CALDERWOOD & HARKNESS LLP Counselors at Law
1401 K Street NW, Suite 900 Washington, D.C. 20005 Telephone: (202) 555-7400 Facsimile: (202) 555-7401 www.calderwoodharkness.com
PRIVILEGED AND CONFIDENTIAL — ATTORNEY-CLIENT COMMUNICATION ATTORNEY WORK PRODUCT
MEMORANDUM
TO:
Dr. Niamh Tierney, Vice President of Regulatory Affairs, Solstice Biomedical Devices Ltd.
Marcus Hale, Vice President of U.S. Operations, Solstice Biomedical Inc.
FROM:
Miriam Calloway, Responsible Partner, Healthcare & Life Sciences Practice Group
Joel Strauss, Billing Partner, Healthcare & Life Sciences Practice Group
Amy Whitfield, Lead Associate, Healthcare & Life Sciences Practice Group
Sean Morrissey, Working Associate, Healthcare & Life Sciences Practice Group
DATE: April 22, 2025
RE: Regulatory Strategy Memorandum — FDA 510(k) Pathway for the Solstice Lumina™ CGM System (Lumina C14 Implantable Sensor and Lumina R7 Wearable Reader/Transmitter)
Engagement Reference No.: 1037-00002
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I. Executive Summary
Calderwood & Harkness LLP ("C&H" or the "Firm") has been engaged to advise Solstice Biomedical Devices Ltd. ("Solstice," "SBD," or the "Company") and its wholly owned U.S. subsidiary, Solstice Biomedical Inc. ("SBI"), on the development and execution of a regulatory strategy for U.S. market entry of the Solstice Lumina™ Continuous Glucose Monitoring System (the "Lumina CGM System" or the "Device"). This memorandum sets forth our analysis and recommendations regarding the appropriate FDA premarket pathway, predicate device selection, substantial equivalence framework, clinical and non-clinical testing requirements, intellectual property considerations, regulatory timeline, and estimated costs.
The Lumina CGM System comprises two integrated device variants that function together as a unified continuous glucose monitoring system:
• Lumina C14 — a subcutaneously implantable continuous glucose monitoring sensor designed for a 14-day (336-hour) wear duration. The C14 incorporates a fourth-generation enzymatic electrochemical biosensor featuring Solstice's proprietary platinum-iridium electrode coating ("PtIr-4G" technology) and transmits glucose measurement data wirelessly via Bluetooth Low Energy (BLE) 5.2.
• Lumina R7 — a wearable reader/transmitter device in an arm-worn form factor. The R7 receives BLE data from the C14 sensor and provides real-time glucose value display, trend arrows, 8-hour trend graphs, and configurable hypo- and hyperglycemia alerts. The R7 also communicates with the Solstice Lumina™ mobile application (iOS and Android platforms) via BLE for extended data management and reporting functionality.
Based on our analysis, we recommend a traditional 510(k) premarket notification submission covering both the C14 and R7 as a system, filed under product code QKQ and regulation number 21 C.F.R. § 862.1355, consistent with the Class II classification for glucose test systems. We have identified the following predicate devices:
• Primary Predicate: NovaSense GlucoTrack NX-500 CGM System, 510(k) No. K211034, cleared June 18, 2022, manufactured by NovaSense Medical Technologies Inc., San Diego, California.
• Secondary Predicate (Reference Device): NovaSense GlucoTrack NX-700 CGM System, 510(k) No. K230489, cleared March 7, 2024, also manufactured by NovaSense Medical Technologies Inc.
Solstice Biomedical Inc. — a Delaware corporation (File No. 7834291) with principal offices at 220 Westbrook Drive, Suite 400, Cambridge, Massachusetts 02142 — will serve as the U.S. agent and intended 510(k) holder for the submission.
Overall Conclusion: The 510(k) pathway is viable, and the substantial equivalence argument against the identified predicates is well-supported. However, the initial Q1 2026 clearance target articulated by Solstice management is aggressive and, in our assessment, not achievable given the sequencing requirements of the Pre-Submission meeting, pivotal clinical study, and 510(k) submission and review process. We recommend a revised target of Q3 2026 for FDA clearance and Q4 2026 for U.S. commercial launch. This revised timeline reflects a realistic but disciplined execution plan and assumes no material delays arising from FDA feedback, clinical enrollment, or Additional Information (AI) requests during the 510(k) review.
We estimate total external regulatory costs from Pre-Submission through 510(k) clearance at approximately $6,127,417, as detailed in Section XII of this memorandum. This figure encompasses testing costs, clinical study costs, regulatory consulting fees, intellectual property analysis costs, FDA user fees, and C&H legal fees.
The Lumina CGM System has been commercially available in the European Union since September 2024, having obtained CE marking under the EU Medical Devices Regulation (EU MDR 2017/745). EU MDR Certificate No. MCA-2024-07319 was issued on September 12, 2024 by Meridian Conformity Assessment GmbH, Notified Body 0483. Notwithstanding this EU regulatory approval and commercial history, the Device has no existing FDA clearance or approval for any indication, and a complete 510(k) submission will be required for U.S. market entry.
The analysis and recommendations in this memorandum are based on the current state of applicable FDA regulations, guidance documents, and our professional assessment of FDA review practices as of the date of this memorandum. We will update our recommendations as appropriate following the Pre-Submission meeting with FDA and as additional information becomes available throughout the engagement.
