Potential Small Molecule Drugs Research Articles

P1.08 - A phase 1 study of 3 different schedules of the folic acid-tubulysin small-molecule drug conjugate EC1456 in pts with advanced solid tumors

ABSTRACT Background: The therapeutic target folate receptor (FR) is expressed in many epithelial tumors. EC1456, a potent small-molecule drug conjugate of folate and tubulysin B hydrazide (TubBH), is a cytotoxic agent that targets TubBH to FR-expressing cells. TubBH inhibits tubulin polymerization, causing metaphase cell arrest. Preclinical studies show good EC1456's antitumor activity with complete remissions seen in mice bearing FR-expressing xenografts, both as single-agent and in combination with different agents (platinum/taxane/erubilin). Materials and Methods: Part A of the study (NCT01999738) in pts with advanced solid tumors assesses EC1456's MTD. Key inclusion criteria are age ≥18 years, ECOG PS 0–1, and adequate organ function. Patients must have failed standard therapy or not be a candidate for standard therapy. Part B evaluates EC1456's antitumor activity (at MTD) in pts with triple-negative breast, advanced non-small cell lung, or ovarian cancer in which all target lesions express FR as determined by 99mTc-etarfolatide imaging. EC1456 (start dose 0.5 mg/m2) is IV administered BIW on wks 1, 2 of a 3 or 4-week cycle and QW on wks 1, 2 of a 3-week cycle. The standard 3 + 3 dose escalation schema is used for the BIW, and continuous reassessment method (CRM) is used for the QW schedule. Cycle 1 dose-limiting toxicity (DLT) evaluation must be completed by all pts in a cohort before starting the next cohort. The primary study objective is to determine EC1456 MTD and recommended phase 2 dose for pts with solid tumors. Secondary objectives include evaluating EC1456 safety, pharmacokinetic profiles, and antitumor activity. Results: Fifteen patients have been enrolled into 8 dose levels, 11 in the BIW, and 4 in the QW schedule. The number of cycles administered ranged from 1 to 14, with no dose delay/omission due to drug-related AEs. No DLT was observed and only few TEAs, mostly of grade 1, were reported (e.g. fatigue, nausea, anemia). Two patients (mesothelioma and gastroesophageal) have durable stable disease of a year. Conclusions: Dose escalation is ongoing, currently at 2.0 mg/m2 for the BIW and 3.5 mg/m2 for the QW schedule. Durable stable disease was observed in mesothelioma and gastroesophageal cancer. Updated data will be presented at the conference.

Identifying differentially expressed genes and screening small molecule drugs for lapatinib-resistance of breast cancer by a bioinformatics strategy.

Lapatinib, a dual tyrosine kinase inhibitor that interrupts the epidermal growth factor receptor (EGFR) and HER2/neu pathways, has been indicated to have significant efficacy in treating HER2-positive breast cancer. However, acquired drug resistance has become a very serious clinical problem that hampers the use of this agent. In this study, we aimed to screen small molecule drugs that might reverse lapatinib-resistance of breast cancer by exploring differentially expressed genes (DEGs) via a bioinformatics method. We downloaded the gene expression profile of BT474-J4 (acquired lapatinib-resistant) and BT474 (lapatinib-sensitive) cell lines from the Gene Expression Omnibus (GEO) database and selected differentially expressed genes (DEGs) using dChip software. Then, gene ontology and pathway enrichment analyses were performed with the DAVID database. Finally, a connectivity map was utilized for predicting potential chemicals that reverse lapatinib-resistance. A total of 1, 657 DEGs were obtained. These DEGs were enriched in 10 pathways, including cell cycling, regulation of actin cytoskeleton and focal adhesion associate examples. In addition, several small molecules were screened as the potential therapeutic agents capable of overcoming lapatinib-resistance. The results of our analysis provided a novel strategy for investigating the mechanism of lapatinib-resistance and identifying potential small molecule drugs for breast cancer treatment.

