Long-term Effects of Thalidomide for Recurrent Gastrointestinal Bleeding Due to Vascular Malformation

Overview

Background: Repeated episodes of bleeding from gastrointestinal vascular malformations refractory to endoscopic or surgical therapy often pose a major therapeutic challenge. Methods: The investigators performed a randomized, parallel controlled study of thalidomide as a therapy for recurrent gastrointestinal bleeding due to vascular malformation. Patients with at least six episodes of bleeding in the prior year due to vascular malformation were randomly grouped, prescribed a four-month regimen of either 25 mg of thalidomide or 100 mg of iron orally four times daily, and monitored for at least one year. The primary end point was defined as the patients whose rebleeds decreased from baseline by ≥ 50% at 12 months and the cessation of bleeding. Rebleeding was defined based on a positive fecal occult blood test (FOBT) (monoclonal colloidal gold color technology) at any visit after treatment. Secondary outcomes included the participants dependent on blood transfusions and changes from baseline in transfused packed red cell units, bleeding episodes, bleeding durations, and hemoglobin levels at 12 months. Statistical significance was defined at P \< 0.05.

Protocol Description: This is an exploratory, randomized, parallel controlled study of thalidomide for recurrent gastrointestinal bleeding from vascular malformations. Informed consent was taken from all subjects and the Institute Ethics Committee approved the study protocol. All procedures were in accordance with the Declaration of Helsinki. The study was supported by no pharmaceutical funding. Study design and Intervention: From Nov. 2004 to Nov. 2007, patients with repeated episodes of chronic gastro-intestinal bleeding due to vascular malformations identified by oesophagogastroduodenoscopy, capsule endoscope or double-balloon endoscope were enrolled (according our enrollment criteria). The patients were randomly assigned to receive a four-month course of either 25 mg of thalidomide or 100mg iron orally at daily time 6 a.m.,12 noon,6 p.m. and 10 p.m., respectively. Randomization was performed through the proc plan procedure of Statistical Analysis Software (SAS), using the method of randomly permuted blocks of 4. Within each block, the number of patients allocated to each of the two treatments was equal. Each patient who met the inclusion criteria was consecutively assigned a random number in chronological order, which allocated him or her to one of the treatment groups. A blinded research nurse supervised patient randomization and drug administration. In the case of an adverse event, the study medication was temporarily or permanently discontinued based on subject inclination and toxicity intolerance. Concomitant therapies, such as blood transfusions and other symptomatic treatments like iron supplementation, were performed in both groups as necessary during the four-month treatment and subsequent follow-up periods. Blood transfusion was indicated and recorded when the hemoglobin (Hb) level reached \< 7.0 g/dl. Red-cell transfusions were administered according to patient Hb level as follows: 2 units were administered for 6.1 g/dl ≥ Hb ≤ 7.0 g/dl, 3 units for 5.1 g/dl ≥ Hb ≤ 6.0 g/dl, and 4 units for Hb \< 5.0 g/dl. Iron was provided for patients with 7.0 g/dl ≥ Hb ≤ 11.0 g/dl. After the four-month treatment course, all patients discontinued study medications except for cases where symptomatic treatments were necessary as described above. Assessment of response and adverse events: The primary end point was defined as the patients whose rebleeds decreased from baseline by ≥ 50% at 12 months and the cessation of bleeding. Rebleeding was defined based on a positive fecal occult blood test (FOBT) (monoclonal colloidal gold color technology) at any visit after treatment. Secondary outcomes included the participants dependent on blood transfusions and changes from baseline in transfused packed red cell units, bleeding episodes, bleeding durations, and hemoglobin levels at 12 months. Adverse events included any unfavorable change in health, including abnormal laboratory findings, during the study or follow-up period. Evaluation of Patients and Follow-up: * Certified research nurses collected information on the demographics and medical and social histories of all patients enrolled in the study. * After screening and baseline evaluations, the patients were closely monitored in the hospital for at least one week. They were then followed twice monthly during the four-mouth course of treatment and once a month thereafter. * Clinical follow-up was performed by qualified doctors. At all visits, the bleeding-related parameters (number and duration), a physical examination was performed and laboratory values were obtained for FOBT, complete blood counts, serum chemistries, and hepatic and renal function. Neuropathy and other adverse events were also assessed. * Patients were advised to refrain from any other non-prescribed medicines, especially rebleeding-related medications such as aspirin, nonsteroidal antiinflammatory drugs (NSAIDs), anti-platelet drugs, anticoagulants, and Chinese medications (with salicylates), gingko, or Echinacea. Measurement of Vascular Endothelial Growth Factor (VEGF) in Sera: Laboratory assays for VEGF were performed at baseline and after the four-month treatment course in the thalidomide group, by a technician blinded to the assignment and final assessment. Three milliliters of serum of peripheral venous blood samples were centrifuged (3000 r/min at 4°C, 10 min), extracted, separated into freezing tubes, and stored at -70°C for no more than 4 months. Plasma VEGF levels (in pg/ml) were determined in duplicate using sandwich ELISA kits (R\&D Systems, USA) in a laboratory of the Shanghai Research Institute of Digestive Disease. Samples from each patient were batch-tested in a single run. For quality control, all samples were retested two more times in a subsequent run to confirm the results of the first run. Statistical Analysis: To our knowledge, no similar such study has previously been performed, and we were thus unable to refer to published studies to determine our samples. To this end, we performed an unpublished preliminary study. Response in the iron-control group and thalidomide group reached 10% and 80%, due to loose inclusion criteria (bleeding history was not restricted). For this study, we estimated that the primary outcome (the proportion of subjects whose number of yearly bleeds had decreased by ≥ 50%) would occur in 10% of the control group and 80% of the thalidomide group patients. An equally divided sample of 11 subjects was deemed sufficient for detecting the primary end point, with a type I error (two-sided) of 5% and a power of 90%. Assuming a 10% volunteer attrition rate to follow-up, we established a target sample size of 13 per group (calculated with nquery advisor software 5.0). Analyses of the responses and adverse events were performed on all registered patients according to the intention-to-treat principle. Statistical analysis was performed by a blinded biostatistician with the Statistical Product and Service Solutions (SPSS) 13.0 software package. We simultaneously analyzed the primary endpoint of the full analysis set (FAS) and per protocol set (PPS). Continuous variables were compared using a two-sample independent t-test or Wilcoxon rank-sum test. Categorical variables were compared using the chi-squared and Fisher's exact tests. A paired t-test was employed to compare differences in plasma VEGF levels before and after thalidomide treatment. The Breslow-Day test was used to test for the heterogeneity of treatment effects across strata. All reported P-values are two-sided. Data are reported as the mean ± standard deviation (SD) or median (range) for continuous variables and number (%) for categorical variables. Since adjustments to the control group were minimal, we also reported point estimates and 95% confidence intervals (CIs). For all outcomes, a P-value of \< 0.05 was considered statistically significant.