II. Background
A. Client Overview
Solstice Biomedical Devices Ltd. Solstice Biomedical Devices Ltd. is a privately held Irish limited company incorporated under the laws of the Republic of Ireland (Companies Registration Office No. 648231), with its principal offices located at Unit 14, Liffey Innovation Park, Chapelizod, Dublin D20 FX72, Ireland. The Company's core competency lies in the design, development, and manufacture of electrochemical biosensors and wearable diagnostic devices. Since its founding, Solstice has established a reputation as an innovative developer of glucose monitoring technologies, progressing from its initial test strip reader platform through the current Lumina CGM System.
For the fiscal year ended December 31, 2024, Solstice reported consolidated global revenue of approximately €187.4 million, as reflected in audited financial statements prepared by Broadleaf Accounting Partners LLP. The Company employs approximately 820 individuals globally, including engineers, scientists, regulatory specialists, and commercial personnel distributed across its facilities in Ireland, the United States, and Germany.
The Company's senior leadership team includes:
• Dr. Eoin Gallagher, Chief Executive Officer
• Dr. Aisling Burke, Chief Technology Officer
• Dr. Niamh Tierney, Vice President of Regulatory Affairs
• Fiona Drennan, Quality Assurance Director
Solstice Biomedical Inc. Solstice Biomedical Inc. is a wholly owned U.S. subsidiary of Solstice Biomedical Devices Ltd., organized as a Delaware corporation (Delaware Secretary of State File No. 7834291), with its principal offices at 220 Westbrook Drive, Suite 400, Cambridge, Massachusetts 02142. SBI was established to manage U.S. commercial operations, regulatory affairs, and customer support. For fiscal year 2024, SBI recorded revenue of approximately $22.8 million, derived primarily from U.S. sales of the GlucoStrip RX-200 test strip reader and related consumable test strips. SBI currently employs approximately 95 individuals. The Vice President of U.S. Operations is Marcus Hale, who maintains overall responsibility for the U.S. subsidiary's operations and serves as a primary point of contact for this engagement.
Quality Management System. Solstice maintains ISO 13485:2016 certification for the design, development, and manufacture of in vitro diagnostic and continuous glucose monitoring devices, as certified by Meridian Conformity Assessment GmbH (Notified Body 0483). This certification covers the scope of activities relevant to the Lumina CGM System and provides a strong foundation for compliance with U.S. FDA Quality System Regulation requirements.
Previous FDA Interaction. Solstice has prior experience with the FDA premarket notification process. Specifically, the Company obtained 510(k) clearance for the GlucoStrip RX-200 Test Strip Reader, a stand-alone blood glucose test strip reader, under 510(k) No. K192847, which was cleared on November 14, 2019 under product code NBW, classified as a Class II device. While the GlucoStrip RX-200 is a fundamentally different device from the Lumina CGM System — employing photometric reflectance technology for discrete blood glucose measurement rather than continuous electrochemical sensing — the prior clearance demonstrates Solstice's established track record with FDA as a medical device manufacturer and its familiarity with the 510(k) submission process. The Lumina CGM System represents a significant technology evolution from the GlucoStrip platform and introduces substantially more complex regulatory considerations, including the involvement of an implantable component, continuous monitoring algorithms, wireless data transmission, and associated software and cybersecurity requirements.
B. Device Description
The Solstice Lumina™ CGM System is an integrated continuous glucose monitoring system consisting of two components that operate together to provide continuous, real-time glucose monitoring for persons with diabetes mellitus. The two components are described in detail below.
Lumina C14 — Subcutaneously Implantable CGM Sensor. The Lumina C14 is a disposable, single-use, subcutaneously implantable continuous glucose monitoring sensor designed for a maximum wear duration of 14 days (336 hours). The C14 employs a fourth-generation enzymatic electrochemical biosensor platform that utilizes the enzyme glucose oxidase immobilized on a proprietary platinum-iridium electrode coating, referred to commercially and internally as "PtIr-4G" technology. The PtIr-4G electrode coating has been engineered by Solstice to optimize sensitivity, selectivity, and signal stability over the 14-day wear period.
Key technical specifications of the Lumina C14 include:
• Measurement range: 40–400 mg/dL
• Warm-up time: ≤ 60 minutes from insertion to first reportable glucose value
• Sampling frequency: once every 60 seconds, with a reportable glucose value transmitted to the R7 reader every 5 minutes
• Wireless data transmission: Bluetooth Low Energy (BLE) 5.2 protocol
• Sterilization: Ethylene oxide (EO) sterilized; single-use, individually packaged
• Intended patient population: Persons aged 18 years and older diagnosed with Type 1 or Type 2 diabetes mellitus
• Insertion site: Posterior upper arm
• Firmware version: Lumina Firmware v3.4.2
The C14 sensor is applied subcutaneously by the user through a disposable applicator device (the Lumina C14 Applicator), which positions the sensor filament beneath the skin at the proper depth. The applicator is considered an accessory to the C14 sensor and will be included within the scope of the 510(k) submission.
