WARNING LETTER
ExThera Medical Corporation
MARCS-CMS 715068 —
February 06, 2026
Product:
Medical Devices
Recipient:
Recipient Name
Erin R. Borger
Recipient Title
Chief Executive Officer (CEO)
ExThera Medical Corporation
757 Arnold Drive, Suite B
Martinez
,
CA
94553
United States
(b)(4)@extheramedical.com
Issuing Office:
Center for Devices and Radiological Health
United States
WARNING LETTER
February 06, 2026
Dear Mr. Borger:
This Warning Letter is to inform you of objectionable conditions observed during the Food and Drug Administration (FDA) inspection conducted at ExThera Medical Corporation (ExThera) from May 27, 2025, to June 4, 2025, by an investigator from the FDA’s Office of Bioresearch Monitoring Inspectorate (OBMI). This inspection was conducted to determine whether your activities and procedures as a sponsor in the significant risk clinical studies, “Blood Purification for the Treatment of Critically Ill Patients with Pathogen Associated Shock: A Multicenter, Randomized Controlled Feasibility Trial (Purify Study),” for Seraph 100 Microbind Affinity Blood Filter, Investigational Device Exemption (IDE), G210074, and “Prospective Single-Arm Feasibility Study to Determine the Capacity of the Onco-Seraph 100 Microbind Affinity Blood Filter (Onco-Seraph 100) to Remove Circulating Tumor Cells from the Blood of Patients with Metastatic Pancreatic Ductal Adenocarcinoma (Oscar Study),” for Onco-Seraph 100, IDE, G230144, complied with applicable federal regulations.
The Seraph 100 Microbind Affinity Blood Filter, also called the Seraph 100, which is also labeled as the Onco-Seraph 100, also called the ONCObind Seraph 100, is a device as that term is defined in section 201(h)(1) of the Federal Food, Drug, and Cosmetic Act (the Act), 21 U.S.C. § 321(h)(1), because it is intended for use in the diagnosis of disease or other conditions or in the cure, mitigation, treatment, or prevention of disease, or to affect the structure or function of the body. This letter also requests prompt corrective action to address the violations cited and discussed in your written responses dated June 25, 2025, July 25, 2025, and September 15, 2025.
The inspection was conducted under the Bioresearch Monitoring (BIMO) Program designed to ensure that data and information contained in requests for IDEs, Premarket Approval applications, and Premarket Notification submissions are scientifically valid and accurate. Another objective of the program is to ensure that human subjects are protected from undue hazard or risk during the course of scientific investigations.
Our review of the inspection report prepared by the OBMI revealed serious violations of Title 21, Code of Federal Regulations (CFR) Part 812 - Investigational Device Exemptions, which concern requirements prescribed under section 520(g) of the Act, 21 U.S.C. § 360j(g). A device is adulterated under section 501(i) of the Act, 21 U.S.C. § 351(i), if the device for which an exemption has been granted under section 520(g) of the Act, 21 U.S.C. § 360j(g), for investigational use and the person who was granted such exemption or any investigator who uses such device under such exemption fails to comply with a requirement prescribed by or under such section.
At the close of the inspection, the FDA investigator presented an inspectional observations Form FDA-483 for your review and discussed the observations listed on the form with you. The deviations noted on the Form FDA-483, your written responses, and our subsequent review of the inspection report are discussed below:
1. Failure to obtain FDA approval prior to implementing a change to the investigational plan [21 CFR 812.35(a)(1)].
A sponsor is responsible for obtaining FDA approval prior to implementing a change to the investigational plan except for certain changes described in 21 CFR 812.35(a)(2) through (a)(4). Your firm failed to obtain FDA approval for changes to an investigational plan that required FDA approval prior to implementation and no exception applies to these circumstances. Specifically, review of your “Emergency/Compassionate Use Requests” log indicates that investigational devices, specifically Seraph 100 devices, were shipped to
(b)(4), (b)(6)
Hospital on April 29, 2024, for Emergency/Compassionate Use (CU).
