Unrelated donor bone marrow transplantation for children with relapsed acute lymphoblastic leukaemia in second complete remission

Allogeneic sibling bone marrow transplantation (BMT) is the recommended treatment for relapsed childhood acute lymphoblastic leukaemia (ALL), but appropriate donors are only available in 30% of cases. Unfortunately, BMT from unrelated donors (UD) has been associated with high rates of severe graft-versus-host disease (GvHD) and transplant-related mortality (TRM). In an attempt to improve outcome in UD-BMT we have assessed the impact of T-cell depletion using CAMPATH-1 (anti-CD52) monoclonal antibodies in 50 consecutively referred patients with relapsed ALL in second remission. All were previously treated according to MRC protocols UKALL X and XI, and then given chemotherapy on MRC R1 from relapse until UD-BMT, 19 patients had relapsed on and 31 off therapy. Patients and donors were fully matched at HLA-A, -B, -DR and -DQ loci in 29 cases and mismatched in 21 (four mismatched for more than one antigen). Pre-transplant conditioning comprised CAMPATH-1G, cyclophosphamide and total body irradiation. Bone marrow was T-cell depleted in vitro using CAMPATH-1 antibodies. Additional GvHD prophylaxis consisted of cyclosporin A (42 cases), cyclosporin plus methotrexate (four) or none (four). 47 patients engrafted. The incidence of acute GvHD was very low: two patients with grade II disease in the matched group, four with grade II-IV in the mismatched group. Only four patients have chronic GvHD. The actuarial event-free survival (EFS) at 2 years is 53%, with no significant difference between the matched and mismatched group. Further leukaemic relapse was the most important cause of failure. These results are similar to the most favourable published reports for HLA-matched sibling BMT in relapsed ALL.

Anti-CD45 and anti-CD52 (Campath) monoclonal antibodies effectively eliminate systematically disseminated human non-Hodgkin's lymphoma B cells in Scid mice

Severe combined immunodeficient (Scid) mice inoculated with the human (t(14;18)-positive B cell lines DoHH2 and BEVA develop lethal systemically disseminated lymphoma (de Kroon et al., Leukemia 8:1385, and Blood 80 [suppl 1]:436). These models were used to study the therapeutic effect of rat-anti-human CD52 (Campath-1G) or CD45 monoclonal antibodies (mAbs) on systemically disseminated tumor cells and on tumor cells present in solid tumor masses. Both mAbs were effective in inhibiting growth of systemically disseminated malignant cells. When treatment with anti-CD52 or anti-CD45 mAbs at a dose of 30 micrograms/mouse/d for 4 days was started 24 hours after intravenous inoculation of human DoHH2 or BEVA cells, a 3-log kill of tumor cells was observed as measured by prolonged survival. After treatment, surviving animals injected with high numbers of BEVA cells showed tumor masses in liver, kidney, and mesenteric lymph nodes. In contrast to nontreated animals, however, only low numbers of malignant cells were found in peripheral blood, and bone marrow was free of tumor cells. Similarly, after mAb treatment of mice inoculated subcutaneously (sc) with DoHH2 cells, no tumor cells could be found in the bone marrow, and few DoHH2 cells could be detected in the peripheral blood, spleen, liver, kidney, or lung. In contrast, tumor cells present in subcutaneous tumors and axillary lymph nodes were relatively unaffected by mAb therapy. The presence of rat immunoglobulin (Ig) could be demonstrated on surviving tumor cells. The presence of murine macrophages in areas in these tumors that were depleted of DoHH2 cells suggested that the mAb-mediated antitumor effect observed in the Scid mouse model is mediated by cellular mechanisms. Apparently these mechanisms were not sufficient to eliminate the fast-growing tumor cells present in the protected sites. Our results indicate that treatment with anti-CD52 or anti-CD45 mAbs potentially may be useful as adjuvant immunotherapy for systemically disseminated B cell lymphoma.

CAMPATH-IH in multiple sclerosis

In a pilot study, seven patients with multiple sclerosis were treated with CAMPATH-IH which targets the CD52 antigen present on lymphocytes and monocytes. There was a substantial reduction in disease activity as measured by gadoliunium-enhancing lesions on MRI. Encouraged by this result a further seven patients have been treated with CAMPATH-IH; four also received anti-CD4 antibody. Lymphopaenia developed rapidly and was sustained for at least one year. In 12 patients, the first infusion of antibody was characterised by significant exacerbation or re-awakening of pre-existing symptoms lasting several hours. These clinical effects of antibody treatment correlated with increased levels of circulating cytokines. Peak levels of tumour necrosis factor alpha (TNF alpha) and interferon gamma (IFN gamma) occurred at 2 h whereas the rise in interleukin-6 (IL-6) was significantly delayed and peaked at 4 h after starting antibody treatment. The neurological symptoms could not be attributed directly to pyrexia and were not provoked (in one patient) by an artificial rise in temperature. In the remaining two patients, a single pre-treatment with intravenous methylprednisolone (500 mg) prevented both the transient increase in neurological symptoms and the cytokine release. Our results suggest that soluble immune mediators contribute to symptom production in multiple sclerosis by directly or indirectly blocking conduction through partially demyelinated pathways.

