Submit a comment
Abstract
BACKGROUND. Protein disulfide isomerase (PDI) is a thiol isomerase secreted by vascular cells that is required for thrombus formation. Quercetin flavonoids inhibit PDI activity and block platelet accumulation and fibrin generation at the site of a vascular injury in mouse models, but the clinical effect of targeting extracellular PDI in humans has not been studied. METHODS. We conducted a multicenter phase II trial of sequential dosing cohorts to evaluate the efficacy of targeting PDI with isoquercetin to reduce hypercoagulability in cancer patients at high risk for thrombosis. Patients received isoquercetin at 500 mg (cohort A, n = 28) or 1000 mg (cohort B, n = 29) daily for 56 days, with laboratory assays performed at baseline and the end of the study, along with bilateral lower extremity compression ultrasound. The primary efficacy endpoint was a reduction in D-dimer, and the primary clinical endpoint included pulmonary embolism or proximal deep vein thrombosis. RESULTS. The administration of 1000 mg isoquercetin decreased D-dimer plasma concentrations by a median of –21.9% (P = 0.0002). There were no primary VTE events or major hemorrhages observed in either cohort. Isoquercetin increased PDI inhibitory activity in plasma (37.0% in cohort A, n = 25, P < 0.001; 73.3% in cohort B, n = 22, P < 0.001, respectively). Corroborating the antithrombotic efficacy, we also observed a significant decrease in platelet-dependent thrombin generation (cohort A median decrease –31.1%, P = 0.007; cohort B median decrease –57.2%, P = 0.004) and circulating soluble P selectin at the 1000 mg isoquercetin dose (median decrease –57.9%, P < 0.0001). CONCLUSIONS. Isoquercetin targets extracellular PDI and improves markers of coagulation in advanced cancer patients. TRIAL REGISTRATION. Clinicaltrials.gov NCT02195232. FUNDING. Quercegen Pharmaceuticals; National Heart, Lung, and Blood Institute (NHLBI; U54HL112302, R35HL135775, and T32HL007917); and NHLBI Consortium Linking Oncology and Thrombosis (U01HL143365).
Authors
Jeffrey I. Zwicker, Benjamin L. Schlechter, Jack D. Stopa, Howard A. Liebman, Anita Aggarwal, Maneka Puligandla, Thomas Caughey, Kenneth A. Bauer, Nancy Kuemmerle, Ellice Wong, Ted Wun, Marilyn McLaughlin, Manuel Hidalgo, Donna Neuberg, Bruce Furie, Robert Flaumenhaft, on behalf of CATIQ Investigators
Guidelines
The Editorial Board will only consider comments that are deemed relevant and of interest to readers. The Journal will not post data that have not been subjected to peer review; or a comment that is essentially a reiteration of another comment.
- Comments appear on the Journal’s website and are linked from the original article’s web page.
- Authors are notified by email if their comments are posted.
- The Journal reserves the right to edit comments for length and clarity.
- No appeals will be considered.
- Comments are not indexed in PubMed.
Specific requirements
- Maximum length, 400 words
- Entered as plain text or HTML
- Author’s name and email address, to be posted with the comment
- Declaration of all potential conflicts of interest (even if these are not ultimately posted); see the Journal’s conflict-of-interest policy
- Comments may not include figures
