Effective Market Exclusivity of New Molecular Entities for Rare and Non-rare Diseases.

BACKGROUND: Growth in development, approvals, and revenue of drugs treating rare diseases (orphan drugs) has been increasing over the last four decades, which has drawn substantial attention to these products. Much of this growth has been attributed to the incentives created by the Orphan Drug Act, which includes a seven-year exclusivity period for the approval of rare disease indications. OBJECTIVE: This study aims to compare the effective market exclusivity period of small molecule new molecular entities (NMEs) for rare (orphan) and non-rare (non-orphan) diseases approved by the U.S. Food and Drug Administration (FDA) from 2001-2012. While the overall length of a drug's effective market exclusivity period has been explored previously, there is little empirical research evaluating the differences in its duration between drugs for rare and non-rare diseases. METHODS: Data sources utilized in this analysis included the NME Drug and New Biologic Approvals Reports, Orange Book, Orphan Drug Product Designation Database, Drugs@FDA and IQVIA's National Sales Perspective. We computed the effective market exclusivity period for each NME as the time from NME approval until approval of the first generic competitor. We then regressed the effective market exclusivity period for each NME, on orphan disease status, and other NME market factors using a Cox proportional hazards model. Subsequently, we calculated regression-adjusted median effective market exclusivity periods for both orphan and non-orphan NMEs to estimate effective exclusivity extensions from orphan status. RESULTS: We find that only individual NMEs approved for the treatment of both orphan and non-orphan indications lower the hazard of generic entry (hazard ratio 0.464, p = 0.030) in comparison with non-orphan NMEs with a single indication. The associated additional median survival time for these NMEs is 1.9 years. CONCLUSIONS: NMEs' orphan status per se is not associated with a reduction in the hazard of generic entry and longer effective market exclusivity periods in comparison with non-orphan NMEs. Only NMEs that were approved for the treatment of both orphan and non-orphan diseases experience lower hazard of generic entry and longer exclusivity periods compared with non-orphan drugs with a single indication.

Structure-Based Drug Design Strategies and Challenges.

Over the past ten years, the number of three-dimensional protein structures identified by advanced science and technology increases, and the gene information becomes more available than ever before as well. The development of computing science becomes another driving force which makes it possible to use computational methods effectively in various phases of the drug design and research. Now Structure-Based Drug Design (SBDD) tools are widely used to help researchers to predict the position of small molecules within a three-dimensional representation of the protein structure and estimate the affinity of ligands to target protein with considerable accuracy and efficiency. They also accelerate discovery speed of potent drug and reduce the cost and times for drug research. Here we present an overview of SBDD used in drug discovery and highlight its recent successes and major challenges to current SBDD methodologies.

Biosimilars for Immune-Mediated Chronic Diseases in Primary Care: What a Practicing Physician Needs to Know.

The introduction of biologics has revolutionized the treatment of immune-mediated diseases, but high cost and limited patient access remain hurdles, and some physicians are concerned that biosimilars are not similar enough. The purpose of this narrative review is to describe biosimilar safety, efficacy, nomenclature, extrapolation and interchangeability. In the United States, the Biologics Price Competition and Innovation Act created an abbreviated pathway for licensing of a biologic that is biosimilar to another licensed product (i.e., the reference product). This approval pathway differs from that of generic small-molecule drugs because biologics are too complex to be perfectly duplicated, and follows a process designed to demonstrate that any differences between the biosimilar and its reference product have no significant impact on safety and efficacy. The US approval process requires extensive analytical assessments, animal studies and clinical trials, assuring that biosimilar products provide clinical results similar to those of the reference product.

Global medicinal chemistry and GPCR conference: interview with Stevan Djuric.

Stevan Djuric speaks to Benjamin Walden, Commissioning Editor. Stevan Djuric is head of the global Medicinal Chemistry Leadership Team at AbbVie and is also Vice President of the Discovery Chemistry and Technology organization within their Discovery organization and chemistry outsourcing activities. He spoke at the Global-Medicinal-Chemistry and GPCR summit on the imperative to develop chemistry related technology that can reduce cycle time, cost of goods and improve probability of success. To this end, he discussed his efforts in the chemistry technology area with a focus on integrated synthesis-purification bioassay, and flow photochemistry and high temperature chemistry platforms.

