A Phase 2 Study of VLX-1005 Versus Placebo in Suspected Heparin Induced Thrombocytopenia

Over 12 million patients are treated with heparin each year in the United States. Heparin induced thrombocytopenia (HIT) is a recognized complication of heparin therapy and is characterized by the formation of antibodies to heparin and platelet factor 4 (PF4). The scale of the clinical problem is illustrated by cardiopulmonary bypass patients, half of whom develop antibodies to PF4/heparin complexes. In a significant proportion of such seropositive HIT patients, these antibodies will bind to and activate platelets, resulting in a drop in the number of platelets (thrombocytopenia) and activation of the coagulation (clotting) system. Formation of clots in this manner can lead to stroke, heart attacks, damage to internal organs or to limbs, and even death.

The current standard of care with anticoagulants such as argatroban or bivalirudin have not proven effective in reducing poor outcomes in HIT: major morbidity and death rates remain high (> 20%). In addition, these anticoagulants increase the risk of major bleeding (~20%) which can prove to be a fatal complication of such therapy.

VLX-1005 has been developed to address the major unmet clinical need for safer, more effective therapy for HIT. VLX-1005 is a drug that blocks the 12-lipoxygenase (12-LOX) pathway that is believed to be responsible for platelet activation in HIT. In animal models of HIT, VLX-1005 can prevent or treat HIT and halt the development of both thrombocytopenia and abnormal blood clots. The drug has not been associated with increased bleeding in either animals or healthy human volunteers.

The current study will enroll patients suspected of having HIT by clinical measures (4T score) and by laboratory testing (heparin-PF4 immunoassay). Patients will be randomly assigned in a double-blind fashion to either VLX-1005 intravenously or placebo. All patients will receive current guideline mandated therapy for HIT that will include the standard of care anticoagulation: either argatroban or bivalirudin. Patients will be treated for 7 to 14 days until the platelet count has recovered into the normal range. The study will measure important outcomes including platelet count recovery time, stroke, pulmonary embolus, deep vein thrombosis, myocardial infarction, limb and organ injury, and major bleeding.

Inclusion Criteria:

1. Adult participants ≥ 18 years of age.
2. Able to provide informed consent or have informed consent provided on their behalf by a primary caregiver prior to study-related activities being initiated.
3. Recent unfractionated heparin or low-molecular-weight heparin exposure.
4. Qualifying platelet count < 150 X 10^9/L and clinical 4T score of ≥ 4; candidate for argatroban or bivalirudin treatment.
5. Positive PF4-immunoassay (eg, ELISA [≥ 1.0 optical density units], LIA [≥ 1.0 U/mL], CLIA [≥ 1.0 U/mL]).

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Exclusion Criteria:

1. Previous treatment with argatroban or bivalirudin for > 48 hr prior to randomization.
2. Participants cannot receive other anti-coagulants, such as fondaparinux and danaparoid, or direct oral anti-coagulants, such as rivaroxaban as initial standard of care.
3. QT interval corrected by the method of Fridericia (QTcF) > 450 msec for males, > 470 msec for females.
4. History of hepatitis C antibody, hepatitis B surface antigen, or human immunodeficiency virus (HIV) antibody at screening.
5. Current renal disease with a calculated creatinine clearance less than 30 mL/min.
6. Participants with a history of substance abuse or dependency or history of recreational IV drug use (by self-declaration).
7. Participant has a suspected history of alcohol abuse in the 6 months prior to screening.
8. Participants who are unlikely to comply with the study protocol or, in the opinion of the investigator, would not be a suitable candidate for participation in the study.
9. Participants with cancer, having a life expectancy of < 12 months.
10. Current diagnosis of or any other clinically significant indication of active sepsis
11. Pregnant or lactating women.
12. Have participated in any other investigational drug trial within 30 days of dosing or 5 half-lives (whichever is longer) in the current study.