Phase III trial of 5-fluorouracil and leucovorin plus either 3H1 anti-idiotype monoclonal antibody or placebo in patients with advanced colorectal cancer.

BACKGROUND: The monoclonal antibody 3H1 mimics the external structure of the carcinoembryonic antigen (CEA). It therefore has the potential, via the anti-idiotypic network, to stimulate immune responses to CEA that may benefit colorectal cancer patients. PATIENTS AND METHODS: A total of 630 patients with previously untreated metastatic colorectal cancer were randomised in a 2:1 fashion to receive bolus 5-fluorouracil (5-FU) and leucovorin (LV) plus either 3H1 (n = 422) or placebo (n = 208). RESULTS: The addition of 3H1 to 5-FU and LV did not result in increased toxicity. Survival for the full intent-to-treat population was 14.7 months for the 3H1 arm and 15.2 months for the placebo arm (P = 0.80). Anti-CEA antibody responses were observed in 70% of patients treated with 3H1. Patients with a negative CEA response had a median survival of 8.3 months (95% CI 7.5-11.0) compared with patients with a strong response: median survival not reached (P <0.001). CONCLUSION: 3H1 is safe and effectively induces immune responses to CEA. Addition of 3H1 to 5-FU and LV was not shown to improve overall patient outcomes. However, improved survival in patients developing anti-CEA responses to 3H1 are provocative and should be studied in further clinical trials.

Hemorrhagic fever virus-induced changes in hemostasis and vascular biology.

Viral hemorrhagic fever (VHF) denotes a virus-induced acute febrile, hemorrhagic disease reported from wide areas of the world. Hemorrhagic fever (HF) viruses are encapsulated, single-stranded RNA viruses that are associated with insect or rodent vectors whose interaction with humans defines the mode of disease transmission. There are 14 HF viruses, which belong to four viral families: Arenaviridae, Bunyaviridae, Filoviridae and Flaviviridae. This review presents, in order, the following aspects of VHF: (1) epidemiology, (2) anomalies of platelets and coagulation factors, (3) vasculopathy, (4) animal models of VHFs, (5) pathogenic mechanisms, and (6) treatment and future studies. HF viruses produce the manifestations of VHFs either by direct effects on cellular functions or by activation of immune and inflammatory pathways. In Lassa fever, Rift Valley fever and Crimean-Congo HF, the main feature of fatal illness appears to be impaired/delayed cellular immunity, which leads to unchecked viremia. However, in HF with renal syndrome and dengue HF, the immune response plays an active role in disease pathogenesis. The interplay of hemostasis, immune response, and inflammation is very complex. Molecular biologic techniques and the use of animal models have helped to unravel some of these interactions.

Rhesus differential susceptibility to endotoxin is not associated with activation of plasma prekallikrein.

This study is part of a project aimed at understanding individual responses to acute endotoxemia in a catheter-free rhesus (Macaca mulatta) model of inflammation. In the previous study [J. Endotoxin Res. 2 (1995) 411-420.], we showed that of 14 endotoxin 0111:B4 (ETX)-infused monkeys, only three died at < 13.5 h and one at 6 days postinfusion. Doses of ETX correlated neither with the magnitude of hypotension nor with rhesus outcome. Survival (and death at 6 days) or death at < 13.5 h was rather associated with controllable or uncontrollable rise of plasma levels of proinflammatory cytokines and reversible or irreversible shock. In the current study, we used plasmas of 5 survivors and of one of the monkeys that died at < 13.5 h (each infused with 3 X 10(6) EU ETX/kg), and of two saline control monkeys of the previous study. We analyzed changes in parameters of coagulation and contact systems. After ETX infusion, activated partial thromboplastin time (APTT) and prothrombin time (PT) values increased modestly in survivors but markedly in the nonsurvivor; responses of platelet counts and levels of fibrinogen, antithrombin, alpha2-macroglobulin (alpha2M), Cl-inhibitor (C1INH) and alpha1 -antitrypsin were similar in survivors and the nonsurvivor; the rate of plasma prekallikrein (PK) activation measured by hydrolysis of the kallikrein (KAL) substrate D-Pro-Phe-Arg-p-nitroanilide was not altered by ETX infusion; and the distribution of PK activation products, analyzed by MAb 13G11/immunoblotting in plasmas with or without artificial activation, was similar in survivors and the nonsurvivor. Responses in controls were relatively stable. Since we used defined experimental conditions, this primate model has the potential to be useful to study further correlation of inflammatory parameters with differential outcome.

Successful treatment of severe refractory idiopathic thrombocytopenic purpura with liposomal doxorubicin.