A cell-based approach to characterize antimicrobial compounds through kinetic dose response.

The rapid spread of antibiotic resistance has created a pressing need for the development of novel drug screening platforms. Herein, we report on the use of cell-based kinetic dose response curves for small molecule characterization in antibiotic discovery efforts. Kinetically monitoring bacterial growth at sub-inhibitory concentrations of antimicrobial small molecules generates unique dose response profiles. We show that clustering of profiles by growth characteristics can classify antibiotics by mechanism of action. Furthermore, changes in growth kinetics have the potential to offer insight into the mechanistic action of novel molecules and can be used to predict off-target effects generated through structure-activity relationship studies. Kinetic dose response also allows for detection of unstable compounds early in the lead development process. We propose that this kinetic approach is a rapid and cost-effective means to gather critical information on antimicrobial small molecules during the hit selection and lead development pipeline.

[Chemical libraries dedicated to protein-protein interactions]. / Les chimiothèques ciblant les interactions protéine-protéine.

The identification of complete networks of protein-protein interactions (PPI) within a cell has contributed to major breakthroughs in understanding biological pathways, host-pathogen interactions and cancer development. As a consequence, PPI have emerged as a new class of promising therapeutic targets. However, they are still considered as a challenging class of targets for drug discovery programs. Recent successes have allowed the characterization of structural and physicochemical properties of protein-protein interfaces leading to a better understanding of how they can be disrupted with small molecule compounds. In addition, characterization of the profiles of PPI inhibitors has allowed the development of PPI-focused libraries. In this review, we present the current efforts at developing chemical libraries dedicated to these innovative targets.

DNA-encoded chemical libraries: advancing beyond conventional small-molecule libraries.

DNA-encoded chemical libraries (DECLs) represent a promising tool in drug discovery. DECL technology allows the synthesis and screening of chemical libraries of unprecedented size at moderate costs. In analogy to phage-display technology, where large antibody libraries are displayed on the surface of filamentous phage and are genetically encoded in the phage genome, DECLs feature the display of individual small organic chemical moieties on DNA fragments serving as amplifiable identification barcodes. The DNA-tag facilitates the synthesis and allows the simultaneous screening of very large sets of compounds (up to billions of molecules), because the hit compounds can easily be identified and quantified by PCR-amplification of the DNA-barcode followed by high-throughput DNA sequencing. Several approaches have been used to generate DECLs, differing both in the methods used for library encoding and for the combinatorial assembly of chemical moieties. For example, DECLs can be used for fragment-based drug discovery, displaying a single molecule on DNA or two chemical moieties at the extremities of complementary DNA strands. DECLs can vary substantially in the chemical structures and the library size. While ultralarge libraries containing billions of compounds have been reported containing four or more sets of building blocks, also smaller libraries have been shown to be efficient for ligand discovery. In general, it has been found that the overall library size is a poor predictor for library performance and that the number and diversity of the building blocks are rather important indicators. Smaller libraries consisting of two to three sets of building blocks better fulfill the criteria of drug-likeness and often have higher quality. In this Account, we present advances in the DECL field from proof-of-principle studies to practical applications for drug discovery, both in industry and in academia. DECL technology can yield specific binders to a variety of target proteins and is likely to become a standard tool for pharmaceutical hit discovery, lead expansion, and Chemical Biology research. The introduction of new methodologies for library encoding and for compound synthesis in the presence of DNA is an exciting research field and will crucially contribute to the performance and the propagation of the technology.

Cheminformatic models based on machine learning for pyruvate kinase inhibitors of Leishmania mexicana.

