Clinical evaluation of cellular immunotherapy in acute myeloid leukaemia

Immunotherapy is currently under active investigation as an adjuvant therapy to improve the overall survival of patients with acute myeloid leukaemia (AML) by eliminating residual leukaemic cells following standard therapy. The graft-versus-leukaemia effect observed following allogeneic haematopoietic stem cell transplantation has already demonstrated the significant role of immune cells in controlling AML, paving the way to further exploitation of this effect in optimized immunotherapy protocols. In this review, we discuss the current state of cellular immunotherapy as adjuvant therapy for AML, with a particular focus on new strategies and recently published results of preclinical and clinical studies. Therapeutic vaccines that are being tested in AML include whole tumour cells as an autologous source of multiple leukaemia-associated antigens (LAA) and autologous dendritic cells loaded with LAA as effective antigen-presenting cells. Furthermore, adoptive transfer of cytotoxic T cells or natural killer cells is under active investigation. Results from phase I and II trials are promising and support further investigation into the potential of cellular immunotherapeutic strategies to prevent or fight relapse in AML patients.     

Myelodysplastic syndromes: their history, evolution and relation to acute myeloid leukaemia

The myelodysplastic syndromes (MDS) constitute a heterogeneous group of clonal disorders arising from a multipotent haemopoietic progenitor which share a leukaemic propensity, 30% of cases culminating in acute myeloid leukaemia (AML). Their pathogenesis probably entails multiple steps, phenotypic progression being determined by either expansion or evolution of the abnormal clone. The clonal origin of certain cases of de novo AML is analogous to that of MDS and evidence that they share a common pathogenesis and distinct biological characteristics is beginning to emerge.     

Expression and distribution of aphidicolin-induced fragile sites in chronic myeloid leukaemia, acute lymphocytic leukaemia and acute myeloid leukaemia

New information is revealed concerning the frequency of expression and distribution of aphidicolin-induced fragile sites in eight leukaemic patients, namely, four chronic myeloid leukaemic patients (CML), three acute lymphocytic leukaemic (ALL) patients, and one acute myeloid leukaemic (AML) patient. The cytogenetic data demonstrate a statistically significant (p less than 10(-6] increase in the frequency of aphidicolin-induced fragile sites in seven of the eight leukaemic patients compared with healthy age-matched and sex-matched controls. The chromosomal band locations of the aphidicolin-induced fragile sites from 400 metaphase spreads of these leukaemic patients reveal a nonrandom distribution in the karyotype. Some aphidicolin-induced fragile sites in these leukaemic patients were located at chromosome bands known to be induced specifically by folic acid, distamycin A, bromodeoxyuridine or azacytidine. The cross-induction of fragile sites in the leukaemic patients may be indicative of shared molecular homology in the sequence composition of nonrandom chromosomal DNA.     

Active immunotherapy in treatment of acute leukaemia

Active non-specific immunotherapy has been used to prolong remissions in acute lymphoblastic leukaemia. The series reported here used Bordetella pertussis vaccine in a controlle trial after intensive chemotherapy. Possibly immunotherapy delayed the onset of relapse in the treated patients, but no long-term remissions were obtained. Further work is needed to establish the role of immunotherapy in general, and the use of B. pertussis vaccine in particular, in the treatment of acute leukaemia.     

Prolonged remission maintenance in acute myeloid leukaemia.

Twenty-five patients with acute myeloid leukaemia were treated with three quadruple drug combinations in predetermined rotation: TRAP (thioguanine, daunorubicin, cytarabine, prednisolone); COAP (cyclophosphamide, vincristine, cytarabine, prednisolone); and POMP (prednisolone, vincristine, methotrexate, mercaptopurine). Fifteen patients (60%) achieved complete remission and five (20%) partial remission. For maintenance, five-day courses of drugs were administered every 14 to 21 days and doses were increased to tolerance. The median length of complete remission was 66 weeks. In eight patients remission maintenance treatment was discontinued and some remained in complete remission for over two years. In this series the remission induction rate was comparable with that reported for other regimens and complete remission lasted longer with this intensive maintenance regimen than with others. Nevertheless, the TRAP programme must still be regarded as only palliative treatment for acute myeloid leukaemia.     

Factors influencing antibody-mediated cytotoxicity during the immunotherapy of Rauscher-virus-induced myeloid leukemic cells

Summary The present study was undertaken to determine the factors that influence antibody-mediated cytotoxicity during immunotherapy of virally transformed tumor cells. As model a Rauscher-virus-induced myeloid leukemic cell line of BALB/c origin (RMB-1) was used, which forms disseminated tumors, when inoculated intravenously in BALB/c mice. As previously reported, prolonged survival was obtained when tumor-bearing mice were treated in vivo with a single high dose of a tumor-specific IgG2a monoclonal antibody. This study shows that antibody-dependent cellular cytotoxicity is an important mechanism involved in tumor cell destruction. Since in vitro studies showed that peritoneal macrophages were capable of killing RMB-1 cells in the presence of tumor-specific monoclonal antibody and since in the tumors of mice treated with monoclonal antibody a high influx of macrophages was observed histologically, it is likely that macrophages play an important effector role in elimination of tumor cells. Successful therapy in C5-complement-deficient tumor-bearing mice suggests that complement-dependent cytotoxicity does not play a major role. In nude (T-cell-deficient) mice the therapeutic effect of tumor-specific IgG2a antibody was significantly less than in immunocompetent mice. Although infiltration analysis of tumors of treated and untreated mice showed equally low numbers of helper-T and suppressor/cytotoxic T-cells, the mortality studies of T-cell-deficient and immunocompetent mice indicate that T-cells play a substantial, auxillary role during antibody-mediated, tumor destruction in our model.     