Idiopathic thrombocytopenic purpura (ITP) is refractory to initial treatment (steroids and splenectomy) in 25 to 30% of patients. These patients have a significant risk of fatal hemorrhage. Two patients with ITP refractory to multiple interventions and severe depression of platelet counts responded to treatment with liposomal doxorubicin with a return of platelet counts to normal. The drug is easily administered and was well tolerated. Use of this drug in refractory ITP merits further study.

Early analysis of viremia and clinical tests in patients with epidemic hemorrhagic fever.

We analysed the early viremia and clinical tests in 82 patients with epidemic hemorrhagic fever (EHF). The results showed that the changes in viremia and clinical tests are related to the severity of the disease and prognosis. Higher concentrations of the virus in infected patients might cause a more unfavourable prognosis and more abnormalities in clinical tests. CK-MB, SGOT, SGPT, serum creatinine and urea nitrogen contents increased markedly, while serum total protein, albumin and calcium contents decreased markedly, indicating that the heart, liver and kidney in EHF patients were severely damaged. Markedly increased WBC and monocytes showed that the patients were seriously infected. Platelet count, antithrombin-III and plasminogen decreased markedly, demonstrating that there were marked changes in the coagulation-anticoagulation and fibrinolytic system of the EHF patients. Changes in RBC, Hb and HCT contents indicated that the blood in the EHF patients had a higher concentration. This study gives further evidence that EHFV plays an important role in the pathogenesis of EHF.

Structure, kinetics, and function of human and rhesus plasma prekallikreins are similar.

To determine if rhesus monkeys (Macaca mulatta) could serve as a model for studying the role of the contact system in the pathophysiology of human infections, we compared structural, kinetic, and functional characteristics of plasma prekallikrein and its activation products in rhesus and humans. Three prekallikrein variants (85-, 89- and 93-kDa) were revealed in rhesus plasma as compared with the two variants (85- and 88-kDa) in human plasma by immunoblotting with the monoclonal antibody MAb 13G11. The prekallikrein concentration in rhesus plasma was 1.5-fold that in human plasma as determined by computerized immunoblot analyses (CIBA) and amidolytic activity. The electrophoretic mobility of prekallikrein from plasma of both species increased after deglycosylation. Inhibition of prekallikrein activation by MAb 13G11 was 55% (rhesus plasma) and 76% (human plasma), with similar inhibition curves. Immunoblots of activated rhesus plasma showed prekallikrein, complexes of kallikrein with C1 inhibitor, alpha 2-macroglobulin and approximately 60-kDa inhibitor(s) (viz. antithrombin III), and 45-kDa fragments, like those in activated human plasma. Concentrations and molecular masses of factor XII and high molecular weight kininogen were similar in rhesus and human plasma. The activated partial thromboplastin time (APTT) and prothrombin time were 20.1 +/- 1.6 and 9.7 +/- 0.3 s for rhesus and 32.0 +/- 5.6 and 12 +/- 0.5 s for human plasma. Human and rhesus APTTs were similar when prekallikrein concentrations in human and rhesus plasma became alike by adding human purified prekallikrein.(ABSTRACT TRUNCATED AT 250 WORDS)

Prospective, double-blind, concurrent, placebo-controlled clinical trial of intravenous ribavirin therapy of hemorrhagic fever with renal syndrome.

A prospective, randomized, double-blind, concurrent, placebo-controlled clinical trial of intravenous ribavirin (loading dose of 33 mg/kg, 16 mg/kg every 6 h for 4 days, and 8 mg/kg every 8 h for 3 days) was conducted in 242 patients with serologically confirmed hemorrhagic fever with renal syndrome (HFRS) in the People's Republic of China. Mortality was significantly reduced (sevenfold decrease in risk) among ribavirin-treated patients, when comparisons were adjusted for baseline risk estimators of mortality (P = .01; two-tailed). HFRS typically consists of five consecutive but frequently overlapping clinical phases. Only occurrence of oliguric phase and hemorrhage was associated with severity of clinical disease in the placebo group. Ribavirin therapy also resulted in a significant reduction in the risk of entering the oliguric phase and experiencing hemorrhage. The only ribavirin-related side effect was a well-recognized, fully reversible anemia after completion of therapy.

Mechanisms of disease in hemorrhagic fever with renal syndrome.

Hemorrhagic fever with renal syndrome (HFRS) is a dramatic illness characterized by fever, and variable degrees of circulatory failure, hemorrhage, and renal insufficiency. Hantaviruses are the cause of this syndrome. In its severe form, it is associated with significant mortality. Vascular dysfunction is the key physiologic derangement in this disorder. There is a growing body of evidence that suggests that immune mechanisms account for this derangement.

Platelet dysfunction contributes to the haemostatic defect in haemorrhagic fever with renal syndrome.

