Prediction of Venous Thrombosis During chemotherapy-the PINPOINT Study

Overview

Cancer patients are at higher risk of getting a blood clot (known as venous thromboembolism (VTE)) especially during chemotherapy and some patients are more at risk than others. These clots can be prevented by using blood thinners (known as anticoagulants) but these are not suitable for everyone as they also carry a risk of bleeding. This study aims to identify which chemotherapy patients are most at risk of a blood clot and at what point in their treatment this is likely to happen. In this project biomarkers in the blood that are involved in blood clotting will be measured in cancer patients at four stages during chemotherapy to see how the biomarkers change during treatment. The blood samples for these tests are taken at the same time as the normal routine blood tests done before a chemotherapy cycle. Biomarker levels will be compared between those patients who subsequently get a VTE and those who do not get a VTE. This will help develop a biomarker based blood test to predict clots during chemotherapy. The biomarker based test will also be compared with other methods of predicting VTE in cancer patients which are currently in use. In the future, this blood test might be used to see if patients are at high risk of a clot during chemotherapy and provide a method to optimise the use of preventative anticoagulants in cancer patients during chemotherapy.

Background: VTE is the leading cause of death in cancer patients after the cancer itself. Amongst solid tumours, pancreatic, lung, brain, stomach, and ovarian cancer are the most prothrombotic and are associated with high rates of VTE depending on tumour histology and treatment. The recommended tool for VTE risk assessment during chemotherapy is the Khorana risk score, which was designed to identify ambulatory cancer patients at increased risk of VTE during chemotherapy. This tool has been recommended for use in guiding thromboprophylaxis in cancer patients undergoing chemotherapy. However, the Khorana score performs poorly in cancers of a single type, especially cancers at high risk of VTE. Previous studies have used a variety of biomarkers to predict VTE in cancer patients, however prediction was based on one sample and does not account for the dynamic nature of thrombogenesis particularly during chemotherapy. Dynamic risk assessment using serial measurement of biomarkers during therapy has been recommended as a more effective approach to risk assessment. Guidelines have suggested repeated risk assessment using the new Vienna CAT score (a nomogram based on D-dimer levels and tumour site) may improve risk prediction. Preliminary data has shown suggests that three novel biomarkers may be (soluble Thrombomodulin(TM), Thrombin generation assay\[TGA\] and Factor VIIIc (FVIIIc) levels) measured serially may be effective alone or in combination as dynamic predictive biomarkers for VTE during chemotherapy. Study objective: The aim of the study is to measure these three biomarkers (TGA, TM and FVIIIc) serially in lung, ovarian, pancreatic and gastric cancer patients undergoing chemotherapy to dynamically assess the ability of these biomarkers to predict VTE. Study Design: The study will recruit 380 patients across three centres in Ireland. Blood samples will be taken from each patient at the following stages during chemotherapy treatment. 1. Before chemotherapy treatment 2. after 4 weeks treatment 3. after 3 months treatment 4. at the end of the current cycle of treatment. Based on clinical data available, the Khorana Risk Score(KRS) calculated at the start of therapy. The Vienna CAT nomogram will be calculated at each sampling point in the study. Laboratory Biomarker analysis: All biomarker analysis will take place at the Coagulation Research Laboratory, Dept of Obstetrics and Gynaecology, Trinity St. James Cancer Institute, St. James's Hospital. Dublin IRELAND sTM will be measured using Enzyme Linked Immunosorbent Assay (ELISA) and FVIIIc will be measured using chromogenic substrate assay . TGA will be measured using fluorimetric assay. D-dimer (for calculation of the Vienna CAT score) will be measured using a 2-step procedure. All VTE events which occur from baseline to within 3 months of the final sample will be recorded.