, whereas those cell lines without ALK mutations are resistant.

SIGNIFICANCE

Secondary ALK mutations are a common resistance mechanism to second-generation ALK inhibitors and predict for sensitivity to the third-generation ALK inhibitor lorlatinib. These findings highlight the importance of repeat biopsies and genotyping following disease progression on targeted therapies, particularly second-generation ALK inhibitors. Cancer Discov; 6(10); 1118-33. ©2016 AACRSee related commentary by Qiao and Lovly, p. 1084This article is highlighted in the In This Issue feature, p. 1069.

A phase II study of biweekly paclitaxel and carboplatin in elderly patients with advanced non-small cell lung cancer

PURPOSE

The number of elderly patients with advanced non-small cell lung cancer (NSCLC) is increasing. Although several studies have suggested the benefit of chemotherapy with a platinum doublet for elderly patients with advanced NSCLC, this treatment is still controversial in this age group. To evaluate the efficacy and tolerability of combination chemotherapy with biweekly paclitaxel and carboplatin for elderly patients with advanced NSCLC, we conducted a multicenter, non-randomized, open label, phase II trial.

METHODS

We recruited patients aged ≥70 years with clinical stage IIIB and IV NSCLC and ECOG performance status (PS) of 0-2. Patients received paclitaxel (90 mg/m(2)) and carboplatin (AUC = 2.5) on day 1 and 15, every 4 weeks. The primary endpoint was overall response rate (ORR), and the secondary endpoints were progression-free survival (PFS), overall survival (OS), and safety.

RESULTS

Sixty-five patients (median age 79 years; range 70-87 years) were enrolled. Forty-nine patients were men, and 48 were stage IV. The PS was 0, 1, and 2 in 28, 33, and 4 patients, respectively. The histological type of NSCLC was non-squamous in 69.3 % and squamous cell carcinoma in 30.7 % of patients. The median number of treatment cycles was 3 (range 1-6). The response rate was 29.4 % (95 % CI 18.7-43.0), and the disease control rate was 78.0 % (95 % CI 64.8-87.2). Median PFS and OS were 3.8 months (95 % CI 1.9-5.3) and 17.3 months (95 % CI 10.4-25.1), respectively. The most common grade 3 or 4 toxicities were neutropenia (27 %), leukopenia (15 %), infection (10 %), and anemia (8 %).

CONCLUSION

The combination of biweekly paclitaxel and carboplatin was effective and well tolerated in elderly patients with advanced NSCLC.

FOXD1 expression is associated with poor prognosis in non-small cell lung cancer

AIM

Clinical microarray datasets were analyzed to search for new therapeutic targets and prognostic markers of non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

Microarray datasets from 90 lung cancer specimens, were analyzed with focus on the FOXD1 gene. Levels of FOXD1 mRNA were assessed in lung cancer cell lines and these levels were correlated with survival.

RESULTS

FOXD1-knockdown led to suppression of cell proliferation. Moreover, patients with high FOXD1 expression survived for a significantly shorter time than those with low FOXD1 expression.

CONCLUSION

The expression status of FOXD1 is a novel prognostic factor and may lead to new treatment strategies for NSCLC.

Unexpected massive hemorrhage following the removal of a pleural drainage tube

We herein describe a case in which a massive hemorrhage unexpectedly occurred after the removal of a pleural drainage tube which had been in place for five days. One possible explanation for that event was the damage of the intercostal artery during tube insertion into the thoracic cavity. This is an extremely rare but severe complication. Therefore, the present report provides useful information for physicians who treat patients with respiratory diseases.

