A Study of Isoquercetin in People With 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.

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 \ 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 \ 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.