Adaptive resistance to therapeutic PD-1 blockade is associated with upregulation of alternative immune checkpoints

Despite compelling antitumour activity of antibodies targeting the programmed death 1 (PD-1): programmed death ligand 1 (PD-L1) immune checkpoint in lung cancer, resistance to these therapies has increasingly been observed. In this study, to elucidate mechanisms of adaptive resistance, we analyse the tumour immune microenvironment in the context of anti-PD-1 therapy in two fully immunocompetent mouse models of lung adenocarcinoma. In tumours progressing following response to anti-PD-1 therapy, we observe upregulation of alternative immune checkpoints, notably T-cell immunoglobulin mucin-3 (TIM-3), in PD-1 antibody bound T cells and demonstrate a survival advantage with addition of a TIM-3 blocking antibody following failure of PD-1 blockade. Two patients who developed adaptive resistance to anti-PD-1 treatment also show a similar TIM-3 upregulation in blocking antibody-bound T cells at treatment failure. These data suggest that upregulation of TIM-3 and other immune checkpoints may be targetable biomarkers associated with adaptive resistance to PD-1 blockade.

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

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

Management and future directions in non-small cell lung cancer with known activating mutations

Lung cancer accounts for a quarter of all cancer deaths. Non-small cell lung cancer (NSCLC) is currently segregated by the presence of actionable driver oncogenes. This review will provide an overview of molecular subsets of lung cancer, including descriptions of the defining oncogenes (EGFR, ALK, KRAS, ROS1, RET, BRAF, ERBB2, NTRK1, FGFR, among others) and how these predict for response to small molecule tyrosine kinase inhibitors (TKIs) that are either clinically available or in clinical trial development for advanced NSCLC. Particular focus will be placed on subsets with EGFR mutated and ALK rearranged NSCLC. Somatic TKI-sensitizing EGFR mutations (such as exon 19 deletions and L858R substitutions) are the most robust predictive biomarker for symptom improvement, radiographic response, and increment in progression-free survival (PFS) when EGFR TKIs (gefitinib, erlotinib, and afatinib) are used for patients with advanced NSCLC. However, the palliative benefits that EGFR TKIs afford are limited by multiple biologic mechanisms of tumor adaptation/resistance (such as the EGFR-T790M mutation and oncogene bypass tracks), and future efforts toward delaying, preventing, and treating resistance are underway. Similar to EGFR mutations, ALK rearrangements exemplify an oncogene-driven NSCLC that can be effectively palliated with a precision TKI therapy (the multitargeted ALK/MET/ROS1 TKI crizotinib). When resistance to first-line crizotinib therapy occurs, multiple second generation ALK TKIs have demonstrated impressive rates of disease control in clinical trials, and these may modify long-term outcomes for patients with ALK-positive NSCLC. The development of TKIs for other oncogene-driven NSCLCs may expand the portfolio of precision therapies for this recalcitrant cancer.

Abstract B96: Adaptive resistance to therapeutic PD-1:PD-L1 blockade is mediated by upregulation of the TIM-3 immune checkpoint

Introduction:

Programmed death 1 (PD-1): Programmed death ligand 1 (PD-L1) immune checkpoint blockade has been demonstrated to be efficacious in a number of cancer types, including melanoma, renal cell carcinoma, bladder cancer, hematologic malignancies and non-small cell lung cancer (NSCLC) and anti-PD-1 antibodies have recently been approved for use in the United States and Asia. Anti-PD-1 therapeutic antibodies function through binding to PD-1 on tumor-reactive T cells and inhibiting the PD-1:PD-L1 interaction, thereby reinvigorating the anti-tumor T cell response. Expression of PDL1 in tumor cells and infiltrating immune cells and PD-1 in T cells has been associated with responsiveness to blockade of this immune checkpoint; however, mechanisms of both de novo and adaptive resistance to therapy are unclear.

Methods:

We used two genetically engineered mouse models of lung adenocarcinomas corresponding to the two most common oncogene drivers in human lung adenocarcinoma, Kirsten rat sarcoma viral oncogene homolog (KRAS) and EGFR. The EGFR and Kras models were treated with a therapeutic anti-PD-1 antibody until tumors demonstrated progression by MRI and evaluated immune profiles. To confirm the applicability of these findings in patients, we also analyzed immune cells from patients who showed an initial response to PD-1 blockade but developed progressive disease several months after the initiation of treatment.

