Glossary of terms

American College of Rheumatology

American College of Rheumatology 20% response rate signifies a 20% or greater improvement in the number of swollen and tender joints as well as a 20% or greater improvement in three out of five other disease-activity measures. ACR50 and ACR70 reflect the same, for 50% and 70% response rates, respectively

ADAMTS-5 is a key enzyme involved in cartilage breakdown (Larkin 2015)

American Depositary Receipt; Galapagos has a Level 3 ADR listed on NASDAQ with ticker symbol GLPG and CUSIP number 36315X101. One ADR is equivalent to one ordinary share in Galapagos NV

Dutch Authority for the Financial Markets

A Phase 2 study to evaluate GLPG2222 in ivacaftor-treated cystic fibrosis patients with the Class II mutation on one allele

Condition in which there are an inadequate number of red blood cells to carry oxygen to the body’s tissues

AS is a systemic, chronic, and progressive spondyoloarthropathy primarily affecting the spine and sacroiliac joints, and progressing into severe inflammation that fuses the spine, leading to permanent painful stiffness of the back.

Tumor necrosis factor. An anti-TNF drug acts by modulation of TNF

Total cholesterol over HDL ratio. Improvement of the atherogenic index may be a forecast of cardiovascular health

Also known as atopic eczema, atopic dermatitis is a common pruritis inflammatory condition affecting the skin, which most frequently starts in childhood

The historical success rate for drug discovery and development, based on publicly known development paths. Statistically seen, investment in at least 12 target-based programs is required to ensure that at least one of these will reach a Phase 3 study. Most new drug R&D programs are discontinued before reaching Phase 3 because they are not successful enough to be approved

An enzyme important for generating the signaling molecule lysophosphatidic acid (LPA). GLPG1690 targets autotaxin for IPF

Twice daily dosing (bis in die)

Assessment of the amount of product candidate that reaches a body’s systemic circulation after (oral) administration

Substance used as an indicator of a biological process, particularly to determine whether a candidate drug has a biological effect

A mathematical description of financial markets and derivative investment instruments that is widely used in the pricing of European options and warrants

A pre-clinical model involving use of bleomycin (a cancer medication) to induce IPF symptoms

Substance that has satisfied the requirements of early pre-clinical testing and has been selected for development, starting with formal pre-clinical safety evaluation followed by clinical testing for the treatment of a certain disorder in humans

Crohn’s Disease Activity Index, evaluating patients on 8 different factors, each of which has a pre-defined weight as a way to quantify the impact of Crohn’s disease

Cystic Fibrosis Transmembrane conductance Regulator protein. CFTR is an ion channel that transports chloride and thiocyanate ions across epithelial cell membranes. Mutations in the CFTR gene, that codes for the CFTR protein, cause cystic fibrosis

Crédit d’Impôt Recherche, or research credit. Under the CIR, the French government refunds up to 30% of the annual investment in French R&D operations, over a period of three years. Galapagos benefits from the CIR through its operations in Romainville, just outside Paris

A genetic mutation in cystic fibrosis resulting in errors in CFTR folding, transport of functional CFTR to the cell membrane, and CFTR channel opening, whereby chloride ion flow at the cell surface in the membrane of affected organs is impacted negatively. More than 90% of cystic fibrosis patients are carriers of the Class II mutation. It is believed that a potentiator and multiple correctors will be needed to address the CFTR malfunction of Class II mutation patients. Orkambi is the only approved disease-modifying therapy for Class II mutation patients today

A genetic mutation in cystic fibrosis resulting in errors in CFTR channel opening, whereby chloride ion flow at the cell surface in the membrane of affected organs is impacted negatively. Approximately 4% of cystic fibrosis patients are carriers of the Class III mutation. It is believed that a potentiator is needed to address the malfunction of Class III mutation patients. Kalydeco is the only approved disease-modifying therapy for Class III mutation patients today

Point in the drug development process where the candidate drug shows efficacy in a therapeutic setting

