Repeat-cycle study of high-dose intravenous 4162W94 anti-CD4 humanized monoclonal antibody in rheumatoid arthritis. A randomized placebo-controlled trial.

OBJECTIVE: Results of an earlier open-label pilot study showed that 4162W94 was a relatively non-depleting anti-CD4 monoclonal antibody that induced >80% down-modulation of CD4 molecules from the surface of T lymphocytes. This placebo-controlled repeat-cycle study was conducted in active rheumatoid arthritis (RA) patients to determine the duration of CD4 blockade required to achieve lasting clinical benefit. METHODS: Following DMARD washout, 48 patients (i.e. three cohorts of 16 patients) with ACR-defined RA were to be dosed with 1 (cohort 1), 2 (cohort 2) or 3 (cohort 3) cycles of 5x300 mg 4162W94 or placebo (12 and 4 patients per cohort respectively) at monthly intervals. There was at least 3 months of follow-up after dosing. Clinical outcome was assessed in evaluable patients (receiving at least 80% of each dose course) using ACR20 criteria (required on two consecutive visits). CD4 lymphocyte counts and adverse events were also monitored. RESULTS: Sixteen patients were dosed in each of the first two cohorts; however, the dose was reduced in cohort 3 after five patients had received up to two dose cycles due to accumulating evidence of a high frequency of skin rash. These patients were analysed according to the number of cycles received. A further eight patients received 5x100 mg for one to three cycles prior to stopping the study for administrative reasons. Four of 13 (P=0.119 vs placebo) and 7/13 (P=0.015 vs placebo) in cohorts 1 and 2 respectively achieved ACR20 response on at least two consecutive occasions. No patient receiving 5x100 mg/day or placebo achieved ACR20. Four patients were still responding at the end of the 3-month follow-up period. CD4 lymphocyte suppression (<0.2x10(9)/l on at least two successive occasions) occurred in 11/34 patients who received 4162W94 vs none on placebo. Rash occurred in 21/34 monoclonal antibody-treated patients, including one case of biopsy-confirmed cutaneous vasculitis and 1/11 placebo patients. CONCLUSION: 4162W94 demonstrated significant clinical efficacy in this study. However, because of unacceptable CD4 lymphopenia and rash, the original hypothesis that prolonged CD4 blockade would give lasting clinical benefit was not tested.

Pharmacokinetic, pharmacodynamic and clinical effects of a humanized IgG1 anti-CD4 monoclonal antibody in the peripheral blood and synovial fluid of rheumatoid arthritis patients.

BACKGROUND: CD4(+) T cells are important mediators in the pathogenesis of rheumatoid arthritis (RA). In this open-label, dose-escalating study, we examined the pharmacokinetic (PK), clinical, biological and immunological effects of a humanized IgG1 anti-CD4 monoclonal antibody (mAb), 4162W94, in the peripheral blood (PB) and synovial fluid (SF) of RA patients. METHOD: Twenty-four patients in four cohorts (six patients in each cohort) were allocated to be treated with five consecutive daily doses of 4162W94 (10, 30, 100 or 300 mg i.v.). Disease activity was measured by the American College of Rheumatology (ACR) criteria and disease activity score (DAS). We also measured 4162W94 concentration, the percentage of 4162W94-coated CD4(+) lymphocytes, percentage down-modulation of CD4, interleukin-6 (IL-6) and tumour necrosis factor alpha (TNFalpha) levels in the PB and SF. RESULTS: A direct relationship between 4162W94 dose, biological response and clinical outcome was seen. Treatment with 10 and 30 mg of 4162W94 for 5 consecutive days resulted in transient coating and down-modulation of CD4(+) lymphocytes, with little effect observed beyond the final dose. However, treatment with 100 and 300 mg resulted in sustained coating and/or down-modulation for 3 weeks and 4 weeks, respectively, in PB and >4 weeks in SF in one patient from the 300 mg cohort. There was a dose-related moderate but transient depression in the CD4(+) lymphocyte count in most patients, with all but three returning to >0.40 x 10(9)/l or >75% baseline by the end of the study period. Significant clinical improvement (ACR 20%) was seen in only 1/6 patients in each of the 10- and 30-mg cohorts; however, 3/6 and 5/5 patients in the 100 and 300-mg cohorts, respectively, were ACR 20% responders. In addition, there were significant reductions in PB acute phase reactants as well as SF IL-6 and TNFalpha concentrations in parallel to clinical improvement. CONCLUSION: Data from this pilot study suggest that 4162W94 is a clinically active novel immunotherapeutic agent that may suppress inflammation in RA.

