GLPG-5101

Mechelen, Belgium; August 6, 2025, 7:30 CET; regulated information – inside information – Galapagos NV (Euronext & NASDAQ: GLPG) today announced that the United States Food and Drug Administration (FDA) has granted RMAT designation to GLPG5101, a second generation anti-CD19/4-1BB CAR-T product candidate for the treatment of relapsed/refractory mantle cell lymphoma (R/R MCL). The RMAT designation was established under the U.S. 21st Century Cures Act to accelerate development and review of promising cell and gene therapies for serious or life-threatening conditions. To qualify for RMAT designation, GLPG5101 demonstrated preliminary clinical evidence suggesting it has the potential to treat, modify, reverse, or cure a serious or life-threatening disease. Clinical data derived from the ongoing ATALANTA-1 study with GLPG5101 in patients with R/R B-cell Non-Hodgkin Lymphoma (B-NHL), including a subset of patients with MCL, supported the RMAT designation. These data1 demonstrated both high objective and high complete response rates, with a manageable safety profile, including low rates of high-grade cytokine release syndrome (CRS), immune effector cell associated neurotoxicity syndrome (ICANS) and low dropout rates. “This designation reflects the promising clinical activity and safety profile observed in our ongoing Phase 1/2 study and supports our commitment to delivering an effective and timely treatment option to patients in need,” said Omotayo Fasan, M.D., Clinical Development Program Head at Galapagos. “With RMAT status allowing for closer collaboration with the FDA, this will enable additional opportunities for accelerated development and assessment timelines.” Benefits of RMAT designation include increased FDA guidance and more frequent interactions during development, eligibility for accelerated approval based on surrogate or intermediate endpoints, all Fast Track and Breakthrough Therapy advantages such as priority review and rolling submissions, and early discussions of potential study endpoints. Galapagos intends to report updated data from the ATALANTA-1 study at a future medical conference. About GLPG5101 and ATALANTA-1 GLPG5101 is a second generation anti-CD19/4-1BB CAR-T product candidate, administered as a single fixed intravenous dose. The safety, efficacy and feasibility of decentralized manufactured GLPG5101 are currently being evaluated in the ATALANTA-1 Phase 1/2 study in eight hematological malignancies with high unmet need. The primary objective of the Phase 1 part of the study is to evaluate safety and to determine the recommended dose for the Phase 2 part of the study. Secondary objectives include assessment of efficacy and feasibility of decentralized manufacturing of GLPG5101. The dose levels that were evaluated in Phase 1 are 50×106 (DL1), 110×106 (DL2) and 250×106 (DL3) CAR+ viable T-cells. The primary objective of the Phase 2 part of the study is to evaluate the Objective Response Rate (ORR) while the secondary objectives include Complete Response Rate (CRR), duration of response, progression free survival, overall survival, safety, pharmacokinetic profile, and the feasibility of decentralized manufacturing. Each enrolled patient will be followed for 24 months. The ATALANTA-1 study is currently enrolling patients in the U.S. and Europe. About relapsed/refractory mantle cell lymphoma Mantle cell lymphoma is a rare and aggressive subtype of non-Hodgkin lymphoma originating from B cells. Patients with relapsed or refractory disease have progressed after standard therapies and face limited treatment options and reduced survival rates. About Galapagos’ cell therapy manufacturing platformGalapagos’ innovative decentralized cell therapy manufacturing platform is designed to enable the administration of fresh, fit, stem-like early memory cells with a median vein-to-vein time of seven days, greater physician visibility, and improved patient experience. The platform consists of an end-to-end xCellit® workflow management and monitoring software system, a decentralized, functionally closed, automated manufacturing platform for cell therapies (using Lonza’s Cocoon®) and a proprietary quality control testing and release strategy. About GalapagosGalapagos is a biotechnology company with operations in Europe, the U.S., and Asia, dedicated to transforming patient outcomes through life-changing science and innovation for more years of life and quality of life. Focusing on high unmet medical needs, we synergize compelling science, technology, and collaborative approaches to create a deep pipeline of best-in-class medicines. With capabilities from lab to patient, including a decentralized cell therapy manufacturing platform, we are committed to challenging the status quo and delivering results for our patients, employees, and shareholders. Our goal is to meet current medical needs, and to anticipate and shape the future of healthcare, ensuring that our innovations reach those who need them most. For additional information, please visit www.glpg.com or follow us on LinkedIn or X. This press release contains inside information within the meaning of Regulation (EU) No 596/2014 of the European Parliament