Inhibition of Casein Kinase 1 Alpha Prevents Acquired Drug Resistance to Erlotinib in EGFR-Mutant Non-Small Cell Lung Cancer.

Patients with lung tumors harboring activating mutations in the EGF receptor (EGFR) show good initial treatment responses to the EGFR tyrosine kinase inhibitors (TKI) erlotinib or gefitinib. However, acquired resistance invariably develops. Applying a focused shRNA screening approach to identify genes whose knockdown can prevent and/or overcome acquired resistance to erlotinib in several EGFR-mutant non-small cell lung cancer (NSCLC) cell lines, we identified casein kinase 1 α (CSNK1A1, CK1α).

A phase I study of erlotinib and hydroxychloroquine in advanced non-small-cell lung cancer.

Introduction: This investigator-initiated study explores the safety, maximum tolerated dose, clinical response, and pharmacokinetics of hydroxychloroquine (HCQ) with and without erlotinib in patients with advanced non-small-cell lung cancer.

Methods: Patients with prior clinical benefit from an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor were randomized to HCQ or HCQ plus erlotinib in a 3 + 3 dose-escalation schema.

Results: Twenty-seven patients were treated, eight with HCQ (arm A) and 19 with HCQ plus erlotinib (arm B).

Systematic identification of genomic markers of drug sensitivity in cancer cells.

Clinical responses to anticancer therapies are often restricted to a subset of patients. In some cases, mutated cancer genes are potent biomarkers for responses to targeted agents. Here, to uncover new biomarkers of sensitivity and resistance to cancer therapeutics, we screened a panel of several hundred cancer cell lines--which represent much of the tissue-type and genetic diversity of human cancers--with 130 drugs under clinical and preclinical investigation.

A chemical biology approach to developing STAT inhibitors: molecular strategies for accelerating clinical translation.

STAT transcription factors transduce signals from the cell surface to the nucleus, where they regulate the expression of genes that control proliferation, survival, self-renewal, and other critical cellular functions. Under normal physiological conditions, the activation of STATs is tightly regulated. In cancer, by contrast, STAT proteins, particularly STAT3 and STAT5, become activated constitutively, thereby driving the malignant phenotype of cancer cells.

Allosteric inhibition of BCR-ABL.

Impaired regulation of kinase activity can lead to a variety of diseases, including cancer. Inhibition of kinase activity has, therefore, been considered an attractive anti-cancer therapeutic strategy. The success of targeted therapy with kinase inhibitors has been well documented with BCR-ABL, where imatinib specifically inhibits kinase activity with impressive pharmacological responses in chronic myelogenous leukemia (CML).

A chromatin-mediated reversible drug-tolerant state in cancer cell subpopulations.

Accumulating evidence implicates heterogeneity within cancer cell populations in the response to stressful exposures, including drug treatments. While modeling the acute response to various anticancer agents in drug-sensitive human tumor cell lines, we consistently detected a small subpopulation of reversibly "drug-tolerant" cells. These cells demonstrate >100-fold reduced drug sensitivity and maintain viability via engagement of IGF-1 receptor signaling and an altered chromatin state that requires the histone demethylase RBP2/KDM5A/Jarid1A.

A structure-guided approach to creating covalent FGFR inhibitors.

The fibroblast growth factor receptor tyrosine kinases (FGFR1, 2, 3, and 4) represent promising therapeutic targets in a number of cancers. We have developed the first potent and selective irreversible inhibitor of FGFR1, 2, 3, and 4, which we named FIIN-1 that forms a covalent bond with cysteine 486 located in the P loop of the FGFR1 ATP binding site. We demonstrated that the inhibitor potently inhibits Tel-FGFR1-transformed Ba/F3 cells (EC(50) = 14 nM) as well as numerous FGFR-dependent cancer cell lines.

Cell line-based platforms to evaluate the therapeutic efficacy of candidate anticancer agents.

Efforts to discover new cancer drugs and predict their clinical activity are limited by the fact that laboratory models to test drug efficacy do not faithfully recapitulate this complex disease. One important model system for evaluating candidate anticancer agents is human tumour-derived cell lines. Although cultured cancer cells can exhibit distinct properties compared with their naturally growing counterparts, recent technologies that facilitate the parallel analysis of large panels of such lines, together with genomic technologies that define their genetic constitution, have revitalized efforts to use cancer cell lines to assess the clinical utility of new investigational cancer drugs and to discover predictive biomarkers.

Exploiting the balance between life and death: targeted cancer therapy and "oncogenic shock".

