The quantity and quality of worldwide new drug introductions, 1982-2003.

We examined trends in the introduction of new chemical entities (NCEs) worldwide from 1982 through 2003. Although annual introductions of NCEs decreased over time, introductions of high-quality NCEs (that is, global and first-in-class NCEs) increased moderately. Both biotech and orphan products enjoyed tremendous growth, especially for cancer treatment. Country-level analyses for 1993-2003 indicate that U.S. firms overtook their European counterparts in innovative performance or the introduction of first-in-class, biotech, and orphan products. The United States also became the leading market for first launch.

Evaluation of Altered Kras Codon Bias and NOS Inhibition During Lung Tumorigenesis

The small GTPases HRAS, NRAS and KRAS are mutated in approximately one-third of all human cancers, rendering the proteins constitutively active and oncogenic. Lung cancer is the leading cause of cancer deaths worldwide, and more than 20% of human lung cancers harbor mutations in RAS, with 98% of those occurring in the KRAS isoform. While there have been many advances in the understanding of KRAS–driven lung tumorigenesis, it remains a therapeutic challenge. To further this understanding and assess novel approaches for treatment, I have investigated two aspects of Kras–driven tumorigenesis in the lung:

(I) Despite nearly identical protein sequences, the three RAS proto-oncogenes exhibit divergent codon usage. Of the three isoforms, KRAS contains the most rare codons resulting in lower levels of KRAS protein expression relative to HRAS and NRAS. To determine the consequences of rare codon bias during de novo tumorigenesis, we created a knock-in Krasex3op mouse in which synonymous mutations in exon 3 converted codons from rare to common. These mice had reduced tumor burden and fewer oncogenic mutations in the Krasex3op allele following carcinogen exposure. The reduction in tumorigenesis appeared to be a product of rare codons affecting both the oncogenic and non–oncogenic alleles. Converting rare codons to common codons yielded a more potent oncogenic allele that promoted growth arrest and enhanced tumor suppression by the non-oncogenic allele. Thus, rare codons play an integral role in Kras tumorigenesis.

(II) Lung cancer patients exhale higher levels of NO and iNOS-/- mice are resistant to chemically induced lung tumorigenesis. I hypothesize that NO promotes Kras–driven lung adenocarcinoma, and NOS inhibition may decrease Kras–driven lung tumorigenesis. To test this hypothesis, I assessed efficacy of the NOS inhibitor L–NAME in a genetically engineered mouse model of Kras-driven lung adenocarcinoma. Adenoviral Cre recombinase was delivered into the lungs intranasally, resulting in expression of oncogenic KrasG12D and dominant-negative Trp53R172H in lung epithelial cells. L–NAME treatment was provided in the water and continued until survival endpoints. In this model, L–NAME treatment decreased tumor growth and prolonged survival. These data establish a potential clinical role for NOS inhibition in lung cancer treatment.

Design, Synthesis, and Biological Characterization of Largazole Analogues

Histone deacetylases (HDACs) have been shown to play key roles in tumorigenesis, and

have been validated as effective enzyme target for cancer treatment. Largazole, a marine natural

product isolated from the cyanobacterium Symploca, is an extremely potent HDAC inhibitor that

has been shown to possess high differential cytotoxicity towards cancer cells along with excellent

HDAC class-selectivity. However, improvements can be made in the isoform-selectivity and

pharmacokinetic properties of largazole.

In attempts to make these improvements and furnish a more efficient biochemical probe

as well as a potential therapeutic, several largazole analogues have been designed, synthesized,

and tested for their biological activity. Three different types of analogues were prepared. First,

different chemical functionalities were introduced at the C2 position to probe the class Iselectivity profile of largazole. Additionally, docking studies led to the design of a potential

HDAC8-selective analogue. Secondly, the thiol moiety in largazole was replaced with a wide

variety of othe zinc-binding group in order to probe the effect of Zn2+ affinity on HDAC

inhibition. Lastly, three disulfide analogues of largazole were prepared in order to utilize a

different prodrug strategy to modulate the pharmacokinetic properties of largazole.

Through these analogues it was shown that C2 position can be modified significantly

without a major loss in activity while also eliciting minimal changes in isoform-selectivity. While

the Zn2+-binding group plays a major role in HDAC inhibition, it was also shown that the thiol

can be replaced by other functionalities while still retaining inhibitory activity. Lastly, the use of

a disulfide prodrug strategy was shown to affect pharmacokinetic properties resulting in varying

functional responses in vitro and in vivo.

v

Largazole is already an impressive HDAC inhibitor that shows incredible promise.

However, in order to further develop this natural product into an anti-cancer therapeutic as well as

a chemical probe, improvements in the areas of pharmacokinetics as well as isoform-selectivity

are required. Through these studies we plan on building upon existing structure–activity

relationships to further our understanding of largazole’s mechanism of inhibition so that we may

improve these properties and ultimately develop largazole into an efficient HDAC inhibitor that

may be used as an anti-cancer therapeutic as well as a chemical probe for the studying of

biochemical systems.

