Alpha-mannosidosis in goats caused by the swainsonine-containing plant Ipomoea verbascoidea.

A disease of the nervous system is reported in goats in the semiarid region of northeastern Brazil. Histological examination showed diffuse vacuolation of neurons and epithelial cells of the pancreas, thyroid, renal tubules, and liver. The swainsonine-containing plant Ipomoea verbascoidea was found on both farms where the goats originated. This plant was experimentally administered to 3 goats, inducing clinical signs and histologic lesions similar to those observed in spontaneous cases. On the lectin histochemical analysis, cerebellar cells and pancreatic acinar cells gave positive reactions to Triticum vulgaris agglutinin (WGA), succinylated Triticum vulgaris agglutinin (sWGA), Lens culinaris agglutinin (LCA), Canavalia ensiformis agglutinin (ConA), Pisum sativum agglutinin (PSA), Ricinus communis agglutinin (RCA(120)), Arachis hypogaea agglutinin (PNA), and Phaseolus vulgaris erythroagglutinin (PHA-E) suggesting storage of α-fucose, α-D-mannose, α-D-glucose, ß-D-N-acetyl-glucosamine, N-acetyl-galactosamine, and acetyl-neuraminic acid. This pattern of lectin staining partially agrees with results previously reported for poisoning by swainsonine-containing plants. The chemical analysis of dried leaves of I. verbascoidea detected swainsonine (0.017%), calystegine B(1) (0.16%), calystegine B(2) (0.05%), and calystegine C(1) (0.34%). It is concluded that I. verbascoidea causes α-mannosidosis in goats.

Phase II study of the efficacy and safety of oral GD0039 in patients with locally advanced or metastatic renal cell carcinoma.

Seventeen patients with locally advanced or metastatic renal cell carcinoma (RCC) were enrolled in this phase II trial. The purpose of the trial was to assess the efficacy of the administration of oral GD0039, and to further assess the pharmacokinetics and pharmacodynamics of this drug. Patients were given an initial dose of 37.5 micro g/kg b.i.d for 3 weeks followed by one week off in each cycle, with the treatment continuing until disease progression or adverse effects. All 17 patients discontinued treatment due to disease progression or toxicity. Adverse events such as fatigue, nausea and diarrhea were common but generally mild. No evidence of anti-tumor activity of GD0039 was seen in this study.

Phase IB clinical trial of the oligosaccharide processing inhibitor swainsonine in patients with advanced malignancies.

The indolizidine alkaloid swainsonine, a potent inhibitor of Golgi alpha-mannosidase II, has been shown to reduce tumor cell metastasis, enhance cellular immune responses, and reduce solid tumor growth in mice. In our previous Phase I study, swainsonine administered by 5-day continuous infusion inhibited L-phytohemagglutinin-reactive N-linked oligosaccharide expression on peripheral blood lymphocytes. Significant toxicities included edema and elevated serum aspartate aminotransferase (AST). One patient with head and neck cancer had objective (>50%) tumor remission. Two patients showed symptomatic improvement. The objectives of this Phase IB trial were to examine the pharmacokinetics, toxicities, and biochemical effects of bi-weekly oral swainsonine at escalating dose levels (50-600 microgram/kg) in 16 patients with advanced malignancies and 2 HIV-positive patients unsuitable for conventional therapy. Eastern Cooperative Oncology Group performance status was 20% of patients included increase in serum AST (all patients), fatigue (n = 9), anorexia (n = 6), dyspnea (n = 6), and abdominal pain (n = 4). Inhibition of Golgi alpha-mannosidase II occurred in a dose-dependent manner. Examination of immunological parameters revealed a transient decrease in CD25(+) peripheral blood lymphocytes and, in seven of eight patients, an increase in CD4(+):CD8(+) ratios at 2 weeks. Serum drug levels peaked 3-4 h following a single oral dose in most patients and were proportional to dose at levels >/=150 microgram/kg. We conclude that oral swainsonine is tolerated by chronic intermittent administration at doses up to 150 microgram/kg/day. Adverse events considered drug related were similar to those observed in the infusional study but with fatigue and neurological effects also noted. Investigations of alternative dosing schedules with low starting doses are suggested for further clinical testing.

