ABSTRACT
BACKGROUND: Measuring platelet activation in patients has become a potent method to investigate pathophysiological processes. However, the commonly applied markers are sensitive to detrimental influences by in vitro platelet activation during blood analysis. OBJECTIVES: Protein isoforms of platelet-derived thrombospondin-1 (TSP-1) were investigated for their potential to identify in vitro platelet activation when monitoring in vivo processes. METHODS: TSP-1 was determined in plasma, serum or supernatant of purified platelets by ELISA and immunoblotting and was compared with standard markers of platelet activation. A collective of 20 healthy individuals and 30 cancer patients was analyzed. RESULTS: While in vitro platelet degranulation led to a selective increase in the 200-kDa full-length molecule, an in vivo process involving platelet activation such as wound healing resulted in the predominant rise of the 140-kDa TSP-1 protein. The physiological ratio of circulating TSP-1 variants was determined and a cut-off level at 1.0 was defined to identify plasma samples with artificial in vitro platelet activation exceeding the cut-off level. In contrast, cancer patients known to frequently exhibit increased in vivo activation of platelets presented with a significantly decreased ratio of TSP-1 variants as compared with healthy volunteers. CONCLUSIONS: In comparison to standard platelet markers, TSP-1 constitutes a sensitive and stable parameter suited to monitor in vitro platelet activation. The analysis of TSP-1 protein isoforms further offers a valuable tool to reliably discriminate between in vitro and in vivo effects, to exclude variability introduced during blood processing and improve clinical monitoring.
Subject(s)
Platelet Activation , Thrombospondin 1/blood , Adult , Aged , Case-Control Studies , Female , Humans , In Vitro Techniques , Male , Middle Aged , Neoplasms/blood , Protein Isoforms , Recombinant Proteins/chemistry , Temperature , Thrombospondin 1/chemistry , Time Factors , Wound HealingABSTRACT
Fifty-two previously untreated patients with multiple myeloma were randomized to either a combination of recombinant interferon (rIFN) alpha-2 and chemotherapy or chemotherapy alone. Patients were treated with vincristine, melphalan, cyclophosphamide and prednisolone every 4-6 weeks. In the combined treatment arm rIFN was administered concurrently with chemotherapy as well as during chemotherapy free intervals. The combined regimen effected 17/21 (80.9%) responses as compared to 19/27 (70.4%) responses in VMCP treated patients. Addition of rIFN to chemotherapy did not enhance hematologic toxicity. These findings suggest a somewhat higher rate of objective response in the VPMC + rIFN group, although a significant improvement in median survival by adding rIFN to conventional first line polychemotherapy in myeloma patients has not yet been achieved.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Interferon Type I/administration & dosage , Interferon-alpha/administration & dosage , Multiple Myeloma/therapy , Adult , Aged , Clinical Trials as Topic , Combined Modality Therapy , Cyclophosphamide/administration & dosage , Female , Humans , Interferon alpha-2 , Male , Melphalan/administration & dosage , Middle Aged , Prednisone/administration & dosage , Prospective Studies , Random Allocation , Recombinant Proteins , Vincristine/administration & dosageABSTRACT
A total of 18 patients with advanced metastatic renal cell cancer were treated with recombinant interferon alpha-2C (rIFN alpha-2C) at daily doses of 10 X 10(6) IU by intramuscular injection. All patients had evaluable metastatic lung, liver, or abdominal disease as measured by radiographic or computerized tomographic scans. In 2 of the 18 patients an objective response (1 CR, 1 PR) with a duration of +28 and 12 months, respectively was achieved. A 25$ to 50$ decrease in tumor measurements (MR) was seen in 2 additional patients; in 3 cases a stabilisation of the disease (SD) was observed, whereas it progressed in 11. 3/4 responding patients (including MR) and all 3 cases with SD had measurable disease in the lungs as predominant site of metastatic disease. Additional clinical characteristics of patients exhibiting response or SD to IFN therapy included prior nephrectomy, favourable initial performance status and limited metastatic disease. No serious haematologic or irreversible organ toxic effects were attributed to interferon. Several patients, however, had constitutional symptoms, and major dose reductions due to CNS toxicity became necessary in two. Further studies are warranted to evaluate the use of interferons in combination with cytotoxic drugs or other biologic response modifiers.