Meeting the Challenge of Developing Drugs for Ebola and Other Neglected Tropical Diseases James McKerrow Director, Center for Discovery and Innovation in Parasitic Diseases, UCSF(www.cdipd.org)

Neglected tropical diseases: no effective drugs, no safe drugs, or drug resistance

T.cruzi/Chagas

Schistosomiasis

Amebiasis

T.brucei/ Sleeping Sickness

But hundreds of millions of people infected!!!

Filoviruses

Challenges of Antiparasitic Drug Development • Little interest in the pharmaceutical industry • •

Must be inexpensive If possible must have flexible enough strategy to quickly develop analogues for overcoming resistance

Time and Cost of Drug Development 5 years Target Family Selection

Target to Lead (Library of Related compounds)

Pre-clinical Studies (beyond rodents)

Phase I

10 years ($500 million dollars)

File and Launch

Phase III

Phase II

Ebola Virus: Major Outbreaks

New York Times, October 13, 2013 (Data provided by WHO)

1298 Cases 768 Deaths

Total 8031 Cases 3865 Deaths

2789 Cases 879 Deaths

3924 Cases 2210 Deaths ew York Times, Updated October 8, 2014

Nigeria 20 Cases 8 Deaths

Ebola Cases as of October 8, 2014

NY Times, October 8, 2014

Physicians/1000 Population 3

2.42 2.5 2 1.5 1 0.5

0.1

0.01

Guinea

Liberia

0.02

0 Sierra Leone

United States

From Dr. Chip Schooley: Why Guinea? • Stalled economy – Drives people farther into the forest for sustenance – Erodes health care system • Tardy recognition • Inadequate isolation equipment

– Disorganized governmental response • Porous borders • Remote location Bausch DG, Schwarz L (2014) Outbreak of Ebola Virus Disease in Guinea: Where Ecology Meets Economy. PLoS Negl Trop Dis 8(7): e3056. doi:10.1371/journal.pntd.0003056

Hypsignathus monstrosus a.k.a. Hammerhead Fruit Bat

www.inaturalist.org

www.tumblr.com

Putative Transmission Chain for 2007 Luebo DRC Outbreak

Putative chain of Ebola virus transmission from bats to the initial human cases in the 2007 outbreak in Luebo, DRC. The first picture shows a village near the islands where migrating bats settle during April and May. The second picture shows the main migratory bat species (H. monstrosus) hunted by villagers during April to May. The third picture shows how villagers handle the bats they kill and eat, which underlines the direct contact with blood and other potentially infected bat body fluids. Vector-Borne and Zoonotic Diseases. December 2009, 9(6): 723-728. DOI: 10.1089/vbz.2008.0167

Frequency (%) of Symptoms and Signs Among 103 hospitalized Patients

Kikwit Outbreak, DRC

Bwaka M A et al. J Infect Dis. 1999;179:S1-S7

WHO Interim Guidelines • Isolate patients in single room whenever possible – Cohort if not possible

• • • • • •

Barrier precautions (gloves, rubber shoes, aprons) Eye protection N95 masks Do not care for patients in “civilian” clothes Beware of sharps Collect bed linen and other materials in contact with patients in impervious plastic containers for disinfection

Diagnosis • • • •

Appropriate exposure history (eg. travel) Severe progressive course with abdominal pain and diarrhea Characteristic rash Labs – – – – –

Thrombocytopenia Leukopenia elevated transaminase levels (AST>ALT) Elevated amylase Elevated d-dimers

• Etiologic diagnosis – Viral RNA by PCR – Antibodies (current ELISA better but much less sensitive or specific than viral RNA)

Management • • • •

Vigorous supportive care Fluid and electrolyte balance Minimal trauma Treatment of secondary complications – Bacterial infection – Myocardial infarction – Renal failure

• Correction of coagulation abnormalities – Platelets when available

Three Approaches Target based/cell based screens Natural Products Repurposed Drugs

Cell-based(pathogen-based) screens There and back again: an example of cell-based phenotype suggesting a molecular target

Searching BIG libraries of small molecules [Millions of chemicals of 2 million compounds

Structure determination New inhibitor design

Ambit Biosciences

Acea Biotech Titan

Amgen

Syntex Anacor Sequoia

AnorMED

Prototek

ArQule AstraZeneca Celera / ARRIS / AXYS / Khepri

Praecis

CDIPD

Pharmadyne

Corvas Endocrine Technologies

Pfizer / Parke-Davis / Warner-Lambert

ESP

Novartis

FerroKin Genzyme

Morvus Technologies

GlaxoSmithKline / SmithKline Beecham

Kosan Iconix

Immunex

A protease inhibitor with activity versus T.cruzi, S.mansoni, SARS virus, cryptosporidium Scheme 1 K11777