Monoclonal antibody therapy of diffuse cutaneous scleroderma with CAMPATH-1H

A worker in a polyvinyl chloride factory with rapidly progressive diffuse cutaneous scleroderma was treated with the humanized monoclonal antibody (Mab) CAMPATH-1H. Treatment was followed by rapid and substantial improvement in skin score, which was maintained during followup without additional therapy. The mode of action of CAMPATH-1H and its relationship to clinical improvement are discussed.

Campath-1G in vivo confers a low incidence of graft-versus-host disease associated with a high incidence of mixed chimaerism after bone marrow transplantation for severe aplastic anaemia using HLA-identical sibling donors

We have evaluated the effect of in vivo Campath-1G on engraftment and GVHD in 23 patients with severe aplastic anaemia transplanted from HLA-identical sibling donors. In 14 patients Campath 1g was given pre-transplant for up to 9 days in an attempt to overcome graft rejection (group 1). In nine patients Campath-1G was given pre-transplant, but also continued post-transplant until day +5 to reduce GVHD (group 2). There were three patients with late graft failure in group I following initial neutrophil engraftment, and four cases of grade II+ GVHD. In group II, two patients had early graft failure (no take), and there were no cases of acute GVHD out of seven evaluable patients. One patient in group I developed chronic GVHD of the liver, and two patients (one in each group) had transient localised chronic GVHD. PCR of short tandem repeats was used to evaluate chimaeric status in 13 patients. Of 11 patients with initial neutrophil engraftment, only one had 100% donor haemopoiesis at all times. The remaining patients had either transient mixed chimaerism or persistence of recipient (< 20%) cells. We conclude that in vivo Campath-1G is associated with a high incidence of mixed chimaerism which tips the balance away from GVHD but towards graft rejection.

Cell-to-cell transfer of glycosylphosphatidylinositol-anchored membrane proteins during sperm maturation

In spermatozoa, as in other eukaryotic cells, integral membrane proteins may be anchored by a hydrophobic protein domain, or by a glycosylphosphatidylinositol (GPI) lipid anchor. Contrary to the current understanding of sperm membrane biogenesis, recent evidence shows that some of the GPI-anchored proteins are not synthesized by the spermatozoa themselves, but by cells of the male genital tract. They are transported to the fluid secretions, possibly associated with membrane vesicles, and then incorporate into the sperm membrane. This novel mechanism, by which proteins can move from the membrane of one cell to that of another in vivo, may account for a significant proportion of the surface changes occurring during sperm maturation. The function of these GPI-anchored molecules is largely unknown. However, they are remarkably abundant, and the phenomenon of cell-to-cell transfer seems to be well conserved across mammalian species. All of the post-testicularly acquired GPI-anchored proteins identified thus far have also been found on cells of the immune system (CD62, CD55, CD59, CD73), and we speculate that they may have a role in protecting spermatozoa from immune attack in the male and female reproductive tracts.

Recent results using CAMPATH-1 antibodies to control GVHD and graft rejection

Recent data from the CAMPATH users group are reported. Different protocols have been tested using the CD52 antibodies Campath-1M and Campath-1G for prevention of GVHD and graft rejection in allogeneic transplants from both sibling and volunteer unrelated donors. Leukaemia relapse remains a significant problem for patients with CML, but in other diseases the recent results using T cell depletion appear to be as good as, or better than, published data with conventional GVHD prophylaxis. In addition, the morbidity and mortality associated with chronic GVHD are substantially reduced. Future collaborative studies to consolidate these findings include a randomised trial of the humanised antibody Campath-1H organised under the auspices of the EBMT. There are also plans to carry out experimental studies using Campath-1 antibodies to deplete T cells from peripheral blood stem cell harvests.

