SpaceOAR Flex™ System

{0} **FDA** U.S. FOOD & DRUG ADMINISTRATION September 11, 2026 Boston Scientific Corporation Shirin Mate Principal Regulatory Affairs Specialist 100 Boston Scientific Way Marlborough, Massachusetts 01752 Re: K262151 Trade/Device Name: SpaceOAR Flex™ System Regulation Number: 21 CFR 892.5725 Regulation Name: Absorbable perirectal spacer Regulatory Class: Class II Product Code: OVB Dated: June 25, 2026 Received: June 25, 2026 Dear Shirin Mate: We have reviewed your section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (the Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. Although this letter refers to your product as a device, please be aware that some cleared products may instead be combination products. The 510(k) Premarket Notification Database available at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm identifies combination product submissions. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading. If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register. U.S. Food & Drug Administration 10903 New Hampshire Avenue Silver Spring, MD 20993 www.fda.gov {1} K262151 - Shirin Mate Page 2 Additional information about changes that may require a new premarket notification are provided in the FDA guidance documents entitled "Deciding When to Submit a 510(k) for a Change to an Existing Device" (https://www.fda.gov/media/99812/download) and "Deciding When to Submit a 510(k) for a Software Change to an Existing Device" (https://www.fda.gov/media/99785/download). Your device is also subject to, among other requirements, the Quality Management System Regulation (QMSR) (21 CFR Part 820), which includes, but is not limited to, ISO 13485 clause 7.3 (Design controls), ISO 13485 clause 8.3 (Nonconforming product), ISO 13485 clause 8.5.2 (Corrective action), and ISO 13485 clause 8.5.3 (Preventative action). Please note that regardless of whether a change requires premarket review, the QMSR requires device manufacturers to review and approve changes to device design and production (ISO 13485 clause 7.3 and ISO 13485 clause 7.5) and document changes and approvals in the Medical Device File (ISO 13485 clause 4.2.3). Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801); medical device reporting (reporting of medical device-related adverse events) (21 CFR Part 803) for devices or postmarketing safety reporting (21 CFR Part 4, Subpart B) for combination products (see https://www.fda.gov/combination-products/guidance-regulatory-information/postmarketing-safety-reporting-combination-products); good manufacturing practice requirements as set forth in the Quality Management System Regulation (QMSR) (21 CFR Part 820) for devices or current good manufacturing practices (21 CFR Part 4, Subpart A) for combination products; and, if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR Parts 1000-1050. All medical devices, including Class I and unclassified devices and combination product device constituent parts are required to be in compliance with the final Unique Device Identification System rule ("UDI Rule"). The UDI Rule requires, among other things, that a device bear a unique device identifier (UDI) on its label and package (21 CFR 801.20(a)) unless an exception or alternative applies (21 CFR 801.20(b)) and that the dates on the device label be formatted in accordance with 21 CFR 801.18. The UDI Rule (21 CFR 830.300(a) and 830.320(b)) also requires that certain information be submitted to the Global Unique Device Identification Database (GUDID) (21 CFR Part 830 Subpart E). For additional information on these requirements, please see the UDI System webpage at https://www.fda.gov/medical-devices/device-advice-comprehensive-regulatory-assistance/unique-device-identification-system-udi-system. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to https://www.fda.gov/medical-devices/medical-device-safety/medical-device-reporting-mdr-how-report-medical-device-problems. For comprehensive regulatory information about medical devices and radiation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/medical-devices/device-advice-comprehensive-regulatory-assistance) and CDRH Learn (https://www.fda.gov/training-and-continuing-education/cdrh-learn). Additionally, you may contact the Division of Industry and Consumer Education (DICE) to ask a question about a specific regulatory topic. See the DICE website (https://www.fda.gov/medical-devices/device-advice-comprehensive-regulatory- {2} K262151 - Shirin Mate Page 3 assistance/contact-us-division-industry-and-consumer-education-dice) for more information or contact DICE by email (DICE@fda.hhs.gov) or phone (1-800-638-2041 or 301-796-7100). Sincerely, Lora D. Weidner, Ph.D. Assistant Director Radiation Therapy Team DHT8C: Division of Radiological Imaging and Radiation Therapy Devices OHT8: Office of Radiological Health Office of Product Evaluation and Quality Center for Devices and Radiological Health Enclosure {3} DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration # Indications for Use Form Approved: OMB No. 0910-0120 Expiration Date: 07/31/2026 See PRA Statement below. 