Your firm’s email communications with
(b)(4), (b)(6)
Hospital dated April 27-28, 2024, indicate that these devices were shipped for treatment of a patient under the CU pathway. However, FDA approval for CU was not obtained prior to the devices being distributed. Furthermore, your firm failed to adhere to work instruction, WI017, “Use of Unapproved Devices in United States,” which states “For Compassionate Use Case, FDA approval is required prior to use of the unapproved device,” and specifies that “If there is an IDE for the device, ExThera Medical (IDE sponsor) needs to submit an IDE supplement requesting approval for a compassionate use under section §812.35(a) to treat the patient.”
Additionally, the log indicates that a second Emergency/CU request for
(b)(4), (b)(6)
Hospital was received on November 5, 2024, for which the “Emergency/Compassionate Use Requests” log indicates “devices on hand.” Review of your firm’s email communications dated November 5-6, 2024, indicates that these devices were approved for emergency use. However, a report was never submitted to FDA documenting the distribution of devices for use in treating the identified patient.
Approval of an IDE permits investigational device use only in accordance with the approved investigational plan and within the specific study parameters, investigational sites, and patient populations described in the approved study protocol. Distribution of an investigational device for compassionate use to patients not enrolled in the study constitutes a change to the investigational plan requiring prior FDA approval. Obtaining prior approval for compassionate use is essential to ensuring that the rights, safety, and well-being of patients being treated under compassionate use are adequately protected. Furthermore, distributing investigational devices for compassionate use without prior approval has the potential to introduce additional risks, including inadequate device accountability, which can lead to unapproved uses of the device that further compromise the protective safeguards for patients and threaten public health safety.
Your written responses to Form FDA-483 are inadequate. Your June 25, 2025, response provided clarification that in both the April and November 2024 cases, devices that were shipped for compassionate use were not used due to changes in the patient’s circumstances. This response also mentioned corrective actions that you have completed, including initiating updated work instruction WI-00011 (piloted as an update from WI017), “Use of Unapproved Devices in United States,” and providing training to personnel on the updated work instruction. However, your work instruction WI-00011 raises significant concerns as further described below. Your July 25, 2025, and September 15, 2025, responses did not provide additional information regarding this observation.
Work instruction WI-00011 incorrectly suggests that your device can be distributed and used in certain states based on your compliance with Federal and state “Right to Try” laws and includes template letters for physicians to request device access that cite the use as being “in accordance with the Federal Right to Try Act of 2017, 21 U.S.C. §§ 360bbb-Oa through 360bbb-Oc.” The Federal Trickett Wendler, Frank Mongiello, Jordan McLinn, and Matthew Bellina Right to Try Act of 2017 (Right to Try); however, is not applicable to devices, and compliance with a state “Right to Try” law that conflicts with applicable Federal law would not relieve your firm of compliance with Federal law. WI-00011 should be corrected to help ensure compliance and prevent inappropriate distribution and use of your device. Additionally, your response to this letter should include information on the disposition of any devices inappropriately distributed in accordance with these procedures and plans to report to the IDE(s) the specific cases (if any) in which these devices were used.
Additionally, your responses did not indicate whether the devices authorized for use at
(b)(4), (b)(6)
Hospital in April and November 2024, were returned or properly disposed of following those cases, which raises concerns that the disposition of these investigational devices was not properly managed. Poor handling of device disposition creates safety and public health risks, as this can lead to unapproved and inappropriate uses of the investigational device. Therefore, your corrective actions should include a plan to conduct a complete accounting of all investigational devices distributed to
(b)(4), (b)(6)
Hospital and other entities listed on the “Emergency/Compassionate Use Request” log. Please include details of the disposition of these devices in your response to this letter. Furthermore, work instruction WI017 should be revised to include additional instructions on handling of unused or leftover devices.
2. Failure to ensure proper monitoring of the investigation and failure to secure clinical investigator’s compliance with investigational plans [21 CFR 812.40, 21 CFR 812.46(a)].
