Recombinant human TNF-alpha: preclinical studies and results from early clinical trials

The application of recombinant DNA technology to the production of tumor necrosis factor has resulted in the availability of large quantities of a highly purified protein product. This product has been evaluated extensively in preclinical studies, which have documented a direct cytostatic and cytotoxic effect on human tumor cells, as well as a variety of immunomodulatory effects on various immune effector cells, including neutrophils, macrophages, and T cells. In addition, a number of anti-infective and metabolic effects have been documented. In addition to its in vitro effects, rTNF has been shown to have antitumor activity in vivo in preclinical studies involving both transplantable murine tumors and human tumor xenografts. Such observations have led to the evaluation of rTNF as a potential antineoplastic agent in humans. Both single- and multiple-dose phase I studies have confirmed that rTNF can be safely administered to patients with advanced malignancies in a dose range associated with anticancer effect without concomitant serious toxicities such as shock and cachexia. The most commonly observed clinical toxicities include constitutional symptoms, such as fever, chills, headache, and fatigue, and toxicities, which can be at least partially controlled with concomitant administration of nonsteroidal anti-inflammatory drugs, such as acetaminophen and meperidine. Hypotension, which occurs at high doses administered by short intravenous infusion, can usually be prevented by prehydration with intravenous fluids or otherwise controlled by the administration. An intense local inflammatory reaction at the injection site as well as thrombocytopenia appear to be the dose-limiting toxicities after subcutaneous and intramuscular administration. Neurologic toxicity is infrequent, except following continuous intravenous infusion, where it may manifest as transient focal neurologic deficits or seizure. Prolonged administration of rTNF at higher doses may be associated with transient, subclinical decreases in diffusing capacity. Patients with underlying cardiopulmonary disease should be excluded from rTNF therapy in future clinical studies until the end-organ toxicities of this agent are better defined. For at least one preparation of rTNF there appears to be no evidence for the formation of antibodies to rTNF in patients who receive multiple administrations of the agent. Pharmacokinetic studies have shown a relatively rapid clearance following intravenous infusion with a half-life of 15 to 30 min and dose-dependent pharmacokinetics. rTNF can be detected in the serum following intramuscular or subcutaneous injection at only relatively high doses, suggesting a decreased bioavailability with the routes of administration. Early phase I studies defined tolerable dose ranges for each route of administration and began to explore immunomodulatory and metabolic effects of rTNF.(ABSTRACT TRUNCATED AT 400 WORDS)