Biologically Inspired Design of Protein-Silica Hybrid Nanoparticles for Drug Delivery Applications

The design and application of effective drug carriers is a fundamental concern in the delivery of therapeutics for the treatment of cancer and other vexing health problems. Traditionally utilized chemotherapeutics are limited in efficacy due to poor bioavailability as a result of their size and solubility as well as significant deleterious effects to healthy tissue through their inability to preferentially target pathological cells and tissues, especially in treatment of cancer. Thus, a major effort in the development of nanoscopic drug delivery vehicles for cancer treatment has focused on exploiting the inherent differences in tumor physiology and limiting the exposure of drugs to non-tumorous tissue, which is commonly achieved by encapsulation of chemotherapeutics within macromolecular or supramolecular carriers that incorporate targeting ligands and that enable controlled release. The overall aim of this work is to engineer a hybrid nanomaterial system comprised of protein and silica and to characterize its potential as an encapsulating drug carrier. The synthesis of silica, an attractive nanomaterial component because it is both biocompatible as well as structurally and chemically stable, within this system is catalyzed by self-assembled elastin-like polypeptide (ELP) micelles that incorporate of a class of biologically-inspired, silica-promoting peptides, silaffins. Furthermore, this methodology produces near-monodisperse, hybrid inorganic/micellar materials under mild reaction conditions such as temperature, pH and solvent. This work studies this material system along three avenues: 1) proof-of-concept silicification (i.e. the formation and deposition of silica upon organic materials) of ELP micellar templates, 2) encapsulation and pH-triggered release of small, hydrophobic chemotherapeutics, and 3) selective silicification of templates to potentiate retention of peptide targeting ability.

Knowledge-based IMRT treatment planning for prostate cancer.

PURPOSE: To demonstrate the feasibility of using a knowledge base of prior treatment plans to generate new prostate intensity modulated radiation therapy (IMRT) plans. Each new case would be matched against others in the knowledge base. Once the best match is identified, that clinically approved plan is used to generate the new plan. METHODS: A database of 100 prostate IMRT treatment plans was assembled into an information-theoretic system. An algorithm based on mutual information was implemented to identify similar patient cases by matching 2D beam's eye view projections of contours. Ten randomly selected query cases were each matched with the most similar case from the database of prior clinically approved plans. Treatment parameters from the matched case were used to develop new treatment plans. A comparison of the differences in the dose-volume histograms between the new and the original treatment plans were analyzed. RESULTS: On average, the new knowledge-based plan is capable of achieving very comparable planning target volume coverage as the original plan, to within 2% as evaluated for D98, D95, and D1. Similarly, the dose to the rectum and dose to the bladder are also comparable to the original plan. For the rectum, the mean and standard deviation of the dose percentage differences for D20, D30, and D50 are 1.8% +/- 8.5%, -2.5% +/- 13.9%, and -13.9% +/- 23.6%, respectively. For the bladder, the mean and standard deviation of the dose percentage differences for D20, D30, and D50 are -5.9% +/- 10.8%, -12.2% +/- 14.6%, and -24.9% +/- 21.2%, respectively. A negative percentage difference indicates that the new plan has greater dose sparing as compared to the original plan. CONCLUSIONS: The authors demonstrate a knowledge-based approach of using prior clinically approved treatment plans to generate clinically acceptable treatment plans of high quality. This semiautomated approach has the potential to improve the efficiency of the treatment planning process while ensuring that high quality plans are developed.

Clinical Insights Into the Biology and Treatment of Pancreatic Cancer.

Pancreatic cancer is a devastating disease with a universally poor prognosis. In 2015, it is estimated that there will be 48,960 new cases of pancreatic cancer and that 40,560 people will die of the disease. The 5-year survival rate is 7.2% for all patients with pancreatic cancer; however, survival depends greatly on the stage at diagnosis. Unfortunately, 53% of patients already have metastatic disease at diagnosis, which corresponds to a 5-year survival rate of 2.4%. Even for the 9% of patients with localized disease confined to the pancreas, the 5-year survival is still modest at only 27.1%. These grim statistics highlight the need for ways to identify cohorts of individuals at highest risk, methods to screen those at highest risk to identify preinvasive pathologic precursors, and development of effective systemic therapies. Recent clinical and translational progress has emphasized the relationship with diabetes, the role of the stroma, and the interplay of each of these with inflammation in the pathobiology of pancreatic cancer. In this article, we will discuss these relationships and how they might translate into novel management strategies for the treatment of this disease.

The Feasibly of Functionally Guided Intensity Modulated Radiation Therapy Treatment Planning Using Perfluoropropane-Enhanced MRI for Lung Cancer

Radiotherapy is commonly used to treat lung cancer. However, radiation induced damage to lung tissue is a major limiting factor to its use. To minimize normal tissue lung toxicity from conformal radiotherapy treatment planning, we investigated the use of Perfluoropropane(PFP)-enhanced MR imaging to assess and guide the sparing of functioning lung. Fluorine Enhanced MRI using Perfluoropropane(PFP) is a dynamic multi-breath steady state technique enabling quantitative and qualitative assessments of lung function(1).

Imaging data was obtained from studies previously acquired in the Duke Image Analysis Laboratory. All studies were approved by the Duke IRB. The data was de-identified for this project, which was also approved by the Duke IRB. Subjects performed several breath-holds at total lung capacity(TLC) interspersed with multiple tidal breaths(TB) of Perfluoropropane(PFP)/oxygen mixture. Additive wash-in intensity images were created through the summation of the wash-in phase breath-holds. Additionally, model based fitting was utilized to create parametric images of lung function(1).

Varian Eclipse treatment planning software was used for putative treatment planning. For each subject two plans were made, a standard plan, with no regional functional lung information considered other than current standard models. Another was created using functional information to spare functional lung while maintaining dose to the target lesion. Plans were optimized to a prescription dose of 60 Gy to the target over the course of 30 fractions.

A decrease in dose to functioning lung was observed when utilizing this functional information compared to the standard plan for all five subjects. PFP-enhanced MR imaging is a feasible method to assess ventilatory lung function and we have shown how this can be incorporated into treatment planning to potentially decrease the dose to normal tissue.