De novo design based pharmacophore query generation and virtual screening for the discovery of Hsp-47 inhibitors

Heat shock protein-47 (Hsp-47) is exclusive collagen specific molecular chaperone involved in the maturation, processing and secretion of procollagen. Hsp-47 is consistently upregulated in several fibrotic diseases. Till date there is no potential antifibrotic small molecule drug available and Hsp-47 is known to be potential therapeutic target for fibrotic disorder and drug designing. We used the de novo drug design approach followed by pharmacophore generation and virtual screening to propose Hsp-47 based antifibrotic molecules. We used e-LEAD server for de novo drug design and ZINCPharmer for 3D pharmacophore generation and virtual screening. The virtually screened molecule may inhibit direct recruitment of collagen triple helix to interact with Hsp-47 and act as antifibrotic drug.

Identification of differentially expressed genes and small molecule drugs for the treatment of tendinopathy using microarray analysis.

Tendinopathy is a critical clinical problem as it is often asymptomatic at onset and during development, and is only recognized upon rupture of the tendon. It is common among recreational and competitive athletes. The present study sought to examine the molecular mechanism of the progression of tendinopathy by screening out differentially expressed genes (DEGs) and investigating their functions. In addition, the present study aimed to identify the small molecules, which exhibit potential effects, which could be utilized for the treatment of tendinopathy. The gene expression profile of tendinopathy, GSE26051 was downloaded from the Gene Expression Omnibus database, which included 23 control samples and 18 samples of tendinopathy. The DEGs were identified using the Limma package in the R programming language, and gene ontology and pathway enrichment analysis were performed. In addition, the potential regulatory microRNAs and the target sites of the transcription factors were screened out based on the molecular signature database. In addition, the DEGs were mapped to the connectivity map database to identify the potential small molecule drugs. A total of 318 genes were filtered as DEGs between diseased samples and normal control tendons. Additionally, genes, including laminin, α4, platelet‑derived growth factor α, laminin γ1 and Src homology 2 transforming protein 1 may induce tendinopathy through the focal adhesion pathway. Furthermore, the transcription factor, lymphoid enhancer‑binding factor 1 and its target genes, pantothenate kinase 2 and G protein‑coupled receptor kinase 5 were identified. The most significant microRNA, miR‑499, was screened and was found to regulate specific genes, including CUGBP2 and MYB. Additionally, the small molecules, Prestwick‑1082 and viomycin were identified to have the potential to repair disordered metabolic pathways and furthermore to remedy tendinopathy. The results of the present study assessed the mechanism of tendinopathy and screened small molecule drugs as potential treatments for this condition. In addition, the present findings have the potential for use in a clinical setting for the treatment of tendinopathy in the future.

481P - Phase 1 Dose-Escalation Study of the Folic Acid-Tubulysin Small-Molecule Drug Conjugate Ec1456 in Patients (Pts) with Advanced Solid Tumors

ABSTRACT Aim: The therapeutic target folate receptor (FR) is expressed in many epithelial tumors. EC1456, a potent small-molecule drug conjugate of folate and tubulysin B hydrazide (TubBH), is a cytotoxic agent that targets TubBH to FR-expressing cells. TubBH inhibits tubulin polymerization, causing metaphase cell arrest. Preclinical studies demonstrated EC1456's antitumor activity as it induced complete remissions in mice bearing FR-expressing xenografts (≤750 mm3), in absence of weight loss or major organ tissue degeneration (Reddy JA. AACR 2014; abstr 832). EC1456 can also be safely combined with chemotherapeutics (platinum-based agents/topoisomerase inhibitors/taxanes) to enhance antitumor effects and showed to be highly active against both paclitaxel- and cisplatin-resistant FR-expressing cell lines. These findings support EC1456's clinical evaluation. Methods: Part A of the multicenter dose-escalation study (NCT01999738) in pts with advanced histologically confirmed solid tumors assesses EC1456's maximum tolerated dose (MTD). Key inclusion criteria are age ≥18 years, ECOG performance status 0–1, and adequate organ function. Part B evaluates EC1456's antitumor activity (at MTD) in pts with triple-negative breast, advanced non-small cell lung, ovarian, or hepatocellular cancer in which all target lesions (RECIST 1.1. criteria) express FR as determined by 99mTc-etarfolatide imaging. EC1456 (start dose 0.5 mg/m2) is intravenously administered on days 1/4/8/11 of a 4-week cycle per standard 3 + 3 dose-escalation schema (3–6 pts/dose level). Cycle 1 dose-limiting toxicity (DLT) evaluation must be completed by all pts in a cohort before dosing is initiated in the next cohort. The primary study objective is to determine EC1456 MTD and recommended phase 2 dose for pts with solid tumors. Secondary objectives include evaluating EC1456 safety, pharmacokinetic profiles, and antitumor activity in selected pts. Results: Up until April 2014, enrolled pts did not experience grade ≥3 toxicity after ≥4 cycles and had stable disease. Conclusions: Study enrollment is ongoing and no DLTs have been observed by April 2014. Preliminary efficacy data will be presented at ESMO. Disclosure: E.A. Sausville: Corporate-sponsored research: research sponsored by Endocyte, Inc.; W.A. Harb: Corporate-sponsored research: Endocyte sponsored participation in EC1456 study; R.K. Ramanathan: Corporate-sponsored research: Clinical trial with Endocyte; R. Clark: Ownership: Endocyte stock Corporate-sponsored research: Employee of Endocyte: All other authors have declared no conflicts of interest.