Repopulation of blood lymphocyte sub-populations in rheumatoid arthritis patients treated with the depleting humanized monoclonal antibody, CAMPATH-1H.

Patients with severe rheumatoid arthritis who had failed treatment with conventional therapies were treated with a course of five or 10 daily intravenous infusions of CAMPATH-1H, a humanized antibody against the CD52 antigen, resulting in profound depletion of peripheral blood mononuclear cells. During the subsequent 18 months, lymphocytes were analysed for sub-populations by fluorescence-activated cell sorter (FACS) and for proliferation in response to polyclonal T-cell stimulation with anti-CD3 or staphylococcal enterotoxin B (SEB). Treatment resulted in almost complete depletion of lymphocytes from the blood followed by gradual repopulation. CD16+ natural killer (NK) cells and CD14+ monocytes returned to pretreatment levels within 1-2 months. CD19+ B cells returned to within 50% of pre-treatment levels by day 66 and to within normal range by day 150, whereas CD8+ T cells recovered to 50% of pretreatment levels by day 66, but did not show any further increase during the rest of the study period. The most profound effects were on the CD4+ T lymphocyte sub-population, as the mean CD4+ count did not increase above 20% of pre-treatment level at any time during the study period (550 days), at all the doses tested. The T cells which initially repopulated the blood 1-2 months after treatment, nearly all expressed the activation markers human leucocyte antigen (HLA)-DR and CD45RO, although the percentage of T cells expressing these molecules gradually declined to normal levels over time. Proliferative responses to polyclonal T-cell stimulation (anti-CD3 and SEB) were also significantly reduced in the first few months after treatment, but recovered to pre-treatment levels by day 250. The relationship between these observations and the clinical response is discussed.

CAMPATH-1H in rheumatoid arthritis--an intravenous dose-ranging study.

Forty-one patients with active and refractory rheumatoid arthritis(RA) received a total of 100, 250 or 400 mg of CAMPATH-1H (CAMPATH is a trademark of Glaxo-Wellcome group companies, registered in the US Patent and Trademark Office) over 5 or 10 days in an open, uncontrolled study. Following therapy, patients were monitored for adverse effects and disease activity for 6 months. Therapy was associated with prolonged peripheral blood lymphopenia in all dosing cohorts. During the month immediately following therapy, lymphopenia was most profound in the 400 mg cohorts. The first dose of monoclonal antibody (Mab) was associated with a 'flu'-like syndrome, more pronounced at higher initial doses. One patient developed haemolytic-uraemic syndrome. There were a number of dose-related infections during the early post-treatment period and one fatal opportunistic infection which followed additional immunosuppressive therapy. Antiglobulin responses developed in 9 of 31 patients tested. The majority of patients showed symptomatic improvement following therapy and 20% of patients maintained a 50% Paulus response at 6 months, all of whom were in the 250 or 400 mg cohorts. CAMPATH-1H appears to be an effective treatment for RA. Allowing for the small number of patients treated, infections were more common with higher doses, although this was not true for adverse events overall, and therapeutic responses were more sustained at higher dosing levels. The broad specificity of CAMPATH-1H may be appropriate for the immunotherapy of RA and future studies should aim to define a dose with an optimal therapeutic ratio.

Emergence of CD52-, glycosylphosphatidylinositol-anchor-deficient lymphocytes in rheumatoid arthritis patients following Campath-1H treatment.

