Paul Goodyer, McGill University

.

A No Nonsense

Approach to Cystinosis

1998 (Antignac)

Homozygous mutations of the CTNS gene (17q) encoding a cystine efflux channel in the lysosomal membrane

CYS

Lysosome

Protein

Cystine

6

3

½ Cystine

(umol/g prot)

Leukocytes

LYSOSOME

CYS

European CTNS deletion

The 57 kb deletion arose ~ 500 AD in Northern Europe.

It is present in abut 50% of Northern European patients

French immigration to Quebec: 1608-1763

Irish Immigration to Quebec (Potato Famine) 1846-1851

By 1871, Irish=10-15% of Quebec population

Montreal: Oldest St. Patrick’s Day Parade

W138X

Irish/French Canadian Nonsense Mutation

T G A

Nonsense Mutations (Premature STOP Codons)

STOP

?

T G G

W138X

CTNS Nonsense Mutations

2

2 16

16 11

Type of CTNS Mutation Matters!

It may be possible to overcome Nonsense Mutations

Using compounds related to Aminoglycoside antibiotics

Translational

Readthrough !!

Aminoglycoside antibiotics

trick the ribosome

into “reading through”

a nonsense mutation

STOP

1st generation 2nd generation 3rd generation 4th generation 5th generation

Bioorg. Med. Chem. Lett. 2006 J. Med. Chem. 2009 Bioorg. Med. Chem. 2010 Med. Chem. Comm. 2011 J. Med. Chem. 2012

Designer aminoglycosides - nontoxic Eloxx

Pharmaceuticals

ELX-02

--TGA--

Tryptophan

Does ELX-02 work?

A nonsense mutation in the Tyrosinase

gene halts production of melanin, the

black pigment in mouse hair cells

PROOF OF PRINCIPLE

Wildtype C57Black mouse

Albino mouse with Tyr489X

nonsense mutation

Fatima

Tokhmafshan

Tyrosinase

AAG TAG (STOP)

489

533

(LYSINE)

ELX02

Tyrosinase

Treated Albino Mouse

Untreated Albino Mouse Black Mouse

ELX02 restores melanin production

(black pigment) to hair cells

Fibroblast Line CTNS Allele1 CTNS Allele2

WG1012 W138X W138X

WG1896 W138X W138X

WG0881 del57Kb del57Kb

WG2379 del57Kb W138X

MCH070 Wildtype Wildtype

Cystinosis Fibroblast Lines

Emma

Brasell

No evidence of ELX-02 toxicity in human fibroblasts

or human proximal tubular cell line (HK2)

E L X -0 2 (u g /m L )

nm

ol

Ha

lf C

ys

tin

e/m

g p

ro

tein

0100

200

400

0

1 0

2 0

3 0

4 0

**

*

Does ELX-02 permit sufficient CTNSW138X/W138X

readthrough to reduce cystine accumulation ?

CTNS

MUTATION

Autophagy

Live Cell Imaging of LC3B-stained

autophagosomes in proximal tubular

cells from a CTNSW138X/del patient

Normal

CTNSW138X/del CTNSW138X/del

+ELX-02 24 hrs

ELX-02 reverses

accumulation of abnormal

autophagosomes

Does ELX-02 reduce WBC cystine in

patients with a CTNSW138X Mutation?

Eloxx Pharmaceuticals Inc

Genome Quebec/Genome

Canada and CRF

Montreal

ELX02 Dose-Finding Clinical Trial (2019)

0.3mg/kg

0.75mg/kg

1.5mg/kg

3mg/kg

CTNS Nonsense Mutations

Discontinue Cysteamine X 6 weeks

Stay in Montreal for 4-5 weeks

Not Yet approved/recruiting

N=3 >18 yrs

N=3 > 12 yrs

Goal: Find appropriate dose for long-term trial

Safety

Safety

Safety

1 Week

ELX02 < gentamycin (7.5mg/kg)

Emma Brasell

LeeLee Chu

Murielle Akpa

Diana Iglesias

Fatima Tokhmafshan

Yojiro Yamanaka

Elena Torban

Elena Levchenko

Franciso Emma

Corinne Antignac CRF, CRN, CFI

KFOC

GENOME CANADA

ELOXX PHARMA