Results:

We identified upregulation of Tim-3 checkpoint receptor on therapeutic antibody-bound T cells as a marker of treatment resistance in mouse tumors. To determine whether blockade of Tim-3 at the time of resistance might be therapeutically efficacious, we performed Tim-3 blocking treatment in these mice and demonstrated a clinical benefit. Specimens from the two patients who developed progressive disease after an initial response to anti-PD1 treatments also exhibited similar upregulation of TIM-3 on therapeutic antibody-bound T cells, further supporting TIM-3 as a marker of treatment resistance.

Conclusions:

TIM-3 is upregulated in anti-PD-1 antibody bound T cells at the time of tumor regrowth in both genetically engineered mouse models and non-small cell lung cancer patients who initially responded to PD-1 blocking treatment. Targeting TIM-3 could be a promising option to reinitiate tumor-reactive T cell activation in patients who have developed adaptive resistance to anti-PD-1 treatment.

Citation Format: Esra A. Akbay, Shohei Koyama, Yvonne Y. Li, Grit S. Herter-Sprie, Kevin A. Buczkowski, William G. Richards, Leena Gandhi, Amanda J. Redig, Scott J. Rodig, Hajime Asahina, Robert E. Jones, Meghana M. Kulkarni, Peter E. Fecci, Bruce E. Johnson, Pasi A. Janne, Jeffrey A. Engelman, Sidharta P. Gangadharan, Daniel B. Costa, Gordon J. Freeman, Raphael Bueno, F. Stephen Hodi, Glenn Dranoff, Kwok-Kin Wong, Peter S. Hammerman. Adaptive resistance to therapeutic PD-1:PD-L1 blockade is mediated by upregulation of the TIM-3 immune checkpoint. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B96.

Responses to the multitargeted MET/ALK/ROS1 inhibitor crizotinib and co-occurring mutations in lung adenocarcinomas with MET amplification or MET exon 14 skipping mutation

INTRODUCTION

Genomic aberrations involving ALK, ROS1 and MET can be driver oncogenes in lung adenocarcinomas. Identification of tyrosine kinase inhibitors (TKIs) with activity against these tumors and of preclinical systems to model response are warranted.

METHODS

We analyzed cases with lung adenocarcinomas for representative genomic aberrations, evaluated the response to the multitargeted MET/ALK/ROS1 crizotinib TKI in cases with MET aberrations and profiled lung cancer cell lines with the aforementioned genomic changes.

RESULTS

Lung cancer cell lines with ALK rearrangement, ROS1 rearrangement or MET amplification had expected in vitro responses to crizotinib and the ALK/ROS1 TKI ceritinib. However, a commercially-available cell line with MET exon 14 skipping mutation and co-occurring PIK3CA-p.Glu545Lys mutation did not respond to crizotinib; suggesting the latter abrogated response. 10% of MET exon 14 skipping mutation co-occurred with PIK3CA mutation in the TCGA cohort. Putative crizotinib-responsive somatic mutations (ALK rearrangements, ROS1 rearrangements, high level MET amplification or MET exon 14 skipping mutations) were present in 10% of lung adenocarcinomas analyzed at our service and in 9.5% of the TCGA lung adenocarcinoma database. One patient each whose advanced tumors harbored high level MET amplification with wild-type PIK3CA or MET exon 14 skipping mutation with PIK3CA-p.Glu542Lys had significant responses to crizotinib; suggesting that PIK3CA co-mutation did not affect clinical response.

CONCLUSIONS

Approximately 10% of lung adenocarcinomas harbor aberrations that are targetable using the approved multitargeted TKI crizotinib. MET exon 14 skipping mutation predicts for response to MET TKIs in human lung adenocarcinomas but co-occurrence of PIK3CA mutation needs to be better evaluated as a modifier of response to TKI therapy. MET TKIs should not be omitted from MET exon 14 skipping mutated tumors until further preclinical and clinical data can confirm or refute mechanisms of primary or acquired resistance to crizotinib and other MET TKIs in these recalcitrant cancers.

