1

Depletion of naïve CD4+T cell compartment by immune hyperactivation

can be rapidly reversed by AntiViral- HyperActivation Limiting Therapeutics

(AV-HALTs)

D.V. Baev, E. Katabira, R. Maserati, P. Cahn, D. De Forni, B. Poddesu, M.R. Stevens, F. Lorion behalf of the VS411 Study Team

WELBX03

AV-HALTsAntiViral-HyperActivation Limiting Therapeutics

2

Oral agents combining antiviral and immunomodulating properties to

both

reduce viral load and

decrease immune-activation

AntiViral -HyperActivation Limiting Therapeutics

ViroStatics AV-HALTs

VS411: Proof of Concept

2nd generation AV-HALTs: To be developed

Why decrease immune activation?

AV-HALTsA New Class of Antiretroviral Drugs

3

Scientific Rationale behind AV-HALTS

Pneumocystis carinii pneumonia and mucosal candidiasis in previously healthy homosexual men: evidence of a new acquired cellular immunodeficiency

MS Gottlieb, R Schroff, HM Schanker, JD Weisman, PT Fan, RA Wolf, and A Saxon

An outbreak of community-acquired Pneumocystis carinii pneumonia: initial manifestation of cellular immune dysfunction

H Masur, MA Michelis, JB Greene, I Onorato, RA Stouwe, RS Holzman, G Wormser, L Brettman, M Lange, HW Murray, and S Cunningham-Rundles

Dec 10, 1981

The first reports of what is now known as HIV-disease/AIDS indicated that the individuals’ immune systems were experiencing excessive activation despite low CD4+ cell counts

4

1 45 57 0 59 0 2 47 52 0 59 0 3 49 57 10 79 0.18 4 67 47 2 81 0.04 Mean ± S.D. 52 * 53.3 † 3.0 † 69.5 0.05 ± 10.1 ± 4.7 ± 4.76 ± 12.1 ± 0.08Normal subjects 71.0 28.0 46.0 15.0 1.6 (n = 16 [mean ± 10.0 ± 8.0 ± 12.0 ± 6.6 ± 0.74 ± S.D.])

T10 is now known as CD38. The CD38 protein is

a marker of cell activation.

A 4- to 5-fold increase above

healthy normals

Table 3. Characterization of T-Lymphocyte SubsetsGROUP LYMPHOCYTE SUBSET LEU 3/ LEU 2 RATIO LEU 1 LEU 2 LEU 3 T10

per cent lymphocytes reactive with monoclonal antibodiesPatients

HIV disease is driven by immune system hyperactivationImmune hyperactivation is not normalized by HAART

Cardiovascular Bone loss

Neurological Impairment

Accelerated aging

Mortality

Why Decrease Immune Activation ?

0.75

1.0

0.50

0.25

0

25 30 35 40 45 50 55 60 65 70

Ι Ι Ι Ι ΙΙ Ι Ι ΙΙ

Life Expectancy (years)

Pre-HAART(1995 – 1996)

Early HAART(1997 – 1999)

Current HAART (2000 – 2005)

Population Controls

10 years

Prob

abili

ty o

f Sur

viva

l

Life Expectancy, yearsAdapted from:

Lohse N et al. Ann Intern Med 2007;146-95

6

The ViroStatics AV-HALT Drug Development Program

Proving the AV-HALT concept in humans and

Moving novel agents into clinical development

First Generation AV-HALTVS411

Proof of ConceptAchieved in HIV/AIDS

• Contained two readily available generic drugs • One acted as an “AV” (didanosine)

• One acted as a “HALT” (hydroxyurea)

• Multinational Phase 2a Clinical Trial

AV-HALTsDrug Development Program

• AV-HALT properties proven• AV: Viral load up to -1.8 logs,

• AV: CD4 cell counts up to +135 cells/mm3

• HALT: - 30% hyperactivation decrease in only 28 days, similar to what HAART achieves

after months/years

AV-HALTsDrug Development Program

First Generation AV-HALTVS411

Proof of ConceptAchieved in HIV/AIDS

VS411 Proof of Concept Phase 2a Trial A 28-day Randomized, Double-blinded Study

Safety precautions:

Standard didanosine and hydroxyurea dosages reduced by one-half or more

Didanosine Cmaxblunted in Phase I

9

Didanosine Hydroxyurea200 mg 300 mg

200 mg 600 mg

200 mg 900 mg

400 mg 300 mg

400 mg 600 mg

58 ART naïve subjects (50% female; 50% black)Safety - Viral Load Reduction – CD4+ Counts - Immunological Assays

Low dose ddI

High DoseddI

Countries

Uganda 1

Argentina 2

Italy 3

Russia 4

1 Elly Katabira, MD President - International AIDS Society

2 Pedro Cahn, MD Past President - International AIDS Society; Sergio Lupo, MD; Arnaldo Casiro, MD; Jorge Contarelli (Buenos Aires, Rosario)

3 Renato Maserati, MD; Giancarlo Pasetti, MD (Pavia, Parma)

4 Aza Rakhmanova, MD; Natalia Zakharova, MD (St. Petersburg)

Investigators

VS411 was safe and well tolerated, no SAE

Didanosine/hydroxyurea

200mg/300mg

Didanosine/hydroxyurea

200mg/600mg

Didanosine/hydroxyurea

200mg/900mg

Didanosine/hydroxyurea

400mg/300mg

Didanosine/hydroxyurea

400mg/600mg

Mean Change From Baseline cells/mm3 OT

+ 71.9 + 56.9 + 95.7 + 67.4 + 50.7

Mean Change From Baseline cells/mm3 ITT

+ 48.0 + 56.9 +95.7 + 67.4 + 50.7

Median Change From Baseline cells/mm3 OT

+ 24.0 + 52.0 + 135.0 + 54.0 + 67.0

Median Change From Baseline cells/mm3 ITT

+ 1.5 + 52.0 + 135.0 + 54.0 + 67.0

VS411: Phase II Study ResultsCD4+ Increases up to +135 cells/mm3

10

The “blunting” of CD4+ cell increases historically seen with the didanosine/hydroxyurea combination was not seen with VS411