BACKGROUND: Leishmaniasis is a neglected tropical disease which affects approx. 12 million individuals worldwide and caused by parasite Leishmania. The current drugs used in the treatment of Leishmaniasis are highly toxic and has seen widespread emergence of drug resistant strains which necessitates the need for the development of new therapeutic options. The high throughput screen data available has made it possible to generate computational predictive models which have the ability to assess the active scaffolds in a chemical library followed by its ADME/toxicity properties in the biological trials. RESULTS: In the present study, we have used publicly available, high-throughput screen datasets of chemical moieties which have been adjudged to target the pyruvate kinase enzyme of L. mexicana (LmPK). The machine learning approach was used to create computational models capable of predicting the biological activity of novel antileishmanial compounds. Further, we evaluated the molecules using the substructure based approach to identify the common substructures contributing to their activity. CONCLUSION: We generated computational models based on machine learning methods and evaluated the performance of these models based on various statistical figures of merit. Random forest based approach was determined to be the most sensitive, better accuracy as well as ROC. We further added a substructure based approach to analyze the molecules to identify potentially enriched substructures in the active dataset. We believe that the models developed in the present study would lead to reduction in cost and length of clinical studies and hence newer drugs would appear faster in the market providing better healthcare options to the patients.

Polymer-supported alpha-acylamino ketones: preparation and application in syntheses of 1,2,4-trisubstituted-1H-imidazoles.

Polymer-supported alpha-acylamino ketones were prepared from resin-bound amines, bromoketones, and carboxylic acids. Selective monoalkylation of amines by bromoketones was carried out via 4-nitrobenzenesulfonamides. There was a striking difference in the reaction outcome between 2-Nos and 4-Nos derivatives. Alpha-acylamino ketones were converted to imidazoles. The cyclization was performed on resin, allowing further polymer-supported elaboration of imidazoles including synthesis of bis-heterocyclic compounds. A small combinatorial array of imidazoles was synthesized. Target compounds were prepared under mild conditions using commercially available building blocks for the introduction of three points of diversity.

One-pot multicomponent synthesis of 1-aryl-5-methyl-N-R2-1H-1,2,3-triazole-4-carboxamides: an easy procedure for combinatorial chemistry.

A convenient synthetic protocol was elaborated for creation of combinatorial libraries of 1-(R(1)-phenyl)-5-methyl-N-R(2)-1H-1,2,3-triazole-4-carboxamides. As starting materials, commercially available or readily prepared azides, amines, and diketene were selected for the reaction which has proceeded in a one-pot system with high yields and in short time.

Efficient N-arylation/dealkylation of electron deficient heteroaryl chlorides and bicyclic tertiary amines under microwave irradiation.

A highly efficient procedure was developed for the microwave-assisted synthesis of N-heteroaryl-4-(2-chloroethyl)piperazines and N-heteroaryl-4-(2-chloroethyl)piperidines. Microwave irradiation of electron deficient heteroaryl chlorides with 1,4-diazabicyclo[2.2.2]octane (DABCO) at 160 degrees C for 15 min led to N-heteroaryl-4-(2-chloroethyl)piperazines in good to excellent yields. In a similar manner, microwave irradiation of electron deficient heteroaryl chlorides with quinuclidine at 180 degrees C for 15 min provided N-heteroaryl-4-(2-chloroethyl)piperidines in good to excellent yields. Extension of the method was demonstrated by the development of a one-pot, two-step microwave-assisted protocol for the synthesis of 4-(2-acetoxyethyl)-substituted N-heteroarylpiperazines and N-heteroarylpiperidines to demonstrate the production of a small library in a parallel fashion.

New one-pot four-component synthesis of disubstituted pyrido[2,3-d]pyrimidine-6-carboxamide derivatives.

In this work, 1,2,3,4,5,8-hexahydro-1,3,7-trimethyl-2,4-dioxopyrido[2,3-d]pyrimidine-6-carboxamide derivatives were synthesized in a simple and efficient method from the four-component condensation reaction of diketene, an aliphatic or aromatic amine, an aromatic aldehyde, and 6-amino-1,3-dimethyluracil in the presence of a catalytic amount of p-toluenesulfonic acid under mild conditions at ambient temperature in high yields.

Efficient traceless solid-phase synthesis of 3,4-dihydropyrazino[1,2-b]indazoles and their 6-oxides.

A highly efficient novel traceless solid-phase synthesis of 3,4-dihydropyrazino[1,2-b]indazoles and their 6-oxides was developed by using commercially available building blocks, diamines, 2-nitrobenzenesulfonyl chlorides, and bromoketones/bromoacetates. Mild reaction conditions, diversely substituted building blocks, and high purity of crude products enabled effective combinatorial syntheses of libraries.