Lumina R7 — Wearable Reader/Transmitter. The Lumina R7 is a reusable, arm-worn wearable device that serves as the primary reader and transmitter for the Lumina CGM System. The R7 is affixed to the posterior upper arm proximate to the C14 sensor and communicates with the sensor via BLE 5.2. The R7 performs the following functions:
• Receives raw sensor signal data from the C14 sensor via BLE
• Processes raw sensor data through the Solstice proprietary LuminaPredict Algorithm (v2.1) to generate calibrated glucose values
• Displays real-time glucose values on an integrated OLED display
• Displays glucose trend arrows (rate of change indicators) and 8-hour trend graphs
• Provides configurable hypo- and hyperglycemia alerts with an alert latency of ≤ 5 minutes from detection of an alert condition
• Communicates processed glucose data and alert information to the Solstice Lumina™ mobile application (iOS and Android platforms) via BLE for extended data management, reporting, and sharing with healthcare providers
• Reader operating system version: Lumina Reader OS v2.1.0
Software Components. The Lumina CGM System incorporates the following software components, all of which will require documentation and validation as part of the 510(k) submission:
• Lumina Firmware v3.4.2 — embedded firmware controlling the C14 sensor's electrochemical measurement and wireless transmission functions
• Lumina Reader OS v2.1.0 — operating system and user interface software for the R7 reader/transmitter
• LuminaPredict Algorithm v2.1 — proprietary glucose prediction and calibration algorithm that processes raw sensor signal data to generate reportable glucose values
• Lumina Mobile App v1.0.3 — companion mobile application (iOS and Android) providing extended data visualization, glucose reports, data sharing, and connectivity to the Solstice Cloud platform
C. Current Regulatory Status
European Union. The Lumina CGM System received CE marking under the European Union Medical Devices Regulation (EU MDR 2017/745). EU MDR Certificate No. MCA-2024-07319 was issued on September 12, 2024 by Meridian Conformity Assessment GmbH, Notified Body 0483, following a full conformity assessment under Annex IX of the EU MDR. The Device has been classified as a Class IIb medical device under the EU MDR classification rules. The Lumina CGM System has been commercially available in the European Union since September 2024, and Solstice reports initial commercial uptake consistent with its launch projections.
United States. The Lumina CGM System does not hold any existing FDA clearance, approval, or De Novo authorization. The only Solstice device with current FDA clearance is the GlucoStrip RX-200 Test Strip Reader (510(k) No. K192847, cleared November 14, 2019, product code NBW, Class II). A complete premarket notification submission to FDA will be required before the Lumina CGM System can be legally marketed in the United States.
Other Markets. Solstice has indicated that it is pursuing regulatory approvals in additional markets, including the United Kingdom (MHRA pathway), Canada (Health Canada pathway), and Australia (TGA pathway). This memorandum addresses only the U.S. FDA regulatory pathway; regulatory strategies for other jurisdictions are outside the scope of this engagement.
D. Engagement Scope
Calderwood & Harkness LLP was retained by Solstice Biomedical Devices Ltd. and Solstice Biomedical Inc. pursuant to an engagement letter dated April 15, 2025 (Engagement Reference No. 1037-00002). The scope of this engagement encompasses the following:
1. FDA Pre-Submission (Pre-Sub) Strategy and Meeting Request Preparation. C&H will prepare the Pre-Submission meeting request, including the meeting request cover letter, FDA Form 3514, and the complete Pre-Sub meeting package with questions for FDA, device description, proposed predicate device analysis, proposed clinical study protocol summary, and proposed testing plan.
2. 510(k) Submission Planning and Drafting. C&H will provide strategic counsel on the structure, content, and organization of the 510(k) submission, including review and revision of technical sections prepared by Solstice internal teams and external consultants.
3. Predicate Device Analysis and Substantial Equivalence Framework. C&H will analyze candidate predicate devices and develop the substantial equivalence argument, including identification and mitigation of differences between the Lumina CGM System and the selected predicates.
4. Clinical Study Regulatory Guidance. C&H will advise on the regulatory requirements for the pivotal clinical study (LUMINA-US), including IDE exemption analysis, study design considerations, and preparation of regulatory components of the study protocol.
5. Coordination with Pinnacle Regulatory Consulting Group LLC. Solstice has separately retained Pinnacle Regulatory Consulting Group LLC ("Pinnacle") as its primary regulatory consultancy for the 510(k) project. Pinnacle's engagement commenced on January 15, 2025. The key contacts at Pinnacle are Dr. Sandra Ellison, Managing Director, and Thomas Greenbaum, Senior Regulatory Specialist. C&H will coordinate with Pinnacle on technical and regulatory matters to ensure alignment between legal and regulatory consulting workstreams.
6. Interface with Other Advisors. As needed, C&H will coordinate with Crestline IP Advisory LLC ("Crestline"), Solstice's freedom-to-operate and patent counsel (key contact: Dr. Raymond Cho, Patent Attorney, 75 Federal Street, Suite 1800, Boston, MA 02110), and Hargrove & Endicott LLP ("Hargrove"), Solstice's Irish corporate and regulatory counsel (key contact: Ciara Brennan, Partner, 38 Fitzwilliam Square East, Dublin D02 NH85, Ireland), on intellectual property and international regulatory coordination matters, respectively.
This memorandum represents the initial comprehensive regulatory strategy assessment delivered under this engagement. Subsequent memoranda addressing specific topics — including iCGM special controls, IDE exemption analysis, software and cybersecurity gap analyses, labeling review, and post-clearance obligations — will be provided on a rolling basis as the project progresses.
III. Recommended Regulatory Pathway
A. 510(k) Premarket Notification — Rationale
The Lumina CGM System is a Class II medical device that falls within an established classification framework for continuous glucose monitoring systems. After careful analysis of the available regulatory pathways, C&H recommends that Solstice pursue a traditional 510(k) premarket notification under Section 510(k) of the Federal Food, Drug, and Cosmetic Act ("FD&C Act"), 21 U.S.C. § 360(k), and implementing regulations at 21 C.F.R. Part 807, Subpart E.