Absorption, distribution, metabolism, and excretion considerations for the development of antibody-drug conjugates.

Antibody-drug conjugates (ADCs) are a class of therapeutics that are designed to deliver potent small-molecule drugs selectively to cells that express a specific target antigen while limiting systemic exposure to the drug. This is accomplished by conjugating a potent drug onto an antibody-based therapeutic with a linker that is exquisitely stable in plasma. The development of an effective ADC requires optimizing a number of design elements and an extensive understanding of absorption, distribution, metabolism/catabolism, and elimination (ADME) processes for the ADC construct. Furthermore, as ADCs are a combination of an antibody and small-molecule drug, understanding key aspects of the ADME of each individual component is needed. This review aims to provide considerations for the development of ADCs from an ADME point of view.

Potent New Weapons in the Oncology Arsenal (Antibody-Drug Conjugates) Require Unique Biological Manufacturing Expertise

Recent advances in coupling antibodies to potent cytotoxic drugs have resulted in stable delivery platforms with improved pharmacokinetics which spares patients from the debilitating systemic toxicity observed with traditional chemotherapy [1]. In 2011 the FDA granted accelerated approval to Seattle Genetics Adcetris® (Bentuximab vedotin) and on Feb. 4th 2013 Health Canada approved the drug which uses a chimeric monoclonal antibody to target CD-30 positive cells. The cytotoxic warhead conjugated to the antibody consists of the potent antimitotic agent monomethyl auristatin E. This is the first new therapy approved since 1977 for treatment of Hodgkin’s lymphoma and it is the first therapy to receive approval against anaplastic large cell lymphoma. Roche-Genentech received approval to offer Kadcyla® (Trastuzumab emtansine) for the treatment of patients with HER2-positive metastatic breast cancer in Feb. 2013. Results from the pivotal EMILIA trial demonstrated significantly improved overall survival compared to current standard of care which uses capecitabine and lapatinib. Kadcyla is the Herceptin antibody conjugated to the maytansine derivative DM1. Manufacturing these highly potent biopharmaceuticals presents a series of unique engineering and chemistry challenges which has resulted in several contract manufacturers constructing facilities to address the unique engineering and chemistry challenges associated with this promising class of therapeutic drugs. By leveraging experience in biopharmaceuticals and potent small molecule drug process development this class of promising new therapies can be reliably and safely manufactured to meet clinical and commercial demands. This article will investigate the experience of Lonza as it synergistically pooled internal resources to address this promising class of therapeutics. Keywords: ADC facilities, ADC linkers, ADC manufacturing, antibody-drug conjugates, cytotoxins.

Identification of Differently Expressed Genes and Small Molecule Drugs for Tetralogy of Fallot by Bioinformatics Strategy

This study aimed to screen out differentially expressed genes (DEGs) and explore small molecule drugs for Tetralogy of Fallot (TOF). The gene expression profile of TOF GSE26125 was downloaded from the Gene Expression Omnibus database, including 16 idiopathic TOF samples and five healthy controls. The DEGs were identified by the Limma package in R language and underwent functional enrichment analysis via Database for Annotation, Visualization and Integrated Discovery tools. A protein-protein interaction (PPI) network of DEGs was then constructed and the significant clusters were selected for functional analysis. In addition, the DEGs were mapped to the connectivity map (CMap) database to identify potential small-molecule drugs. As a result, a total of 499 DEGs were selected between TOF and healthy controls. Meanwhile, the functional changes of DEGs related to TOF were mainly associated with cellular respiration and energy metabolism. Furthermore, in the PPI network, two clusters were identified via cluster 1 analysis. And only cluster 1 was significantly enriched into gene ontology terms, including respiratory chain, electron transport chain, and oxidation reduction. The hub gene of cluster 1 was NDUFAB1. Additionally, small molecules, such as harmine, solanine, and testosterone, may have the potential to repair the disordered metabolic pathways of TOF.

