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Updated May 2026 · ClinicalTrials.gov

RECRUITINGPhase 2 / Phase 3INTERVENTIONAL

Gut Microbiome Profiles in Patients with Chemotherapy-induced Neuropathy in the RCT OzoParQT (NCT06706544).

Evaluation of the Gut Microbiome Profiles in Patients with Chemotherapy-induced Peripheral Neuropathy Treated in the Randomized Clinical Trial with Ozone OzoParQT (NCT06706544).

Gut Microbiome Profiles in Patients with Chemotherapy-induced Neuropathy in the RCT OzoParQT (NCT06706544). (NCT06799351) is a Phase 2 / Phase 3 interventional studying Chemotherapy Induced Peripheral Neuropathy (CIPN) and Paresthesia, sponsored by Bernardino Clavo, MD, PhD. RECRUITING as of the most recent ClinicalTrials.gov update. Talk to your doctor before contacting the trial site.

Important: This information is not medical advice. Talk to your doctor about whether a clinical trial is right for you.

About This Trial

Chemotherapy-induced peripheral neuropathy (CIPN) is a common and debilitating side effect of chemotherapy (CT), often requiring dose reductions or treatment interruptions, which can compromise efficacy of the planned CT (limiting its efficacy). Additionally, CIPN usually decreases patients' quality of life. Unfortunately, effective treatments for CIPN are limited. Emerging evidence suggests potential benefits of rectal ozone therapy and points to a possible role of the gut microbiome in CIPN development and treatment response. This observational study, ancillary to the randomized clinical trial (RCT) OzoParQT (NCT06706544), investigates the relationship between gut microbiome composition and CIPN severity in patients receiving rectal ozone therapy. Primary Objectives: To evaluate if gut microbiome profiles differ between patients: 1. with and without symptomatic improvement of CIPN. 2. receiving rectal ozone therapy and those receiving placebo. Secondary Objectives: To evaluate the relationship between gut microbiome composition and: 1. Health-related quality of life, 2. Anxiety and depression, 3. Biochemical markers of oxidative stress and inflammation. Main Trial Endpoints. Changes from baseline at the end of ozone therapy (week 16) in: * Gut microbiome profile * Patient-reported numbness and tingling * Neuropathy severity (QLQ-CIPN20 scale) * Paresthesia toxicity grade (CTCAE v.5.0) Secondary Trial Endpoints. Changes from baseline at the end of ozone therapy (week 16) in: * Patient-reported quality of life (EQ-5D-5L questionnaire) * Quality of life (QLQ-C30 questionnaire) * Anxiety and depression levels (HADS questionnaire) * Biochemical markers of oxidative stress * Biochemical markers of inflammation Trial Design: This observational study will analyze data from patients enrolled in the randomized, triple-blind, placebo-controlled OzoParQT clinical trial (NCT06706544). Trial Population in the OzoParQT trial (NCT06706544): Adults (≥18 years) with any tumor type, experiencing CIPN-related paresthesias (numbness and/or tingling), with a toxicity grade ≥ 2 according to the Common Terminology Criteria for Adverse Events (CTCAE v.5.0) for ≥ 3 months. Intervention in the OzoParQT trial (NCT06706544). All patients will receive standard care for their CIPN symptoms plus 40 sessions of rectal insufflation of an O3/O2 gas mixture over 16 weeks: * Ozone group: O3/O2 concentration increasing from 10 to 30 µg/mL * Control-placebo group: O2 only (0 µg/mL O3) Study Duration: Each patient will participate in this study (OzoParQTmicrob) for 16 weeks, concurrent with the ozone therapy intervention. The total planned project duration is 60 months.

What Stage of Research Is This?

Phase 2 trials evaluate whether a treatment actually works against Chemotherapy Induced Peripheral Neuropathy (CIPN) and continue monitoring side effects. Phase 2 enrolls larger groups (typically 100–300 patients) and produces the first real efficacy signal. A successful Phase 2 readout is what unlocks the much larger Phase 3 confirmatory trials needed for FDA approval.

This trial is currently recruiting participants. The sponsor has registered the study with ClinicalTrials.gov as actively enrolling, which means new applicants who meet the eligibility criteria can be considered for screening. Trial status can change between updates — confirm current recruiting status with the study contact before traveling for a screening visit.

With a target enrollment of 42 participants, this is a small study — typical of early-phase research, rare-disease trials, or pilot studies designed to generate preliminary signal before a larger study is launched.