Rational approaches to targeted cancer therapy have begun to predominate the pipelines of oncology drug development. Our rapidly increasing understanding of the "wiring" of tumor cells and the vulnerabilities of such cells that can potentially be exploited through targeted treatments has opened up enormous opportunities for improved therapies. Accumulating evidence suggests that many of these vulnerabilities reflect states of dependency or "addiction" that are unique to cancer cells (versus normal cells).

Lkb1 inactivation is sufficient to drive endometrial cancers that are aggressive yet highly responsive to mTOR inhibitor monotherapy.

Endometrial cancer--the most common malignancy of the female reproductive tract--arises from the specialized epithelial cells that line the inner surface of the uterus. Although significant advances have been made in our understanding of this disease in recent years, one significant limitation has been the lack of a diverse genetic toolkit for the generation of mouse models. We identified a novel endometrial-specific gene, Sprr2f, and developed a Sprr2f-Cre transgene for conditional gene targeting within endometrial epithelium.

Targeting the cyclin E-Cdk-2 complex represses lung cancer growth by triggering anaphase catastrophe.

Purpose: Cyclin-dependent kinases (Cdk) and their associated cyclins are targets for lung cancer therapy and chemoprevention given their frequent deregulation in lung carcinogenesis. This study uncovered previously unrecognized consequences of targeting the cyclin E-Cdk-2 complex in lung cancer.

Experimental Design: Cyclin E, Cdk-1, and Cdk-2 were individually targeted for repression with siRNAs in lung cancer cell lines.

Ligand-dependent platelet-derived growth factor receptor (PDGFR)-alpha activation sensitizes rare lung cancer and sarcoma cells to PDGFR kinase inhibitors.

Platelet-derived growth factor (PDGF) receptors (PDGFR) and their ligands play critical roles in several human malignancies. Sunitinib is a clinically approved multitargeted tyrosine kinase inhibitor that inhibits vascular endothelial growth factor receptor, c-KIT, and PDGFR, and has shown clinical activity in various solid tumors. Activation of PDGFR signaling has been described in gastrointestinal stromal tumors (PDGFRA mutations) as well as in chronic myeloid leukemia (BCR-PDGFRA translocation), and sunitinib can yield clinical benefit in both settings.

Inhibition of gamma-secretase activity inhibits tumor progression in a mouse model of pancreatic ductal adenocarcinoma.

Background & Aims: The Notch signaling pathway is required for the expansion of undifferentiated pancreatic progenitor cells during embryonic development and has been implicated in the progression of pancreatic ductal adenocarcinoma (PDAC). The interaction of Notch ligands with their receptors promotes a gamma-secretase-dependent cleavage of the Notch receptor and release of the Notch intracellular domain, which translocates to the nucleus and activates transcription. We investigated the role of this pathway in PDAC progression.

Drug-target identification from total cellular lysate by drug-induced conformational changes.

Identification of drug targets is a key step in the development of novel pharmaceuticals. To this end, chemical probes or affinity matrices are often used, requiring substantial structure-activity relationship (SAR) studies. Here we report on the development of a novel technique for drug-target identification from total cellular lysate conducted independently of SAR information.

Reduced Erlotinib sensitivity of epidermal growth factor receptor-mutant non-small cell lung cancer following cisplatin exposure: a cell culture model of second-line erlotinib treatment.

Purpose: Epidermal growth factor receptor (EGFR) kinase inhibitors induce dramatic clinical responses in a subset of non-small cell lung cancer (NSCLC) patients with advanced disease, and such responses are correlated with the presence of somatic activating mutations within the EGFR kinase domain. Consequently, one of these inhibitors, erlotinib, has been Food and Drug Administration-approved as a second- or third-line treatment for chemotherapy-refractory advanced NSCLC. However, responses are typically relatively short-lived due to acquired drug resistance, prompting studies to determine whether first-line treatment with EGFR inhibitors could provide greater clinical benefit.

ErbBs in lung cancer.

Lung cancer remains the leading cause of cancer deaths worldwide, and advanced stage disease is largely refractory to conventional chemotherapy. Thus, there is an important need for alternative treatment strategies, and the ErbB proteins have emerged as potentially important therapeutic drug targets in this setting, apparently reflecting a state of "oncogene addiction" in some lung tumors. In this review, we discuss the recent identification of mutations that promote activation of ErbB family proteins in a subset of lung cancers, and the development of selective inhibitors of these proteins that have demonstrated clinical efficacy.

Elevated CRAF as a potential mechanism of acquired resistance to BRAF inhibition in melanoma.

