A feasibility randomised controlled trial assessing the use of platelet transfusions versus modified dose blood thinners in patients with low platelets and cancer-related blood clots

INTERVENTION: Randomisation will be by Sealed Envelope, an anonymised online randomisation service. Study arm without platelet transfusion Modified dose LMWH Participants will be given a modified dose LMWH as below based on the first platelet count of the day (checked daily in admitted participants or at least two times a week in outpatients), without platelet transfusion: 1. Platelet count 25‐50 x10e9/L: 50% dose LMWH (approximately 50% of the full dose listed below for different LMWH) 2. Platelet count <25 x10e9/L: hold anticoagulation Study arm with platelet transfusion Higher dose LMWH with platelet transfusion support For the first 14 days, participants will be transfused one unit of platelet when the first platelet count of the day falls below 50 X10e9/L (checked daily in inpatient or at least two times a week in outpatient) and given the higher dose of LMWH after platelet transfusion based on pre‐transfusion platelet count as below. As post‐transfusion counts may not be readily available and can delay the administration of anticoagulation, it will not be routinely required (but not prohibited): 1. Pre‐transfusion platelet count 25‐50 X10e9/L: 100% dose LMWH after platelet transfusion 2. Pre‐transfusion platelet count <25 X10e9/L: 50% dose LMWH after platelet transfusion Platelet transfusion intervention will be performed until Day 14 after enrolment in the transfusion arm. Starting Day 15, participants will be transitioned to modified dose LMWH without platelet transfusion as the other arm. Participants will continue to be followed for a total of 30 +/‐3 days. Both study arms fall within the international guidance from the International Society on Thrombosis and Haemostasis (ISTH) and current UK practice as described in the CAVEAT observational study. LMWH will CONDITION: Patients with cancer‐associated thrombosis and thrombocytopaenia ; Haematological Disorders PRIMARY OUTCOME: The primary feasibility outcome is the number of participants recruited from all centres per month over 18 months INCLUSION CRITERIA: 1. Adult participants (age =18 years) with active malignancy (malignancy diagnosed or treated within the previous 6 months, or progressive/relapsed) 2. Imaging confirmed pulmonary embolism, deep vein thrombosis (proximal or distal, including central venous catheter‐related DVT), or unusual site VTE (either symptomatic or incidentally diagnosed) within the last 14 days for which anticoagulation is planned (including VTE in the deep vein system that progressed from a prior superficial vein thrombosis for which anticoagulation is to be started) 3. Platelet count <50 X10e9/L from cancer therapy or malignancy itself 4. Able to provide written informed consent SECONDARY OUTCOME: Feasibility:; 1. Proportion of eligible participants who provide consent by 18 months; 2. Reasons for non‐participation in eligible participants by 18 months; 3. Proportion of participants who complete study procedures by 18 months; 4. Proportion of participants who adhere to the protocol (such as anticoagulation, transfusion, platelet count monitoring according to the protocol) by 18 months; 5. Rates of withdrawal, loss to follow‐up, or crossover between treatment arms by 18 months; ; Other:; 1. Duration of thrombocytopaenia (days of platelet count <25 or 50 x10e9 /L) per participant by day 30 +/‐ 3 days; 2. Number of transfused packed red cells and platelet units – with one red cell unit being one standard UK adult unit of packed red cells with a volume of 220‐340 ml and one platelet unit being one standard UK adult platelet dose with a mean of around 3 × 10e11 platelets by day 30 +/‐ 3 days; 3. Feasibility of collection of health‐related quality of life data using EuroQoL‐EQ‐5D‐5L questionnaire (% completed) by day 30 +/‐ 3 days