CD52 is a glycosylphosphatidyl-inositol (GPI)-linked glycoprotein expressed at high levels on normal T and B lymphocytes and at lower levels on monocytes, while being absent on granulocytes and bone marrow stem cell precursors. The emergence of CD52- lymphocytes of both T and B cell lineages was observed in three out of 25 rheumatoid arthritis patients treated with teh humanized antibody Campath-1H in phase II clinical trial. Whereas the majority of CD52- B cells had disappeared from the peripheral blood by 3 months post-treatment, both CD52- CD4+ and CD8+ T cells persisted in the circulation for at least 20 months. In the two patients that were tested, the GPI-anchored surface molecules CD55 and CD59 were also absent on the CD52- cells, although expression of other cell surface transmembrane, proteins (CD3, CD4 and CD2) was unaffected. The CD52- cells maintained a stable phenotype in vitro despite repeated re-stimulation in culture. Both CD52- and C52+ clones, established from one of the patients, responded to a similar extent to several T cell mitogens, as assessed by proliferation, suggesting that a general defect in expression of GPI-linked molecules does not impair T cell activation. These data show that an immune attack against a GPI-anchored surface molecule can result in the selection of a GPI-anchor-deficient cell population. Despite the persistence of CD52- T cells in the peripheral blood, no adverse reactions associated with the presence of these cells were noted in any of the patients; in fact they responded with longer remission times after Campath-1H treatment than the other patients in the trial.

Development of a serum-free culture medium for the large scale production of recombinant protein from a Chinese hamster ovary cell line.

A serum-free medium, WCM5, has been developed for the large scale propagation of CHO (Chinese hamster ovary) cells which express recombinant protein using dihydrofolate reductase as a selectable marker. WCM5 was prepared by supplementing Iscoves medium without lecithin, albumin or transferrin with a number of components which were shown to benefit growth. WCM5 medium contained 5 mg l(-1) human recombinant insulin (Nucellin) but was otherwise protein-free. CHO 3D11(*) cells which had been engineered to express a humanised antibody, CAMPATH(*)-1H, were routinely grown using serum-containing medium. From a seeding density of 10(5) cells ml(-1), cells grown in static culture with serum reached a maximal cell density of 6.5×10(5) cells ml(-1) after 6 days in culture and produced a maximal antibody concentration of 69 mg l(-1) after 11 days in culture. CHO 3D11(*) cells grown with serum were washed in serum-free medium then cultured in WCM5 medium. Following a period of adaptation the cell growth and product yield was superior to that achieved with serum-containing medium. CHO cells producing CAMPATH-1H grown in an 8000 l stirred bioreactor seeded with 2×10(5) cells ml(-1) reached a maximal viable cell density of 2.16×10(6) cells ml(-1) after 108 h in culture and a maximal antibody concentration of 131.1 mg l(-1) after 122 h in culture.

Immunohistochemical analysis of CDw52 antigen expression in non-Hodgkin's lymphomas.

AIM: To determine the antigen expression of CDw52 using Campath-1 antibodies in a series of non-Hodgkin's lymphomas (NHLs). METHODS: Tissue sections of lymphoma were stained immunohistochemically using rat Campath-1G and humanised Campath-1H with avidin-biotin-peroxidase complex techniques. Fifty-two fresh frozen lymphomas and a further 26 paraffin wax embedded sections were studied. RESULTS: Thirty-seven out of 41 B cell lymphomas were positive with Campath-1H in frozen sections (low grade, 24 of 24; high grade, 13 of 17) as were three out of five T cell lymphomas. Reed-Sternberg cells in six cases of Hodgkin's disease did not react. Eleven out of 16 high grade B cell lymphomas also stained positively with Campath-1G in paraffin wax sections as did five out of 10 T cell lymphomas. CONCLUSIONS: The Campath-1 antibodies showed that CDw52 antigen expression was present in all cases of low grade B cell NHL examined. Immunohistochemical staining in high grade B cell NHL and in T cell NHL was variable. These findings may be relevant to patient selection when considering treatment with Campath-1 antibodies.