Methylation-induced downregulation of TFPI-2 causes TMPRSS4 overexpression and contributes to oncogenesis in a subset of non-small-cell lung carcinoma

We identified transmembrane protease, serine 4 (TMPRSS4) as a putative, druggable target by screening surgically resected samples from 90 Japanese non-small-cell lung cancer (NSCLC) patients using cDNA microarray. TMPRSS4 has two druggable domains and was upregulated in 94.5% of the lung cancer specimens. Interestingly, we found that TMPRSS4 expression was associated with tissue factor pathway inhibitor 2 (TFPI-2) expression in these clinical samples. In contrast to TMPRSS4, TFPI-2 expression was downregulated in NSCLC samples. The in vitro induction of TFPI-2 in lung cancer cell lines decreased the expression of TMPRSS4mRNA levels. Reporter assay showed that TFPI-2 inhibited transcription of TMPRSS4, although partially. Knockdown of TMPRSS4 reduced the proliferation rate in several lung cancer cell lines. When lung cancer cell lines were treated with 5-aza-2′-deoxycytidine or trichostatin A, their proliferation rate and TMPRSS4mRNA expression levels were also reduced through the upregulation of TFPI-2 by decreasing its methylation in vitro. The TFPI-2 methylation level in the low TMPRSS4 group appeared to be significantly low in NSCLC samples (P = 0.02). We found a novel molecular mechanism that TFPI-2 negatively regulates cell growth by inhibiting transcription of TMPRSS4. We suggest that TMPRSS4 is upregulated by silencing of TFPI-2 through aberrant DNA methylation and contributes to oncogenesis in NSCLC.

Abstract 5195: Claudin-1, a novel target of miR-375 in non-small cell lung cancer

MicroRNAs, the small and noncoding RNAs, regulate the translation of specific protein-coding genes. Accumulated evidence strongly suggests that microRNAs play important and complex roles in human cancers, including lung cancer. We previously reported that miR-375 expression was low in squamous cell carcinoma (SCC) and high in adenocarcinoma (AC) of lung cancer. The target gene of miR-375 in non-small cell lung cancer (NSCLC) has not been elucidated. The purpose of this study was to identify a target of miR-375 and clarify the function of miR-375 in NSCLC. Candidate genes of miR-375 targets were determined using the prediction databases and also previous findings about the different gene expression between SCC and AC. We focused on claudin-1 (CLDN1), which has four putative target sites of miR-375 in its 3′-untranslated region (UTR). CLDN1 was reported to express high in SCC and low in AC opposite to miR-375. We evaluated miR-375 and CLDN1 expression levels by quantitative polymerase chain reaction (qPCR) and Western blotting in 12 NSCLC cell lines. The effect of miR-375 overexpression upon the CLDN1 expression was evaluated in 5 NSCLC cell lines by transfecting miR-375 precursor. It showed that the expression of CLDN1 messenger RNA and protein were attenuated by miR-375 overexpression. Luciferase reporter assay was performed to confirm direct interaction between miR-375 and CLDN1. We cloned 3′-UTR of CLDN1 cDNA into the downstream of a luciferase reporter gene and co-transfected this vector into A549 cells with miR-375 precursor. MiR-375 overexpression resulted in a 3-fold repression of luciferase activity (p &lt; 0.001). To ascertain the clinical validity, we analyzed the relationship between miR-375 and CLDN1 expression in 63 clinical samples of NSCLC. There was a negative correlation between miR-375 and CLDN1 expression (r = -0.35, p = 0.005). In addition, we analyzed the correlation between miR-375 expression and overall survival in the same samples. High miR-375 expression correlated with poor survival in NSCLC (p = 0.043). To investigate the reason why high miR-375 expression lead to poor survival, wound healing assay was performed to evaluate the effect of miR-375 overexpression on the cell migration in SK-MES-1 cells. The cell migration was promoted by miR-375 overexpression, suggesting the high potential of invasion and metastasis in NSCLC expressing high level of miR375. In conclusion, we found that CLDN1 is a novel target of miR-375, and high miR-375 expression leads to poor survival in NSCLC.