Activating BRAF kinase mutations arise in approximately 7% of all human tumors, and preclinical studies have validated the RAF-mitogen-activated protein/extracellular signal-regulated kinase (ERK) kinase-ERK signaling cascade as a potentially important therapeutic target in this setting. Selective RAF kinase inhibitors are currently undergoing clinical development, and based on the experience with other kinase-targeted therapeutics, it is expected that clinical responses to these agents, if observed, will lead to the eventual emergence of drug resistance in most cases. Thus, it is important to establish molecular mechanisms underlying such resistance to develop effective therapeutic strategies to overcome or prevent drug resistance.

High-throughput lung cancer cell line screening for genotype-correlated sensitivity to an EGFR kinase inhibitor.

Human cancer cell lines that can be propagated and manipulated in culture have proven to be excellent models for studying many aspects of gene function in cancer. In addition, they can provide a powerful system for assessing the molecular determinants of sensitivity to anticancer drugs. They have also been used in recent studies to identify genomic alterations and gene expression patterns that provide important insights into the genetic features that distinguish the properties of tumor cells associated with similar histologies.

Oncogene addiction: setting the stage for molecularly targeted cancer therapy.

In pugilistic parlance, the one-two punch is a devastating combination of blows, with the first punch setting the stage and the second delivering the knock-out. This analogy can be extended to molecularly targeted cancer therapies, with oncogene addiction serving to set the stage for tumor cell killing by a targeted therapeutic agent. While in vitro and in vivo examples abound documenting the existence of this phenomenon, the mechanistic underpinnings that govern oncogene addiction are just beginning to emerge.

Identification of genotype-correlated sensitivity to selective kinase inhibitors by using high-throughput tumor cell line profiling.

Kinase inhibitors constitute an important new class of cancer drugs, whose selective efficacy is largely determined by underlying tumor cell genetics. We established a high-throughput platform to profile 500 cell lines derived from diverse epithelial cancers for sensitivity to 14 kinase inhibitors. Most inhibitors were ineffective against unselected cell lines but exhibited dramatic cell killing of small nonoverlapping subsets.

Epidermal growth factor receptor mutations in lung cancer.

The development and clinical application of inhibitors that target the epidermal growth factor receptor (EGFR) provide important insights for new lung cancer therapies, as well as for the broader field of targeted cancer therapies. We review the results of genetic, biochemical and clinical studies focused on somatic mutations of EGFR that are associated with the phenomenon of oncogene addiction, describing 'oncogenic shock' as a mechanistic explanation for the apoptosis that follows the acute treatment of susceptible cells with kinase inhibitors. Understanding the genetic heterogeneity of epithelial tumours and devising strategies to circumvent their rapid acquisition of resistance to targeted kinase inhibitors are essential to the successful use of targeted therapies in common epithelial cancers.

Oncogenic shock: turning an activated kinase against the tumor cell.

Accumulating evidence indicates that mutationally activated kinases are especially good targets for anti-cancer drugs. It has been suggested that this reflects a state of "oncogene addiction" of tumor cells. We recently reported experimental studies that may provide a molecular mechanism to explain such apparent dependency.

A common signaling cascade may underlie "addiction" to the Src, BCR-ABL, and EGF receptor oncogenes.

"Oncogene addiction" describes an unexplained dependency of cancer cells on a particular cellular pathway for survival or proliferation. We report that differential attenuation rates of prosurvival and proapoptotic signals in oncogene-dependent cells contribute to cell death following oncogene inactivation. Src-, BCR-ABL-, and EGF receptor-dependent cells exhibit a similar profile of signal attenuation following oncogene inactivation characterized by rapid diminution of phospho-ERK, -Akt, and -STAT3/5, and a delayed accumulation of the proapoptotic effector phospho-p38 MAPK.

"Oncogenic shock": explaining oncogene addiction through differential signal attenuation.

"Oncogene addiction" describes the curious acquired dependence of tumor cells on an activated oncogene for their survival and/or proliferation, a phenomenon that has important implications for the success of targeted cancer therapies. However, the mechanisms explaining oncogene addiction remain elusive. We propose that "addiction" may be an illusion generated as a consequence of differential attenuation rates of prosurvival and proapoptotic signals emanating from an oncoprotein acutely following its inactivation.

Inherited susceptibility to lung cancer may be associated with the T790M drug resistance mutation in EGFR.

Somatic activating mutations in EGFR identify a subset of non-small cell lung cancer that respond to tyrosine kinase inhibitors. Acquisition of drug resistance is linked to a specific secondary somatic mutation, EGFR T790M. Here we describe a family with multiple cases of non-small cell lung cancer associated with germline transmission of this mutation.