AB Science — Investor Presentation 2011

Jan 13, 2011

Paris,!January!13th!2011 –!8.45!am

AB#Science#announces#recruitment#of#first#patient##################################### in#phase#2#study#in#metastatic#melanoma

AB! Science! SA% (NYSE% Euronext% 4% FR0010557264% 4% AB),% a% pharmaceutical% company% specialising% in% the% research,% development% and% commercialisation% of% protein% kinase% inhibitors% (PKIs), announced% today% the% recruitment%of%the%first%patient%in%the%phase%2%study%evaluating%masitinib%in%metastatic%melanoma.%

This%is%a prospective,%multicentre,%open4label,%phase%2%study%to%evaluate%efficacy%and%safety%of%masitinib%at% 9 mg/kg/day% in% monotherapy% and% combination% with% dacarbazine% in% the% treatment% of% patients% with% non4 resectable%or%metastatic%stage%3%or%stage%4%melanoma%not%carrying%a%mutation%in%the%juxta%membrane%of%c4 kit.

Masitinib% is% currently% evaluated% in% phase% 3% in% the% 5%% of% patients% with% metastatic% melanoma% carrying% a% mutation% in% the% juxta%membrane% of% c4kit,% with% first% patients% having% been% enrolled.% This%proof% of% concept% phase% 2% study% complements% the% phase% 3% by% targeting% the% remaining% 95%% of% patients% with% metastatic% melanoma.% This% phase% 2% in% melanoma% will% test% the% monotherapy% strategy% as% in% the% phase% 3% and% the% combination%with%chemotherapy%strategy.%This%study%is%fully%financed

Alain%Moussy,% Chairman%and% CEO% of%AB% Science% declared% «% This% development% in%melanoma%was% initiated% after% observation% of% positive% case% reports% in% dogs% suffering% from%metastatic%melanoma% and% treated%with masitinib.%After% registration% of%masitinib% both%in%Europe%and%in% the%USA%in% canine%mast% cell% tumours,% the% veterinary%platform%creates%also%value% for% the%development%of%masitinib%in%human%medicine%by%delivering% information%on%what%indications%could%be%pursued.%This%type%of%cross%species%development%is%encouraged%by% NCI%guidelines%for%drugs%developable%in%the%two%species,%which%is%the%case%of%tyrosine%kinase%inhibitors%since% kinases%are%fairly%homologous%across%mammals ».

Details!of!the!clinical!development!program!(on!next!page).

About!NCI!guidelines!

The%National% Cancer%Institute's% Center% for% Cancer% Research% (CCR)% has% launched% the% Comparative%Oncology% Program% (COP)%to%help%researchers%better%understand%the%biology%of%cancer%and%to%improve%the%assessment%of%novel%treatments% for%humans%by%treating%pet%animals4primarily%cats%and%dogs4with%naturally%occurring%cancer.% Further%information%is%available%at https://ccrod.cancer.gov/confluence/display/CCRCOPWeb/Home

About!masitinib

Masitinib%is%a%new%orally%administered%tyrosine%kinase%inhibitor%that%targets%mast%cells,%important%cells%for%immunity,%as% well%as%a%limited% number%of%kinases% that% play%key% roles%in%various%cancers.%Owing% to%its% novel%mechanism%of%action,% masitinib% can% be% developed% in% a% large% number% of% conditions% in% oncology,% in% inflammatory% diseases% and% in% certain% diseases% of% the% central% nervous% system.% Through% its% activity% of% inhibiting% certain% kinases% that% are% essential% in% some% oncogenic%processes,%masitinib%may%have%an%effect%on%tumour%regression,%alone%or%in%combination%with%chemotherapy.% Through% its% activity% on% the% mast% cell% and% certain% kinases% essential% to% the% activation% of% the% inflammatory% cells% and% fibrosing% tissue% remodelling,%masitinib%can%have%an%effect%on% the%symptoms%associated%with%some%inflammatory%and% central%nervous%system%diseases.

About!AB!Science

Founded% in% 2001,% AB% Science% is% a% pharmaceutical% company% specialising% in% the% research,% development% and% commercialisation% of% protein% kinase% inhibitors% (PKIs),% a% new% class% of% targeted% molecules% whose% action% is% to% modify% signalling% pathways%within% cells.%Through% these% PKIs,% the% Company% targets% diseases%with% high% unmet%medical% needs% (cancer,% inflammatory% diseases% and% central% nervous% system% diseases),% in% both% human% and% veterinary% medicines.% Thanks% to% its% extensive% research% and% development% capabilities,% AB% Science% has% its% own% portfolio% of% molecules.% Masitinib, a lead compound, has already been registered in veterinary medicine in Europe and is pursuing nine phase 3 studies in human medicine, including four studies on-going in pancreatic cancer, GIST, in metastatic melanoma expressing JM mutation of c-Kit, and mastocytosis.

Further information is available on AB Science's website: www.ab-science.com

This document contains prospective information. No quarantee can be given as for the realisation of these forecasts, which are subject to those risks described in documents deposited by the Company to the Authority of the financial markets, including trends of the economic conjuncture, the financial markets and the markets on which AB Science is present.

AB Science - Financial Communication & Press Relations

Citigate
Dewe Rogerson

Contacts Citigate Dewe Rogerson: Agnès Villeret - Tel: +33 1 53 32 78 95 - agnes.villeret@citigate.fr

$ * $

DETAILS OF THE CLINICAL DEVELOPMENT PROGRAM

Scientific rationale for developing masitinib in metastatic melanoma.