Regulation of tumor necrosis factor production by adrenaline and beta-adrenergic agonists.

The effects of adrenaline and isoproterenol, a specific beta-adrenergic agonist, on TNF production were investigated. Both agents inhibited the production of TNF by human blood and THP-1 cells stimulated by LPS. The effect of adrenaline was prevented by a beta-receptor antagonist, but not by an alpha-receptor antagonist. Levels of TNF mRNA were not reduced by adrenaline. Inhibition of TNF production was observed only if cells were first exposed to adrenaline or isoproterenol at about the same time as to LPS; incubation of THP-1 cells with isoproterenol for 24 h before LPS stimulation dramatically increased response, and prevented suppression of TNF production by a second dose of isoproterenol. Intracellular cAMP levels were increased by adrenaline and isoproterenol, at concentrations that inhibited TNF production. However, prolonged incubation of THP-1 cells with isoproterenol resulted in depression of cAMP concentrations to below basal levels. These data suggest that TNF production can be regulated by beta-receptor stimulation, that such regulation is mediated by changes in intracellular cAMP concentrations and is exerted at a posttranscriptional level. Adrenaline may be an important endogenous regulator of TNF production in sepsis.

A convenient human whole blood culture system for studying the regulation of tumour necrosis factor release by bacterial lipopolysaccharide.

Bacterial lipopolysaccharide (LPS, endotoxin) induces a dose-dependent release of TNF in whole human blood which has been diluted five-fold. It is modulated by interferon-gamma, prostaglandin E2 and indomethacin in the same manner as observed with tumour necrosis factor (TNF) release from human monocyte/macrophage cells cultured in vitro. The whole blood culture system (WBCS) can provide up to 250 samples from 10 ml of venous blood and enables an individual blood to be assessed in terms of TNF inducibility and its modulation by other biological agents. The whole blood culture system was used to demonstrate the individual variation between blood donors. The results demonstrated that the information provided by induced cytokine release and its regulation in the ex vivo system would be a valuable addition to that obtained from in vitro methods.

A comparison of specificity and biological activity of polyclonal and monoclonal antibodies raised against Salmonella minnesota R595 lipopolysaccharide.

Murine monoclonal antibodies (MAbs) and immune rabbit serum were raised against the rough mutant of Salmonella minnesota strain R595. These antibodies were tested for their ability to inhibit LPS-induced B-cell mitogenicity and neutralise LPS toxicity in chick embryos. Immune rabbit serum inhibited both mitogenicity and LPS lethality. None of the MAbs or a cocktail of antibodies were able to neutralise LPS lethality in chick embryos. However, they were able to inhibit mitogenicity by varying degrees.

Comparison of the opsonic activity of polyclonal and monoclonal antibodies raised against Salmonella minnesota strain R595.

Murine monoclonal antibodies and immune rabbit serum were raised against the rough mutant Salmonella minnesota strain R595. These antibodies were tested for their opsonic activity against the homologous strain and the smooth wild type S. minnesota by luminol-dependent chemiluminescence and a microscopic assessment of phagocytosis. Immune rabbit serum opsonised both strains. Treatment with normal rabbit serum inhibited the phagocytic uptake of S. minnesota R595. None of the monoclonal antibodies RE01 (anti-KDO), RE12 (anti-KDO) and RE23 (anti-lipid A) were opsonic. Unopsonised S. minnesota R595 stimulated marked chemiluminescence possibly because of its hydrophobic surface, but this was not reflected in increased uptake by phagocytic cells. Results obtained with luminol-dependent chemiluminescence should be interpreted with caution when the opsonisation of rough bacterial strains or those with high surface hydrophobicity is being investigated.

Antibody to endotoxin core glycolipid reverses reticuloendothelial system depression in an animal model of severe sepsis and surgical injury.

