Ablynx : 20/10/2016 ABLYNX OUTLINES NEXT STEPS FOR ITS ANTI-IL-6R NANOBODY, VOBARILIZUMAB, A POTENTIAL BEST-IN-CLASS TREATMENT FOR RHEUMATOID ARTHRITIS

• AbbVie has decided at this time not to exercise its right to opt-in and license vobarilizumab in RA
• Additional analysis of the Phase IIb RA studies of vobarilizumab further demonstrate its best-in- class efficacy and safety profile
• Ablynx will now rapidly move vobarilizumab into a Phase III RA programme while initiating partnering discussions

Webcast presentation, including additional results from the Phase IIb RA studies of vobarilizumab, will take place today at 4pm CET/10am EST (details below) - slides available on the Ablynx website

(R&D portfolio)

GHENT, Belgium, 20 October 2016 - Ablynx [Euronext Brussels: ABLX; OTC: ABYLY] today announced that it will initiate the processes for End-of-Phase II and scientific advice meetings with the regulators in the USA and Europe (FDA and EMA1) for its anti-IL-6R Nanobody®, vobarilizumab, as part of the preparations to start Phase III clinical development in patients with rheumatoid arthritis (RA).

In two Phase IIb RA studies in 596 patients, vobarilizumab was shown to have a strong and sustained effect on signs and symptoms of disease, with an excellent safety and tolerability profile2. As a monotherapy, in a head-to-head study, vobarilizumab was much more efficacious compared to tocilizumab (the only currently approved anti-IL-6R drug) with up to 60% more patients in clinical remission at week 12. In combination with methotrexate, in a cross study analysis, vobarilizumab had an excellent efficacy profile based on the most stringent efficacy parameters (ACR70; remission) as compared to the leading commercial biologicals and oral anti-RA drugs in development. A class advantage of vobarilizumab versus antibodies was also demonstrated, with anti-drug antibodies having no effect on clinical efficacy and safety in contrast to the experience with some of the most established antibody products in RA.

Ablynx will host a conference call/webcast today at 4 pm CET, 10 am EST during which additional results from the Phase IIb RA studies of vobarilizumab and the next steps in the development plan will be presented. The webcast and presentation may be accessed by clicking here. A copy of the presentation is

1 FDA: Food and Drug Administration; EMA: European Medicines Agency

2 Press releases July/Augustus 2016; presentation additional Phase IIb results available on the Ablynx website

also available on the Ablynx website, under the R&D portfolio section. To participate in the Q&A, please dial +32 (0)2 404 06 60, using confirmation code 6916752.

Vobarilizumab targets the interleukin 6 pathway via its IL-6 receptor (IL-6R). IL-6 is a pro-inflammatory cytokine that plays a role in T-cell activation, production of acute phase proteins in response to inflammation, induction of immunoglobulin production, and stimulation of osteoclast differentiation and activation. Vobarilizumab (26kD) is an anti-IL-6R Nanobody linked to an anti-human serum albumin (HSA) Nanobody (to increase the in vivo half-life of the molecule). 24-week data from a Phase I/IIa proof-of- concept combination study of ALX-0061 (vobarilizumab) together with methotrexate were published in February 2013, followed by the signing of a global exclusive option licensing deal with AbbVie in September 2013 for the development and commercialisation of vobarilizumab in RA and systemic lupus erythematosus (SLE).

In July 2016, Ablynx announced strong topline results from the 12 week Phase IIb study of vobarilizumab as a monotherapy in patients with moderate to severe RA which demonstrated that vobarilizumab was very effective and resulted in ACR20, ACR50 and ACR70 scores of up to 81%, 49% and 24% respectively at week

P

12. Moreover, vobarilizumab induced clinical remission (based on DAS28CR 3) in up to 41% of patients, as

compared to 27% for tocilizumab-treated patients, and it had a favourable safety profile at all administered doses.

In August 2016, Ablynx reported compelling results from the 24 week Phase IIb study of vobarilizumab administered as a combination therapy with methotrexate (MTX) in patients with moderate to severe RA. ACR20, ACR50 and ACR70 scores were 79%, 59% and 43% respectively at week 24, and vobarilizumab had a rapid and strong impact on disease activity with up to 49% of vobarilizumab-treated patients achieving clinical remission (based on DAS28CRP1) at week 24. Whilst the primary endpoint of a statistically significant difference in the number of patients who achieved an ACR20 at week 12 with vobaralizumab plus methotrexate compared to placebo plus methotrexate was not achieved due to an unusually high placebo response, this has no impact on the future development potential for vobarilizumab since its impressive effect on clinically relevant efficacy endpoints, such as ACR70 and DAS28 remission, confirm its potential to be a best-in-class drug candidate in RA. Importantly, the results also confirmed the favourable safety profile of vobarilizumab in a larger patient population and the potential for convenient monthly administration.

An open-label extension study in RA patients is currently ongoing (94% roll-over rate) as well as a Phase II study in patients with systemic lupus erythematosus (SLE). The results from both these studies are expected in 2018.

Ablynx is a biopharmaceutical company engaged in the development of Nanobodies®, proprietary therapeutic proteins based on single-domain antibody fragments, which combine the advantages of conventional antibody drugs with some of the features of small-molecule drugs. Ablynx is dedicated to creating new medicines which will make a real difference to society. Today, the Company has more than 45 proprietary and partnered programmes in development in various therapeutic areas including inflammation, haematology, immuno-oncology, oncology and respiratory disease. The Company has collaborations with multiple pharmaceutical companies including AbbVie, Boehringer Ingelheim, Eddingpharm, Genzyme, Merck & Co., Inc., Merck KGaA, Novartis, Novo Nordisk and Taisho Pharmaceuticals. The Company is headquartered in Ghent, Belgium. More information can be found on www.ablynx.com.

3 Remission: DAS28

CRP

Julia Phillips, Brett Pollard, Mo Noonan, Matthew Moss

t: +44 20 3727 1000

e: ablynx@fticonsulting.com

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