Malignant melanoma continues to remain a significant health threat with death often occurring as a result of metastasis. Moreover, metastatic melanoma is a highly chemotherapy resistant tumour.

The use of newer targeted therapies, alone and in combination with chemotherapy may offer new hope of improving treatment in this cancer.

Although it seems obvious to evaluate masitinib in monotherapy in the sub-population of melanoma JM ckit mutated population (phase 3 on-going), it is also interesting to evaluate the efficacy of masitinib in combination with chemotherapies in the population of melanoma not presenting a JM c-kit mutation. Through its ability to block two kinases, FAK (Focal Adhesive Kinase), and PDGFR, as well as the Wnt/ $\beta$ catenin Signalling pathway, masitinib combined with chemotherapy, could prevent the development and progression of melanoma lesions, as well as decrease the melanoma resistance to chemotherapy by increasing the drug uptake and therapeutic effectiveness of chemotherapy. Moreover, based on the results obtained in veterinary medicine in dogs with melanoma not presenting a c-kit JM mutation, masitinib in monotherapy might also represent a therapeutic option in human melanomas not presenting c-kit JM mutation.

Focal adhesion kinase (FAK) is a ubiquitously expressed non-receptor tyrosine kinase involved in cancer progression and metastasis. It is found overexpressed in a large number of tumours. FAK regulates integrin and growth factor signalling pathways involved in cell migration, proliferation and survival. These cellular processes, by promoting invasion and metastasis, are implicated in the development and progression of cancer. Studies have shown increased in the constitutive activation of FAK in melanoma cells. In vitro, masitinib (1µM) reduces FAK kinase activity.

PDGFR is a transmembrane receptor tyrosine kinase reported to stimulate angiogenesis and to recruit pericytes. Melanomas widely express PDGFR, and their in vivo resistance to chemotherapy is attributable to high tumour interstitial fluid pressure (IFP). Recent studies have suggested that PDGFR-beta inhibition reduces tumour IFP, and thus increases the uptake of concomitantly administered drugs. In vitro, masitinib is able to inhibit PDGFR kinase activity at submicromolecular ranges (IC50 = $0.49 \mu M$ ). In cell proliferation assays, masitinib displays an interesting selectivity and inhibits PDGFR-dependent cell proliferation (IC50 = 0.02 $\mu$ M). These data suggest that masitinib may increase drug uptake and therapeutic effectiveness of chemotherapy for melanoma by inhibiting PDGFR kinase activity.

Wnt/β4catenin%Signalling%has%been%shown%to%be%involved%in%progression,%renewal%of%cancer%stem%cells%and% drug% resistance% of% several% tumours.% This% pathway% play% a% role% in% melanocyte% development% and% could% be% involved%in%their%transformation%in%malignant%melanoma.%Therefore%its%inhibition%could%potentially%translate% in%a%clinical%benefit%of%patients%with%melanoma.

Characteristics!of!the!phase!2!study!in!metastatic!melanoma

This%is%a%prospective,%multicentre,%open4label,%two4parallel%groups,%phase%2%study% to%evaluate%efficacy%and% safety%of%masitinib%at%9 mg/kg/day%in%monotherapy%and%combination%with%dacarbazine%in%the%treatment%of% patients% with% non4resectable% or% metastatic% stage% 3% or% stage% 4% melanoma% not% carrying% a% mutation% in% the% juxta%membrane%of%c4kit.

Patients%will%be%randomized%in%two%groups:

• Group%1:%patients%will%receive%masitinib%in%association%with%dacarbazine
• Group%2:%patients%will%receive%masitinib.

The%primary%criterion%will%be%the%Overall%Progression%Free%Survival%(PFS),%defined%as%the%delay%between%the% date% of% randomisation% to% the% date% of% documented% progression% or% any% cause% of% death% during% the% study.% Overall%Survival%will%be%the%main%secondary%criterion.

Positioning!of!masitinib!in!the!treatment!of!melanoma

Melanoma%is%a%malignant%tumour%that%develops%from%cells%called%melanocytes,%which%are%present%primarily% in% the%skin%but%are%also% found%in% the%eye%and%mucous%membranes%of% the%mouth,%nose,%sinus,% rectum%and% genitals.

The% incidence% of% melanoma% has% multiplied% ten4fold% in% 50% years.% The% American% Cancer% Society% estimated% there%were%68,000%newly%diagnosed%melanoma%cases%in%the%US%with%8,700%related%deaths%in%2009.%In%France,% it%is%estimated%that%7,000%new%cases%of%melanoma%are%diagnosed%each%year.%%

Masitinib%is%positioned%in%phase%3%in%5%%of%the%melanoma%carrying%a%mutation%in%the%juxta%membrane%of%c4 kit.%In%this%patient%population,%masitinib%is%administered%in%monotherapy%at%the%dose%of%7.5 mg/kg/day

Masitinib%is%also%positioned%in%phase%2%in% the%other%95%%of% the%melanoma%Not%carrying%a%mutation%in% the% juxta% membrane% of% c4kit.% In% this% patient% population,% masitinib% is% evaluated% in% monotherapy% and% in% combination%with%standard%chemotherapy,%at%the%dose%of%9 mg/kg/day.