510(k) Number (if known) K262151 Device Name SpaceOAR Flex System Indications for Use (Describe) SpaceOAR Flex System is intended to temporarily position the anterior rectal wall away from the prostate during radiotherapy for prostate cancer and in creating this space it is the intent of SpaceOAR Flex System to reduce the radiation dose delivered to the anterior rectum. The SpaceOAR Flex System is composed of a radiopaque, biodegradable material that maintains space for the entire course of prostate radiotherapy treatment and is completely absorbed by the patient's body over time. Type of Use (Select one or both, as applicable) ☑ Prescription Use (Part 21 CFR 801 Subpart D) ☐ Over-The-Counter Use (21 CFR 801 Subpart C) CONTINUE ON A SEPARATE PAGE IF NEEDED. This section applies only to requirements of the Paperwork Reduction Act of 1995. *DO NOT SEND YOUR COMPLETED FORM TO THE PRA STAFF EMAIL ADDRESS BELOW.* The burden time for this collection of information is estimated to average 79 hours per response, including the time to review instructions, search existing data sources, gather and maintain the data needed and complete and review the collection of information. Send comments regarding this burden estimate or any other aspect of this information collection, including suggestions for reducing this burden, to: Department of Health and Human Services Food and Drug Administration Office of Chief Information Officer Paperwork Reduction Act (PRA) Staff PRAStaff@fda.hhs.gov "An agency may not conduct or sponsor, and a person is not required to respond to, a collection of information unless it displays a currently valid OMB number." FORM FDA 3881 (8/23) Page 1 of 1 PSC Publishing Services (701) 443-6740 EF {4} K262151 # 510(k) Summary # A. Submitter Boston Scientific Corporation 100 Boston Scientific Way Marlborough, MA 01752 USA Prepared on: August 26, 2026 # B. Contact Information Primary Contact: Shirin Mate Principal Regulatory Affairs Specialist +1 (508) 683-4392 shirin.mate@bsci.com Alternate Contact: Cody Johnson Senior Regulatory Affairs Manager +1 (952) 930-5736 cody.johnson@bsci.com # C. Subject Device | Trade name | SpaceOAR Flex™ System | | --- | --- | | Common Name | Hydrogel Spacer Absorbable Perirectal Spacer | | Regulation Name | Absorbable perirectal spacer | | Device Classification | Class II | | Regulation Number | 21 CFR §892.5725 | | Product Code | OVB | # D. Predicate Device | Trade name | SpaceOAR Vue™ System | | --- | --- | | Common Name | Hydrogel Spacer Absorbable Perirectal Spacer | | Regulation Name | Absorbable perirectal spacer | | Device Classification | Class II | | Regulation Number | 21 CFR §892.5725 | | Product Code | OVB | | 510(k) Submitter/ Holder | Boston Scientific Corporation | | 510(k)# and Clearance Date | K182971 cleared on July 19, 2019 | Page 1 of 7 {5} # E. Device Description SpaceOAR Flex System is a sterile and single-use device. It consists of biodegradable, radiopaque, pre-polymerized Polyethylene Glycol (PEG)-based hydrogel intended for perirectal spacing. Two pre-filled glass syringes, each with an endcap, containing approximately 6 mL of pre-polymerized Polyethylene Glycol (PEG)-based hydrogel. A plastic luer connector with silicone O-rings is used to connect the two syringes to facilitate a homogenized presentation of the hydrogel between the two glass syringes prior to use. The prefilled syringes and luer connector are packaged in a hydrogel tray and terminally sterilized using moist heat. Once prepped, the full volume of hydrogel is contained within a single syringe, and the other syringe and luer connector are discarded. Upon preparing the device for use, and once hydrodissection is performed to open the perirectal space, the needle is then attached to the syringe containing 10 mL of SpaceOAR Flex hydrogel. The needle is packaged separately in a pouch and sterilized using X-ray radiation. The sterilized hydrogel tray and pouched needle and labeling components are packaged in a carton as a final finished device. Following device preparation in accordance with the Instructions for Use (IFU), SpaceOAR Flex hydrogel is transperineally injected into the perirectal space between the anterior rectal wall and Denonvilliers' fascia. The hydrogel creates a space that temporarily positions the anterior rectal wall away from the prostate during radiotherapy for prostate cancer and in creating this space, reduces the radiation dose delivered to the anterior rectum. The hydrogel is biodegradable. It maintains space for the entire course of prostate radiotherapy treatment (approximately 12 