The rationale for this recommendation is as follows:
Availability of Cleared Predicates. The traditional 510(k) pathway is predicated on the submitter's ability to demonstrate that the subject device is substantially equivalent to one or more legally marketed predicate devices. As detailed in Section V below, we have identified two cleared predicate devices — the NovaSense GlucoTrack NX-500 (K211034) and the NovaSense GlucoTrack NX-700 (K230489) — that share the same product code (QKQ), the same intended use, and the same fundamental technology as the Lumina CGM System. The existence of these predicates makes the 510(k) pathway available and appropriate.
Class II Classification. The Lumina CGM System falls within an established Class II device classification. Class II devices are subject to general controls and special controls and are eligible for clearance through the 510(k) pathway. A Premarket Approval Application (PMA), which applies to Class III devices, is not required because the applicable product code and regulation number designate the device as Class II.
De Novo Classification Is Not Required. The De Novo classification pathway under Section 513(f)(2) of the FD&C Act is designed for novel, low-to-moderate-risk devices for which no legally marketed predicate exists. Because legally marketed predicates with the same product code and substantially similar intended use are available, the De Novo pathway is neither necessary nor appropriate for the Lumina CGM System. A De Novo submission would introduce unnecessary delay and regulatory uncertainty without corresponding benefit.
Consistency with Industry Practice. The traditional 510(k) pathway is the well-established route by which CGM systems of comparable design and intended use have entered the U.S. market. Both of the identified predicate devices — K211034 and K230489 — were themselves cleared through the 510(k) process. Filing a traditional 510(k) for the Lumina CGM System is consistent with this established precedent and will be familiar to the FDA review team within CDRH.
B. Single Submission Strategy for C14 and R7
We recommend that both the Lumina C14 implantable sensor and the Lumina R7 wearable reader/transmitter be submitted as components of a single integrated system within one 510(k) submission. This system-level approach is warranted because the C14 and R7 are designed to function together as an integrated unit: the C14 sensor generates raw glucose measurement data that is transmitted to, processed by, and displayed on the R7 reader, and the two devices share a unified intended use statement.
This approach mirrors the submission strategy employed by NovaSense Medical Technologies Inc. for both of the identified predicate devices. The NovaSense GlucoTrack NX-500 (K211034) was submitted and cleared as a system comprising the sensor and handheld reader/receiver as integrated components. Similarly, the NovaSense GlucoTrack NX-700 (K230489) was submitted as a system-level submission. Filing the Lumina CGM System as a single system submission is consistent with these precedents and with FDA's general approach to system-level submissions for CGM devices where the sensor and reader/transmitter function together as an integrated system.
The Solstice GlucoStrip RX-200 Test Strip Reader (510(k) No. K192847) is cited in this memorandum solely for the purposes of establishing Solstice's corporate pedigree and prior FDA interaction history. The GlucoStrip RX-200 is a blood glucose test strip reader (product code NBW) with a fundamentally different intended use and technology platform from the Lumina CGM System, and it is not being identified as a predicate device for purposes of the substantial equivalence determination.
C. iCGM Classification Considerations
In addition to pursuing the traditional 510(k) clearance described above, Solstice should evaluate whether the Lumina CGM System qualifies for classification as an integrated continuous glucose monitoring system (iCGM) under the De Novo classification order issued by FDA under classification reference DEN170088, and the associated special controls applicable to iCGM devices.
The iCGM classification was established by FDA to define a standardized set of performance requirements for CGM systems that, when met, would allow the device to be marketed for interoperability with compatible, digitally connected medical devices, including automated insulin dosing (AID) systems. Achieving iCGM classification would represent a significant commercial advantage for the Lumina CGM System, as it would enable Solstice to market the Device for integration with third-party AID systems without requiring a new 510(k) submission each time a new compatible device is introduced. The iCGM classification has become a key differentiator in the competitive CGM marketplace, and several of Solstice's commercial competitors have obtained or are pursuing this designation.
Preliminary review of the Lumina CGM System's performance data suggests that the Device may meet the performance criteria applicable to iCGM devices. Specifically:
• The MARD target of ≤ 9.0% established for the LUMINA-US clinical study is consistent with the iCGM performance criteria set forth in FDA's guidance document titled "Integrated Continuous Glucose Monitoring Systems" (September 2023), which specifies MARD targets and point accuracy requirements across multiple glucose concentration ranges.
• The consensus error grid target of ≥ 99% of paired data points falling within Zones A and B on the Clarke Error Grid Analysis is likewise consistent with iCGM requirements.
However, the iCGM special controls impose additional, granular performance criteria beyond overall MARD and error grid results, including accuracy requirements within specific glucose concentration ranges (e.g., < 70 mg/dL, 70–180 mg/dL, and > 180 mg/dL), as well as requirements related to data communication reliability and system-level cybersecurity. A full evaluation of the Lumina CGM System's compliance with these specific criteria will require detailed analysis of the clinical study data once available.
We recommend that the iCGM pathway be addressed as a specific question in the Pre-Submission meeting with FDA. Specifically, Solstice should seek FDA's feedback on whether the LUMINA-US clinical study protocol, as designed, would generate sufficient data to support an iCGM classification determination either concurrently with or subsequent to the initial 510(k) clearance. This feedback will be critical in determining whether Solstice should pursue iCGM classification as part of the initial submission or as a supplemental submission following clearance.
