Prevention of immunotoxin-mediated vascular leak syndrome in rats with retention of antitumor activity.

Abstract

Immunotoxins are hybrid molecules composed of a cell-surface bin domain and a protein toxin moiety that together target sifc cell popaons for elimination. These Vascular leak syndrome (VLS) is the dose-limiting toxicity found in many clinical trials utilizing immunotoxins, including those prepared with blocked ricin, ricin A chain (in native and deglycosylated forms), and saporin (1-10). VLS is characterized in humans by hypoalbuminemia, weight gain, and edema, resulting from the extravasation offluids and proteins from the vascular system into the periphery. VLS restricts the use of immunotoxins in humans and in many cases necessitates either a significant reduction in dose or a complete cessation of therapy. While peripheral edema is clinically manageable, pulmonary edema can be life threatening. Recently, VLS was found to have contributed to the death of two B-cell lymphoma patients who were treated with anti-CD22-deglycosylated ricin A chain (9). Other toxic effects in patients treated with immunotoxins may be a result of VLS, including tachycardia, nausea, aphasias as a result ofcerebral edema, and myocardial damage (4).Other proteins also have been found to induce VLS in humans. Systemic administration of the cytokine interleukin 2 (IL-2) results in the development ofVLS when approaching doses that may provide antitumor efficacy in patients with metastatic cancer (11,12). VLS has also been observed in patients following treatment with granulocyte/macrophage colony-stimulating factor or the anti-GD3 antibody R24 (13,14).BR96 sFv-PE40 is a single-chain immunotoxin fusion protein that has been shown to cure established human tumor xenografts in both athymic rats and mice (15,16). In this study, a rat model for VLS was established following administration of BR96 sFv-PE40 at doses beyond those required for cures of tumor xenografts in rodent models. The identification of an animal model for VLS that closely approximates the human VLS response to immunotoxins provides an opportunity to evaluate specific drugs for their ability to block immunotoxin-induced VLS and to determine whether they affect the antitumor activity of BR96 sFv-PE40. MATERIALS AND METHODSReagents. The single-chain immunotoxin fusion protein BR96 sFv-PE40 was expressed in Escherichia coli and purified as described (16). Diphenhydramine hydrochloride was purchased from Elkins-Sinn (Cherry Hill, NJ). Cyclosporine A (CsA) was purchased from Sandoz Pharmaceutical. 15-Deoxyspergualin (DSG) was purchased from Nippon Kayaku (Tokyo). Dexamethasone (Dex) was purchased from Anpro Pharmaceuticals (Arcadia, CA).Toxicity Studies. Six-to 8-week-old female Wistar Furth and Rowett, nu/nu (athymic) rats (Harlan-Sprague-Dawley) were i.v. injected with various amounts of BR96 sFv-PE40 (0.25-4 mg/kg). After 24 hr, they were euthanized by exposure to C02, and the tissues were analyzed using gross and microscopic techniques. Cardiac blood was collected from comatose animals and placed either in serum collection tubes for blood chemistry analysis or in EDT...

Advances in Anticancer Immunotoxin Therapy

“…All patients on our studies receive premedication with dexamethasone, which has been shown to diminish severity of VLS [29,30]. In addition, bolus intravenous fluids are administered before each immunotoxin dose to transiently increase intravascular volume.…”

Acute Toxicity of Pierisin-1, a Cytotoxic Protein From Pieris Rapae, in Mouse and Rat

“…TNF-α and agonistic Fas are known to have also anticancer activity and administration of high dose TNF-α in humans (Schilling et al, 1992) and anti-Fas antibody in mouse (Ogasawara et al, 1993) is reported to cause hepatotoxicity by an unknown mechanism. In mice, an administration of BR96 sFv-PE40 induced no VLS but hepatic injuries (Siegall et al, 1994). In the present study, large administration of pierisin caused only hepatitis-type hepatic injury in mice without showing lymphoid organs injuries.…”

“…BR96 sFv-PE40-induced VLS are known to be suppressed by pretreatment of dexamethazone (Siegall et al, 1994) and nonsteroidal antiinflammatory drugs (NASIDs) (Siegall et al, 1997) and but not by histamine or serotonine (Siegall et al, 1994(Siegall et al, , 1997 or not reproduced in athymic rats (Siegall et al, 1994), suggesting a lack of T-cell response. Interleukin-2 (IL-2) induces VLS in mice and tumor necrosis factor-α (TNF-α) plays a central role in their mechanism (Rosenstain et al, 1986;Dubinett et al, 1994).…”

“…Immunotoxins, BR96 sFv-PE40 can induce VLS in rats as established as an animal model of VLS (Siegall et al, 1994). BR96 sFv-PE40-induced VLS are known to be suppressed by pretreatment of dexamethazone (Siegall et al, 1994) and nonsteroidal antiinflammatory drugs (NASIDs) (Siegall et al, 1997) and but not by histamine or serotonine (Siegall et al, 1994(Siegall et al, , 1997 or not reproduced in athymic rats (Siegall et al, 1994), suggesting a lack of T-cell response.…”

Immunotoxins for leukemia

“…37 The efficacy of steroid prophylaxis against PE-induced CLS has been demonstrated in a preclinical model. 77 Weldon et al have reported on an immunotoxin that has a deletion of a large portion of domain II of PE that is fully cytotoxic yet its nonspecific toxicities in mice, which may reflect the ability of these immunotoxins to cause CLS in patients, are greatly diminished. 13 …”