weeks), degrades through hydrolysis and is absorbed in about 6 months, sufficient time to support the intended use. However, it may take longer to fully absorb. The hydrogel is designed to clear naturally from the body via renal filtration over time. # F. Indications for Use The Indications for Use Statement for SpaceOAR Flex System is identical to the predicate device, SpaceOAR Vue System. SpaceOAR Flex System is intended to temporarily position the anterior rectal wall away from the prostate during radiotherapy for prostate cancer and in creating this space it is the intent of SpaceOAR Flex System to reduce the radiation dose delivered to the anterior rectum. The SpaceOAR Flex System is composed of a radiopaque, biodegradable material that maintains space for the entire course of prostate radiotherapy treatment and is completely absorbed by the patient's body over time. Page 2 of 7 {6} ### G. Technological Characteristics Compared to Predicate The subject device and predicate device have the same indications for use and principles of operation and share several technological characteristics that are identical. A comparison of the key technological characteristics between the two devices is provided in the table below. Table 1: Comparison of Key Technological Characteristics | Attribute | SpaceOAR Flex™ System (Subject Device) | SpaceOAR Vue™ (Predicate Device – K182971) | | --- | --- | --- | | **Device Components** | | | | System Components | - Two glass syringes pre-filled with PEG hydrogel - Plastic luer connector with silicone O-rings - Stainless steel needle (18 G x 15 cm) | - Two pre-filled polypropylene syringes, pre-filled with either Diluent or Accelerator solution - Glass PEG powder vial - Plastic/ stainless Y-connector containing a static mixer - Plastic syringe holder, 2 syringe capacity - Plastic plunger cap - Vented vial adapter (A plastic adaptor consisting of a spike with membrane to facilitate transfer of fluid between the syringe and the vial) - Stainless steel needle (18 G x 15 cm) | | **Device Packaging, Sterilization and Shelf-life/ Shipping** | | | | Packaging Configuration | Tray: Two pre-filled syringes and a luer connector packaged in a polycarbonate tray sealed with a tyvek lid. Pouched needle: needle pouched in Polyethylene Terephthalate/Low Density Polyethylene (LDPE) and Tyvek pouch. | All components packaged within a polyethylene tray, which is subsequently sealed in a Tyvek/film pouch. | | Sterilization | Tray: Moist heat Pouched needle: X-ray | Gamma | | Shelf life | 18 months | 24 months | | **Hydrogel Characteristics and Implantation** | | | | Hydrogel material | Polyethylene Glycol (PEG) | Polyethylene Glycol (PEG) | | Hydrogel Polymerization | Polymerized during manufacturing | Polymerization begins *in situ* (within the Y-connector) and continues in vivo | | Hydrogel Volume | 10 ml | 10 ml | | Visibility | Ultrasound, MRI, CT, CBCT | Ultrasound, MRI, CT, CBCT | | Hydrogel Placement Location | Between Denonvilliers' fascia & anterior rectal wall | Between Denonvilliers' fascia & anterior rectal wall | | Proper opening of the perirectal space and needle tip confirmation | Hydrodissection and aspiration | Hydrodissection and aspiration | | Hydrogel Delivery Mechanism | Transperineal injection using real-time TRUS image guidance | Transperineal injection using real-time TRUS image guidance | Page 3 of 7 {7} | Implantation Technique | Hydrogel is delivered into the perirectal space in two aliquots with ability to pause and restart during the procedure. | Hydrogel is formed in situ and is delivered as a single aliquot using a smooth, continuous injection technique. | | --- | --- | --- | | Perirectal Space Maintenance | Maintains perirectal space for the entire duration of prostate radiotherapy (12 weeks) | Maintains perirectal space for the entire duration of prostate radiotherapy (12 weeks) | | Degradation Mechanism | Hydrolysis | Hydrolysis | | Clearance Mechanism | Renal filtration | Renal filtration | The differences between the devices have been evaluated through comprehensive preclinical and clinical studies, which provide objective evidence that they do not raise any new questions of safety or effectiveness. Based on this assessment, the SpaceOAR Flex System is considered substantially equivalent to the predicate device, the SpaceOAR Vue System (K182971). ### H. Performance Data Comprehensive preclinical and clinical testing was conducted in accordance with Boston Scientific's design control processes. The testing results met all predefined acceptance criteria, supporting the determination of substantial equivalence. - Design Verification: All design verification testing was executed with passing results; all predefined acceptance criteria were met, demonstrating that the product met all design and packaging specifications for its intended