Treatment for patients with cancer

Cancer-associated thromboembolism: antithrombotic management of hospitalized patients

Cancer increases risk for venous thromboembolism. Incident thrombocytopenia increases hemorrhagic risk. Hospitalized adults with a cancer diagnosis who received subcutaneous dalteparin in doses adjusted according to platelet count were retrospectively evaluated. Outcomes of interest included nadir platelet counts, transfusions, thromboembolism, and hemorrhage. During a 2-year period of observation, 1854 cancer patients received individualized inpatient treatment with dalteparin. Transfusion was required in 38 of 77 (49.4%) patients with nadir platelet counts < 25 × 10⁹ cells/L as compared with 16 of 75 (21.3%) patients whose nadir platelet counts were 25-50 × 10⁹ cells/L [risk ratio (RR) 2.31; 95% CI 1.42 to 3.78, p < 0.001] and 45 of 1657 (2.7%) patients with platelet counts > 50 × 10⁹ cells/L (RR - 8.07; 95% CI - 4.79 to - 13.59, p < 0.001). Transfusions were administered primarily as supportive therapy. Among transfusion recipients, new or recurrent venous thromboembolism was documented in 2.6%, 0%, and 2.2% of patients with nadir platelet counts of < 25, 25-50, or > 50 × 10⁹ cells/L, respectively (p > 0.9 for all comparisons). Acute blood loss or major bleeding was documented in 10.5%, 12.5%, and 15.6% of patients with platelet counts of < 25, 25-50, or > 50 × 10⁹ cells/L, respectively (p > 0.9 for all comparisons). Among hospitalized cancer patients who received individualized dalteparin treatment, transfusion requirements varied inversely with platelet count. Irrespective of platelet counts, occurrence rates for venous thromboembolism and acute hemorrhage were similar across all treatment groups. Individualized dalteparin treatment provided a consistent pattern of safety and effectiveness.

von Willebrand factor fibers promote cancer-associated platelet aggregation in malignant melanoma of mice and humans

Tumor-mediated procoagulatory activity leads to venous thromboembolism and supports metastasis in cancer patients. A prerequisite for metastasis formation is the interaction of cancer cells with endothelial cells (ECs) followed by their extravasation. Although it is known that activation of ECs and the release of the procoagulatory protein von Willebrand factor (VWF) is essential for malignancy, the underlying mechanisms remain poorly understood. We hypothesized that VWF fibers in tumor vessels promote tumor-associated thromboembolism and metastasis. Using in vitro settings, mouse models, and human tumor samples, we showed that melanoma cells activate ECs followed by the luminal release of VWF fibers and platelet aggregation in tumor microvessels. Analysis of human blood samples and tumor tissue revealed that a promoted VWF release combined with a local inhibition of proteolytic activity and protein expression of ADAMTS13 (a disintegrin-like and metalloproteinase with thrombospondin type I repeats 13) accounts for this procoagulatory milieu. Blocking endothelial cell activation by the low-molecular-weight heparin tinzaparin was accompanied by a lack of VWF networks and inhibited tumor progression in a transgenic mouse model. Our findings implicate a mechanism wherein tumor-derived vascular endothelial growth factor-A (VEGF-A) promotes tumor progression and angiogenesis. Thus, targeting EC activation envisions new therapeutic strategies attenuating tumor-related angiogenesis and coagulation.

Antithrombotic Therapy in Patients With Thrombocytopenic Cancer

Background:

Guidelines are discordant concerning management of patients having thrombocytopenia with cancer-associated thrombosis (CAT).

Methods:

Hospitalized adults with CAT and platelets ≤50 × 109 cells/L were managed with dalteparin 100 units/kg subcutaneously once daily. Comparator patients with CAT and platelets >50 × 109 cells/L were managed with dalteparin 200 units/kg/d.

Results:

Outcomes of 35 patients with thrombocytopenia (mean platelet count 26 ± 8.3 × 109 cells/L) and 58 comparator patients (mean platelet count 155 ± 75 × 109 cells/L) were evaluated. In all, 2 (5.7%) patients in the thrombocytopenia group and 1 patient (1.9%) in the comparator group experienced new-onset venous thromboembolism (odds ratio 3.31, 95% confidence interval [CI] 0.29-37.90, P = .556). The incidence of bleeding in patients with thrombocytopenia (8.6%) was similar to that in comparator patients (9.4%; risk ratio 0.94, 95% CI 0.37-2.39, P = .607).

Conclusion:

In hospitalized patients having thrombocytopenia with CAT, reduced-dose low-molecular-weight heparin was generally efficacious.