To characterize further the nature of haemostatic impairment in haemorrhagic fever with renal syndrome, we assessed platelet function in 9 patients in whom the diagnosis was serologically confirmed. Defective platelet aggregation was demonstrated in every patient. An abnormality of the granule release reaction was demonstrated in all of 7 patients tested. Gel-filtered platelets from a normal subject showed normal aggregation in plasma from a patient with impaired aggregation, which is evidence for an intrinsic platelet defect, and against the presence of a circulating inhibitor in this patient.

Changes in populations of immune effector cells during the course of haemorrhagic fever with renal syndrome.

To characterize the immune response in haemorrhagic fever with renal syndrome, serial changes in immune effector cells were measured in 14 patients. Significant findings included initial elevations of all major leucocyte populations, increases in suppressor T cells and B cells, decreases in helper/suppressor cell ratios, and a dramatic increase in activated T cells. These changes were most marked in severely ill patients. Changes reverted to normal over approximately one week.

Interruption study of viremia of patients with hemorrhagic fever with renal syndrome in the febrile phase.

Kinetic changes of viremia were observed in 287 cases of hemorrhagic fever with renal syndrome (HFRS) in whom ribavirin was administered with double blind random control studied by means of virus isolation, indirect immunofluorescence assay and enzyme-linked immunosorbent assay. The positive rate of viremia was 79.7% (Sp = 3%) and positive rate of HERS IgM was 85% (Sp = 3.1%) before treatment. Viremia could be interrupted by ribavirin as in the ribavirin treated group, the viremia positive rate decreased, duration of viremia was shortened, viral antigen products, virus titer and HFRS IgG antibody level were reduced as compared with the control group. This showed that viremia was very frequent in patients in the febrile phase and ribavirin is an effective antiviral drug in HFRS during the febrile phase. Dosage and course of treatment of this drug are discussed.

Mechanisms of disease in Hantavirus infection: pathophysiology of hemorrhagic fever with renal syndrome.

Hemorrhagic fever with renal syndrome (HFRS) is an acute viral disease that occurs over wide areas of Europe and Asia. Hantaviruses are the cause of this syndrome. The hallmark of HFRS is the triad of fever, hemorrhage, and renal failure. In its severe form it is associated with significant mortality. The syndrome evolves through five phases: febrile, hypotensive, oliguric, diuretic, and convalescent. The central physiologic derangement in HFRS is vascular dysfunction, manifested by impaired vascular tone and increased vascular permeability. The systemic effects of this dysfunction account for the occurrence of hypotension and shock, while local effects are probably important in the development of renal failure. Shock in HFRS has distributive and oligemic features, while renal failure has features of acute tubular necrosis. Hemorrhage is a consequence of vascular injury and a deficit of functional platelets. Vascular and platelet dysfunction are both compounded by uremia. Disseminated intravascular coagulation contributes to hemorrhage in some patients. Although hantaviruses are infectious for endothelial cells and may cause direct injury, a large body of evidence suggests that immune mechanisms play an important role in the pathogenesis of HFRS.

Safety and immunogenicity of a Plasmodium vivax sporozoite vaccine.

A recombinant DNA Plasmodium vivax sporozoite vaccine containing the repeating region of the Salvador I strain circumsporozoite (CS) protein was produced in Escherichia coli. This vaccine was tested in 13 naive volunteers at doses of 10-1,000 micrograms. No serious adverse reactions were noted. None of 4 volunteers receiving the 10 micrograms dose developed antibodies measurable by ELISA. Six of 9 volunteers in the other dose groups developed measurable antibodies: 5 of 5 volunteers receiving 100 micrograms and 1 of 4 receiving 1,000 micrograms. Antibody responses measured by immunofluorescence assays paralleled those seen by ELISA. None of the volunteers developed antisera that inhibited sporozoite invasion of human hepatoma cells in vitro. Lack of a classical anamnestic response and lack of a typical dose response to increasing amounts of antigen suggests the possible presence of an immunosuppressive epitope in the repetitive region of the CS protein.

Epidemic hemorrhagic fever. The mechanism of coagulation and fibrinolysis.

To understand the mechanism of hemorrhage, coagulation and fibrinolysis in epidemic hemorrhagic fever (EHF), thrombin time (TT), prothrombin time (PT), fibrinogen (FIG), the platelet count (PLAT), plasminogen (PLG), antithrombin-III (AT-III), fibrin-fibrinogen degraded products (FDP) and platelet functions of aggregation and release were studied dynamically with advanced methods in 134 EHF patients. TT and PT were prolonged, FIG, AT-III and PLG were decreased and FDP was increased. Besides, the decrease of PLAT, the platelet functions of aggregation and release were below the normal level. The results showed that the balance of blood coagulation and fibrinolysis was lost from the early stage of the disease.