use. - Sterilization validation: Moist heat sterilization validation testing for hydrogel tray was conducted in accordance with EN ISO 17665:2024 and ISO 11138-3:2017 standards. X-ray sterilization validation was conducted in accordance with ISO 11137-1:2025 and ISO 11137-2:2013/A1:2022 standards. The results from sterilization validation for moist heat and X-ray met acceptance criteria and successfully validated the sterilization cycle to achieve a Sterility Assurance Level (SAL) of \(1 \times 10^{-6}\). - Microbiology Testing: The results from this testing demonstrate process consistency and confirm that the subject device complies with all applicable pyrogen limit specifications under ANSI/AAMI ST72:2019. Based on this evaluation, SpaceOAR Flex is labeled as non-pyrogenic. - Pre-clinical Animal GLP Study: An in vivo evaluation in accordance with Good Laboratory Practice (GLP) regulations was conducted to ensure the quality and integrity of the safety data included in this 510(k) submission. The study was designed to assess chronic safety and performance, including device handling. The study was conducted using a canine model that has anatomy similar enough to humans that the device could be deployed in a simulated clinical environment representative of the device's intended use and proposed labeling. To meet the objective, following study endpoints were evaluated. Page 4 of 7 {8} | Study Endpoint | Acceptance Criteria | | --- | --- | | Acute Procedural Safety | No animal deaths, major adverse events, or clinically significant complications related to the intended use of the Test Article (e.g., embolism) during implantation or in the immediate post-implant procedural timeframe on Day 0. | | In-life Safety | No animal deaths, major adverse events, or clinically significant complications during the in-life phase of the study related to the intended use of the Test Article, based minimally on assessment of overall animal health, in-life clinical observations, body weight, body condition score, animal vital signs, clinical pathology, and digital rectal exams. | | Performance - Visibility by CT | Test Article will be detectable by CT for a minimum of 90 days as assessed by the Clinical Evaluator based on the evaluation of CT images collected at the specified timepoints. | | Performance - Maintenance of Space Between Prostate and Rectum | Test Article will maintain Clinically Acceptable space between the prostate and rectum for a minimum of 90 days based on the qualitative clinical judgement of the Clinical Evaluator and based on the evaluation of CT images collected at specified timepoints. | | Performance - Migration | Test Article shall remain at the implant site between the prostate and the rectum for a minimum of 90 days based on the qualitative clinical judgement of the Clinical Evaluator and based on the evaluation of CT images collected at specified timepoints. | | Necropsy, Gross Pathology and Histopathology of Implant Sites (Local Tissue Response) | No evidence of clinically significant gross or histopathological findings related to the intended use of the Test Article compared to Control Article at the implant sites or related tissues as assessed by the Study Pathologist. | | Clinically Significant Incidence of Systemic Toxicity | No major or clinically significant systemic toxicity in tissues/organs related to the intended use of the Test Article compared to the Control Article. | Observational data was also collected over the course of the study from the Test article and Control article treated animals to evaluate the ability to successfully prepare and deploy each spacer per their respective labeling as well as the lack of impact on animal health (no serious adverse events or clinically significant complications). In addition, local tissue response and CT assessments were performed. CT assessment evaluated visibility by CT, space created, migration, material expansion, and absorption. All predefined acceptance criteria for the study endpoints were met, and all observational data collection and reporting requirements were satisfied. Clinical observations and veterinary assessments demonstrated that the chronic safety and performance profile of the subject device, SpaceOAR Flex (test article), is comparable to the predicate device, SpaceOAR Vue (K182971, control article). - Biocompatibility Testing: A full suite of biocompatibility testing in accordance with ISO 10993-1 standard and FDA guidance for Use of ISO 10993-1 standard was conducted to establish safety and biocompatibility of SpaceOAR Flex for its intended clinical use. The results from this testing Page 5 of 7 {9} met pre-defined acceptance criteria demonstrating that the biological risk associated with SpaceOAR Flex is considered acceptable. - **Design Validation and Summative Usability Testing:** The Design Validation results