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

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

Management of advanced non-small cell lung cancers with known mutations or rearrangements: latest evidence and treatment approaches

Precision oncology is now the evidence-based standard of care for the management of many advanced non-small cell lung cancers (NSCLCs). Expert consensus has defined minimum requirements for routine testing and identification of epidermal growth factor (EGFR) mutations (15% of tumors harbor EGFR exon 19 deletions or exon 21 L858R substitutions) and anaplastic lymphoma kinase (ALK) rearrangements (5% of tumors) in advanced lung adenocarcinomas (ACs). Application of palliative targeted therapies with oral tyrosine kinase inhibitors (TKIs) in advanced/metastatic lung ACs harboring abnormalities in EGFR (gefitinib, erlotinib, afatinib) and ALK/ROS1/MET (crizotinib) has consistently led to more favorable outcomes compared with traditional cytotoxic agents. In addition, mutations leading to resistance to first-line EGFR and ALK TKIs can now be successfully inhibited by soon to be approved third-generation EGFR TKIs (osimertinib, rociletinib) and second-generation ALK TKIs (ceritinib, alectinib). Notably, increasing feasibility, accessibility, and application of molecular profiling technologies has permitted dynamic growth in the identification of actionable driver oncogenes. Emerging genomic aberrations for which TKIs have shown impressive results in clinical trials and expansion of drug labels for approved agents are awaited include ROS1 rearrangements (1-2% of tumors, drug: crizotinib) and BRAF-V600E mutations (1-3% of tumors, drugs: vemurafenib, dafrafenib + trametinib). Evolving genomic events in which TKI responses have been reported in smaller series include MET exon 14 skipping mutations (2-4% of tumors, drug: crizotinib); high-level MET amplification (1-2% of tumors, drug: crizotinib); RET rearrangements (1% of tumors, drug: cabozantinib); and ERBB2 mutations (2-3% of tumors, drug: afatinib), among others. Unfortunately, the most common genomic event in NSCLC, KRAS mutations (25-30% of tumors), is not targetable with approved or in development small molecule inhibitors. Here, we review currently approved, emerging, and evolving systemic precision therapies matched with their driver oncogenes for the management of advanced NSCLC.

In vitro modeling to determine mutation specificity of EGFR tyrosine kinase inhibitors against clinically relevant EGFR mutants in non-small-cell lung cancer

EGFR mutated lung cancer accounts for a significant subgroup of non-small-cell lung cancer (NSCLC). Over the last decade, multiple EGFR tyrosine kinase inhibitors (EGFR-TKIs) have been developed to target mutated EGFR. However, there is little information regarding mutation specific potency of EGFR-TKIs against various types of EGFR mutations. The purpose of this study is to establish an in vitro model to determine the "therapeutic window" of EGFR-TKIs against various types of EGFR mutations, including EGFR exon 20 insertion mutations. The potency of 1st (erlotinib), 2nd (afatinib) and 3rd (osimertinib and rociletinib) generation EGFR-TKIs was compared in vitro for human lung cancer cell lines and Ba/F3 cells, which exogenously express mutated or wild type EGFR. An in vitro model of mutation specificity was created by calculating the ratio of IC50 values between mutated and wild type EGFR. The in vitro model identified a wide therapeutic window of afatinib for exon 19 deletions and L858R and of osimertinib and rociletinib for T790M positive mutations. The results obtained with our models matched well with previously reported preclinical and clinical data. Interestingly, for EGFR exon 20 insertion mutations, most of which are known to be resistant to 1st and 2nd generation EGFR-TKIS, osimertinib was potent and presented a wide therapeutic window. To our knowledge, this is the first report that has identified the therapeutic window of osimertinib for EGFR exon 20 insertion mutations. In conclusion, this model will provide a preclinical rationale for proper selection of EGFR-TKIs against clinically-relevant EGFR mutations.

Lung cancer diagnosis and staging in the minimally invasive age with increasing demands for tissue analysis

The diagnosis and staging of patients with lung cancer in recent decades has increasingly relied on minimally invasive tissue sampling techniques, such as endobronchial ultrasound (EBUS) or endoscopic ultrasound (EUS) needle aspiration, transbronchial biopsy, and transthoracic image guided core needle biopsy. These modalities have been shown to have low complication rates, and provide adequate cellular material for pathologic diagnosis and necessary ancillary molecular testing. As an important component to a multidisciplinary team approach in the care of patients with lung cancer, these minimally invasive modalities have proven invaluable for the rapid and safe acquisition of tissue used for the diagnosis, staging, and molecular testing of tumors to identify the best evidence-based treatment plan. The continuous evolution of the field of lung cancer staging and treatment has translated into improvements in survival and quality of life for patients. Although differences in clinical practice between academic and community hospital settings still exist, improvements in physician education and training as well as adoption of technological advancements should help narrow this gap going forward.