A chemical substance, often a small molecule with drug-like properties

Organization which provides drug discovery and development services

Drug that restores the correct protein formation in cystic fibrosis patients. In most CF patients, a potentiator and corrector drug are needed in combination to restore the channel function of the CFTR. Galapagos and AbbVie are planning to combine a potentiator with two correctors to investigate in CF patients with the most prevalent mutation of CFTR

An inflammatory bowel disease involving inflammation of the small and large intestines, leading to pain, bleeding, and ultimately in some cases surgical removal of parts of the bowel

C-reactive protein is a protein found in the blood, the levels of which rise in response to inflammation

Lupus is an autoimmune disease affecting multiple organs and systems in the body, resulting in a wide variety of signs and symptoms. CLE is a form of lupus in the skin which can be triggered or exacerbated by exposure to sunlight

A life-threatening genetic disease that affects approximately 80,000 people worldwide. Although the disease affects the entire body, difficulty breathing is the most serious symptom as a result of clogging of the airways due to mucus build-up and frequent lung infections

A category of small proteins which play important roles in signaling in processes in the body

Phase 2 program for filgotinib in rheumatoid arthritis: completed and reported in 2015 (except for the currently still ongoing DARWIN 3 study). DARWIN 1 explored three doses, in bid and qd administration, for up to 24 weeks in RA patients with insufficient response to methotrexate (MTX) and who remained on their stable background treatment with MTX. DARWIN 2 explored three qd doses for up to 24 weeks in RA patients with insufficient response to methotrexate (MTX) and who washed out of their treatment with MTX. DARWIN 1 and 2 were double- blind, placebo-controlled studies which recruited approximately 900 patients globally. DARWIN 3 is a long term extension study currently ongoing; all patients are on 200 mg filgotinib, except for U.S. males who are on 100 mg

DAS28 is an RA Disease Activity Score based on a calculation that uses tender and swollen joint counts of 28 defined joints, the physician’s global health assessment and a serum marker for inflammation, such as C-reactive protein. DAS28 (CRP) includes c-reactive protein in the score calculation: scores range from 2.0 to 10.0, with scores below 2.6 being considered remission

All activities required to bring a new drug to the market. This includes pre-clinical and clinical development research, chemical and pharmaceutical development and regulatory filings of drug candidates

Process by which new medicines are discovered and/or designed. At Galapagos, this is the department that oversees target and drug discovery research through to nomination of pre-clinical candidates

Addresses the cause of disease and modifying the disease progression, not just the symptoms of the disease

Phase 3 program evaluating filgotinib in Crohn’s disease

Phase 2 clinical study exploring the balance between efficacy and safety among various doses of treatment in patients. Results are used to determine doses for later studies

Term to characterize a clinical study in which neither the physician nor the patient knows if the patient is taking placebo or the treatment being evaluated

Effectiveness for intended use

European Medicines Agency, in charge of European market authorization of new medications

A non-surgical procedure involving use of an endoscope to examine a person’s digestive tract

An approved drug (pirfenidone) for IPF, marketed by Roche

The U.S. Food and Drug Administration is an agency responsible for protecting and promoting public health and in charge of American market authorization of new medication

Payment system where the service provider is paid a specific amount for each procedure or service performed

The Ashcroft fibrotic score involves measuring pulmonary fibrosis through examination of histopathology tissue

First-in-human clinical study, usually conducted in healthy volunteers with the aim to assess the safety, tolerability and pharmacokinetics of the candidate drug

Formerly known as GLPG0634. Small molecule selective JAK1 inhibitor which was evaluated in RA and Crohn’s disease patients in Phase 2 studies. Filgotinib is partnered with Gilead. Galapagos and Gilead are running Phase 3 studies with filgotinib in RA, CD and UC. Gilead initiated Phase 2 studies with filgotinib in small bowel Crohn’s disease, fistulizing Crohn’s disease, Sjögren’s syndrome, cutaneous lupus erythematosus, uveitis, and lupus membranous nephropathy; Galapagos initiated Phase 2 studies with filgotinib in ankylosing spondylitis and psoriatic arthritis. We expect to initiate more Phase 2 studies with filgotinib in new indications. Filgotinib is an investigational drug and its efficacy and safety have not been established