Who May Be Eligible (Plain English)

Who May Qualify: - 0\. Patients who agree to participate in the randomized clinical trial OzoParQT, and who also agree to participate in this study of gut microbiota by providing stool samples. - 1\. Adults \> = 18 years old. - 2\. Previous treatment with any chemotherapy because of any tumor. - 3\. Clinical diagnosis of paresthesia (numbness, tingling) secondary to CIPN, with toxicity Grade \> = 2 (according to the Common Toxicity Criteria for Adverse Events (CTCAE) from the National Cancer Institute of EEUU, v.5.0) for \> = 3 months. - 4\. Without neurotoxic chemotherapy \> = 3 months. - 5\. Cancer disease is stable or in remission. - 6\. Life expectancy \> = 6 months. - 7\. Before enrollment, women of childbearing potential should obtain a negative result in the serum or urine pregnancy test at the screening visit and accept the use of appropriate contraceptive methods at least from 14 days before the first ozone therapy session up to 14 days after the last one. - 8\. To sign and date the specific willing to sign a consent form of both studies (OzoParQT and OzoParQTmicrob) Who Should NOT Join This Trial: - 1\. Age \< 18 years. - 2\. A woman who is lactating, pregnant, suspected of being pregnant, or a woman of childbearing potential who does not use adequate contraceptive methods. - 3\. Suspected symptoms are due to diabetic or compressive neuropathy. - 4\. Severe psychiatric disorders. - 5\. Inability to complete the quality of life questionnaires. - 6\. Elevation above 5 times the maximum limit of normal creatinine. - 7\. Patient who is hemodynamic or clinically unstable or who requires urgent or short-term interventional measures. - 8\. Neoplasia in progression requiring recent initiation of systemic treatment or maintenance with neurotoxic chemotherapy. - 9\. Life expectancy (for any reason) \< 6 months. - 10\. Known allergy to ozone, known glucose 6 phosphate dehydrogenase (G6PD) deficiency, or hemochromatosis. ...See full criteria on ClinicalTrials.gov Always talk to your doctor about whether this trial is right for you.

These are translations of the protocol\'s inclusion and exclusion criteria, simplified for patients and caregivers. The original clinical text appears below. Eligibility is ultimately confirmed by the trial site\'s screening process — this summary is a starting point for a conversation with your doctor, not a final determination.

Original Eligibility Criteria

View original clinical language
Inclusion Criteria: * 0\. Patients who agree to participate in the randomized clinical trial OzoParQT, and who also agree to participate in this study of gut microbiota by providing stool samples. * 1\. Adults \> = 18 years old. * 2\. Previous treatment with any chemotherapy because of any tumor. * 3\. Clinical diagnosis of paresthesia (numbness, tingling) secondary to CIPN, with toxicity Grade \> = 2 (according to the Common Toxicity Criteria for Adverse Events (CTCAE) from the National Cancer Institute of EEUU, v.5.0) for \> = 3 months. * 4\. Without neurotoxic chemotherapy \> = 3 months. * 5\. Cancer disease is stable or in remission. * 6\. Life expectancy \> = 6 months. * 7\. Before enrollment, women of childbearing potential should obtain a negative result in the serum or urine pregnancy test at the screening visit and accept the use of appropriate contraceptive methods at least from 14 days before the first ozone therapy session up to 14 days after the last one. * 8\. To sign and date the specific informed consent of both studies (OzoParQT and OzoParQTmicrob) Exclusion Criteria: * 1\. Age \< 18 years. * 2\. A woman who is lactating, pregnant, suspected of being pregnant, or a woman of childbearing potential who does not use adequate contraceptive methods. * 3\. Suspected symptoms are due to diabetic or compressive neuropathy. * 4\. Severe psychiatric disorders. * 5\. Inability to complete the quality of life questionnaires. * 6\. Elevation above 5 times the maximum limit of normal creatinine. * 7\. Patient who is hemodynamic or clinically unstable or who requires urgent or short-term interventional measures. * 8\. Neoplasia in progression requiring recent initiation of systemic treatment or maintenance with neurotoxic chemotherapy. * 9\. Life expectancy (for any reason) \< 6 months. * 10\. Known allergy to ozone, known glucose 6 phosphate dehydrogenase (G6PD) deficiency, or hemochromatosis. * 11\. Contraindications or impossibility for rectal ozone treatment or to attend regularly to the treatment. * 12\. Not meeting each and every one of the inclusion criteria

Treatments Being Tested

DRUG

Ozone therapy

Usual treatment (by their oncologist or hematologist) + Ozone therapy by rectal insufflation. O3/O2 concentration progressively increased from 10 to 30 μg/ml; 40 sessions in 16 weeks.