Costa D, Wegiel B. Abstract 416: Carbon monoxide targets Notch1 and MAPK-ERK1/2 signaling pathways to block growth of lung carcinoma

We have recently shown that inhalation of low, non-toxic doses of carbon monoxide (CO) is a potential therapeutic adjuvant treatment for lung cancer and prostate cancer (Cancer Research, 2013, Wegiel B et al). We found that CO doses of 100 ppm daily or twice per week were the most effective in suppressing A549 xenograft tumors growth, Ki67 expression and increased cleaved caspase-3 staining. Additionally, we found that inhibition of xenografts and KRAS-driven lung tumor growth in response to CO was associated with increased expression of M1 macrophage markers (CD86, CD197, RANTES) and decreased M2 markers (MMR) and HO-1 blockage. We demonstrated a direct interaction between HO-1 and Notch1. Further, that CO promotes Notch 1 cleavage as well as phosphorylation of ERK1/2 in the stroma cells, which are the markers of M1 polarization. Moreover, we demonstrated a significant correlation between low HO-1 expression and high p-ERK ½ expression in primary human lung cancers (n = 30 patients). In summary, we describe a mechanism by which CO affects cancer growth through regulation of macrophage polarization via Notch1 and Erk1/2 pathways.

Citation Format: Zsuzsanna Nemeth, Eva Csizmadia, Lisa Vikstrom, Mailin Li, Kavita Bisht, Alborz Feizi, David Gallo, Leo Otterbein, Janos Fillinger, Balazs Dome, Daniel B. Costa, Barbara Wegiel. Carbon monoxide targets Notch1 and MAPK-ERK1/2 signaling pathways to block growth of lung carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 416. doi:10.1158/1538-7445.AM2015-416

Brain metastases in patients with EGFR-mutated or ALK-rearranged non-small-cell lung cancers

INTRODUCTION

Brain metastases (BM) are common in non-small-cell lung cancer (NSCLC). However, the baseline incidence and evolution of BM over time in oncogene-driven NSCLCs are seldom reported. In this study, we evaluated the frequency of BM in patients with epidermal growth factor receptor (EGFR)-mutated or anaplastic lymphoma kinase (ALK)-rearranged NSCLC.

METHODS

The presence of BM, clinicopathologic data, and tumor genotype were retrospectively compiled and analyzed from a cohort of 381 patients.

RESULTS

We identified 86 EGFR-mutated (90.7% with metastatic disease; 85.9% received an EGFR inhibitor) and 23 ALK-rearranged (91.3% with metastatic disease; 85.7% received an ALK inhibitor) NSCLCs. BM were present in 24.4% of EGFR-mutated and 23.8% of ALK-rearranged NSCLCs at the time of diagnosis of advanced disease. This study did not demonstrate a difference in the cumulative incidence of BM over time between the two cohorts (EGFR/ALK cohort competing risk regression [CRR] coefficient of 0.78 [95% CI 0.44-1.39], p=0.41). In still living patients with advanced EGFR-mutated NSCLC, 34.2% had BM at 1 year, 38.4% at 2 years, 46.7% at 3 years, 48.7% at 4 years, and 52.9% at 5 years. In still living patients with advanced ALK-rearranged NSCLC, 23.8% had BM at 1 year, 45.5% at 2 years, and 58.4% at 3 years.

CONCLUSIONS

BM are frequent in advanced EGFR-mutated or ALK-rearranged NSCLCs, with an estimated >45% of patients with CNS involvement by three years of survival with the use of targeted therapies. These data point toward the CNS as an important unmet clinical need in the evolving schema for personalized care in NSCLC.

De novo pulmonary small cell carcinomas and large cell neuroendocrine carcinomas harboring EGFR mutations: Lack of response to EGFR inhibitors

INTRODUCTION

Epidermal growth factor receptor (EGFR) mutations are present in 10-20% of all non-small-cell lung cancers and predict for response to EGFR tyrosine kinase inhibitors (TKIs). However, the incidence of these mutations and their ability to predict response to TKIs in high-grade pulmonary neuroendocrine carcinomas [i.e. small cell lung cancer (SCLC) and large cell neuroendocrine carcinoma (LCNEC)] is unknown.

METHODS

The presence of EGFR mutations, clinicopathologic and anti-cancer therapy response data were retrospectively compiled and analyzed from a cohort of 608 patients-lung tumors to identify EGFR mutated high-grade pulmonary neuroendocrine carcinomas. We identified 126 EGFR-mutated (21.8% of 578 successful genotyped cases) lung cancers and only 2 (1.6%) were high-grade neuroendocrine carcinomas.