Phase 3 program evaluating filgotinib in RA

Fistulae are inflammatory tracts that most often occur between the distal colon and the perianal region. Fistulae are one of the most severe sequelae of luminal CD and the lifetime risk of occurrence is close to 50% of those with active CD

A double-blind, placebo controlled Phase 2 study with filgotinib in 177 CD patients for up to 20 weeks; full results were published in The Lancet in 2016

A Phase 2 study to evaluate GLPG2222 in patients with cystic fibrosis with the Class II mutation on both alleles

A double-blind, placebo-controlled exploratory Phase 2a study with GLPG1690 in 24 IPF patients; we announced that GLPG1690 halted lung function decline and was reported to be generally well tolerated in this study

The Belgian market authority: Financial Services and Markets Authority, or Autoriteit voor Financiële Diensten en Markten

Fulltime equivalent; a way to measure a worker’s involvement in a project. For example, an FTE of 1.0 means that the equivalent work of one full-time worker was used on the project

Molecule number currently known as filgotinib

A GPR84 inhibitor fully proprietary to us. We plan to initiate a patient study with GLPG1205 in an undisclosed indication

A novel product candidate targeting autotaxin, with potential application in idiopathic pulmonary fibrosis. Fully proprietary to us. We announced that GLPG1690 halted lung function decline and was reported to be well tolerated in the Phase 2a FLORA study in patients with moderate to severe IPF. GLPG1690 is an investigational drug and its efficacy and safety have not been established

A potentiator product candidate which was evaluated in the SAPHIRA 1 and 2 studies in Phase 2 in Class III CF mutation patients

A novel mode-of-action product candidate that is part of the OA alliance with Servier, who inlicensed the non-U.S. rights to GLPG1972 in July 2017. Servier and Galapagos will make joint decisions on further co-development of GLPG1972. GLPG1972 was reported to be well- tolerated and showed no emerging safety signals in a Phase 1 study with healthy volunteers. In addition, GLPG1972 showed up to a 60% reduction in a relevant OA biomarker within 14 days in these volunteers. We completed recruitment for a Phase 1b study with GLPG1972 in OA patients in the U.S.

A C1 (early) corrector product candidate which was evaluated in Phase 1 and is currently being tested in the ALBATROSS Phase 2 study in combination with Kalydeco in Class III mutation patients and in the FLAMINGO Phase 2 study in Class II mutation patients. In June 2017 we announced that the study of GLPG2222 in combination with GLPG2451 in healthy volunteers was successfully completed. GLPG2222 is expected to be combined with a potentiator and C2 (late) corrector in future triple combination investigational therapies

A pre-clinical candidate molecule targeting GPR84. The indication for GLPG2384 remains undisclosed

A potentiator product candidate. In June 2017 we announced that the study of GLPG2222 in combination with GLPG2451 in healthy volunteers was successfully completed. GLPG2451 is expected to be combined with a C1 (early) corrector and C2 (late) corrector in future triple combination investigational therapies

A pre-clinical candidate with novel mode of action with potential application in AtD

A C2 (late) corrector product candidate. In June 2017 we announced the successful completion of Phase 1 studies with GLPG2737. GLPG2737 is expected to be combined with a potentiator and a C1 (early) corrector in future triple combination investigational therapies

A C1 (early) corrector product candidate currently at the pre-clinical stage

A potentiator drug candidate in Phase 1. GLPG3067 is expected to be combined with C1 and C2 corrector in future triple combination investigational therapies

A pre-clinical candidate with undisclosed novel mode of action directed toward inflammation

A C2 (late) corrector drug candidate currently at the pre-clinical stage

A pre-clinical candidate with undisclosed mode of action directed toward inflammation

A pre-clinical candidate with undisclosed mode of action in the IPF program

A pre-clinical candidate with undisclosed mode of action directed toward pain in the alliance with Calchan

High-density lipoprotein. HDL scavenges and reduces low-density lipoprotein (LDL) which contributes to heart disease at high levels. High levels of HDL reduce the risk for heart disease, while low levels of HDL increase the risk of heart disease