and of the Council of 16 April 2014 on market abuse (market abuse regulation).For further information, please contact: Media inquiries: Marieke Vermeersch +32 479 490 603media@glpg.com Investor inquiries: Glenn Schulman+1 412 522 6239 ir@glpg.com Forward-looking statementsThis press release includes forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended. These statements are often, but are not always, made through the use of words or phrases such as “anticipate,” “expect,” “plan,” “estimate,” “will,” “continue,” “aim,” “intend,” “future,” “potential,” “could,” “indicate,” “forward,” as well as similar expressions. Forward-looking statements contained in this release include, but are not limited to, statements regarding the expectations regarding the benefits of RMAT designation, statements regarding the expected timing, design and readouts of the ATALANTA-1 study, statements regarding Galapagos’ cell therapy manufacturing platform, and statements regarding the clinical development and potential benefits of, and regulatory interactions regarding, GLPG5101. Forward-looking statements involve known and unknown risks, uncertainties and other factors which might cause Galapagos’ actual results to be materially different from those expressed or implied by such forward-looking statements. These risks, uncertainties and other factors include, without limitation, the risk that preliminary or interim clinical results may not be replicated in ongoing or subsequent clinical trials, the risk that ongoing and future clinical studies with GLPG5101 may not be completed in the currently envisaged timelines or at all, the inherent uncertainties associated with competitive developments, clinical trial and product development activities and regulatory approval requirements (including that data from the ongoing and planned clinical research program may not support registration or further development of GLPG5101 due to safety, efficacy or other reasons), Galapagos’ reliance on collaborations with third parties (including its collaboration partner Lonza), and that Galapagos’ estimations regarding its GLPG5101 development program and regarding the commercial potential of GLPG5101 may be incorrect,, as well as those risks and uncertainties identified in Galapagos’ Annual Report on Form 20-F for the year ended 31 December 2024 filed with the U.S. Securities and Exchange Commission (SEC) and its subsequent filings with the SEC. All statements other than statements of historical fact are statements that could be deemed forward-looking statements. The forward-looking statements contained herein are based on management’s current expectations and beliefs and speak only as of the date hereof, and Galapagos makes no commitment to update or publicly release any revisions to forward-looking statements in order to reflect new information or subsequent events, circumstances, or changes in expectations, unless specifically required by law or regulation. 1 Data cut-off: January 21, 2025 Attachment Galapagos Press Release_RMAT Designation_GLPG5101_ENG_final

iStock, cyano66 SpringWorks Therapeutics is the perfect case study for rescuing a discontinued assets. It’s time to repeat the process for every rare disease, experts say. The biopharma industry has never been better at making drug candidates than it is in this moment. But not everything that comes out of the drug discovery engine will get developed, even if curative. It’s hard to comprehend the scope of the drugs, research and intellectual property sitting on pharma shelves, or being lost as biotechs shut down. Annette Bakker, CEO of the Children’s Tumor Foundation (CTF) that supported the development of SpringWorks Therapeutics’ newly approved rare disease drug Gomekli, estimates that there are probably 30 more drugs out there right now that could help patients with neurofibromatosis if they weren’t in limbo. “This is one drug, but it’s definitely not the last one,” Bakker said. “And what we actually really hope is that this may trigger a motivation for some other companies.” Gomekli’s journey from Pfizer’s storeroom to approval is a perfect case study that Bakker and SpringWorks Chief Medical Officer Jim Cassidy say could be replicated over and over. “What we’re building now can actually be copied to every rare disease under the sun,” Bakker said. Gomekli is now estimated to bring in about $760 million by 2030, according to Bakker, so the opportunity is real for companies willing to wade into the dust and cobwebs of pharma’s attic. “There is just a whole energy here that I think is worth exploring now that we have a success, Bakker said. “How can we make this a sustainable endeavor going forward? Because for [Gomekli], this . . . was a fantastic experience, but now we need to think about making this a scalable opportunity.” The Ghosts of Biotechs Past Smaller biotechs also churn out assets that never see the light of the day. Carl Schoellhammer, associate partner at consulting firm DeciBio, calls these “ghost assets.” Myriad reasons can drive a biotech out of business, but it’s not always because a drug failed. A company may simply be unable to secure a new round of fundraising. This