Pathogenesis of Rift Valley fever in rhesus monkeys: role of interferon response.

Rhesus monkeys inoculated intravenously with Rift Valley fever (RVF) virus presented clinical disease syndromes similar to human cases of RVF. All 17 infected monkeys had high-titered viremias but disease ranged from clinically inapparent to death. Three (18%) RVF virus-infected monkeys developed signs of hemorrhagic fever characterized by epistaxis, petechial to purpuric cutaneous lesions, anorexia, and vomiting prior to death. The 14 remaining monkeys survived RVF viral infection but, 7 showed clinical signs of illness characterized by diminished food intake, cutaneous petechiae, and occasional vomiting. The other 7 monkeys showed no evidence of clinical disease. All monkeys had detectable serum interferon 24-30 h after infection, but 4 of 7 monkeys that did not develop clinical illness had serum interferon titers within 12 h after infection. In lethally infected macaques, indices of hepatic function and blood coagulation were abnormal within 2 days, implicating early pathogenetic events as critical determinants of survival. Serum transferase values were elevated in proportion to severity of clinical disease and outcome of infection. Both myocardial damage and laboratory evidence consistent with disseminated intravascular coagulation were present in fatal infections. All surviving monkeys developed neutralizing antibodies to RVF virus 4-7 days after infection, and this coincided with termination of viremia. Two fatally infected monkeys were viremic until death on days 6 and 8, and the third cleared viremia on day 5 and developed antibody on day 6 but died on day 15. There was a significant correlation between a delayed interferon response and mortality, suggesting that the early appearance of interferon was influential in limiting the severity of disease.

Hemorrhage in hemorrhagic fever with renal syndrome in China.

Hemorrhage is a prominent feature of hemorrhagic fever with renal syndrome (HFRS) in China. It occurs in all phases of the disease and is an important cause of death. Petechiae involving skin and oropharyngeal mucosa are the commonest manifestation of hemorrhage, occurring in more than 90% of patients. Gastrointestinal hemorrhage is the next commonest manifestation, occurring in approximately 50% of patients. Suggested mechanisms of hemorrhage include vascular injury, thrombocytopenia and platelet dysfunction, disseminated intravascular coagulation, circulating heparin-like activity, and uremia. Controlled trials of treatment regimens for hemostatic impairment in HFRS have not been performed. Support of blood pressure can lessen hemorrhage by limiting the adverse consequences of hypotension and shock. Dialysis is of benefit in patients with hemorrhage and significant renal failure.

Prevention of Rift Valley fever in rhesus monkeys with interferon-alpha.

Prophylactic and therapeutic efficacy of recombinant leukocyte A interferon (rIFN-alpha A) and Sendai virus-induced human leukocyte interferon (HuIFN-alpha) administered intramuscularly to Rift Valley fever virus (RVFV)-infected rhesus monkeys was studied. Clinical, virologic, immunologic, and hemostatic parameters were monitored. Five daily inoculations of 5 X 10(5) units of either interferon product per kilogram of body weight, initiated 24 hours before or 6 hours after RVFV infection, prevented or greatly suppressed viremia. No clinical signs of disease or laboratory evidence of impaired hemostasis was observed. Serum neutralizing antibody to RVFV was detected within 6 days of virus inoculation. Prophylactic administration of 5 X 10(4) or 5 X 10(3) units of rIFN-alpha A per kilogram also limited viremia, hepatocellular damage, and hemostatic derangement. Untreated, RVFV-infected, control monkeys developed high-titered viremia, clinical disease, and impaired hemostasis. These data suggest that rIFN-alpha A and HuIFN-alpha are effective in protecting RVFV-infected rhesus monkeys from viremia and hepatocellular damage and may be beneficial in human RVF infection.

Hemostatic derangement produced by Rift Valley fever virus in rhesus monkeys.

Rift Valley fever (RVF) is an important cause of disease in animals and humans in sub-Saharan Africa. In a small percentage of human cases, the disease is complicated by hemorrhage, which often is associated with a fatal outcome. Inoculation of rhesus monkeys with the Zagazig Hospital strain of RVF virus produced a clinical picture similar to illness in humans. Ten of 17 monkeys developed clinical evidence of hemostatic impairment. When coagulation tests were performed, this group of monkeys had significant abnormalities, including evidence for disseminated intravascular coagulation. These abnormalities were much less pronounced in the remaining seven monkeys-whose only sign of illness was transient fever-and, in general, they paralleled the level of viremia and the degree of elevation in levels of serum hepatic enzymes. Autopsy of the three monkeys with severe disease revealed hepatic necrosis.