Dear Niamh,
I hope you had a good weekend. I wanted to follow up with a comprehensive overview of the critical path for our Pre-Submission (Q-Sub) meeting request and meeting package for the Solstice Lumina™ CGM System — encompassing both the Lumina C14 implantable sensor and the Lumina R7 wearable reader/transmitter. Since opening the engagement on April 22 (Engagement Ref. No. 1037-00002) and receiving the retainer on April 28, our team has been making good progress on the overall regulatory strategy. As you know, we have been finalizing both the Regulatory Strategy Memorandum and the Predicate Device Comparison Table, which will form the analytical backbone of our Pre-Sub package. This email is intended to lay out the full timeline, identify the deliverables we need from each member of the working group, flag open items requiring your input, and propose next steps.
This is a long email — by design. I want to make sure everyone copied here has a single reference document for the weeks ahead.
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**I. TIMELINE OVERVIEW — KEY DATES**
The following milestones define our critical path:
1. **June 2, 2025 — Pre-Sub Meeting Request Submitted to FDA CDRH.** We will submit the cover letter and FDA Form 3514, directed to the Office of Health Technology 2 (OHT2), Division of Chemistry and Toxicology Devices.
2. **June 16, 2025 — Pre-Sub Meeting Package Submitted to FDA.** Per CDRH's Q-Sub guidance, the meeting package must be submitted at least 60 calendar days before the target meeting date. June 16 is 60 days before August 14, accounting for the standard CDRH scheduling window.
3. **August 14, 2025 — Pre-Sub Meeting with FDA (CDRH, OHT2).** Our preferred format will be teleconference, which we will specify in the request.
A few framing notes on this timeline. The June 2 meeting request submission is approximately four weeks away, so we need to finalize the meeting request letter and Form 3514 promptly. While that initial submission is relatively streamlined, the meeting package itself (due June 16) requires significantly more substantive content — device descriptions, proposed testing plans, the clinical study synopsis, our predicate analysis, and the draft questions for FDA. That means we need to mobilize parallel workstreams now to ensure we hit the June 16 date without compromising the quality of the package.
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**II. DELIVERABLES NEEDED FROM SOLSTICE**
The following items are needed from the Solstice team to complete the Pre-Sub package. I have tried to be as specific as possible regarding content, responsible parties, and deadlines.
**1. Device Description Materials**
We need finalized technical specifications for both devices to anchor the device description section of the Pre-Sub package:
- *Lumina C14 Sensor:* Fourth-generation enzymatic electrochemical biosensor; PtIr-4G platinum-iridium electrode coating; 14-day wear duration; BLE 5.2 data transmission; measurement range 40–400 mg/dL; warm-up time ≤ 60 minutes. - *Lumina R7 Reader/Transmitter:* Arm-worn form factor; real-time glucose display; trend arrows; 8-hour trend graphs; configurable hypo/hyperglycemia alerts; alert latency ≤ 5 minutes.
I would ask that Dr. Aisling Burke provide updated engineering drawings and device schematics **by May 16, 2025**. These do not need to be production-quality illustrations for the Pre-Sub — clear, accurate technical drawings will suffice — but they should reflect the current design configuration.
Additionally, please confirm that the following software versions are still current and will be the versions referenced in the Pre-Sub:
- Lumina Firmware v3.4.2 (C14) - Lumina Reader OS v2.1.0 (R7) - LuminaPredict Algorithm v2.1 - Lumina Mobile App v1.0.3
If any of these have been updated or are expected to be updated before June 16, please let us know immediately, as this will affect the documentation.
**2. EU Regulatory Documentation**
For the executive summary and corporate regulatory history sections, we will need:
- A copy of the EU MDR CE certificate issued by Meridian Conformity Assessment GmbH (NB 0483), Certificate No. MCA-2024-07319, dated September 12, 2024. - A summary of EU clinical data and post-market performance since the September 2024 EU commercial launch. Even a high-level summary will be valuable as background context for FDA. - The current ISO 13485:2016 certificate (certified by Meridian).
If you can get these to us **by May 16, 2025**, that would be ideal.
**3. Clinical Study Protocol Draft**
We need a draft synopsis of Protocol SBD-LUM-CL-001 ("LUMINA-US") — the prospective, single-arm, multicenter study. Key parameters for the Pre-Sub package:
- Enrollment: 350 subjects (175 Type 1 diabetes + 175 Type 2 diabetes) at 6 U.S. clinical sites. - Key endpoints: sensor accuracy (MARD target ≤ 9.0%), safety profile, and user labeling comprehension. - Estimated study duration: approximately 6 months total (14 weeks enrollment + 14-day sensor wear + 8 weeks data analysis), with planned start September 15, 2025.