Citation Format: Satoshi Yoda, Kenzo Soejima, Hiroyuki Yasuda, Takashi Sato, Daisuke Arai, Keiko Ohgino, Kota Ishioka, Tetsuo Tani, Ayano Oashi, Aoi Kuroda, Makoto Nishino, Masayoshi Miyawaki, Junko Hamamoto, Katsuhiko Naoki, Tomoko Betsuyaku. Claudin-1, a novel target of miR-375 in non-small cell lung cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5195. doi:10.1158/1538-7445.AM2014-5195

Abstract 5652: Activation of FGF2-FGFR1 pathway in EGFR-mutant lung cancer cell line with long-term gefitinib exposure

Many of the patients with non-small cell lung cancer (NSCLC) with sensitive epidermal growth factor receptor (EGFR)-mutation who initially responded well to EGFR-tyrosine kinase inhibitors (TKIs) eventually relapse. In spite of many studies over the last few years to elucidate this mechanism of acquired resistance to EGFR-TKIs, approximately 30% of the mechanisms of acquired resistance are still unknown. Recently autocrine signaling of fibroblast growth factors (FGFs) and their receptors (FGFRs) has been demonstrated in NSCLC cell lines. And several studies suggest that the FGF-FGFR autocrine growth pathway could be an important mechanism for intrinsic resistance to EGFR-TKIs in NSCLC cell lines with wild-type EGFR. But until now, no report has clarified the role of FGF-FGFR pathway in acquired resistance to EGFR-TKIs in NSCLC cell lines with sensitive EGFR mutations. We have established a gefitinib-resistant cell line (PC9 GR), by serial exposure of gefitinib to PC9, an originally gefitinib-sensitive lung cancer cell line (PC9 na). We confirmed that these cell lines did not harbor two well-known EGFR-TKI resistance mechanisms, the second mutation in the EGFR gene itself, EGFR T790 and the amplification of the MET oncogene. We collected total RNA from both PC9 na and PC9 GR and examined mRNA expression profile, by using cDNA microarray analysis. We found the expressions of FGFR1 and FGF2 were increased in PC9 GR compared to in PC9 na. The growth of PC9 GR cells was inhibited either by PD173074 (inhibitors of FGFRs) or knocking down of FGFR1 or FGF2 by siRNA in combination with gefitinib. FACS analysis revealed that the combination treatment with PD173074 and gefitinib induced apoptosis more efficiently in PC9 GR cells compared to gefitinib alone. PC9 na cells and PC9 GR cells did not show any change in the proportion of apoptotic cells after treatment with PD173074 alone. To further investigate how FGF2-FGFR1 pathway affects resistance to gefitinib in these cell lines, the downstream targets of EGFR signaling including the MEK-ERK and PI3K-AKT pathways were examined. In PC9 na cells, the phosphorylation of EGFR, ERK, and AKT was efficiently inhibited by gefitinib alone. On the other hand, in PC9 GR cells, the phosphorylation of ERK and AKT was not efficiently inhibited by gefitinib alone. However, the inhibition of phosphorylation of ERK was completely and AKT was less efficiently rescued by gefitinib and PD173074 combination therapy. In conclusion, these data suggest the activation of FGF2-FGFR1 signaling pathway contributes to the gefitinib resistance in PC9 GR. FGF2-FGFR1 pathway will be a therapeutic target for a subset of NSCLC that acquires EGFR-TKI resistance.

Citation Format: Hideki Terai, Kenzo Soejima, Katsuhiko Naoki, Hiroyuki Yasuda, Ryosuke Satomi, Sohei Nakayama, Satoshi Yoda, Shinnosuke Ikemura, Takashi Sato, Kota Ishioka, Daisuke Arai, Keiko Ohgino, Tetsuo Tani, Aoi Kuroda, Junko Hamamoto, Tomoko Betsuyaku. Activation of FGF2-FGFR1 pathway in EGFR-mutant lung cancer cell line with long-term gefitinib exposure. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5652. doi:10.1158/1538-7445.AM2013-5652

Abstract 5257: FGF9 overexpression promotes tumorigenic potential of non-small cell lung cancer (NSCLC) cells, and is associated with poor prognosis in NSCLC patients

Background. Fibroblast growth factor 9 (FGF9) is a member of the FGF family, which modulates cell proliferation, differentiation and motility. Recent studies show that activation of FGF signals including FGF9 is associated with pathogenesis of several cancers. In lung cancer, some reports showed that FGF9 indirectly promoted the growth of lung adenocarcinoma and the intensity of FGF9 staining was positively correlated with the status of disease and the degree of lymph node metastasis in lung adenocarcinoma patients. However, the direct effect of FGF9 on the development and growth of lung cancer has not been clear.