Operant analysis of chronic locoweed intoxication in sheep.

Five sheep were fed a 10% locoweed (Oxytropis sericea) pellet or alfalfa pellets for 3- to 5-wk periods to determine the effects of intermittent locoweed ingestion on operant responding; three controls were fed alfalfa pellets for 22 wk. Sheep were trained to respond to a multiple schedule with a fixed ratio (FR) 5 and fixed interval (FI) 50 s as major elements; performance was reinforced with rolled barley. Locoweed-treated sheep decreased (P < .05) FR response rate after 4 wk of locoweed feeding, but this decrease first appeared during the first recovery period (wk 6). The FR response rate of intoxicated sheep did not return to baseline during the remainder of the study and differed from controls during most of the study. Controls did not deviate (P > .05) from their FR baseline except during wk 2. Sheep did not stabilize on the FI component. As locoweed-treated sheep became progressively more intoxicated, they altered their pattern of FR responses, with longer post-reinforcement pauses, and a slower overall FR rate. Intoxicated sheep ingested an average of .21 mg swainsonine.kg-1.d-1. Overt signs of intoxication were noted when two sheep were stressed on wk 17. These two sheep had neuroviseral vacuolation typical of locoweed poisoning, whereas the three remaining locoweed-treated sheep that were euthanatized 5 wk later showed little histologic evidence of intoxication. Our findings indicate that "on-off" or cyclic grazing of locoweed ranges should be approached cautiously. Such a grazing program may be feasible because of the rapid resolution of histologic pathology; however, an initial toxic insult of 4 wk seems to be excessive, even at low doses, because sheep may exhibit persistent behavioral abnormalities that require > 6 wk to resolve.

A phase I study of swainsonine in patients with advanced malignancies.

Swainsonine, an alpha-mannosidase inhibitor which blocks Golgi oligosaccharide processing, represents a new class of compounds that inhibit both rate of tumor growth, and metastasis, in murine experimental tumor models. In this first phase I study, the quantitative and qualitative toxicities of swainsonine have been studied in patients given a continuous i.v. infusion over 5 days, repeated at 28-day intervals. Dose levels were escalated in increments of 100 micrograms/kg/day from 50-550 micrograms/kg/day. Nineteen patients with both solid tumor and hematological malignancies were given a total of 31 courses. Hepatotoxicity, particularly in patients with liver metastases, was the dose-limiting toxicity. The maximum tolerated dose (MTD) and the recommended starting dose (MTD -1 level) were 550 and 450 micrograms/kg/day, respectively. Common side effects included edema, mild liver dysfunction, a rise in serum amylase, and decreased serum retinol. Acute respiratory distress syndrome possibly precipitated by swainsonine resulted in a treatment-related death in a patient with significant pretreatment hepatic dysfunction. One patient with head and neck cancer showed > 50% shrinkage of tumor mass for 6 weeks after treatment. Two patients with lymphangitis carcinomatosis on chest X-ray noted improvement in cough and shortness of breath during the infusion of swainsonine and for 1 week thereafter. Clearance and serum half-life for swainsonine were determined to be approximately 2 ml/h/kg, and 0.5 day, respectively. Golgi oligosaccharide processing, a putative anticancer target for swainsonine was inhibited in peripheral blood lymphocytes as evidenced by a marked decrease in leukoagglutinin binding after 5 days of treatment. Oligomannosides in patient urine increased 5-to 10-fold over the 5 days of treatment, indicating that tissue lysosomal alpha-mannosidases were also blocked by swainsonine. Urine oligomannoside accumulation reached steady state at 3 days, approximately 1 day after serum drug levels reached steady state. The fraction of HLA-DR-positive cells in peripheral blood lymphocytes increased following 5 days of swainsonine treatment, an effect similar to that observed for peripheral blood lymphocytes from normal subjects cultured with swainsonine. No significant changes in CD3, CD4, CD8, CD16, and CD25 were observed. Swainsonine produces minimal toxicity when administered i.v. to cancer patients at dosages that inhibit both Golgi alpha-mannosidase II and lysosomal alpha-mannosidases. Detection of hepatic metastases or liver enzyme abnormalities prior to treatment predict for more significant toxicity.