Transient increase in symptoms associated with cytokine release in patients with multiple sclerosis

Fourteen patients with multiple sclerosis were treated with the humanized monoclonal antibody CAMPATH-1H which targets the CD52 antigen present on all lymphocytes and some monocytes; four also received anti-CD4 antibody. Lymphopaenia developed rapidly and was sustained for at least 1 year. In 12 patients, the first infusion of antibody was characterized by significant exacerbation or re- awakening of pre-existing symptoms lasting several hours. These clinical effects of antibody treatment correlated with increased levels of circulating cytokines. Peak levels of tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma occurred at 2 h, whereas the rise in interleukin-6 (IL-6) was significantly delayed and peaked at 4 h after starting antibody treatment. There was a decline in CH50, indicating complement activation. The neurological symptoms could not be attributed directly to pyrexia and were not provoked (in one patient) by an artificial rise in temperature. In the remaining two patients, a single pre-treatment with intravenous methylprednisolone (500 mg) prevented both the transient increase in neurological symptoms and the cytokine release. Our results, involving 14 intensively studied patients treated with humanized monoclonal antibodies, suggested that soluble immune mediators contribute to symptom production in multiple sclerosis; the mechanism remains uncertain but, on the available evidence, we favour the interpretation that cytokines directly affect conduction through partially demyelinated pathways.

Synthetic peptide mimotope of the CAMPATH-1 (CD52) antigen, a small glycosylphosphatidylinositol-anchored glycoprotein

BACKGROUND

CAMPATH-1 (CD52) antibodies are among the most powerful and specific lympholytic agents in humans and have numerous potential applications for human therapy. The CD52 antigen is a GPI-anchored glycoprotein with an exceptionally short peptide sequence of only 12 amino acids and a single, complex, N-linked oligosaccharide. Antibodies bind to the deglycosylated antigen and to a proteolytic fragment, but not to the synthetic peptide alone.

OBJECTIVES

To characterise the antigenic epitope more precisely and to construct a synthetic analogue. Such an analogue would be useful for assay and purification of the therapeutic CAMPATH-1 antibodies as well as for studies of the antibody-antigen binding site.

STUDY DESIGN

Collections of synthetic peptides based on the natural sequence were screened with a panel of CD52 antibodies.

RESULTS AND CONCLUSION

A synthetic peptide composed of the natural C-terminal amino acids plus two additional residues was found to mimic the antigen with sufficient affinity to be useful for a variety of assays and for construction of an affinity matrix for antibody purification. Systematic mutation of this peptide enabled the definition of the critical residues for antibody binding, which will be of great help in building a model of the antibody-antigen interaction. Peptide mimotopes synthesised using a natural sequence as a starting point, rather than a completely random library, may be useful in many other similar circumstances.

Monoclonal antibody therapy of chronic intraocular inflammation using Campath-1H

Images

Bone marrow transplantation for chronic myeloid leukemia with volunteer unrelated donors using ex vivo or in vivo T-cell depletion: major prognostic impact of HLA class I identity between donor and recipient

Between August 1985 and July 1994, we performed 115 volunteer unrelated donor (VUD) bone marrow transplants (BMT) for first chronic phase (n = 86) or advanced phase (n = 29) chronic myeloid leukemia (CML). Standard serologic HLA typing of potential donors and recipients was supplemented with one-dimensional isoelectric focusing (IEF) for class I proteins, allogenotyping for DR and DQ alleles using DNA restriction fragment length polymorphism (RFLP) analysis, and the measurement of antirecipient major histocompatibility complex (MHC) cytotoxic T-lymphocyte precursor cells in the donors' blood (CTLp assay). Recipients were conditioned for transplantation with a combination of high-dose chemotherapy and total body irradiation (n = 103) or high-dose chemotherapy alone (n = 12). Twenty eight recipients received ex vivo T-cell-depleted marrow, and 84 underwent some form of in vivo T-cell depletion. The probability of severe (grades III or IV) acute graft-versus-host disease (aGVHD) was 24%, and that of extensive chronic graft-versus-host disease (cGVHD), 38%. Proportional hazards regression analysis showed an association between low frequency CTLp and a reduced incidence of severe aGVHD (relative risk [RR], 0.28; P = .0035). The probability of relapse at 3 years was 23%, with first chronic phase disease being independently associated with a lower risk of relapse (RR, 0.71; P = .01). The overall leukemia-free survival (LFS) at 3 years was 37%; the LFS for the first chronic phase and advanced phase recipients was 41% and 26%, respectively. First chronic phase disease (RR, 0.56; P = .063) and the combination of recipient cytomegalovirus (CMV) seronegativity and an IEF-matched donor (RR, 0.48; P = .011) were both associated with improved LFS. The probabilities of survival and LFS for patients under 40 years of age transplanted in first chronic phase from an IEF-matched donor were 73% and 50%, respectively. We conclude that VUD BMT is a reasonable option for patients with CML; when using ex vivo or in vivo T-cell depletion, optimal results are achieved in patients transplanted in chronic phase with marrow from donors without demonstrable class I HLA mismatch and a low CTLp frequency.