N-demethylation, N-oxidation

CH2 H N

H 3C HN+

N

C

N H

O S

C

O

O

CH 2

O

Clhydroxylation

CH 2

CH 2 H N HN+

N

C O

N H

O

C O

S CH2

ClCH2

WRR497

O

Chagas’ Disease (Trypanosoma cruzi)

Wanderley de Souza (http://www.youtube.com/watch?v=1ais69H0li8)

Co-crystals of four vinylsulfone inhibitors with cruzain(Bill Roush and Linda Brinen)-lead optimization for selectivity/binding

Ki= 5nM

Image captured from untreated T. cruzi and L.donovani-infected cells using the IN Cell Analyzer 2000 with a 10x objective, 7 fields/well, exposure time 150 msec/field, 350/460 nm ex/em

ICONIX drug library(16 parasite selective hits, 6 unique) Engel et al Antimicrob. Agents and Chemotherapy, 54, 3326, 2010 Advantage-does not require transfected parasites for HTS

Short term screen of compounds in mice using  luminescent parasites(dpi=days post infection)

3rd dpi

UNTREATED

6th dpi

UNTREATED

8th dpi

UNTREATED

8th dpi POSACONAZOLE 20 mg/kg

4 days of treatment

Ebola Life Cycle RNA Viruses

Mononegavirales

Filoviruses

Time and Cost of Drug Development 5 years Target Family Selection

Target to Lead (Library of Related compounds)

Pre-clinical Studies (beyond rodents)

Phase I

10 years ($500 million dollars)

File and Launch

Phase III

Phase II

(The Scientist 19, #21,2005:”Pharmastart”)

But who pays for this?

Exploring Mother Nature’s chemical space

Roger Linington and Phil Crews QB3 UCSC Michael Fishbach,UCSF Jay Keasling, UCB

Marine Natural Products

21st Century Natural Products Discovery Automated, high resolution ‘function-first’ discovery platform

Circumventing the pipeline Repurposing Existing Drugs

Time and Cost of Drug Development 5 years Target Family Selection

Target to Lead (Library of Related compounds)

Pre-clinical Studies (beyond rodents)

Phase I

10 years ($500 million dollars)

File and Launch

Phase III

Phase II

Amebiasis - a global but “neglected disease”

 50 million people suffer annually from amebiasis, caused by a protozoan Entamoeba histolytica, and 480 million people are at risk  70,000 deaths each year worldwide  Current therapy relies on both metronidazole and paromomycin  Treatment is accompanied by adverse side effects and regimens of 20 days make compliance difficult  Metronidazole resistance is a growing concern  Because this is a disease primarily of the poor, new drug development for amebiasis is not a priority for major pharmaceutical companies

Iconix Library Hits against E. histolytica Compound Auranofin Sporidesmin A Cycloheximide Cladribine Fludarabine Homochlorcyclizine Trifluoperazine Idarubicin 4,4'-Diethylaminoethoxyhexestrol Clomiphene Amiodarone

% Inhibition (5 µM) IC50 (µM) 99.79 0.5 98.87 97.51 79.47 77.33 72.63 68.66 65.32 58.43 53.78 51.14

IC50 of Metronidazole = 5.2 µM 125 100 75 50 25

-3

-2

-1

1 -25

log[M]

Anjan Debnath Primary hits with  50% inhibition and 3 SD above the mean of the population of compounds = 11

2

Auranofin

Oral drug used 30 years for rheumatoid arthritis, MW 678 (FDA approved, sold as Ridaura by Prometheus Laboratories Inc., San Diego)

 $0.25/pill  Auranofin dosages in human = 6 mg/day (max 9 mg/day)

Role of Thioredoxin reductase in protection against ROS of host

Lennon et al., (2000) Science 289, pp. 1190-1194

Auranofin Effect on E. histolytica Trophozoites in vitro

Larissa Podust

EhTrxR mechanics ~66°

NADPH domain

FAD domain

1.50 Å

1.96 Å

EhTrxR mechanics NADPH

~66°

Cys‐Cys

NADPH domain

FAD

FAD

Next Steps  Clinical trial for amebiasis/giardiasis in Bangladesh by Dr. Sharon Reed of UCSD  Clinical trial in Ghana versus Onchocerca volvulus  Auranofin has efficacy against Giardia lamblia-Jiri Gut, UCSF Cryptosporidium parvum-Momar Ndao, McGill U. Trichomonas vaginalis-Kirk Land, Fresno State

Ebola Virus: Clinical Course Incubation Period 0

2

5

10 Illness Period 5

7

Shock and Multiorgan Failure Defervescence And Recovery

19 Death 14

Arthralgia, Arthritis, Hepatitis, Myelitis, Orchitis