A Study of Isoquercetin in People With Ovarian Cancer

April 15, 2026 updated by: Memorial Sloan Kettering Cancer Center

Randomized, Multi-dose, Placebo-controlled Phase 2 Trial of Oral Isoquercetin to Reduce Thrombin Generation in Ovarian Cancer

The purpose of this study is to test whether isoquercetin can reduce markers in the blood that may indicate the risk of blood clots in people with ovarian cancer. The effects of isoquercetin will be compared with those of a placebo.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

90

Phase

  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

  • United States
    • Massachusetts
      • Boston, Massachusetts, United States, 02215
        • Not yet recruiting
        • Beth Israel Deaconess Medical Center (Data Collection Only)
        • Contact:
          • Robert Flaumenhaft, MD, PhD
          • Phone Number: 617-735-4005
    • New Jersey
      • Basking Ridge, New Jersey, United States, 07920
        • Recruiting
        • Memorial Sloan Kettering Basking Ridge (All protocol activities)
        • Contact:
          • Jeffrey A Zwicker, MD
          • Phone Number: 646-608-3723
      • Middletown, New Jersey, United States, 07748
        • Recruiting
        • Memorial Sloan Kettering Monmouth (All Protocol Activities)
        • Contact:
          • Jeffrey Zwicker, MD
          • Phone Number: 646-608-3723
      • Montvale, New Jersey, United States, 07645
        • Recruiting
        • Memorial Sloan Kettering Bergen (All Protocol Activities)
        • Contact:
          • Jeffrey Zwicker, MD
          • Phone Number: 646-608-3723
    • New York
      • Commack, New York, United States, 11725
        • Recruiting
        • Memorial Sloan Kettering Suffolk-Commack (All Protocol Activities )
        • Contact:
          • Jeffrey Zwicker, MD
          • Phone Number: 646-608-3723
      • Harrison, New York, United States, 10604
        • Recruiting
        • Memorial Sloan Kettering Westchester (All Protocol Activities)
        • Contact:
          • Jeffrey Zwicker, MD
          • Phone Number: 646-608-3723
      • New York, New York, United States, 10065
        • Recruiting
        • Memorial Sloan Kettering Cancer Center (All Protocol Activites)
        • Contact:
          • Jeffrey Zwicker, MD
          • Phone Number: 646-608-3723
      • Rockville Centre, New York, United States, 11553
        • Recruiting
        • Memorial Sloan Kettering Nassau (All protocol activities)
        • Contact:
          • Jeffrey Zwicker, MD
          • Phone Number: 646-608-3723

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Participants must have histological- or cytological-confirmed ovarian cancer (epithelial, serous, or clear cell) and be receiving first-line chemotherapy (day 1 of isoquercetin should align with day 1 of cycle 1 or 2 of chemotherapy) for neoadjuvant, adjuvant, or advanced settings.
  • Minimum age 18 years
  • Life expectancy of greater than 6 months.
  • ECOG performance status <2

  • Participants must have preserved organ and marrow function as defined below:

    • Platelet count > 50,000/mcL
    • Prothrombin time (PT) and partial thromboplastin time (PTT) < 1.5 x institutional upper limit of normal (ULN)
    • Total bilirubin < 3 x ULN without liver metastases and <5 x ULN in presence of liver metastases.
    • Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) < 3 X ULN without liver metastases and <5 x ULN in the presence of liver metastases.
    • Estimated creatinine clearance (CrCl >30 ml/min)
  • The effects of isoquercetin on the developing human fetus are unknown. For this reason, women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately.
  • Ability to understand and the willingness to sign a written informed consent document.

Exclusion Criteria:

  • Prior history of documented venous thromboembolic event within the last 2 years (excluding central line associated events whereby patients completed anticoagulation)
  • Active bleeding or high risk for bleeding (e.g., known acute gastrointestinal ulcer)
  • History of significant hemorrhage (requiring hospitalization or transfusion) outside of a surgical setting within the last 24 months
  • Familial bleeding diathesis
  • Known diagnosis of disseminated intravascular coagulation (DIC)
  • Currently receiving anticoagulant therapy
  • Current daily use of aspirin, clopidogrel (Plavix), cilostazol (Pletal), aspirin-dipyridamole (Aggrenox) (within 10 days) or considered to use regular use of higher doses of non-steroidal anti-inflammatory agents as determined by the treating physician (e.g ibuprofen > 800 mg daily or equivalent)
  • Uncontrolled intercurrent illness including, but not limited to ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements
  • Known intolerance of (iso)quercetin, niacin or ascorbic acid (including known G6PD deficiency).
  • Participants with known brain metastases
  • Pregnant women are excluded from this study because isoquercetin is a PDI inhibitor with the potential for teratogenic or abortifacient effects. Because there is an unknown but potential risk of adverse events in nursing infants secondary to treatment of the mother with isoquercetin, breastfeeding should be discontinued if the mother is treated with isoquercetin.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Placebo Comparator: Cohort A: Placebo
Other: Placebo
Placebo
Experimental: Cohort B: Isoquercetin daily
Drug: Isoquercetin
Cohort B and Cohort C will take isoquercetin
Experimental: Cohort C: Isoquercetin twice daily
Drug: Isoquercetin
Cohort B and Cohort C will take isoquercetin

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Level of PDI-sensitive, platelet-dependent thrombin generation measured as compared to baseline
Time Frame: up to 6 weeks from baseline
The primary endpoint is the maximal inhibition of PDI-sensitive, platelet-dependent thrombin generation measured at either 3 or 6 weeks (relative to baseline).
up to 6 weeks from baseline

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Memorial Sloan Kettering Cancer Center

Collaborators

National Institutes of Health (NIH)

Investigators

  • Principal Investigator: Jeffrey Zwicker, MD, Memorial Sloan Kettering Cancer Center

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 22, 2026

Primary Completion (Estimated)

January 1, 2032

Study Completion (Estimated)

January 1, 2032

Study Registration Dates

First Submitted

December 23, 2025

First Submitted That Met QC Criteria

December 23, 2025

First Posted (Actual)

December 26, 2025

Study Record Updates

Last Update Posted (Actual)

April 16, 2026

Last Update Submitted That Met QC Criteria

April 15, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 25-060

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

• Memorial Sloan Kettering Cancer Center supports the international committee of medical journal editors (ICMJE) and the ethical obligation of responsible sharing of data from clinical trials. The protocol summary, a statistical summary, and informed consent form will be made available on clinicaltrials.gov when required as a condition of Federal awards, other agreements supporting the research and/or as otherwise required. Requests for deidentified individual participant data can be made beginning 12 months after publication and for up to 36 months post publication. Deidentified individual participant data reported in the manuscript will be shared under the terms of a Data Use Agreement and may only be used for approved proposals. Requests may be made to: crdatashare@mskcc.org.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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