A separate detailed memorandum analyzing the Lumina CGM System's compliance with iCGM special controls will be provided by C&H following the completion of the Pre-Sub meeting and receipt of FDA feedback.
IV. Device Classification Analysis
A. Product Code and Regulation Number
Based on our analysis of the FDA product classification database, applicable regulation, and the classification of the identified predicate devices, we anticipate that the Lumina CGM System will be classified under the following:
• Product Code: QKQ — Electrode, Glucose, Subcutaneous
• Regulation Number: 21 C.F.R. § 862.1355 — Glucose test system
• Classification: Class II (Special Controls)
• Review Panel: Clinical Chemistry
Both the primary predicate (NovaSense GlucoTrack NX-500, K211034) and the secondary predicate (NovaSense GlucoTrack NX-700, K230489) are classified under product code QKQ and regulation number 21 C.F.R. § 862.1355. The Lumina CGM System shares the same fundamental intended use and technology as these predicate devices, and we expect it to fall within the same product classification.
It is important to note that FDA issued a reclassification order effective March 2024 that updated the classification framework for continuous glucose monitoring systems. This reclassification order refined the special controls applicable to CGM devices classified under product code QKQ and aligned the classification framework with the iCGM special controls established under DEN170088. The Lumina CGM System falls within the scope of this updated classification framework, and the applicable special controls referenced in Section IV.B below reflect the post-reclassification requirements.
B. Class II Special Controls
As a Class II device with special controls, the Lumina CGM System must satisfy both general controls under Section 510(a)–(h) of the FD&C Act and the applicable special controls identified for product code QKQ devices. The applicable special controls encompass the following categories:
1. Clinical Performance Requirements. The device must demonstrate clinical accuracy through a well-designed clinical study. Performance metrics include MARD, point accuracy across clinically relevant glucose concentration ranges, and consensus error grid analysis. The specific performance criteria are set forth in applicable FDA guidance documents and in the special controls order, and the LUMINA-US clinical study (described in Section VI) has been designed to generate the data necessary to satisfy these requirements.
2. Analytical Performance Requirements. The device must demonstrate analytical performance through bench testing, including accuracy, linearity across the measurement range (40–400 mg/dL), precision (within-sensor and between-sensor), and response to interfering substances. Interference testing must evaluate the effects of common exogenous and endogenous substances (e.g., acetaminophen, ascorbic acid, uric acid, maltose) on sensor accuracy.
3. Biocompatibility. Materials in direct or indirect contact with the body must be evaluated for biocompatibility in accordance with ISO 10993-1:2018 and applicable parts of the ISO 10993 series, as appropriate for the nature and duration of body contact. The C14 sensor, as a subcutaneously implanted device with limited (14-day) contact duration, requires a comprehensive biocompatibility testing program, as detailed in Section VII.A.
4. Software Validation. Software contained in or associated with the device must be validated in accordance with FDA guidance and applicable standards, including IEC 62304:2006/A1:2015. The software level of concern and corresponding documentation requirements are addressed in Section VIII.
5. Electromagnetic Compatibility (EMC). The device must be tested for electromagnetic compatibility to demonstrate that it does not emit electromagnetic interference at levels that could adversely affect other devices, and that it is immune to electromagnetic interference from external sources, in accordance with IEC 60601-1-2.
6. Sterility. The C14 sensor, as a sterile implantable device, must demonstrate sterility assurance consistent with applicable standards (e.g., ISO 11135 for EO sterilization). Sterility validation data must be included in the 510(k) submission.
7. Labeling. Device labeling must comply with 21 C.F.R. Part 801 and must include all information required by the special controls, including instructions for use, user warnings and precautions, sensor insertion instructions, reader operation instructions, alert configuration instructions, and information regarding device limitations and potential interfering substances.
8. Cybersecurity. As a wirelessly connected medical device, the Lumina CGM System must satisfy FDA's cybersecurity expectations as set forth in applicable guidance, including threat modeling, cybersecurity risk assessment, and provision of a Software Bill of Materials (SBOM). These requirements are addressed in Section VIII.B.
C. Product Code Confirmation Strategy
While we have high confidence in the anticipated QKQ product code classification based on the predicate device analysis and our review of the FDA classification database, we recommend that the product code assignment be formally confirmed with FDA during the Pre-Submission meeting. The Pre-Sub meeting will be requested with FDA CDRH, Office of Health Technology 2 (OHT2), Division of Chemistry and Toxicology Devices, which is the division responsible for review of CGM devices classified under product code QKQ.
Confirmation of the product code during the Pre-Sub meeting will also verify the appropriate review division within CDRH, ensuring that the 510(k) submission is routed to the correct review team upon filing. Misrouting of a 510(k) submission to an incorrect review division can result in significant delays, and early confirmation through the Pre-Sub process mitigates this risk.
V. Predicate Device Selection and Substantial Equivalence Framework
The selection of appropriate predicate devices is foundational to the success of a 510(k) submission. Under 21 C.F.R. § 807.100(b), a device is substantially equivalent to a predicate device if it has the same intended use and the same technological characteristics as the predicate, or, if it has the same intended use but different technological characteristics, the information submitted to FDA demonstrates that the device is as safe and effective as the predicate device, and does not raise different questions of safety and effectiveness than the predicate device. Our predicate device selection and substantial equivalence analysis are set forth below.