Prevention of immune-mediated corneal graft destruction with the anti-lymphocyte monoclonal antibody, CAMPATH-1H

We report a patient with peripheral rheumatoid corneal melting who developed a corneal perforation in one eye requiring tectonic keratoplasty. Nine consecutive corneal grafts were rapidly destroyed despite systemic immunosuppression with corticosteroid, cyclophosphamide, azathioprine and cyclosporin A. A rejection episode was observed in one graft before it melted and allograft rejection may have contributed to the destruction of other grafts. Corneal graft survival was ultimately achieved by systemic immunosuppression with the anti-lymphocyte monoclonal antibody, CAMPATH-1H. A single episode of rejection developed in the early post-operative period which was easily reversed by topical corticosteroid. Corneal melting has not recurred and the graft has now remained intact and clear for 24 months. Anti-lymphocyte monoclonal antibodies may therefore provide effective immunosuppression in the treatment of refractory ocular disorders.

Ex-vivo whole blood cultures for predicting cytokine-release syndrome: dependence on target antigen and antibody isotype

Ex-vivo whole blood assays have been evaluated for their ability to accurately predict the risk of a first-dose cytokine reaction developing in vivo following therapeutic antibody infusion. Tumour necrosis factor alpha (TNF alpha) release was rapidly detected in cultures incubated with either anti-CD52 antibodies of the human IgG1 or rat IgG2b isotype, and to a lesser extent with a human IgG4 isotype. Endotoxin contamination of the antibodies was not responsive for cytokine release, since polymixin B failed to inhibit cytokine release using concentrations of this antibiotic which neutralized the enhanced cytokine release seen from LPS-spiked antibody. A rat IgG2b antibody to CD45 and a human IgG1 anti-CD3 also induced significant TNF release, however, an aglycosyl anti-CD3 mutant devoid of adverse side-effects in vivo, did not result in cytokine release in vitro. Since the pattern of cytokine release seen following the clinical use of these antibodies was in good agreement with the findings of the ex-vivo whole cultures, this demonstrates the usefulness of this assay to predict cytokine release in vivo.

Low immunogenicity of therapeutic rat CD45 antibodies when used for pre-treatment of donor organs for transplantation

Immunoassays for the measurement of human anti-immunoglobulin responses against the CD45 specific rat monoclonals, YTH 24.5 and YTH 54.12, have been developed. The assays are based on a 'double antigen' ELISA system and are reproducible with coefficients of variation of less than 15%. The assays were used to measure anti-immunoglobulin responses in sera from 40 patients who had received kidneys pre-treated with the pair of anti-CD45 monoclonals YTH 24.5 and YTH 54.12. Only two patients elicited a weak human antimurine antibody (HAMA) response.

Cross-linking of the CAMPATH-1 antigen (CD52) triggers activation of normal human T lymphocytes

The CAMPATH-1 (CD52) antigen is a 21-28 kDa glycopeptide which is highly expressed on lymphocytes and macrophages and is coupled to the membrane by a glycosylphosphatidylinositol (GPI) anchoring structure. The function of this molecule is unknown. However, it is an extremely good target for complement-mediated attack and antibody-mediated cellular cytotoxicity. The humanized CAMPATH-1H antibody, which is directed against CD52, is very efficient at mediating lymphocyte depletion in vivo, and is currently being used in clinical trials for lymphoid malignancy and rheumatoid arthritis. It is therefore important to examine the functional effects of this antibody on different lymphocyte sub-populations. Because several other GPI-linked molecules expressed on the surface of T lymphocytes are capable of signal transduction resulting in cell proliferation, we have investigated whether the CAMPATH-1 antigen can also mediate these effects. In the presence of phorbol esters and cross-linking anti-Ig antibodies, mAbs specific for CD52 induced proliferation and lymphokine production in highly purified resting CD4+ and CD8+ T lymphocytes. The rat IgG2c YTH 361.10 anti-CD52 antibody, however, was able to activate resting CD4+ and CD8+ T cells directly without cross-linking or phorbol myristate acetate in the absence of Fc-bearing cells. Anti-CD52 antibodies also augmented the anti-CD3 mediated proliferative response of CD4+ and CD8+ T cells when the two antibodies were co-immobilized onto the same surface or cross-linked in solution by the same second antibody. Both CD4+ CD45RA and CD4+ CD45RO T cells were stimulated to proliferate by anti-CD52 antibodies in the presence of appropriate co-stimulatory factors. Anti-CD52 mAbs did not, however, synergize with anti-CD2 or CD28 mAb to induce CD4+ T cell proliferation. The activation of CD4+ T cells by anti-CD52 antibodies was inhibited by cyclosporin A, suggesting a role for the calcineurin-dependent signal transduction pathways. Although CD52 could transduce a signal in T cells, anti-CD52 antibodies did not inhibit antigen-specific or polyclonal T cell responses, suggesting this molecule does not play an essential co-stimulatory role in normal T cell activation.

