The purpose of this study is to study the safety and efficacy of pooled buffy-coat derived platelets which had been frozen with dimethyl sulphoxide (DMSO), in the prevention of bleeding for patients with hypoproliferaitve thrombocytopenia. These platelets are hereafter referred to as cryopreserved platelets. Patients who have severely low platelet count due to impaired bone marrow function from chemotherapy or certain haematological conditions may need platelet transfusion to prevent spontaneous bleeding. Currently, platelets are stored in liquid form, and must be used within five to seven days of collection. In this study, DMSO is used to preserve platelets during freezing so that they can be stored for longer than five to seven days. Investigators hope to learn if thawed cryopreserved platelets are functional and safe for transfusion in humans.

Platelets are currently stored in liquid form for a maximum of five to seven days. To extend the shelf-life of platelets, DMSO is added to freeze platelets for long-term storage. In vitro studies have shown that such cryopreserved platelets can be kept for at least two years at -80oC. This study is a clinical trial that aims to primarily assess the safety of cryopreserved pooled buffy coat-derived platelets in patients with hypoproliferative thrombocytopenia and no platelet refractoriness.

Subjects will be randomised into two arms either a liquid platelet (control) or frozen platelet arm (treatment) and may receive four or more platelet transfusions per thrombocytopenic cycle. Each subject may participate in the study for up to two thrombocytopenic period, assuming a wash-out period of at least five days (during which the subject receives no platelet transfusions) between the two thrombocytopenic periods. If subjects participate in the study for more than one thrombocytopenic period, they will automatically be enrolled in the opposing arm for their second thrombocytopenic period.

Inclusion Criteria:

1. ≥ 21 years of age
2. Be able to provide written informed consent
3. Current or potential hypoproliferative thrombocytopenia with expected platelet count of <20 X 109/L for a minimum of 5 days in a 28-day period
4. If pre-menopausal female of child bearing potential, then the subject must have a negative serum pregnancy test prior to study commencement, and must be using an acceptable method of contraception during the study.
5. Calculated creatinine clearance of >30 ml/min (as calculated based on the Cockcroft-Gault equation; National Kidney Foundation 2017) at the point of recruitment, and within one week before transfusion

Exclusion Criteria:

1. Not meeting the inclusion criteria specified above
2. Pregnant
3. Breastfeeding
4. Current platelet refractoriness
5. History of allergy or adverse reaction to DMSO
6. History of veno-occlusive disease
7. History of acute venous or arterial thromboembolism within the last 3 months.
8. History of unprovoked venous thromboembolism
9. On antiplatelets, NSAIDs or anticoagulants within 1 week, and TCM (traditional Chinese medicine) which are known to decrease platelet count or platelet function or increase bleeding tendency within 2 weeks of study enrolment.
10. Received or will be receiving L-asparaginase chemotherapy within 7 days of platelet transfusion
11. Renal impairment with calculated creatinine clearance of <30ml/min.
12. Non-cutaneous Grade 2 and above bleeding at the time of study assessment
13. Presently with or a history of acute promyelocytic leukemia (APML), immune thrombocytopenic purpura (ITP), thrombotic thrombocytopenic purpura (TTP), haemolytic-uremic syndrome (HUS), or any thrombotic microangiopathy (TMA)
14. Presently with or a history of heparin-induced thrombocytopenia
15. Presently with disseminated intravascular coagulation (DIC) or other risk factor(s) for bleeding other than thrombocytopenia (including platelet dysfunction, PT ≥ 1.3 X upper limit of normal for the laboratory, PTT ≥ 1.3 X upper limit of normal for the laboratory, or fibrinogen ≤ 1 g/L)
16. History of anaphylaxis from blood transfusion
17. Involved in any other therapeutic clinical trials in the last 6 months prior to the start of this research
18. Concomitant participation in other therapeutic clinical trials during the full period of this study
19. Receiving non-trial-related medication that might compromise transfusion safety
20. Known history of congenital bleeding disorder
21. Subject who declined to consent for platelet transfusion

Will not be sharing individual participant data collected in this study to other researchers.