A. Primary Predicate Device
We have selected the NovaSense GlucoTrack NX-500 CGM System as the primary predicate device for the Solstice Lumina™ CGM System.
The NovaSense GlucoTrack NX-500 is a continuous glucose monitoring system comprising a subcutaneously implantable enzymatic electrochemical CGM sensor with a 10-day sensor wear duration and a handheld reader/receiver that communicates with the sensor via BLE. The sensor employs a platinum electrode for electrochemical glucose detection.
Basis for Selection as Primary Predicate. The NX-500 was selected as the primary predicate because it shares the same product code (QKQ), the same intended use (continuous glucose monitoring in persons with diabetes mellitus), and the same fundamental technology (enzymatic electrochemical sensing with wireless data transmission to an external reader) as the Lumina CGM System. The NX-500 is the most directly comparable cleared device and provides the strongest available foundation for a substantial equivalence argument. Additionally, the NX-500's clearance history and the publicly available 510(k) summary provide a well-established substantial equivalence precedent upon which the Lumina submission can build.
B. Secondary Predicate (Reference Device)
We have selected the NovaSense GlucoTrack NX-700 CGM System as the secondary predicate device (reference device).
The NovaSense GlucoTrack NX-700 is a next-generation iteration of the NX-500, featuring a 14-day sensor wear duration, enhanced BLE 5.0 data transmission, and an updated glucose prediction algorithm. The NX-700 was itself found substantially equivalent to the NX-500 (K211034).
Basis for Selection as Secondary Predicate. The NX-700 is cited as a secondary predicate (reference device) to support the argument that several of the Lumina CGM System's features that differ from the primary predicate — most notably the 14-day sensor wear duration — have already been evaluated and found substantially equivalent by FDA in a cleared device sharing the same product code and intended use. The use of a secondary predicate to address specific feature differences is a well-recognized and accepted practice in 510(k) submissions, and FDA guidance permits the use of multiple predicates to support a substantial equivalence determination.
C. Additional Reference Device
Solstice GlucoStrip RX-200 Test Strip Reader
The GlucoStrip RX-200 is cited in this memorandum solely for the purpose of establishing Solstice's corporate pedigree and prior FDA interaction history. It is not identified as a predicate device for purposes of the substantial equivalence determination. The GlucoStrip RX-200 is a photometric reflectance-based blood glucose test strip reader (product code NBW) with a fundamentally different intended use and technology platform from the Lumina CGM System. However, its prior clearance demonstrates that Solstice has an established relationship with FDA as a medical device manufacturer, has successfully navigated the 510(k) process, and maintains a quality management system that has been found acceptable by FDA.
D. Key Differences from Primary Predicate (K211034) and Substantial Equivalence Arguments
A thorough comparison of the Lumina CGM System to the primary predicate device (NovaSense GlucoTrack NX-500, K211034) reveals five key differences. For each difference, we have identified a mitigation strategy that, in our assessment, adequately addresses any potential question of safety or effectiveness that the difference might raise.
1. Sensor Wear Duration
The Lumina C14 sensor is designed for a 14-day (336-hour) sensor wear duration, compared to the 10-day sensor wear duration of the NX-500 primary predicate.
Mitigation: The secondary predicate, NovaSense GlucoTrack NX-700 (K230489), was cleared by FDA on March 7, 2024 with a 14-day sensor wear duration. This clearance establishes that a 14-day wear duration has been evaluated and accepted by FDA for an enzymatic electrochemical CGM sensor with the same product code and intended use. The difference in wear duration between the Lumina C14 and the NX-500 primary predicate does not raise new questions of safety or effectiveness, as the 14-day duration is already represented in the cleared predicate landscape. Solstice will further support this difference with biocompatibility testing conducted for the full 14-day contact duration, including subchronic toxicity and implantation testing per ISO 10993-6 and ISO 10993-11, as well as sensor accuracy and signal stability data demonstrating consistent performance throughout the 14-day wear period.
2. Electrode Material
The Lumina C14 sensor employs Solstice's proprietary platinum-iridium electrode coating (PtIr-4G technology), whereas the NX-500 primary predicate utilizes a platinum electrode.
Mitigation: The PtIr-4G coating architecture achieves the same functional purpose as the platinum electrode in the NX-500 — namely, electrochemical sensing of glucose through catalytic oxidation at the electrode surface. The addition of iridium to the platinum electrode is an established practice in electrochemical sensor design that serves to enhance mechanical durability, signal stability, and resistance to biofouling over extended wear durations. The fundamental electrochemical sensing mechanism is identical. A full biocompatibility testing program compliant with ISO 10993-1:2018 will demonstrate the safety of the PtIr-4G material for subcutaneous implantation at the 14-day contact duration, and performance testing (including the pivotal clinical study) will demonstrate equivalent or superior analytical accuracy compared to the predicate device. The electrode material difference does not alter the fundamental technology or raise a different type of safety or effectiveness question.
3. BLE Version
The Lumina CGM System utilizes Bluetooth Low Energy (BLE) 5.2 for wireless data communication between the C14 sensor and R7 reader, and between the R7 reader and the Lumina mobile application. The NX-500 primary predicate utilizes BLE 5.0.