One important issue we intend to raise with FDA in the Pre-Sub is the IDE exemption question under 21 C.F.R. § 812.2(c)(3) for non-significant risk (NSR) diagnostic devices. Our team is preparing the legal analysis, but we will need Solstice to confirm the non-significant risk determination rationale — I would suggest looping in Fiona Drennan (QA Director) on this. **Please provide the draft protocol synopsis and NSR rationale by May 23, 2025.**
Also, please confirm that Veltrano Clinical Research Organization Inc. (Dr. Lisa Fontaine, VP of Clinical Operations) remains the selected CRO, and that Clearwater Institutional Review Board LLC (IRB Registration No. IRB-2019-04821) remains the designated IRB.
**4. Biocompatibility Testing Status**
We need a current status update from Whitmore Laboratories Inc. on the ISO 10993 testing program:
- *C14 sensor:* cytotoxicity, sensitization, irritation, acute systemic toxicity, subchronic toxicity, implantation, hemocompatibility, and genotoxicity. - *R7 reader:* cytotoxicity, sensitization, and irritation.
As I understand it, the testing engagement started March 3, 2025, with a target completion of August 31, 2025. We need to confirm the program is on track and whether any preliminary results are available for reference in the proposed testing plan section of the Pre-Sub package. **Please provide a status update by May 19, 2025.**
**5. Software and Cybersecurity Documentation**
We will need the following from Solstice's software engineering team:
- Software architecture documentation - Software Bill of Materials (SBOM) - Threat modeling report (STRIDE framework)
Sean Morrissey on our team is preparing a software documentation gap analysis and cybersecurity checklist and will need input from your software engineering leads. We should also confirm the software level of concern designation as Major (per FDA guidance and IEC 62304:2006/A1:2015). **Please provide available documentation by May 23, 2025**, and let us know who from the engineering team should be Sean's primary point of contact.
**6. Prior FDA Interaction History**
Finally, if Solstice has retained any correspondence from the prior 510(k) clearance of the GlucoStrip RX-200 (K192847, cleared November 14, 2019), that material may be relevant for establishing Solstice's regulatory track record with CDRH. Please share any available files at your convenience, ideally **by May 16, 2025**.
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**III. DELIVERABLES NEEDED FROM PINNACLE REGULATORY**
Dr. Ellison and Thomas — thank you for your continued excellent work since your engagement started on January 15. As you know, Pinnacle has been preparing technical summaries, performance testing protocols, and biocompatibility assessments that will feed directly into the Pre-Sub package. Specific deliverables we need:
1. **Performance Testing Plan** — Draft proposed bench testing protocol (sensor accuracy, linearity, precision, interference testing) for inclusion in the Pre-Sub package. **Target draft to C&H by May 23, 2025.**
2. **Biocompatibility Rationale** — Written rationale for the ISO 10993 testing scope, mapped to the current FDA biocompatibility guidance, including the risk assessment for the PtIr-4G electrode coating material. **Target draft by May 23, 2025.**
3. **Technical Summary of Device** — Pinnacle's technical summary of the Lumina C14 and R7 for incorporation into the device description section of the Pre-Sub. **Target draft by May 19, 2025.**
As a reminder to all parties, C&H's coordination letter to Pinnacle — outlining roles, responsibilities, and work product sharing protocols — was sent separately. Privilege considerations apply to our communications. Please ensure that all substantive regulatory strategy discussions are routed through or copied to C&H.
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**IV. CALDERWOOD & HARKNESS INTERNAL WORKSTREAMS**
For your awareness, Niamh, here is a summary of what we are handling internally so you have visibility into the full scope of activity:
- **Pre-Sub Meeting Request Cover Letter and FDA Form 3514:** Amy Whitfield is drafting; target completion by May 19, 2025, for your review.
- **Pre-Sub Executive Summary:** Amy and I are co-drafting this, which will provide the framing narrative for the entire package.
- **Predicate Comparison and Substantial Equivalence Discussion:** Building on the Predicate Device Comparison Table, we are analyzing the five key differences between the Lumina system and the primary predicate, the NovaSense GlucoTrack NX-500 (K211034): (1) sensor wear duration of 14 days vs. 10 days; (2) electrode material PtIr-4G vs. standard Pt; (3) BLE 5.2 vs. BLE 5.0; (4) arm-worn reader vs. handheld reader; and (5) proprietary LuminaPredict v2.1 algorithm vs. NovaSense's algorithm. We will also reference the secondary predicate, the NovaSense GlucoTrack NX-700 (K230489, cleared March 7, 2024), which supports the 14-day wear duration claim.
- **Questions for FDA:** Sean Morrissey is preparing the draft list, organized by topic: predicate acceptance, clinical study design, IDE exemption, software documentation, cybersecurity, biocompatibility scope, and iCGM classification pathway. Target internal draft by May 16 for my review, with a version circulated to the working group shortly thereafter.