Tau-based therapeutics for alzheimer's disease and related tauopathies

Neurofibrillary pathology composed of the microtubule associated protein tau is a characteristic feature of Alzheimer's Disease as well as multiple rare tauopathies such as FTLD-tau and Progressive Supranuclear Palsy. In each case, the density and distribution of the tau lesions correlates with the extent of neuronal loss and with the clinical progression of the disorder. Moreover multiple mutations in the tau (MAPT) gene have been shown to cause FTD linked to chromosome 17 establishing that tau dysfunction is sufficient to cause neurodegeneration. These mutations impact tau in different ways but significantly all are predicted to enhance tau aggregation suggesting that protein misfolding is a critical component of the neurodegenerative cascade. As a result of these findings, considerable research effort has focused on determining the mechanism of neurofibrillary degeneration and on identifying potential therapies for the treatment of tauopathy. Kinase inhibitors that have been postulated to block tau hyperphosphorylation and toxicity, aggregation inhibitors designed to prevent the formation of filamentous inclusions, and various approaches to enhance the clearance of pathological tau have been proposed and have undergone varying degrees of preclinical development. More recently, therapeutic antibodies designed to block the transmission and spreading of tau pathology have also received considerable attention. However despite the significance of tau and the high level of research activity, only a handful of potential small molecule drugs have progressed into early clinical trials and to date none of these have produced robust evidence of clinical efficacy. Several issues explain this relative lack of success, in particular there remains no consensus on the pathogenic mechanism that underlies tau-based neurodegeneration and in addition there is currently a lack of validated, tractable targets for which translatable biomarkers exist to enable clinical development. Despite this there remains grounds for considerable optimism with the recognition that tau likely spreads through the brain in a prion-like manner and the development of the first tau PET imaging agents providing new opportunities for drug discovery. This presentation will therefore review the current state of tau therapeutic development and will discuss progress towards translating preclinical findings into effective treatments for patients with tauopathy.

Abstract 2543: PRLX 93936, is a potent, novel, tumor-selective, small molecule with a unique mechanism of action

Abstract Currently in Phase I testing, PRLX 93936 was developed and characterized at Prolexys Pharmaceuticals. It is a potent small molecule drug that shows robust and selective anti-cancer activity in a wide array of solid tumors including those with mutations that activate the RAS pathway. PRLX 93936 was chosen as a clinical lead as a result of extensive medicinal chemistry efforts and pharmacological profiling of over 400 novel small molecules. These compounds were designed to cover the chemical space originating from a molecule, Erastin, identified in a screen against isogenic cell lines differentially expressing genes such as those that activate the RAS pathway (Dolma et. al, Cancer Cell 3: 285-296, 2003). Cells that are sensitive to PRLX 93936 undergo caspase dependent apoptosis, necrosis, cell cycle arrest, ion flux and cell shrinkage leading to death and tumor growth inhibition. Characterization of drug treated cells shows that selective activation of RAS and JNK pathway members correlates with compound sensitivity. Research to elucidate the precise mechanism(s) and target(s) through which these biological responses are achieved has revealed that PRLX 93936's mechanism of action is unique. Several key lines of evidence support this conclusion including: 1. COMPARE analysis of PRLX 93936 activity in the NCI 60 panel of cell lines which showed that it is functionally distinct among the agents tested, 2. Profiling studies which examined PRLX 93936 binding or inhibition of enzyme activity against CYP450 enzymes, cell surface receptors and action potential mediating cardiac ion channels revealed only Cyp 3A4 and hERG as potential targets, 3. Kinase profiling of PRLX 93936 against evolutionarily diverse enzymes which identified no significant inhibitory activity, and 4. Genotyping and gene expression profiling studies which have yet to reveal a clear target profile correlation. Since the most common target classes were eliminated as potential suspects, additional non-traditional enzyme targets were screened for relevance to PRLX 93936 activity. Proteomics experiments identified the mitochondrial protein VDAC (Voltage Dependent Anion Channel) as a specific binding protein and potential molecular target of PRLX 93936 (Yagoda et al., Nature. 447: 865-869, 2007). More recent findings indicate that PRLX 93936 is a potent, selective inhibitor of several RAS pathway proteins including key enzymes which regulate the phosphorylation and activity of proteins involved in the RAS/JNK pathway. RNAi based validation studies and synergistic anti-cancer activity observed in combination with specific targeted drugs support these findings. PRLX 93936 may therefore represent a novel class of cancer therapeutics that target the majority of tumors characterized by RAS pathway activation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2543.

