Kuros Biosciences announces enrollment of first patient in ASTRA study –
A global, prospective, randomized, multi-center clinical trial in foot and ankle fusion

Schlieren (Zürich), Switzerland, December 2, 2025 – Kuros Biosciences (“Kuros” or the “Company”) a leader in innovative biologic technologies, today announced that the first patient has been enrolled in its global ASTRA (Ankle Subtalar arThrodesis Randomized Assessment) study. ASTRA is a prospective, randomized, single-blinded, controlled, multi-center study to assess the safety and performance of MagnetOs^TM compared to autograft (patient’s own bone) in patients undergoing hindfoot or ankle fusions. Subtalar fusion will be one of many surgical approaches included in the study.

The ASTRA study is part of Kuros’ expanding global extremities strategy and represents the company’s continued commitment to building high-quality clinical evidence across a variety of surgical applications. This international study will include sites in the U.S., Australia, New Zealand, Europe and/or the Middle East.

Approximately 126 patients undergoing hindfoot or ankle fusions will be prospectively enrolled and randomized to receive treatment in either the MagnetOs arm (MagnetOs Putty or MagnetOs Easypack Putty used standalone, not mixed with other bone grafting materials) or the autograft arm. This study is registered on ClinicalTrials.gov under identifier: NCT07225751.

Chris Fair, Chief Executive Officer of Kuros Biosciences, stated: “Enrollment of the first patient in the ASTRA trial marks another important milestone in our Kuros mission to expand the clinical reach of MagnetOs. Building on the strength of our ongoing Level I PROOF and PRECISE clinical trials in posterolateral spine fusion, ASTRA extends our clinical evidence portfolio into foot and ankle. We’re proud to continue advancing the science of bone healing into new anatomical regions where surgeons need reliable solutions for their patients.”

“We’re excited to participate and get the enrollment underway in this important global study,” said Dr. Jesse Doty, Orthopedic Surgeon and Principal Investigator at Erlanger Orthopaedics in Chattanooga, Tennessee. “Successful bone fusion in complex hindfoot and ankle procedures can be challenging, especially when autograft availability or quality is limited. I’m excited to be a part of this Level I study looking at the efficacy of a novel advanced bone graft in my hindfoot fusion patients.”

The study name ASTRA was inspired by astragalus, the historical term for what is now known as the talus or ankle bone, underscoring the study’s focus on improving outcomes in ankle and hindfoot fusion procedures.

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About MagnetOs
Growing bone with MagnetOs^TM gives surgeons confidence where it matters most – delivering predictable fusion outcomes.¹ In a Level I human clinical study published in Spine, MagnetOs achieved nearly twice the fusion rate of autograft (79% vs. 47%) in posterolateral fusions (PLFs).¹ Among active smokers – who made up 1 in 5 patients – the fusion difference between MagnetOs and autograft was even more dramatic.*^†1,2 MagnetOs grows bone on its own thanks to NeedleGrip^TM – a proprietary submicron surface technology that harnesses the immune system to stimulate bone growth, without added cells or growth factors.^§‡4-6 Ready-to-use, easy to mold, and reliably staying put, MagnetOs carries no intrinsic risk of human tissue-related disease transmission and is FDA cleared for use throughout the spine, including interbody procedures. ^¶7-12

Indications Statement
Please refer to the instructions for use for your local region for a full list of indications, contraindications, warnings, and precautions.

About Kuros Biosciences
Kuros Biosciences is on a mission to discover, develop and deliver innovative biologic technologies. With locations in the United States, Switzerland and the Netherlands, the company is listed on the SIX Swiss Exchange. The company’s first commercial product, MagnetOs^TM, is a unique advanced bone graft that has already been used across five continents. For more information on the company, its products and pipeline, visit kurosbio.com.

Forward Looking Statements
This media release contains certain forward-looking statements that involve risks and uncertainties that could cause actual results to be materially different from historical results or from any future results expressed or implied by such forward-looking statements. You are urged to consider statements that include the words “will” or “expect” or the negative of those words or other similar words to be uncertain and forward-looking. Factors that may cause actual results to differ materially from any future results expressed or implied by any forward-looking statements include scientific, business, economic and financial factors. Against the background of these uncertainties, readers should not rely on forward-looking statements. The Company assumes no responsibility for updating forward-looking statements or adapting them to future events or developments.

^* 19 of initial 100 patients were active smokers.
^† Radiographic fusion data of the smoker subgroup were not statistically analyzed as a subgroup and were not included in the peer-reviewed publication of the study.
^‡ Results from in vitro or in vivo laboratory testing may not be predictive of clinical experience in humans. For important safety and intended use information please visit kurosbio.com.
^§ MagnetOs is not cleared by the FDA or TGA as an osteoinductive bone graft. 
^¶ MagnetOs must also be used with an intervertebral body fusion device cleared by FDA for use with a bone void filler. MagnetOs Flex Matrix must be hydrated with BMA & mixed with autograft in posterolateral spine & intervertebral disc space. MagnetOs Granules must be hydrated with blood in the intervertebral disc space.

1. Stempels, et al. Spine. 2024;49(19):1323-1331.
2. Van Dijk, LA. 24th SGS Annual Meeting (Swiss Society of Spinal Surgery). Basel, Switzerland. Aug 2024.
3. Data on file. MagnetOs Putty and MagnetOs Easypack Putty.
4. Van Dijk, et al. eCM. 2021;41:756-73.
5. Van Dijk, et al. J Immunol Regen Med. 2023;19:100070.
6. Duan, et al. eCM. 2019; 37:60-73.
7. Instructions for Use (IFU) MagnetOs Granules.
8. Instructions for Use (IFU) MagnetOs Putty.
9. Instructions for Use (IFU) MagnetOs Easypack Putty.
10. Instructions for Use (IFU) MagnetOs Flex Matrix.
11. Instructions for Use (IFU) MagnetOs MIS.
12. Data on file. MagnetOs Putty and MagnetOs Easypack Putty.

Attachment

• Kuros Press Release ASTRA First Patient 12-1-25