RESULTS

Case one was of a 63 year-old white never smoker woman with extensive stage SCLC harboring EGFR-delL747_P753insS but without EGFR protein expression. After progression on carboplatin/etoposide, the patient was treated with erlotinib and developed progressive disease with a survival <3 months from start of erlotinib. Case two was of a 73 year-old Asian 30 pack-year smoker man with metastatic LCNEC harboring EGFR-delL747_P753insQS and also lacking EGFR protein expression. The patient received first line therapy with erlotinib and had progressive disease with a survival of 4 months.

CONCLUSIONS

The lack of response to EGFR TKIs in EGFR mutated de novo SCLC and LCNEC reported here may indicate that tumor differentiation affects tumor dependency on EGFR as a driver oncogene.

The Clinical Use of Genomic Profiling to Distinguish Intrapulmonary Metastases From Synchronous Primaries in Non-Small-Cell Lung Cancer: A Mini-Review

The ability to reliably distinguish synchronous primary non-small-cell lung cancer (NSCLC) from intrapulmonary metastatic spread affects staging and treatment decisions in resected NSCLC. Adjuvant therapy for early-stage NSCLC is complicated and recommendations are primarily based on older data from trials that used now-outdated staging systems. Patients found to have 2 tumors with similar morphology in the same lobe are currently staged as pathologic T3 (pT3) but such cases represent a minority of patients in adjuvant lung cancer trials. Potentially more precise than tumor morphology alone, comprehensive genomic profiling technologies have the power to discriminate whether tumors in the same lobe represent 2 separate primary lesions or localized spread of a single lesion. In addition to lineage insights, tumor profiling simultaneously provides information on actionable genomic alterations. In this review we discuss the data that support the ability of molecular technologies to distinguish synchronous primary tumors from intrapulmonary metastases and discuss the use of molecular assays as an adjunct to current staging systems. Two cases are presented to highlight the potential immediate clinical implications of comprehensive genomic profiling.

CCAAT/enhancer binding protein β is dispensable for development of lung adenocarcinoma

Lung cancer is the leading cause of cancer death worldwide. Although disruption of normal proliferation and differentiation is a vital component of tumorigenesis, the mechanisms of this process in lung cancer are still unclear. A transcription factor, C/EBPβ is a critical regulator of proliferation and/or differentiation in multiple tissues. In lung, C/EBPβ is expressed in alveolar pneumocytes and bronchial epithelial cells; however, its roles on normal lung homeostasis and lung cancer development have not been well described. Here we investigated whether C/EBPβ is required for normal lung development and whether its aberrant expression and/or activity contribute to lung tumorigenesis. We showed that C/EBPβ was expressed in both human normal pneumocytes and lung adenocarcinoma cell lines. We found that overall lung architecture was maintained in Cebpb knockout mice. Neither overexpression of nuclear C/EBPβ nor suppression of CEBPB expression had significant effects on cell proliferation. C/EBPβ expression and activity remained unchanged upon EGF stimulation. Furthermore, deletion of Cebpb had no impact on lung tumor burden in a lung specific, conditional mutant EGFR lung cancer mouse model. Analyses of data from The Cancer Genome Atlas (TCGA) revealed that expression, promoter methylation, or copy number of CEBPB was not significantly altered in human lung adenocarcinoma. Taken together, our data suggest that C/EBPβ is dispensable for development of lung adenocarcinoma.

RB loss in resistant EGFR mutant lung adenocarcinomas that transform to small-cell lung cancer

Tyrosine kinase inhibitors are effective treatments for non-small-cell lung cancers (NSCLCs) with epidermal growth factor receptor (EGFR) mutations. However, relapse typically occurs after an average of 1 year of continuous treatment. A fundamental histological transformation from NSCLC to small-cell lung cancer (SCLC) is observed in a subset of the resistant cancers, but the molecular changes associated with this transformation remain unknown. Analysis of tumour samples and cell lines derived from resistant EGFR mutant patients revealed that Retinoblastoma (RB) is lost in 100% of these SCLC transformed cases, but rarely in those that remain NSCLC. Further, increased neuroendocrine marker and decreased EGFR expression as well as greater sensitivity to BCL2 family inhibition are observed in resistant SCLC transformed cancers compared with resistant NSCLCs. Together, these findings suggest that this subset of resistant cancers ultimately adopt many of the molecular and phenotypic characteristics of classical SCLC.