Mitigation: BLE 5.2 is a backward-compatible, incremental upgrade from BLE 5.0 within the Bluetooth specification maintained by the Bluetooth Special Interest Group (SIG). The transition from BLE 5.0 to BLE 5.2 does not introduce a fundamentally different wireless technology; rather, it provides enhancements in data throughput, connection stability, and power efficiency while maintaining full protocol-level compatibility. This difference does not raise new questions of safety or effectiveness. The Lumina CGM System's wireless performance will be validated through electromagnetic compatibility testing (per IEC 60601-1-2), wireless coexistence testing, and clinical study data demonstrating reliable data transmission under real-world conditions. We note that the secondary predicate (NX-700, K230489) was itself cleared with BLE 5.0, and the incremental upgrade to BLE 5.2 does not alter the wireless communication paradigm.
4. Reader Form Factor
The Lumina R7 reader/transmitter is an arm-worn wearable device, whereas the NX-500 primary predicate includes a handheld receiver.
Mitigation: The difference in reader form factor between the Lumina R7 (arm-worn) and the NX-500 receiver (handheld) is primarily an ergonomic and industrial design difference. The functional purpose of the reader — receiving sensor data via BLE, processing the data through a glucose prediction algorithm, displaying real-time glucose values and trend information, and providing configurable alerts — is identical between the Lumina R7 and the NX-500 receiver. The arm-worn form factor does not alter the intended use, the fundamental technology, or the clinical performance of the CGM system. Biocompatibility testing of the R7's external skin-contact materials (per ISO 10993 for limited skin contact duration) will address any safety considerations related to the wearable form factor. The arm-worn design may in fact offer a safety advantage over a handheld receiver by reducing the risk of missed alerts when the user is not actively carrying the handheld device.
5. Algorithm
The Lumina CGM System employs Solstice's proprietary LuminaPredict Algorithm v2.1 for converting raw sensor signal data into calibrated glucose values. The NX-500 primary predicate uses NovaSense's proprietary algorithm.
Mitigation: Differences in the glucose prediction algorithm between the Lumina CGM System and the NX-500 predicate are expected, as each manufacturer develops its own proprietary signal processing and calibration algorithms. Algorithm differences are inherent in every 510(k) submission for a CGM system against a predicate manufactured by a different company. FDA's established approach to evaluating algorithm differences in the CGM context is to assess the clinical performance outcome — specifically, the MARD and consensus error grid results — rather than to require algorithmic equivalence at the code level. The LUMINA-US pivotal clinical study has been designed to demonstrate that the LuminaPredict Algorithm v2.1 produces MARD and error grid results that are equivalent to or superior to the performance demonstrated by the NX-500 predicate. Full software documentation of the algorithm will be provided in accordance with IEC 62304:2006/A1:2015 and FDA guidance documents on software validation, including hazard analysis, verification and validation testing, and traceability matrices.
Overall Substantial Equivalence Assessment. Based on our analysis, none of the five identified differences between the Lumina CGM System and the NX-500 primary predicate, either individually or in combination, raise new questions of safety or effectiveness that cannot be adequately addressed through the proposed non-clinical testing program, clinical study, and software documentation. Each difference is either (a) already represented in the cleared predicate landscape (e.g., 14-day wear duration in K230489), (b) an incremental enhancement to an established technology (e.g., BLE 5.2 vs. BLE 5.0), or (c) addressable through standard testing and clinical data (e.g., electrode material biocompatibility, algorithm performance). The substantial equivalence argument is well-supported and is consistent with the analytical framework that FDA applies to CGM device submissions.
VI. Clinical Data Requirements
A. Clinical Study Overview
Solstice has designed a pivotal clinical study, designated Solstice Protocol SBD-LUM-CL-001 ("LUMINA-US"), to generate the clinical performance data required to support the 510(k) substantial equivalence determination. The LUMINA-US study has been designed in consultation with Pinnacle Regulatory Consulting Group LLC and is intended to be consistent with FDA's current expectations for CGM clinical studies as set forth in applicable guidance documents.
The key parameters of the LUMINA-US study are as follows:
The study will enroll adult subjects (aged 18 years and older) diagnosed with either Type 1 or Type 2 diabetes mellitus. Each subject will wear the Lumina C14 sensor for the full 14-day wear duration while glucose values from the Lumina CGM System are compared against reference measurements obtained from a laboratory-grade blood glucose analyzer (YSI 2300 STAT Plus or equivalent). The study will include both in-clinic measurement sessions (with frequent paired blood glucose draws) and ambulatory wear periods to assess system performance under real-world conditions.
The six U.S. clinical sites will be geographically distributed across the United States to ensure demographic diversity in the study population. Final site selection is in progress and will be coordinated between Solstice, Veltrano CRO, and the C&H team.
B. Primary and Secondary Endpoints
Primary Endpoint. The primary efficacy endpoint of the LUMINA-US study is the Mean Absolute Relative Difference (MARD) between the Lumina CGM System's glucose readings and paired reference blood glucose measurements. The target MARD is ≤ 9.0% overall, which is consistent with FDA's current expectations for iCGM classification as set forth in FDA guidance "Integrated Continuous Glucose Monitoring Systems" (September 2023). Achieving this MARD target will serve the dual purpose of supporting the 510(k) substantial equivalence determination and positioning the Device for potential iCGM classification (as discussed in Section III.C above).
Secondary Endpoints. The following secondary endpoints will be evaluated:
• Consensus Error Grid Analysis: A target of ≥ 99% of paired data points falling within Zones A and B of the Clarke Error Grid Analysis, demonstrating clinically acceptable accuracy across the measurement range.
• Safety Assessment: Comprehensive evaluation of adverse event rates, including device-related adverse events (e.g., sensor insertion site reactions, skin irritation, infection), serious adverse events, and unanticipated adverse device effects.