leaves them attempting a fire sale of the assets, or they simply fade away and the science is never seen again, Schoellhammer explained. The issue is particularly prominent among platform companies, which were all the rage a few years ago but have petered out as the industry turned to focus on single assets with data behind them. Bakker thinks the problem is getting worse. “You see that a lot of companies are restructuring these days, and I think we’re going to have even a more pronounced wave of what I call shell drugs that actually will never see the patient. And for a rare disease, that is a problem.” Schoellhammer predicts that areas like mRNA or cell therapy are likely to create these poltergeists in the years to come. Companies that launched in the heyday of COVID to advance mRNA have not really figured out the next phase of this technology. Even Moderna, the most famous name in the mRNA game, is struggling to find the right indications for its tech. For cell therapy, Schoellhammer predicts that CD19 CAR T programs will likely be cast off in the years to come. Several of these therapies have already been approved, leaving dozens still in development. Galapagos just deprioritized CD19 CAR T candidate GLPG5201 after years of development, he noted. For a lot of smaller cell therapy companies, they raised funds when the industry was at a high. “Everyone thought that cell therapies are gonna be the end all be all,” Schoellhammer said. “There’s some question marks [now], and they couldn’t raise again.” Galapagos is well capitalized with about €500 million ($525.8 million) in the bank to last into 2028 and can afford to move onto the next candidate in line, in this case GLPG5101. A smaller company cannot. When facing this problem, biotechs can try and sell the assets off. If they can’t find a buyer, they could pay to maintain the IP, but that’s a huge expense that a failing biotech probably does not have the cash to cover. A venture capital firm that had backed the company is unlikely to want the hassle of trying to form a new company around an old asset, Schoellhammer said. If the IP came from a research organization, it can be transferred back there. But often the assets drift off never to be seen again. According to Bakker, drugs from small biotechs can get lost in an acquisition focused on another drug. If the smaller company had filed an investigational new drug application for another asset with the FDA prior to being acquired, no one can access those data because the smaller company no longer exists after it’s absorbed into a bigger one. The data are simply lost. “That, I think, is a huge problem for the patients, but also it’s pretty unethical that we would have to do these toxicology studies on cats and dogs because we can’t access that data,” Bakker said. Policy solutions could help incentivize development of shelves assets, too. Bakker suggested tax incentives for companies and that the FDA loosen its policies on old IND filings to ensure that data are not lost if a company goes away. According to Cassidy, the key for getting Gomekli across the FDA’s finish line was CTF. And if you ask Bakker, it was having a company like Pfizer that was willing to spin out the intellectual property, and then the volunteers to make it happen. Cassidy said SpringWorks was very lucky that Pfizer was willing, but that’s not always the case. “It’s all very well making a fuss over a drug that’s been discontinued. . . . Most drug companies, they’ll be deaf to that from the outside world. You have to be really persistent, really tenacious and really go for the right people in the company . . . and influence them in the right way,” Cassidy said. “We can’t do that. That’s got to be a CTF-like organization.” Investors also need to be identified who would be willing to take a chance and form new entities around these orphaned assets. Bakker also thinks that biotech accelerators could focus on them. “What I’m working on now is creating almost like an investor club of people that are willing to sustain these companies to make sure that they make it to the finish line,” Bakker said. Both Cassidy and Schoellhammer said that another strategy to capturing dismissed assets is via a holding company, which would pick up assets being sold off as companies shut down and assemble the resources to advance them. Now that Gomekli is approved, Bakker is eager to share her expertise and move on to the next potential asset. She is working with the FDA, Sanofi and the Myhre Syndrome Foundation to see if rare diseases can be clustered together by type to broaden the treatment opportunities. CTF is also developing an infrastructure to help public and private institutions collaborate to develop drugs efficiently and a clinical trials consortium to facilitate the movement of drugs into the clinic. “Our approach is, let us build a prototype that actually can be expanded to other rare disease,” Bakker said. “So it’s not just for NF.” Editor’s note: The following story is part one in a two part story looking at discontinued assets in biopharma. You can read Part One, How SpringWorks Took Pfizer’s Rare Disease Ghost Drug And Got it to Patients , here .