A sponsor is responsible for ensuring proper monitoring of an investigation. As part these monitoring responsibilities, a sponsor is responsible for securing its clinical investigator’s compliance with the investigational plan. ExThera failed to properly monitor its clinical investigations and failed to provide evidence for verification and attestation that informed consent was signed for enrolled subjects. Examples include, but are not limited to, the following:
During the inspection on May 30, 2025, your firm was asked to provide documentation demonstrating that informed consent was obtained from enrolled subjects for the Purify Study (IDE G210074) and Oscar Study (IDE G230144) and that the required monitoring procedures were conducted. However, your firm was unable to provide evidence of verification and attestation that informed consent was signed for enrolled subjects and that monitoring procedures were followed. Additionally, on June 4, 2025, you signed an affidavit confirming that, “When requested during inspection to provide evidence of informed consent verification, ExThera was unable to provide such evidence.” This indicates that, for both studies, you failed to ensure proper monitoring of the informed consent process, a critical aspect of clinical study conduct, and that you failed to adhere to your clinical monitoring plan which requires verification of informed consent as described below.
For IDE G210074 (Purify Study), Clinical Monitoring Plan v2.0 states the following:
o Section 2, “Objectives,” states, “Verify that informed consent is obtained prior to study procedures.”
o Section 8.3.1, “Review of Informed Consent Forms (ICFs),” states, “If the ICF is not available and cannot be verified, the monitoring visit will be delayed until the ICFs can be reviewed.”
For IDE G230144 (Oscar Study), Clinical Monitoring Plan v2.0 states the following:
o Section 8.3.1, “Review of Informed Consent Forms,” states, “Verify that ICFs are up-to-date, properly documented, and maintained in accordance with GCP and ethical guidelines.”
Proper monitoring helps ensure that the safety, rights, and well-being of study subjects are protected, the study data are complete and accurate, and that the study is conducted in accordance with good clinical practice. Monitoring should be an on-going program performed with the frequency necessary to ensure that the investigation is conducted according to the investigational plan, FDA regulations, and any conditions of approval required by the FDA or the reviewing IRB. Inadequate monitoring of informed consent puts subjects at risk of being enrolled and treated in the study without having given proper informed consent and potentially can lead them to undergo experimental procedures or forego standard of care treatment alternatives without fully understanding the associated risks and likelihood of benefit.
Your responses to Form FDA-483 are inadequate. Your June 25, 2025, response indicated that the root cause of this violation was due to informed consent verification and documentation processes outlined in the clinical monitoring plan as well as the clinical monitoring procedures (CP018) not being followed completely, which led to inadequate documentation and inability to provide documents upon request. Additionally, procedure CP018 did not require verification of screening and verification logs against an informed consent form log, and there was no master log of screening and enrollment maintained. This response further indicated that the firm has implemented corrective actions, including verification of all signed informed consent forms and/or monitoring reports included in the trial master file and revision of clinical standard operating procedures (SOPs) and work instruction along with training. Your June 25, 2025, and July 25, 2025, responses also stated a plan to update the clinical monitoring plan for IDE G230144 to reflect the changes made within the updated procedures and submit to the FDA for approval, prior to any new enrollment. However, a copy of the revised document was not provided. A copy of the revised clinical monitoring plan is needed in order for FDA to verify that the proposed changes have been adequately implemented. Your September 15, 2025, response did not provide additional information regarding this observation.
Unapproved Device Violations
In addition, FDA has determined that the Seraph 100 Microbind Affinity Blood Filter is adulterated under section 501(f)(1)(B) of the Act, 21 U.S.C. § 351(f)(1)(B), because your firm does not have an approved application for premarket approval (PMA) in effect pursuant to section 515(a) of the Act, 21 U.S.C. § 360e(a), or an approved application for an investigational device exemption (IDE) under section 520(g) of the Act, 21 U.S.C. § 360j(g), for the device as described and marketed. The Seraph 100 Microbind Affinity Blood Filter is also misbranded under section 502(o) the Act, 21 U.S.C. § 352(o), because your firm introduced or delivered for introduction into interstate commerce for commercial distribution this device without submitting a new premarket notification to FDA as required by section 510(k) of the Act, 21 U.S.C. § 360(k), and 21 CFR 807.81. The device is further misbranded under 502(a) of the Act, 21 U.S.C. § 352(a) because of false and misleading statements about the regulatory status of the device.