What can be done to prevent graft versus host disease?

Graft versus host disease presents a major obstacle to the widespread application of allogeneic bone marrow transplantation despite improvements in drug prophylaxis. Although animal models are providing an understanding of the biology of the process, opportunities for exploitation of that knowledge for therapeutic purposes are still limited. One way to overcome this impasse is to build on the positive benefits of T-cell purging of marrow, by combining it with intelligent correction of the known negative effects.

Preliminary evidence from magnetic resonance imaging for reduction in disease activity after lymphocyte depletion in multiple sclerosis

The central nervous system lesions of multiple sclerosis (MS) can be detected by magnetic resonance imaging (MRI) and the initial perivascular inflammatory component is distinguished by the presence of gadolinium enhancement. To assess the effect of systemic lymphocyte depletion on disease activity, seven patients with MS received a 10-day intravenous course of the humanised monoclonal antibody CAMPATH-1H (anti-CDw52). With some variations in the protocol, enhanced cerebral MR images were obtained monthly for 3-4 months before and at least 6 months after treatment. 28 enhancing areas were detected on the first series of 7 scans; 51 additional active lesions were identified on 18 scans before treatment; 15 were detected on 20 scans done over the next 3 months, but only 2 active lesions were seen on 23 scans during follow-up beyond 3 months. The difference in lesion incidence rate before and after treatment varied and the rate ratio was significantly reduced in only three patients. Collectively, in a "meta-analysis", the rate ratios were 0.15 [corrected] (95% CI 0.09-0.24) for all seven patients and 0.24 (0.14-0.42; p < 0.001) with exclusion of the patient whose scanning schedule differed. The effect of CAMPATH-1H on disease activity provides direct, but preliminary, evidence that disease activity in MS depends on the availability of circulating lymphocytes and can be prevented by lymphocyte depletion. It is too early to say anything about the clinical results of treatment with this agent.

T cell depletion by exposure to Campath-1G in vitro prevents graft-versus-host disease

Campath-1G is an immunosuppressive monoclonal antibody directed against human lymphocytes. Its effectiveness in preventing graft-versus-host disease (GVHD) by simple opsonisation of bone marrow T-cells has been studied in 36 consecutive allografts: in 17 for leukaemia, one for essential thrombocytosis and four for myeloma this was the sole means of GVHD prophylaxis. A further eight patients with aplastic anaemia received 3 months post-transplantation cyclosporin A (CsA) for this purpose whereas in the ninth and tenth the preparative regimen has been modified with this immunosuppressive agent now discontinued. Nucleated cells were harvested and after quantitative recovery of the mononuclear population on the Cobe 2997 separator they were exposed to 20 mg Campath-1G for 30 min at room temperature and then infused. Following standard conditioning, which included total lymphoid irradiation, the median days to reach 0.5 and 1.0 x 10(9)/l neutrophils were respectively 18 (range 9-34) and 28 (range 10-59); to 25 and 100 x 10(9)/l platelets the corresponding times were 17 days (range 5-32 days) and 27 days (range 13-127 days). In all, the day 14 trephine biopsy showed engraftment. At median follow-up of 20 months (range 5-44 months) only one patient has developed possible grade I cutaneous GVHD that responded promptly to corticosteroids: no chronic GVHD or CMV pneumonitis has been encountered. Of those with haematological malignancy transplanted in remission only two with acute leukaemia have relapsed. In aplastic anaemia graft loss initially occurred but this has been overcome by adding Campath-1G in vivo and omitting CsA.(ABSTRACT TRUNCATED AT 250 WORDS)

Repeated cleaning of protein A affinity column with sodium hydroxide

Protein A attached to an affinity adsorbent was shown to be remarkably resistant to 0.5 M NaOH. Even repeated treatments gave only a small decrease in functional capacity and no adverse effect on leakage of the protein A into the eluate. This simple cleaning procedure should be useful in applications where antibodies need to be purified free from the risk of contamination with endotoxins or micro-organisms, e.g., for in vivo therapy, either in clinical trials or experimental animals. It can also prevent cross-contamination when the same protein A adsorbent is used for different batches of antibody.