Assessment of Thalidomide Therapy Effect on Platelet Activation and Selected Blood Coagulation Parameters in Multiple Myeloma Patients

Background: Patients with multiple myeloma are at relatively high risk of developing thromboembolic events (TEE). These life-threatening complications may arise from hypercoagulability associated with malignancy and/or may be connected with anticancer therapy. The risk of developing TEE appears to be particularly high during treatment with thalidomide alone or combined with chemotherapy and/or high-dose dexamethasone. The pathogenesis of thalidomide-related thrombosis in myeloma patients remains unexplained. Some authors suggest that platelet activation can contribute to development of this complication in multiple myeloma patients on thalidomide therapy but until now it has not been a subject of investigation.

Patients and methods: The study was performed in 20 patients with multiple myeloma. The tests were done at diagnosis and after one month of thalidomide therapy at a dose of 100–200 mg/24h. All patients had normal renal function and did not take drugs affecting platelet function. The control group consisted of 15 healthy subjects of similar age. In each patient closure time with ADP/Collagen and Epinephrine/Collagen cartridges by PFA-100 method was assessed. Platelet expression of membrane activation marker P-selectin (CD62p) on resting platelets and after stimulation with ADP/Collagen and Epinephrine/Collagen was analyzed by flow cytometry. Additionally, activity of factor VII, factor VIII and von Willebrand factor (vWF), concentration of fibrinogen and D-dimer, and platelet count were evaluated.

Results: The mean PFA-100 closure time was significantly shortened with ADP/Collagen (87.2 ±17.1 s vs 100.4 ± 19.3 s, p=0.008) and Epinephrine/Collagen cartridges (118.5 ± 20.3 s vs 132.2 ± 27.9 s, p=0.04) after one month of therapy in comparison to baseline. The median CD62p percentage increased markedly after treatment-on resting platelets 5.1 (0.76–22.2) vs 3.6 (0.1–21.5) p=0.03. and after stimulation with Epinephrine/Collagen 16.6 (2.3–57.3) vs 11.1 (1.4–19.5) p=0.03. The observed increased P-selectin expression after ADP/Collagen stimulation 26.3 (8.5–42.8) vs 19.7 (1.0–35.4) was not statistically significant. The median values of P-selectin expression at diagnosis and after thalidomide therapy were also higher than in the control group. The results of factor VIII, vWF activity, fibrinogen and D-dimer concentration did not differ markedly before and after therapy. Significantly lower mean activity of factor VII (p=0.004) and higher mean platelet count (p=0.03) after therapy were observed.

Conclusions: These results demonstrate that platelet activation is one of the pathogenetic factor of thalidomide-related thrombotic complications and can explain some observations that acetylsalicylic acid may protect against TEE during myeloma treatment with thalidomide.