- **Internal Strategy Memo on Anticipated FDA Feedback:** Amy and Sean are preparing an analysis of likely FDA positions and contingency strategies. This document will be maintained as attorney work product / privileged.
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**V. OPEN ITEMS REQUIRING SOLSTICE INPUT**
There are several strategic questions that need your input, Niamh. I'd like to discuss these on our upcoming call (see Section VI below), but it would be helpful if you could begin thinking through them now:
**1. iCGM Classification.** Does Solstice intend to pursue integrated CGM (iCGM) classification, per the De Novo classification order DEN170088? This decision has significant implications for special controls, interoperability labeling, and the questions we pose to FDA. I will note that your MARD target of ≤ 9.0% and the consensus error grid requirement of ≥ 99% in Zones A+B are consistent with iCGM expectations, which suggests this pathway is viable. We have prepared a separate iCGM Special Controls Analysis Memorandum, which is available for your review — I can send it over as soon as you'd like.
**2. FTO / IP Considerations.** As you are aware, Crestline IP Advisory LLC (Dr. Raymond Cho) delivered its preliminary FTO assessment on April 10, 2025, identifying low-to-moderate risk with respect to NovaSense U.S. Patent No. 10,847,221 (enzyme coating). Full claim chart analysis is ongoing, and we have prepared an FTO/IP Risk Assessment Summary. While the Pre-Sub package itself will not address IP matters, I want to flag that any changes to the PtIr-4G electrode design arising from design-around efforts could affect the device description in the Pre-Sub. Has Dr. Burke's engineering team finalized the alternative electrode deposition process that was identified as of April 22, 2025? We need to know whether the device description will change before we finalize the package.
**3. Product Code Confirmation.** We anticipate product code QKQ (Electrode, Glucose, Subcutaneous) under 21 C.F.R. § 862.1355. One of our Pre-Sub questions will seek FDA's confirmation. Has Pinnacle's independent assessment reached the same conclusion? Dr. Ellison, Thomas — please confirm when convenient.
**4. Intended Use Population.** The current intended use is limited to persons aged 18 and older with Type 1 or Type 2 diabetes mellitus. Please confirm there are no plans to expand to pediatric indications for this submission. A pediatric expansion would significantly change both the clinical study design and the regulatory pathway, and we would need to account for that well in advance of the Pre-Sub.
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**VI. NEXT STEPS AND PROPOSED CALL**
I would like to propose a working group call for the **week of May 12, 2025** — ideally Tuesday, May 13 or Wednesday, May 14 — to walk through the deliverables schedule in detail and address the open questions outlined above. Participants should include:
- C&H: Miriam Calloway, Amy Whitfield, Sean Morrissey - Solstice: Dr. Niamh Tierney, Marcus Hale - Pinnacle: Dr. Sandra Ellison, Thomas Greenbaum
Niamh, if you would like Dr. Burke and Fiona Drennan to join for the technical and QA portions of the discussion, please feel free to circulate the call invitation to them. Their input would be welcome.
I also want to confirm that Marcus (cc'd) is aligned on the revised regulatory timeline. As discussed in our separate communication, we are now targeting 510(k) clearance in Q3 2026 (revised from the original Q1 2026 aspiration), with U.S. commercial launch in Q4 2026. The Pre-Sub meeting outcome will be a key gating event for confirming that timeline.
On the budget front, I want to flag that the overall estimated external regulatory costs of approximately $6.1 million are driven in large part by the clinical study budget — $4.2 million for 350 subjects at approximately $12,000 per subject. The Pre-Sub meeting outcome may affect the clinical study scope (e.g., sample size, number of sites, endpoint requirements), and therefore the overall budget. This is another reason why the Pre-Sub meeting is so strategically important.
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**VII. CLOSING**
Niamh, I want to express my confidence in the strength of the substantial equivalence argument and the overall regulatory strategy the team has developed. The Lumina system is a well-designed product with meaningful clinical data from the EU market, a sound predicate basis, and a strong technical team behind it. That said, the Pre-Sub meeting will be critical for validating our approach, testing FDA's receptivity to our predicate selection and clinical study design, and ultimately de-risking the 510(k) submission timeline. Getting the meeting package right is our top priority over the next six weeks.
Please don't hesitate to reach out with any questions in the interim. I am available by phone or email, and Amy and Sean are similarly available to the Solstice and Pinnacle teams as needed.
I look forward to connecting soon.
Warm regards,
Miriam Calloway Partner, Healthcare & Life Sciences Calderwood & Harkness LLP 1401 K Street NW, Suite 900 Washington, D.C. 20005 Tel: (202) 555-0184 Email: mcalloway@calderwoodharkness.com
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