The influence of lead discovery strategies on the properties of drug candidates

Despite the widespread acceptance of guidelines related to desirable physicochemical properties of potential small-molecule drugs, key properties - such as lipophilicity - of recently developed clinical candidates and advanced lead compounds have been shown to differ significantly from those of historical leads and drugs. By analysing the physicochemical properties of a large database of hits and corresponding leads identified in the past decade, we show that this undesirable phenomenon can be traced back to the nature of high-throughput screening hits and hit-to-lead optimization practices. Conceptual and organizational adjustments may be required to enable a smooth lead-evolution process that reduces the chance of high compound-related attrition in clinical trials.

A Candidate Hypertension Gene

See related article, pages 992–999 Hypertension affects >20% of the general population, and yet its etiologic basis remains unknown in the vast proportion of those affected.1 Hypertension greatly increases the risk of stroke, myocardial infarction, congestive heart failure and renal dysfunction thus making it an important focus of clinical research. Although pharmacological reductions in blood pressure have been shown to decrease the incidence of these adverse consequences,2 large numbers of hypertensive patients go undiagnosed, undertreated, or are nonresponsive to lifestyle modifications and medical therapy.1 As such, there remains a pressing need for an improved understanding of the mechanisms underlying hypertension. Recent advances in genomic and proteomic analyses have led to the discovery of Mendelian forms (monogenetic traits) of hypertension.3,4 Although rare, these mutations which mainly involve altered renal salt handling, provide a molecular basis for understanding the critical role of the kidney during normal blood pressure regulation.5 By contrast, our understanding of the relative contributions of kidney, heart, CNS, and blood vessel function to blood pressure variations in the general population is complicated by the fact that spontaneous hypertension typically arises as a complex quantitative trait affected by differing combinations of genetic and environmental factors. A number of quantitative trait loci (QTL) associated with hypertension have been identified in both animal disease models and human patients, however the affected gene(s) at these sites have remained elusive owing to the large size and complexity of the regions identified.6 The use of congenic rodent strains to reduce the genomic size of QTLs is an important advance in the field (Reviewed in 7). Indeed, an article in this issue of Circulation Research highlights the potential of …

Small Molecule Antagonists Targeting Growth Factors/Receptors

Abstract: Control of cell proliferation is regulated by interaction of soluble growth factors and cell membrane receptors. Studies of growth factors and their receptors provide a new approach to elucidate mechanisms of cancer progression, and more importantly, a unique potential for development of targeted anticancer therapy. A growth factor (ligand) binding to its receptor(s) triggers a complex series of intracellular signaling pathways th_at may culminate in a change in cell behavior. Considerable number of studies indicate that the inappropriate expression and/or activation of the growth factor/receptors can mediate abnormal cellular signaling and oncogenic transformation both in vitro and in vivo system. These results strongly support the hypothesis that growth factors/receptors plays an important role in the tumorigenesis of cancer. A number of families of structurally related growth factors and receptors have been identified and were considered as potential targets for specific antitumor therapy. This review will focus on recent advances in drug discovery that have identified small organic molecules that affect ligand binding, kinase activity, and signaling transduction and alter cell function. Recent progress of small molecule-based drug discovery targeting several growth factor/receptor families is presented. Approach utilizing computer based 3D pharmacophore searches is discussed. These approaches to develop novel anticancer therapies focus on mechanisms different from conventional chemotherapeutic and radiotherapeutic regimens. These targeted anticancer therapies may be highly tumor cell specific, since they do not require host accessory factors. Furthermore, these potential small molecule drugs may have the capacity to synergistically or additively improve the presently available hormonal, radiation or chemotherapy of cancer.