DAY 28

DAY 14

Historical nucleoside analogue comparators

Lo

g10 r

ed

uct

ion

fro

m b

ase

line

Lo

g10 r

ed

uct

ion

fro

m b

ase

line

200 mg ddI300 mg HU

200 mg ddI600 mg HU

200 mg ddI900 mg HU

400 mg ddI300 mg HU

400 mg ddI600 mg HU

Lamivudine – 3TCDay 12

200 mg ddI300 mg HU

200 mg ddI600 mg HU

200 mg ddI900 mg HU

400 mg ddI300 mg HU

400 mg ddI600 mg HU

Tenofovir – TDFDay 21

VS411: Phase 2a Antiviral [AV] ResultsMean Viral Log Reduction (ITT)

11Viral load was suppressed below 50 copies/ml in only two individuals

VS411: Phase II [HALT] ResultsComparison of VS411 200/900 to HUNT et al. 2003

12Hunt P, et al. JID 2003;187:1534-1543

8%

4%1%

20-

10-

0-

30-

Day 0 Day 28

6.7%4.3%

Per

cen

tag

e o

f A

ctiv

ated

CD

4+ c

ells

CD

38+/H

LA

-DR

+

Per

cen

tag

e o

f A

ctiv

ated

CD

4+ c

ells

CD

38+/H

LA

-DR

+

20-

10-

0-

30-

VS411, 28 daysddI 200mg / HU 900mg

P =.001

HAART, 21 monthsVL <1,000

CD4+ T lymphocytes

Naïve – but not Central Memory – CD4 T Cell Depletion Correlates with CD4 T Cell Activation

13

0 2 4 6 8 10 12 14 16 18 200

102030405060708090

100

f(x) = − 2.70802556822812 x + 51.3895784266075R² = 0.231621238803075

m

CD

4+ N

aïve

0 2 4 6 8 10 12 14 16 18 200

102030405060708090

100

CD

4+ C

M

Naïve Central Memory (CM)

0 2 4 6 8 10 12 14 16 18 200

0.51

1.52

2.53

3.54

4.55

f(x) = 0.185339803313403 x + 0.108114991211517R² = 0.16263246877592

% CD4+ CD38+HLA-DR+

% K

i-67+

CD

4+ N

aïve

Tota

l P

rolif

erat

ing

0 2 4 6 8 10 12 14 16 18 200

2

4

6

8

10

12

14

16

% CD4+ CD38+HLA-DR+

% K

i-67+

CD

4+ C

M

Reversion of Naïve CD4 T Cell Depletion by AV-HALTs

14

Naïve, Change from Baseline CM, Change from Baseline

0 2 4 6 8 10 12 14 16

-30-20-10

010203040

f(x) = 1.38884754 x − 4.35956464R² = 0.13289792033515

% c

hang

e CD

4+ N

aive

0 2 4 6 8 10 12 14 16

-40-30-20-10

010203040

% c

hang

e C

D4+

CM

0 2 4 6 8 10 12 14 16

-7-6-5-4-3-2-1012

f(x) = − 0.150335945 x + 0.346472219R² = 0.0966308943033439

% CD4+ CD38+HLA-DR+

% c

hang

e Ki

-67+

CD

4+ N

aïve

0 2 4 6 8 10 12 14 16

-12-10

-8-6-4-20246

% CD4+ CD38+HLA-DR+

% c

hang

e K

i-67+

CD

4+ C

M

Tota

l P

rolif

erat

ing

% CD4+ CD38+HLA-DR+ % CD4+ CD38+HLA-DR+

Screening for Second-Generation AV-HALTs

In vitroClinical Proof of Concept

Prediction

Compound 1

Compound 2

Compound 3

AV-HALT profile• AV efficacy• HALT efficacy• Toxicity

Following VS411Pathway

Viral Load CD4

Hyperactivation

ComparatorPrototype

Clinical

Screening

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Viral Load CD4

Hyperactivation

2nd generation

IdealAV-HALT

VS411 combines low doses of two drugs (didanosine and hydroxyurea) to approach the criteria for an Ideal AV-HALT

An ideal AV-HALT would have:- Low mitochondrial and cellular toxicity- Little if any apopototic effect (cell death)- Activity in both activated and resting T helper cells, and- Limit, but not completely block, cell proliferation

(Lack of)Cell toxicity

(Lack of)Apoptotic

effect

Antiproliferative capacity

Antiviral effect in resting/stimulated cells

Antiviral effectin activated cells

(Lack of)Mitochondrial

Toxicity

IdealAV-HALT

VS411

VS1-002

% c

om

pa

red

to

n

ot

tre

ate

d c

on

tro

l

020406080100

VS1-002 provides both antiviral and hyper-activation reducing activity comparable to VS411 with:

- a long patent life - less potential toxicity - in a single molecule

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Measures of Toxicity

Measures of Activity

VS2-091 and VS2-102 approach the criteria of an Ideal AV-HALT

At nanomolar concentrationsIn a single molecule

VS2-091VS2-102

Screening for Second-Generation AV-HALTs

There are two kinds of people:those who do the work,

and those who take the credit

Try to be in the first group. There is less competition there…

Indira Gandhi

Thank you to the Study Subjects, Investigators and the ViroStaticsTeam

ViroStaticsPorto Conte, Italy Princeton, New Jersey Montreal, Canada17