FDA has reviewed your company’s website at https://extheramedical.com, and various public statements by your firm’s officials as described below. Your firm’s promotion of the device is in violation of FDA’s regulations and the Act. For example, ExThera’s Chief Medical Officer, Lakhmir “Mink” Chawla, M.D., stated that the Seraph 100 device is approved in the US, is safe, and is effective for a range of intended uses:
a. In December 2024, Dr. Chawla stated the following in a podcast titled, “Dr. Mink Chawla: Blood Filter Seraph-100 Shows Promise To End Long COVID”:
i. “Look we have had people under an IRB… under compassionate use with long COVID get the filter… clinically, their brain fog has improved, their fatigue has improved, and so clinically we’re seeing real benefit.” (56:48)
ii. “This device has been in over 2,500 patients now, it’s very safe. It’s as safe as a dialysis procedure. So when you have a nice safety profile, you can move from the sickest patients in the intensive care unit which is what we did for COVID, and now we’re moving into outpatients who have cancer, who have long COVID, chronic viremia, chronic Lyme, etc. … and can we help people to treat the disease of aging.” (1:07:38)
This podcast is available to the public at https://open.spotify.com/episode/1Mbq1sL40dB8VIv61lGBzW?si=xGlJSdO0QsiIyHqKmB7Kkw%0A&nd=1&dlsi=dd2604be25b141ee.
b. In September 2024, Dr. Chawla stated at an Abundance360 Longevity Platinum conference in San Diego that the device is safe and that it is effective at removing a broad range of pathogens, is effective for COVID treatment, and is “… approved in the US for COVID-19,” despite a lack of FDA approval for any indication. A recording of this presentation is captioned with the statement, “This video introduces the ExThera Filter
1
which Lumati is offering as part of its unique HemoDetox protocol,” and is available to the public at https://vimeo.com/1014979373?share=copy#t=0.
c. In November 2024, Dr. Chawla stated in a promotional video of HemoDetox treatments that the device is effective at removing pathogens and has shown clinical benefit in the treatment of long COVID. This video is available to the public at https://vimeo.com/1031732539?autoplay=1&muted=1&stream_id=Y2xpcHN8MjIwMDU1MzgyfGlkOmRlc2N8W10%3D.
Your firm’s promotion represents the Seraph 100 as being approved in the United States. However, the Seraph 100 does not have an approved PMA. Your firm’s promotion provides evidence that the device is intended for uses for which you have been advised you would require an approved PMA as well as other uses not previously discussed with FDA, including, but not limited to, the treatment of COVID-19, long COVID, cancer, chronic viremia and Lyme disease.
FDA has corresponded with ExThera regarding ongoing concern about ExThera’s marketing of the Seraph 100. Specifically, during the interactive review of IDE supplement G230144/S002 (email dated July 26, 2024) FDA requested that ExThera remove promotional claims and claims of safety and effectiveness from the company’s labeling and from its public webpage because those claims appeared to violate the IDE labeling regulations for investigational devices as detailed in 21 CFR 812.5(b) and 21 CFR 812.7.
FDA issued an It Has Come to Our Attention (IHCTOA) Letter to ExThera on July 17, 2024, notifying them that Quadrant Clinical Care (Quadrant) was promoting the Seraph 100 device and that Quadrant’s public webpage stated that the device was FDA cleared to treat COVID-19 and sepsis. FDA also notified ExThera in that IHCTOA letter that, as the U.S. device manufacturer for the Seraph 100 Microbind Affinity Blood Filter, ExThera should ensure that distributors outside the U.S. do not falsely claim that their device has FDA clearance or approval. We note that the Quadrant Clinical Care website is currently unavailable.
ExThera’s July 25, 2024, response to the IHCTOA letter acknowledged the following:
“We understand the importance of accurate representations about the regulatory status of the Seraph in the United States, and we also acknowledge the Company’s responsibility to ensure that its foreign distributors do not misrepresent or overstate the device’s regulatory status… The Company takes this issue very seriously and has taken additional precautionary measures out of an abundance of caution following receipt of your letter, as described herein.”
“Your letter accurately describes the regulatory status of the Seraph device, which is not currently approved or cleared by FDA for any indication.”