A protein inside red blood cells that carries oxygen from the lungs to tissues and organs in the body and carries carbon dioxide back to the lungs

Genetic term meaning a cell containing different alleles for a gene

Microscopic examination of tissues for manifestations of a disease

Genetic term meaning identical alleles of the gene are present on both homologous chromosomes

Inflammatory Bowel Disease. This is a general term for an autoimmune disease affecting the bowel, including CD and UC. CD affects the small and large intestine, while UC affects the large intestine. Both diseases involve inflammation of the intestinal wall, leading to pain, bleeding, and ultimately, in some cases, surgical removal of part of the bowel

IL-17C has been shown to be distinct from other members of the IL-17 family of cytokines. IL-17C has been shown to be an important mediator in inflammatory skin diseases, and is the target of MOR106

Receiving/granting permission from/to another company or institution to use a brand name, patent, or other proprietary right, in exchange for a fee and/or royalty

Studies performed with cells outside their natural context, for example in a laboratory

A large, unrelated group of disorders associated with abnormalities in inflammation

Creations of the mind that have commercial value and are protected by patents, trademarks or copyrights

Occurring between the different operations of a company

U.S. federal law requires a pharmaceutical company to obtain an exemption to ship an experimental drug across state lines, usually to clinical investigators, before a marketing application for the drug has been approved. The IND is the means by which the sponsor obtains this exemption, allowing them to perform clinical studies

Idiopathic pulmonary fibrosis. A chronic and ultimately fatal disease characterized by a progressive decline in lung function. Pulmonary fibrosis involves scarring of lung tissue and is the cause of shortness of breath. Fibrosis is usually associated with a poor prognosis. The term “idiopathic” is used because the cause of pulmonary fibrosis is still unknown

Janus kinases (JAKs) are critical components of signaling mechanisms utilized by a number of cytokines and growth factors, including those that are elevated in rheumatoid arthritis. Filgotinib is a selective JAK1 inhibitor

A potentiator drug in CF marketed by Vertex Pharmaceuticals

Low-density lipoprotein. LDL contributes to heart disease at high levels

Inflamed or injured liver cells secrete higher than normal amounts of certain chemicals, including liver enzymes, into the bloodstream

Lysophosphatidic acid, or LPA, is a signaling molecule involved in fibrosis

Membranous nephropathy is a subtype of kidney disease that occurs in 10-20% of Systemic Lupus Erythematosus patients with nephritis and that manifests itself as excess protein in the urine. Patients with LMN are at risk of developing end-stage renal disease due to longstanding protein leak via kidneys into the urine

Type of white blood cell that is part of the immune system

Major achievement in a project or program; in Galapagos’ alliances, this is usually associated with a payment

Chemical libraries, usually consisting of drug-like small molecules that are designed to interact with specific target classes. These collections can be screened against a target to generate initial “hits” in a drug discovery program

A novel mode-of-action antibody product candidate which showed promising signs of activity and was reported to be well tolerated in AtD patients in a Phase 1b study. MOR106 acts on IL-17C, a novel antibody target discovered by Galapagos. MOR106 is part of the alliance with MorphoSys

Methotrexate; a first-line therapy for inflammatory diseases

New Drug Application

Type of immune system cell which is one of the first cell types to travel to the site of an infection in the body. Neutrophils are another type of white blood cell which fight infection by ingesting and killing microorganisms

Natural killer cells, type of white blood cell with granules of enzymes which can attack tumors or viruses

An approved drug (nintedanib) for IPF, marketed by Boehringer Ingelheim

Administration of medicine by the mouth, either as a solution or solid (capsule, pill) form

Miniature organ produced from cells from a donor; organoids have all the phenotypic characteristics of the patient donor, making them useful tools for in vitro drug research

A combination potentiator-corrector therapy in CF marketed by Vertex Pharmaceuticals

The most common form of arthritis, usually occurring after middle age, marked by chronic breakdown of cartilage in the joints leading to pain, stiffness, and swelling