confirm that the design performance meets the user's needs and expectations, demonstrating that the device design conforms to its intended use within the intended use environment. The Summative Usability study was conducted per IEC 62366-1 standard and FDA guidance, *Applying Human Factors and Usability Engineering to Medical Devices*. The results from this testing, in combination with the assessment of the Applier's training material, demonstrated safe and effective use of SpaceOAR Flex, for the intended users and intended use tasks within the intended use environment. - **Clinical Study:** Boston Scientific Corporation (BSC) received FDA approval for IDE #G240157, authorizing initiation of a clinical investigation of the SpaceOAR Flex device. The approved study, titled "*SpaceIT Hydrogel System for Perirectal Spacing in Subjects with Low to Intermediate Risk Prostate Cancer Undergoing External Beam Radiotherapy (EBRT): A Multicenter, Randomized, Controlled Clinical Study (HYDROSPACE)*," is a prospective, randomized, multicenter clinical investigation. The HYDROSPACE study was conducted across 35 institutions with a planned enrollment of 230 subjects. Enrollment has been completed, and subject follow-up is ongoing, with each subject to be followed through 24 months. The mean age of subjects treated in the SpaceOAR Flex and Control group was 68.3 ± 6.5 and 69.5 ± 7.0 years respectively. Subjects enrolled in the SpaceOAR Flex and Control groups had similar average height, weight, and BMI. The trial enrolled participants from diverse racial and ethnic backgrounds. While individuals who identified as White represented the largest proportion of participants in both groups (76.4% SpaceIT, 80.0% Control), the remaining race categories included Asian (2.8% SpaceIT, 2.7% Control), Black (11.1% SpaceIT, 10.7% Control), and Hispanic, Latin American, or Spanish (15.3% SpaceIT, 6.7% Control). In the Control arm, one participant identified as Middle Eastern, North African or Arabian, and one participant identified as Pacific Islander / Pacific Peoples. These racial groups were not represented in the SpaceOAR Flex arm. Five subjects did not disclose their race. There were no subjects who identified as American Indian or Indigenous People of North, Central, and South American. An interim analysis was performed when approximately two-thirds of enrolled subjects reached the 3-month follow-up time point. Results from this interim analysis demonstrate primary safety relative to the control devices (SpaceOAR and SpaceOAR Vue) and effectiveness, thereby supporting a determination of substantial equivalence. Page 6 of 7 {10} The primary safety endpoint was achieved for SpaceOAR Flex. The rate of CTCAE Grade 3 or greater adverse events in the SpaceOAR Flex arm was non-inferior to the control arm (SpaceOAR/SpaceOAR Vue devices). SpaceOAR Flex met the primary effectiveness endpoint as 92.4% of patients had a meaningful reduction in the amount of radiation delivered to the rectum, exceeding the required threshold of 70%. Additional endpoints demonstrated that the SpaceOAR Flex device could be placed successfully, created and maintained space, reduced rectal radiation dose for all radiation modalities, and reduced mean and maximum rectal radiation dose. Hydrogel absorption was assessed at 12 months using MRI. In the interim analysis, complete absorption was demonstrated in a subset of subjects in both the SpaceOAR Flex and Control arm. The data demonstrates that the SpaceOAR Flex absorption profile is consistent with that of the predicate device, SpaceOAR Vue, thereby supporting a determination of substantial equivalence. Additionally, patient reported outcomes demonstrated preservation of quality of life after treatment with the SpaceOAR Flex and Control devices. SpaceOAR Flex demonstrated an equivalent safety profile compared to the control arm. All AEs reported for SpaceOAR Flex in the HYDROSPACE trial were consistent with AEs known for SpaceOAR Vue and SpaceOAR. There were no serious ADEs, unexpected AEs, unexpected SAEs, or deaths reported in the HYDROSPACE study. SpaceOAR Flex device- and procedure-related AEs occurred at a low rate and only within the acute phase (≤ 90 days of the index procedure) of the study; there were no late (≥ 91 days) device- or procedure-related AEs. # I. Conclusion The subject device intended use/ indications for use and several technological characteristics are the same as the predicate device. The minor differences in technological characteristics do not raise new questions of safety or effectiveness. The pre-clinical and clinical evidence demonstrate that the safety, performance, and effectiveness of SpaceOAR Flex is comparable to the predicate device. Based on these data, SpaceOAR Flex is substantially equivalent to the predicate device, SpaceOAR Vue (K182971). Page 7 of 7