Resistance to tyrosine kinase inhibitors occurs in treatments of non-small-cell lung cancers (NSCLCs) with EGFR mutations but the mechanisms underlying this acquired resistance are unknown. Here the authors examine the molecular changes that occur in resistant cancers that transition from NSCLC to small-cell lung cancer phenotype and implicate loss of retinoblastoma in this process.

Clinical Experience With Crizotinib in Patients With Advanced ALK-Rearranged Non-Small-Cell Lung Cancer and Brain Metastases

PURPOSE

Crizotinib is an oral kinase inhibitor approved for the treatment of ALK-rearranged non-small-cell lung cancer (NSCLC). The clinical benefits of crizotinib in patients with brain metastases have not been previously studied.

PATIENTS AND METHODS

Patients with advanced ALK-rearranged NSCLC enrolled onto clinical trial PROFILE 1005 or 1007 (randomly assigned to crizotinib) were included in this retrospective analysis. Patients with asymptomatic brain metastases (nontarget or target lesions) were allowed to enroll. Tumor assessments were evaluated every 6 weeks using RECIST (version 1.1).

RESULTS

At baseline, 31% of patients (275 of 888) had asymptomatic brain metastases; 109 had received no prior and 166 had received prior brain radiotherapy as treatment. Among patients with previously untreated asymptomatic brain metastases, the systemic disease control rate (DCR) at 12 weeks was 63% (95% CI, 54% to 72%), the intracranial DCR was 56% (95% CI, 46% to 66%), and the median intracranial time to progression (TTP) was 7 months (95% CI, 6.7 to 16.4). Among patients with previously treated brain metastases, the systemic DCR was 65% (95% CI, 57% to 72%), the intracranial DCR was 62% (95% CI, 54% to 70%), and the median intracranial TTP was 13.2 months (95% CI, 9.9 to not reached). Patients with systemic disease control were also likely to experience intracranial disease control at 12 weeks (correlation coefficient, 0.7652; P < .001). Among patients without baseline brain metastases who developed progressive disease (n = 253) after initiation of crizotinib, 20% were diagnosed with brain metastases.

CONCLUSION

Crizotinib was associated with systemic and intracranial disease control in patients with ALK-rearranged NSCLC who were ALK inhibitor naive and had brain metastases. However, progression of preexisting or development of new intracranial lesions while receiving therapy was a common manifestation of acquired resistance to crizotinib.

Experience with targeted next generation sequencing for the care of lung cancer: insights into promises and limitations of genomic oncology in day-to-day practice

INTRODUCTION

Tumor genotyping using single gene assays (SGAs) is standard practice in advanced non-small-cell lung cancer (NSCLC). We evaluated how the introduction of next generation sequencing (NGS) into day-to-day clinical practice altered therapeutic decision-making.

METHODS

Clinicopathologic data, tumor genotype, and clinical decisions were retrospectively compiled over 6 months following introduction of NGS assay use at our institution in 82 patient-tumor samples (7 by primary NGS, 22 by sequential SGAs followed by NGS, and 53 by SGAs).

RESULTS

SGAs identified abnormalities in 34 samples, and all patients with advanced EGFR-mutated or ALK-rearranged tumors received approved tyrosine kinase inhibitors (TKIs) or were consented for clinical trials. NGS was more commonly requested for EGFR, ALK, and KRAS-negative tumors (p<0.0001). NGS was successful in 24/29 (82.7%) tumors. Of 17 adenocarcinomas (ACs), 11 (7 from patients with ≤15 pack-years of smoking) had abnormalities in a known driver oncogene. This led to a change in decision-making in 8 patients, trial consideration in 6, and off-label TKI use in 2. Of 7 squamous cell (SC) carcinomas, 1 had a driver aberration (FGFR1); 6 had other genomic events (all with TP53 mutations). In no cases were clinical decisions altered (p=0.0538 when compared to ACs).

CONCLUSIONS

Targeted NGS can identify a significant number of therapeutically-relevant driver events in lung ACs; particularly in never or light smokers. For SC lung cancers, NGS is less likely to alter current practice. Further research into the cost effectiveness and optimal use of NGS and improved provider training in genomic oncology are warranted.