To study the effect of severe sepsis on the function of the reticuloendothelial system (RES) we have measured the clearance kinetics and organ distribution of both low-dose technetium tin colloid (TTC) and 75selenomethionine-labelled E. coli in rabbits 24 hours after either sham laparotomy or appendix devascularization. Sepsis resulted in similar delayed blood clearance and reduced liver (Kupffer cell) uptake of both TTC and E. coli. To investigate the ability of polyclonal antibody to E. coli-J-5 (core glycolipid) to improve RES function in the same model of sepsis, further animals were pretreated with either core glycolipid antibody or control serum (10 ml IV) 2 hours before induction of sepsis. TTC clearance kinetics were determined 24 hours later. Antibody pretreated animals showed: a reduced incidence of bacteremia; normalization of the rate of blood clearance and liver uptake of TTC; and a 'rebound' increase in splenic uptake of TTC. We conclude that antibody to E. coli-J-5 enhances bacterial clearance by the RES.

Increase and inhibition of pre-B cell proliferation in culture, by T cells.

T cells may either increase or decrease in vitro proliferation of marrow pre-B cells from patients with acute lymphatic leukaemia after withdrawal of successful treatment. There is less proliferation when T cells are removed by E rosetting, and repletion of T cells restores proliferation. When additional T cells from the patients were added to the patients' marrows, proliferation was increased more effectively than with T cells from healthy subjects; there was no evidence of an allogeneic effect. In contrast, normal T cells stimulated with concanavalin A suppress proliferation. There was no evidence of differentiation into B cells.

Growth of pre-B cells in cultures of bone marrow from children with acute lymphoblastic leukaemia and other diseases.

Pre-B cells from the bone marrow of children with acute lymphoblastic leukaemia (ALL) survived up to 144 hr after the completion of treatment and divided in culture with maximum cell numbers at 24 hr. There was no rise in B cell number and no evidence of differentiation from pre-B to B cells. Binucleated pre-B cells in cultures containing cytochalasin B confirmed that pre-B cell division was occurring. Cycloheximide reduced cell numbers in culture but bromodeoxyuridine did not. Pre-B cell numbers also increased in culture of morphologically normal marrows from treated and untreated patients with solid tumours, and probably in normal marrows from patients with non-malignant diseases.

Immunosuppression and serious infections in children with acute lymphoblastic leukaemia: a comparison of three chemotherapy regimes.

Eighty-four children presenting with acute lymphoblastic leukaemia were entered into a trial designed to test the effect on host toxicity of regular drug-free periods during chemotherapy. Patients received the same total dose of drugs either continuously (daily), intermittently (a 5 d course every 3 weeks) or in an intermediate way between these two (a 14 d course followed by a 7 d gap). Mean neutrophil counts were lower in the intermittent group and fell significantly at 6 week intervals, after courses which included prednisolone and vincristine in addition to methotrexate and 6-mercaptopurine. Mean lymphocyte counts, mitotic response to phytohaemagglutinin and plasma immunoglobulin levels were significantly lower in the continuous group. The results in the intermediate group fell between those of the other two groups. All six remission deaths occurred in the 42 patients in the continuous group, who had a much higher incidence of infections (mostly viral and protozoal) than the other two groups. It is concluded that the intermittent chemotherapy schedule permits the maintenance of a lymphocyte population size and function which provides a satisfactory level of defence against infection without prejudice to its anti-leukaemic effect.

Terminal transferase-positive human bone marrow cells exhibit the antigenic phenotype of common acute lymphoblastic leukemia.

Combined immunologic assays for TdT enzyme and membrane markers show that TdT+ cells in nonleukemic human bone marrow carry ALL-associated and Ia-like antigens but no thymocyte markers or surface Ig. These cells could be precursors involved in acute lymphoblastic leukemia of the "common" or non-T, non-B type and in lymphoid blast crisis of Ph' positive chronic myeloid leukemia. A few TdT+, Ia+ cells express cytoplasmic IgM, indicating that some pre-B cells may be TdT positive.