“In closing, ExThera affirms its commitment to ensuring that marketing materials posted by its distributors accurately describe the regulatory status of the Company’s products in the United States.”
However, your firm’s website and other current public statements are inconsistent with your commitments in your response to the IHCTOA letter and made during the review of your IDE submissions.
For a device requiring premarket approval, the notification required by section 510(k) of the Act, 21 U.S.C. § 360(k), is deemed satisfied when a PMA is pending before the agency. 21 CFR 807.81(b). The kind of information that your firm needs to submit in order to obtain approval or clearance for the device is described on the Internet at http://www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/HowtoMarketYourDevice/default.htm. The FDA will evaluate the information that your firm submits and decide whether the product may be legally marketed.
Our office requests that ExThera cease any activities that result in the misbranding or adulteration of the Seraph100 Microbind Affinity Blood Filter, such as the commercial distribution of the device for the uses discussed above.
In addition to the above violations found during the inspection, it was observed on May 29, 2025, that your website’s Frequently Asked Questions (FAQ) webpage included a section titled “Are there any known side effects or potential dangers?” under which your firm claimed: “The Seraph 100 safety profile is consistent with standard extracorporeal labeling.” The Seraph 100 Microbind Affinity Blood Filter is not approved for marketing in the United States, meaning that a determination of safety or effectiveness has not been completed, and as such the safety profile including the risks of the device are undetermined for U.S. patients. The statement on your webpage implied that the safety profile of the device had been established and that the risks of the device had been found to be consistent with those of approved devices. This could have misled readers into believing that the device had been proven to be as safe as approved extracorporeal devices.
You acknowledged the observation and revised your webpage as well as took additional corrective and preventative actions, including conducting a review of all advertising, promotional, and website materials. However, your corrective and preventative actions did not include plans for ensuring that promotional materials that are made available by your distributors do not make inappropriate claims of safety and effectiveness, including how you plan to communicate to your distributors to remind them that your device has not been approved and is subject to regulations prohibiting the promotion of an investigational device, and therefore, should not be represented as safe and effective.
The violations described above are not intended to be an all-inclusive list of problems that may exist with your clinical studies. It is your responsibility as a study sponsor to ensure compliance with the Act and applicable regulations.
Within 15 working days of receiving this letter, please provide documentation of the additional corrective and preventative actions that you have taken or will take to correct these violations and to prevent the recurrence of similar violations in current or future studies for which you are the study sponsor. Any submitted corrective action plan must include projected completion dates for each action to be accomplished as well as a plan for monitoring the effectiveness of your corrective actions. Failure to respond to this letter and take appropriate corrective action could result in the FDA taking regulatory action without further notice to you.
Your response should reference “CMS# 715068” and be sent via email to: Irfan.Khan@fda.hhs.gov.
A copy of this letter has been sent to FDA’s OII OBMI Division 4 via email at OIIBIMODivision4Correspondence@fda.hhs.gov. Please send a copy of your response to that office.
The Division of Clinical Policy and Quality has developed introductory training modules in FDA-regulated device clinical research practices, which are available on the FDA website. The modules are for persons involved in FDA-regulated device clinical research activities. These modules are located at the following website address: http://www.fda.gov/Training/CDRHLearn/.
If you have any questions, please contact Melanie Daniels by phone at (301) 837-4289 or email at Melanie.Daniels@fda.hhs.gov.
Sincerely,
/S/
Ouided Rouabhi, MS
Acting Director
Division of Clinical Policy and Quality
Office of Clinical Evidence & Analysis
Office of Product Evaluation and Quality
Center for Devices and Radiological Health
/S/
Michael J. Hoffmann
Director
Office of Health Technology 3
Gastrorenal, ObGyn, General Hospital,
and Urology Devices
Office of Product Evaluation and Quality
Center for Devices and Radiological Health
____________
1
FDA is only aware of one device from ExThera, the Seraph 100 Microbind Affinity Blood Filter, also called the Seraph 100, which is also labeled as the Onco-Seraph 100, also called the ONCObind Procedure.
Content current as of:
02/24/2026
Regulated Product(s)
Medical Devices