DRUG

Oxygen (placebo)

Usual treatment (by their oncologist or hematologist) + Oxygen by rectal insufflation. O3/O2 concentration = 0 μg/ml (only O2); 40 sessions in 16 weeks.

Locations (1)

Trial sites listed on ClinicalTrials.gov for this study. Site activation status can vary — confirm with the specific site before traveling for a screening visit.

Hospital Universitario de Gran Canaria Dr. Negrín, (FIISC)
Las Palmas, Las Palmas, Spain

How to Talk to Your Doctor About This Trial

Bring the printable summary of this trial — including the NCT ID (NCT06799351), the sponsor (Bernardino Clavo, MD, PhD), and the key eligibility criteria — to your next appointment. Your doctor can review the inclusion and exclusion criteria against your medical history, lab values, and current treatments to assess whether you are likely to qualify. They can also help you weigh whether trial participation makes sense alongside your existing care plan.

Useful questions to walk through together: What does the trial protocol require beyond standard care? How long is the active treatment phase, and how long is follow-up? Are there study visits at sites I can reach? Who pays for the trial-specific procedures, and who pays for standard-of-care portions? See our 25 questions to ask about clinical trials guide for a more complete checklist.

Authoritative Sources

The official record for this trial lives on ClinicalTrials.gov — the federal registry maintained by the National Library of Medicine at NIH. For background on how this trial fits into the FDA approval pathway, see the FDA drug approval process. For oncology-specific guidance for patients considering trials, the National Cancer Institute publishes patient-oriented overviews. International trial registries are aggregated by the WHO ICTRP.

Frequently Asked Questions

What is the NCT06799351 clinical trial studying?

Chemotherapy-induced peripheral neuropathy (CIPN) is a common and debilitating side effect of chemotherapy (CT), often requiring dose reductions or treatment interruptions, which can compromise efficacy of the planned CT (limiting its efficacy). Additionally, CIPN usually decreases patients' quality of life. Unfortunately, effective treatments for CIPN are limited. Emerging evidence suggests potential benefits of rectal ozone therapy and points to a possible role of the gut microbiome in CIPN development and treatment response. This observational study, ancillary to the randomized clinical t… The full protocol is registered on ClinicalTrials.gov and includes the primary outcome measures, eligibility criteria, and study endpoints.

Who can participate in NCT06799351?

Eligibility for this trial depends on the specific inclusion and exclusion criteria set by the sponsor. The plain-English summary above translates the most important criteria into accessible language; the official clinical text is preserved in the collapsible section underneath. Whether you fit any specific trial is a medical decision your doctor needs to confirm — bring the trial information to your treating physician for a full review against your medical history.

How do I contact the trial site for NCT06799351?

Contact information registered with ClinicalTrials.gov is shown in the sidebar of this page. Before reaching out, confirm with your treating physician that this trial is appropriate for your situation. The trial site will then walk you through the screening process to determine final eligibility.

Is participating in a clinical trial safe?

Clinical trials in the United States are regulated by the FDA and overseen by Institutional Review Boards (IRBs) that review the protocol for safety. Risk varies by trial — Phase 1 studies test new treatments in humans for the first time, while Phase 3 trials use treatments that have already passed earlier safety screening. The informed consent document for any specific trial details the known risks and what to expect. Discuss those risks with your physician before deciding whether to participate.

Where can I verify the data on this page?

Every detail on this page comes directly from the ClinicalTrials.gov API. Click "View on ClinicalTrials.gov" in the sidebar to see the official, unmodified record. The federal record is always authoritative; this page is a structured presentation with a plain-English eligibility translation. For background on how clinical trials are regulated, see the FDA drug approval process documentation.

How This Page Is Built

Every field on this page is pulled directly from the ClinicalTrials.gov API v2 — no estimates, no proxies. The plain-English eligibility translation is generated from the original protocol text and reviewed for fidelity to the underlying clinical criteria. The original clinical text remains visible in the collapsible section above so users and clinicians can verify the translation. Read the full methodology for the data pipeline and known limitations.

Source: ClinicalTrials.gov API v2 record for NCT06799351. Maintained by the National Library of Medicine at NIH. Public domain. Cite as: "TrialFinderData. NCT06799351. Data: ClinicalTrials.gov."

Medical disclaimer: This page is informational, not medical advice. Talk to your doctor about whether a clinical trial is right for you.

Last updated 2026-05-08 · Data from ClinicalTrials.gov.