• User Labeling Comprehension: Assessment of user comprehension of the device labeling, including sensor insertion instructions, reader operation instructions, and alert interpretation, through a structured labeling comprehension study component.
C. Study Duration and Key Milestones
The estimated total study duration is approximately six months, structured as follows:
• Enrollment Period: Approximately 14 weeks (to enroll 350 subjects across 6 sites)
• Sensor Wear Period: 14 days per subject (subjects enrolled on a rolling basis)
• Data Analysis and Clinical Study Report Preparation: Approximately 8 weeks following completion of the last subject's sensor wear period
Key study milestones are as follows:
These milestones are subject to adjustment based on Pre-Sub feedback from FDA, IRB review timelines, and clinical site activation schedules. The study start date of September 15, 2025 is contingent upon successful completion of the Pre-Sub meeting and receipt of IRB approval.
D. Clinical Study Budget
The estimated budget for the LUMINA-US clinical study is $4,200,000, based on an enrollment of 350 subjects at an estimated cost of $12,000 per subject. This per-subject cost encompasses site fees, investigator fees, clinical monitoring, laboratory reference testing, data management, statistical analysis, and clinical study report preparation. The budget estimate was developed in consultation with Veltrano CRO based on preliminary study parameters; the final budget will be established through negotiation of the Veltrano CRO master services agreement.
The clinical study budget is the single largest cost component of the external regulatory costs for the 510(k) project, representing approximately 68.5% of the total estimated external regulatory costs.
E. IDE Exemption Analysis
Solstice anticipates that the LUMINA-US clinical study will qualify for an exemption from the Investigational Device Exemption (IDE) requirements under 21 C.F.R. § 812.2(c)(3). This regulation exempts investigations of certain diagnostic devices from the IDE requirements, provided the device is used in compliance with the labeling requirements of 21 C.F.R. § 809.10(c) and the investigation does not involve an unreasonable risk to the subject.
Additionally, even if the diagnostic device exemption is not conclusively applicable, the LUMINA-US study may qualify as a non-significant risk (NSR) investigation under 21 C.F.R. § 812.2(b), which would require IRB approval as the sole regulatory authorization for the study (i.e., an abbreviated IDE with no requirement to submit an IDE application to FDA).
The characterization of the study as NSR is supported by the following factors: (a) the Lumina C14 sensor is a short-term (14-day) subcutaneous implant using well-characterized materials and technology; (b) the device does not replace or serve as the primary basis for patient treatment decisions during the study period (subjects will continue their existing diabetes management regimen); and (c) the study does not pose a significant risk of illness, injury, or harm beyond the risks inherent in routine glucose monitoring.
We recommend that the NSR determination be confirmed with FDA during the Pre-Sub meeting. If FDA concurs with the NSR determination, the study may proceed under IRB approval without the need for a separate IDE application, which would simplify and accelerate the regulatory pathway. A separate detailed memorandum on IDE exemption applicability and NSR determination will follow.
VII. Non-Clinical Testing Requirements
A. Biocompatibility Testing
Biocompatibility testing of the Lumina CGM System is a critical component of the 510(k) submission and will be conducted in accordance with the requirements of ISO 10993-1:2018, "Biological evaluation of medical devices — Part 1: Evaluation and review within a risk management process."
The biocompatibility testing program is tailored to the nature and duration of body contact for each component of the Lumina CGM System. The C14 sensor, as a subcutaneously implanted device with a 14-day (limited, per ISO 10993-1) contact duration, requires a comprehensive biocompatibility evaluation. The R7 reader, as an externally worn device with skin surface contact, requires a more limited biocompatibility evaluation.
Lumina C14 Sensor — Testing Scope. The following biocompatibility tests are planned for the C14 sensor and its patient-contacting materials:
• Cytotoxicity (ISO 10993-5)
• Sensitization (ISO 10993-10)
• Irritation (ISO 10993-23)
• Acute Systemic Toxicity (ISO 10993-11)
• Subchronic Toxicity (ISO 10993-11) — required for limited (> 24 hours to 30 days) implant contact duration
• Implantation (ISO 10993-6) — required for subcutaneous implantation
• Hemocompatibility (ISO 10993-4) — evaluated due to potential contact with blood and tissue fluids at the subcutaneous implantation site
• Genotoxicity (ISO 10993-3)
Lumina R7 Reader — Testing Scope. The following biocompatibility tests are planned for the R7 reader's skin-contacting materials:
• Cytotoxicity (ISO 10993-5)
• Sensitization (ISO 10993-10)
• Irritation (ISO 10993-23)
Testing Laboratory. Biocompatibility testing is being conducted by Whitmore Laboratories Inc., 1625 Shady Grove Road, Suite 300, Gaithersburg, Maryland 20878. Whitmore Laboratories holds A2LA (American Association for Laboratory Accreditation) Certificate No. 3847.01 and is an established provider of biocompatibility testing services for medical devices. The key contact at Whitmore for this engagement is Dr. James Haverford, Director of Biocompatibility Testing. Testing commenced on or about March 3, 2025.
Cost and Timeline. The estimated cost for the complete biocompatibility testing program is $485,000, per the Whitmore Laboratories quote dated March 3, 2025. The target completion date for all biocompatibility testing is August 31, 2025. Timely completion of biocompatibility testing is critical to the overall project timeline, as the results must be available for inclusion in the 510(k) submission.