Purpose. The purpose of this study is to clarify the role of FGF9 in NSCLC.

Method. First, we have performed in vitro analysis to clarify the role of FGF9 in NSCLC. FGF9 was introduced by retroviral infection to make stable cell lines. The cell lines which express no or low FGF9 were selected for the study, namely A549, PC9 and H1975. Overexpression of FGF9 in these cells was confirmed at mRNA and protein levels. Tumorigenic potential was evaluated by soft agar colony formation assay. The effect on proliferation of NSCLC cells was evaluated by MTS proliferation assay.

Next, patients survival analysis was also performed to evaluate the effect of FGF9 on the prognosis of NSCLC patients. NSCLC specimens were obtained from 91 patients who underwent surgical resection at Department of Thoracic Surgery, Keio University Hospital from 2001 through 2006 with written informed consent. We have performed cDNA microarray gene expression analysis. Patient survival data was evaluated by genes expression profile.

Results. Of the cells studied, A549 with FGF9 overexpression (A549-FGF9) cells significantly increased the anchorage independent colony formation ability compared with A549-empty cells. The numbers of the colonies were significantly higher in A549-FGF9, and the size of the colonies was bigger compared with A549-empty. For patient study, we found 10 out of 91 (11.0%) NSCLC patients overexpressed FGF9. We found FGF9 overexpression was associated with significantly worse prognosis (p=0.001). While none of other FGFs and FGFRs was associated with the prognosis of the patients. Three-year survival rate of FGF9-high patient group and FGF9-low patient group were 40% and 88% respectively. The rate of relapse was significantly higher in FGF9-high patients compared with FGF9-low patients, 60% vs 36.2% (p=0.016).

Conclusion. Our in vitro and clinical data indicate that FGF-9 may promote tumorigenic potential, and can be a prognostic indicator in NSCLC patients.

Citation Format: Kota Ishioka, Kenzo Soejima, Hiroyuki Yasuda, Keiko Ohgino, Satoshi Yoda, Takashi Sato, Junko Hamamoto, Daisuke Arai, Tetsuo Tani, Aoi Kuroda, Katsuhiko Naoki, Tomoko Betsuyaku. FGF9 overexpression promotes tumorigenic potential of non-small cell lung cancer (NSCLC) cells, and is associated with poor prognosis in NSCLC patients. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5257. doi:10.1158/1538-7445.AM2013-5257

Activation of the FGF2-FGFR1 autocrine pathway: a novel mechanism of acquired resistance to gefitinib in NSCLC

Patients with non-small cell lung cancer (NSCLC) that harbors epidermal growth factor receptor (EGFR) mutations initially respond to EGFR-tyrosine kinase inhibitors (TKI) but eventually experience relapse. Acquired resistance to EGFR-TKIs is strongly associated with patient mortality. Thus, elucidation of the mechanism of acquired resistance to EGFR-TKIs is of great importance. In this study, gefitinib-resistant cell line models were established by long-term exposure to gefitinib using the gefitinib-sensitive lung cancer cell lines, PC9 and HCC827. Expression analyses indicated that both FGFR1 and FGF2 were increased in PC9 gefitinib-resistant (PC9 GR) cells as compared with PC9 naïve (PC9 na) cells. Importantly, proliferation of gefitinib-resistant cells was dependent on the FGF2 -FGFR1 pathway. Mechanistically, inhibition of either FGF2 or FGFR1 by siRNA or FGFR inhibitor (PD173074) restored gefitinib sensitivity in PC9 GR cells. These data suggest that FGF2 -FGFR1 activation through an autocrine loop is a novel mechanism of acquired resistance to EGFR-TKIs.