This study was terminated due to loss of funding for this indication from the Biomedical Advanced Research and Development Authority (BARDA) in November 2022.

This prospective, multicenter, randomized, open-label, Phase 2, parallel, dose ranging, multidose trial will enroll patients into 3 Thrombosomes dose groups and 1 control liquid stored platelets (LSP) group in order to evaluate, in a dose-escalation manner, the safety, and impact on bleeding, and the preliminary effect on coagulation measures of increasing doses of allogeneic Thrombosomes in comparison to standard of care, LSP.

Inclusion Criteria:

1. Adults (≥18 years) with TCP as defined by BOTH (a) and (b):

   1. a platlet count of ≤ 70,000 platelets/μL blood

   2. ANY ONE OR MORE of (1-3):

      1. confirmed diagnosis of hematologic malignancy, myeloproliferative disorder, myelodysplastic syndrome, or aplasia
      2. undergoing chemotherapy, immunotherapy, radiation therapy or hematopoietic stem cell transplantation
      3. refractory to platelet transfusion defined as two 1-hour CCI of <5,000 on consecutive transfusions of LSP or as defined by local site policy (Sacher, 2003)

2. WHO Bleeding Score of 2 or 3

3. Able to provide informed consent directly or through legally authorized representative, and comply with treatment and monitoring

4. Negative pregnancy test for women of childbearing potential

Exclusion Criteria:

1. Any disorder or condition related to any venous thrombosis, embolism, or ischemia within the past 3 months
2. Any disorder or condition related to arterial thrombosis including: ischemia, stroke, MI, or stent placement, within past 6 months
3. Any valve replacement and/or repair of left atrial appendance occlusion device
4. Sinusoidal obstruction syndrom (veno-occlusive disease) or cytopkine release syndrome associated with CAR-T cell therapy
5. Refusal to accept blood products
6. Liver enzyme blood levels greater than 3× the upper limit of normal (ULN)
7. Blood creatinine level greater than 3× ULN
8. Received platelet inhibitor drugs, cyclooxygenase-2 (COX-2) inhibitors, or nonsteroidal anti-inflammatory drugs within 5 days prior to infusion
9. Currently (at the time of randomization) receiving anticoagulant therapy or antiplatelet therapy. Low dose prophylaxis for line clots is not excluded.
10. Receipt of any pro-coagulant agents (e.g., DDAVP, recombinant Factor VIIa or prothrombin complex concentrates (PCC)) other than Tranexamic Acid (TXA) or Epsilon Aminocaproic Acid (EACA, Amicar), within 48 hours of first infusion, or with known hypercoagulable state
11. WHO Bleeding Score of 2 solely due to lumbar puncture, retinal bleeding or GI bleeding or WHO Bleeding Score of 3 solely due to lumbar puncture
12. Receiving L-asparaginase as part of a current cycle of treatment
13. Known inherited or acquired bleeding disorder including, but not limited to: acquired storage pool deficiency or paraproteinemia with platelet inhibition
14. Known inherited or acquired prothrombotic disorders, including antiphospholipid syndrome (Those with lupus anticoagulant or positive antiphospholipid serology without thrombosis are NOT excluded.)
15. Anuria
16. On dialysis
17. Receipt of an investigational drug within 1 month before first infusion, other than for treatment of their underlying disease
18. Females pregnant or nursing or unwilling to use contraception during and for 30 days after taking the study product (females). Evidence of effective birth control may be used, at the discretion of the physician
19. Acute or chronic medical disorder that, in the opinion of the Investigator, would impair the ability of the patient to receive or respond to study treatment
20. Prior participation in this study with successful infusion of the investigational or control product
21. Currently enrolled in other trials not related to their primary disease process or involving platelet transfusions, platelet growth factors, or other pro-coagulant agents