Crizotinib in ROS1-rearranged non-small-cell lung cancer

BACKGROUND

Chromosomal rearrangements of the gene encoding ROS1 proto-oncogene receptor tyrosine kinase (ROS1) define a distinct molecular subgroup of non-small-cell lung cancers (NSCLCs) that may be susceptible to therapeutic ROS1 kinase inhibition. Crizotinib is a small-molecule tyrosine kinase inhibitor of anaplastic lymphoma kinase (ALK), ROS1, and another proto-oncogene receptor tyrosine kinase, MET.

METHODS

We enrolled 50 patients with advanced NSCLC who tested positive for ROS1 rearrangement in an expansion cohort of the phase 1 study of crizotinib. Patients were treated with crizotinib at the standard oral dose of 250 mg twice daily and assessed for safety, pharmacokinetics, and response to therapy. ROS1 fusion partners were identified with the use of next-generation sequencing or reverse-transcriptase-polymerase-chain-reaction assays.

RESULTS

The objective response rate was 72% (95% confidence interval [CI], 58 to 84), with 3 complete responses and 33 partial responses. The median duration of response was 17.6 months (95% CI, 14.5 to not reached). Median progression-free survival was 19.2 months (95% CI, 14.4 to not reached), with 25 patients (50%) still in follow-up for progression. Among 30 tumors that were tested, we identified 7 ROS1 fusion partners: 5 known and 2 novel partner genes. No correlation was observed between the type of ROS1 rearrangement and the clinical response to crizotinib. The safety profile of crizotinib was similar to that seen in patients with ALK-rearranged NSCLC.

CONCLUSIONS

In this study, crizotinib showed marked antitumor activity in patients with advanced ROS1-rearranged NSCLC. ROS1 rearrangement defines a second molecular subgroup of NSCLC for which crizotinib is highly active. (Funded by Pfizer and others; ClinicalTrials.gov number, NCT00585195.).

Epidermal growth factor receptor (EGFR) mutations in lung cancer: preclinical and clinical data

Lung cancer leads cancer-related mortality worldwide. Non-small-cell lung cancer (NSCLC), the most prevalent subtype of this recalcitrant cancer, is usually diagnosed at advanced stages, and available systemic therapies are mostly palliative. The probing of the NSCLC kinome has identified numerous nonoverlapping driver genomic events, including epidermal growth factor receptor (EGFR) gene mutations. This review provides a synopsis of preclinical and clinical data on EGFR mutated NSCLC and EGFR tyrosine kinase inhibitors (TKIs). Classic somatic EGFR kinase domain mutations (such as L858R and exon 19 deletions) make tumors addicted to their signaling cascades and generate a therapeutic window for the use of ATP-mimetic EGFR TKIs. The latter inhibit these kinases and their downstream effectors, and induce apoptosis in preclinical models. The aforementioned EGFR mutations are stout predictors of response and augmentation of progression-free survival when gefitinib, erlotinib, and afatinib are used for patients with advanced NSCLC. The benefits associated with these EGFR TKIs are limited by the mechanisms of tumor resistance, such as the gatekeeper EGFR-T790M mutation, and bypass activation of signaling cascades. Ongoing preclinical efforts for treating resistance have started to translate into patient care (including clinical trials of the covalent EGFR-T790M TKIs AZD9291 and CO-1686) and hold promise to further boost the median survival of patients with EGFR mutated NSCLC.

β-catenin contributes to lung tumor development induced by EGFR mutations

The discovery of somatic mutations in EGFR and development of EGFR tyrosine kinase inhibitors (TKI) have revolutionized treatment for lung cancer. However, resistance to TKIs emerges in almost all patients and currently no effective treatment is available. Here, we show that β-catenin is essential for development of EGFR-mutated lung cancers. β-Catenin was upregulated and activated in EGFR-mutated cells. Mutant EGFR preferentially bound to and tyrosine phosphorylated β-catenin, leading to an increase in β-catenin-mediated transactivation, particularly in cells harboring the gefitinib/erlotinib-resistant gatekeeper EGFR-T790M mutation. Pharmacologic inhibition of β-catenin suppressed EGFR-L858R-T790M mutated lung tumor growth, and genetic deletion of the β-catenin gene dramatically reduced lung tumor formation in EGFR-L858R-T790M transgenic mice. These data suggest that β-catenin plays an essential role in lung tumorigenesis and that targeting the β-catenin pathway may provide novel strategies to prevent lung cancer development or overcome resistance to EGFR TKIs.