SummaryHirulog™ (BG8967) is a direct thrombin inhibitor built by rational design using the protein hirudin as a model (Maraganore et al. [1990]; Biochemistry 29: 7095–101). In order to evaluate the therapeutic potential for hirulog in the management of thrombotic disease, the tolerability and anticoagulant activity of the agent were examined in a study of human volunteers.In a randomized, placebo-controlled study (n = 54), the intravenous infusion of hirulog over 15 min showed a rapid, dose-dependent prolongation of activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT). There was a corresponding dose-dependent increase in plasma hirulog levels. The peptide was rapidly cleared with a half-life of 36 min and a total body clearance rate for the peptide of 0.43 1 kg−1 h−1. Similar activity was observed following subcutaneous injection but with sustained pharmacodynamic and pharmacokinetic behavior. There was a significant correlation between pharmacokinetic and pharmacodynamic variables for both intravenous (r = 0.8, p <0.001) and subcutaneous administration (r = 0.7, p = 0.002).To evaluate the possible interactions of aspirin on the tolerability and anticoagulant activity of intravenous hirulog, a cross-over design was employed in eight subjects. Aspirin administration did not modify the peptide’s activity. At the administered dose of 0.6 mg kg−1 h−1 for 2 h, hirulog infusion prolonged APTT from 230 to 260% baseline. The infusion of hirulog in subjects who had received aspirin was not associated with any significant changes in the template bleeding time.The final phase of the study examined the activity and tolerability of hirulog in ten subjects during prolonged intravenous infusions for up to 24 h. The peptide (0.3 mg kg−1 h−1) exhibited sustained anticoagulant activity with no evidence for a cumulative effect. During hirulog infusion, APTT was prolonged from 210 to 250% baseline.In all phases of the study, hirulog administration was generally well-tolerated.Our observations show that hirulog is an active antithrombin agent with excellent tolerability in humans. As a direct thrombin inhibitor, hirulog provides a novel approach for the management of thrombotic disease.

Br J Clin Pharmacol 59:2 244-248 244

Human recombinant DNA interferon gamma (IFN-G), with a specific activity of 2 X 10(6) IU/mg protein, was administered s.c. 3 days per week for 2 months to patients with solid tumors. The maximum tolerated dose (MTD) was 10 X 10(6) IU/m2 (5.0 mg/m2) per injection, and six patients were treated at the MTD. Two of these ceased treatment because of severe subjective toxicity (headache, rigors and pyrexia) and three patients developed WHO grade 3 leucopenia. Subjective toxicity varied considerably between patients and some patients at low dose levels experienced severe constitutional symptoms whilst others treated at the MTD had few side effects. These differences were unrelated to pharmacokinetic parameters. Bioavailability of this IFN-G administered s.c. was very variable from one patient to another at the same dose level. We therefore counsel caution in using this IFN-G preparation s.c. in phase II studies.

Thirty-five patients with a diagnosis of non-Hodgkin's lymphoma of low histological grade were treated with 2 X 10(6)/m2 of human rDNA alpha 2 IFN-a2 by subcutaneous injection. Treatment was continued until progressive disease was documented or one year of therapy had been given. None of the patients had to stop treatment because of toxicity and no treatment delays or suspensions of therapy were necessary as a consequence of myelosuppression. Thirty four patients were evaluable and seventeen (50%) obtained an objective response (2 CR, 15 PR) with a median duration of eleven months. Sixteen patients were untreated prior to receiving interferon but were felt to need some form of therapy rather than be suitable for a watch policy. Eleven of these patients responded (69%) with 95% confidence limits lying between 41% and 89%. No other pretreatment factors appeared to affect the likelihood of response. Single agent IFN-alpha 2 has significant activity in the low grade non-Hodgkin's lymphomata and warrants further investigation in this disease.