Contracting work to a third party

Study of what a body does to a drug; the fate of a substance delivered to a body. This includes absorption, distribution to the tissues, metabolism and excretion. These processes determine the blood concentration of the drug and its metabolite(s) as a function of time from dosing

First stage of clinical testing of an investigational drug designed to assess the safety and tolerability, pharmacokinetics of a drug, usually performed in a small number of healthy human volunteers

Second stage of clinical testing, usually performed in no more than several hundred patients, in order to evaluate efficacy, tolerability and the dose to use

Large clinical studies, usually conducted in several hundred to several thousand patients to gain a definitive understanding of the efficacy and tolerability of the candidate treatment; serves as the principal basis for regulatory approval

A substance having no pharmacological effect but administered as a control in testing of a biologically active preparation

Drug that restores the CFTR ion channel opening in CF patients. In most CF patients, a potentiator and corrector drug are needed in combination to restore the genetic defect causing CF. Galapagos and AbbVie are planning to combine a potentiator with two correctors to investigate CF patients with the most prevalent mutation of CFTR

Stage of drug research development, undertaken prior to the administration of the drug to humans. Consists of in vitro and in vivo screening, pharmacokinetics, toxicology, and chemical upscaling

A new molecule and potential drug that meets chemical and biological criteria to begin the development process

Phase 2 patient study in which activity as well as safety in patients is evaluated, usually for a new mechanism of action

Extreme itching, as observed in AtD patients

Psoriatic arthritis is an inflammatory form of arthritis, affecting up to 30 percent of psoriasis patients

Once daily dosing (quaque die)

Research and development operations; unit responsible for discovery and developing new candidate drugs for internal pipeline or as part of risk/reward sharing alliances with collaboration partners

A chronic, systemic inflammatory disease that causes joint inflammation, and usually leads to cartilage destruction, bone erosion and disability

A Phase 2 study of potentiator GLPG1837 in cystic fibrosis patients carrying a Class III mutation. Results were reported in 2016, showing activity and presenting safety data in two Class III mutations

Method usually applied at the beginning of a drug discovery campaign, where a target is tested in a biochemical assay against a series of small molecules or antibodies to obtain an initial set of “hits” that show activity against the target. These hits are then further tested or optimized

Phase 2/3 program evaluating filgotinib in UC patients

Business unit primarily focused on delivering products and conducting fee-for-service work for clients. Galapagos’ service operations included the BioFocus and Argenta business units, which were both sold in April 2014 to Charles River Laboratories

Simple Endoscopic Score for Crohn’s Disease, involving review of 5 pre-defined bowel segments, assigning values from 0 (unaffected) to 3 (highly affected)

Sjögren’s Syndrome is a systemic inflammatory disease which can be felt throughout the body, often resulting in chronic dryness of the eyes and mouth

Crohn’s disease causes chronic inflammation and erosion of the intestines. It can affect different regions of GI tract including the stomach and small and large intestines. While isolated SBCD is an uncommon presentation of CD, involvement of some portion of the small bowel (SB), particularly the ileum, is common

SLE is an autoimmune disease. In autoimmune diseases, the immune system turns against parts of the body it is designed to protect. This leads to inflammation and damage to various body tissues. Lupus can affect many parts of the body, including the joints, skin, kidneys, heart, lungs, blood vessels, and brain. Although people with lupus may have many different symptoms, some of the most common ones include extreme fatigue, painful or swollen joints (arthritis), unexplained fever, skin rashes, and kidney problems

Protein that has been shown to be involved in a disease process and forms the basis of therapeutic intervention or drug discovery

Identification and validation of proteins that have been shown to play a role in a disease process

License payment made in return for access to specific technology (e.g. compound or virus collections)

UC is an inflammatory bowel disease (IBD) causing chronic inflammation of the lining of the colon and rectum (unlike CD with inflammation throughout the gastrointestinal tract)

Uveitis is the term that refers to inflammation inside the eye. This inflammation can be caused by infection, autoimmune reaction, or by conditions confined primarily to the eye