The coexistence of chronic lymphocytic leukaemia and polycythaemia vera terminating in acute myeloid leukaemia

A 67-year-old man with the coexistence of CLL and PV converted after 4 years to AML is described. This rare simultaneous occurrence of both chronic lymphoid and myeloid proliferations as well as nonlymphoblastic leukaemia developing in a patient with CLL is discussed in the light of literature data.     

Leukostasis associated with blood transfusion in acute myeloid leukaemia.

Three patients with acute myeloblastic leukaemia and blast cell counts greater than 100 X 10(9)/1 (100 000/mm3) died unexpectedly soon after blood transfusion. In two cases postmortem examination disclosed cerebral leukostasis. Analysis of the records from the MRC''s fourth and fifth acute myeloid leukaemia trials showed that in the first week after diagnosis mortality was five times greater in patients with blast counts above 100 X 10(9)/1 than in patients with lower counts. Age and platelet count did not explain this excess. The mean haemoglobin concentration in the patients with high blast counts who died within the first week was 10.5 +/- 2.8 g/dl, which was significantly higher than that in the surviving group (7.6 +/- 2.4 g/dl). Only half the patients received chemotherapy within two days of diagnosis. Leukostasis is an important cause of early death in patients with high blast counts, and the increase in viscosity produced by transfusing to a haemoglobin concentration above 10 g/dl may lead to sudden deterioration. Transfusion to such concentrations should be avoided until the blast count has been reduced by early chemotherapy.     

Humoral detection of leukaemia-associated antigens in presentation acute myeloid leukaemia

The serological analysis of recombinant cDNA expression libraries (SEREX) technique was used to immunoscreen a testes cDNA expression library with sera from newly diagnosed acute myeloid leukaemia (AML) patients. We used a testis cDNA library to aid our identification of cancer-testis (CT) antigens. We identified 44 antigens which we further immunoscreened with sera from AML, chronic myeloid leukaemia (CML), and normal donors. Eight antigens were solely recognised by patient sera including the recently described CT antigen, PASD1, and the cancer-related SSX2 interacting protein, SSX2IP. RT-PCR analysis indicated that we had identified three antigens which were expressed in patient bone marrow (BM) and peripheral blood (PB) but not in normal donor samples (PASD1, SSX2IP, and GRINL1A). Real-time PCR (RQ-PCR) confirmed the restricted expression of PASD1 in normal donor organs. Antigen presentation assays using monocyte-derived dendritic cells (mo-DCs) showed that PASD1 could stimulate autologous T-cell responses, suggesting that PASD1 could be a promising target for future immunotherapy clinical trials.     

Cell-mediated cytotoxicity to non-MHC alloantigens on mouse epidermal cells

Mice of the C3H/He and A non-H-2 backgrounds are disparate from mice of the B10 background for the tissue-restricted, non-H-2 alloantigen of epidermal cells (EC), Epa-1, that is expressed by EC but not by lymphocytes (LC), as well as for a number of other alloantigens of the B10 background that are expressed by both EC and LC, generically referred to as lymphocyte/epidermal alloantigens (LEA). In this study, we compared the ability of various H-2 congenic strains on the C3H or A backgrounds to mount cytotoxic T-lymphocyte (CTL) responses to EC from H-2 compatible mice of the B10 background. High responses to Epa-1 were detected only in the H-2 ^aand H-2 ^khaplotypes; H-2 ^b, H-2 ^o1, H-2 ^s, H-2 ^t1, and H-2 ^t2 haplotypes were nonresponders to Epa-1. High responses to LEA were detected in H-2 ^a, H-2 ^b, H-2 ^s, H-2 ^t1, and H-2 ^t2 haplotypes; H-2 ^kand H-2 ^o1 were nonresponsive to LEA. Analysis of the H-2K, I and D region alleles of responders indicates that H-2K ^kis essential for anti-Epa CTL responses, whereas D ^d, D ^b, or K ^swere all permissive for strong anti-LEA responses. The ability to mount a given CTL response was not associated with differences in I-region alleles. These results are discussed in terms of K/D region products serving as Ir-gene products for CTL and in determining the apparent tissue-specificity of CTL.     

Infiltration of central nervous system in adult acute myeloid leukaemia.

Out of 64 consecutive unselected patients with acute myeloid leukaemia studied during 1973-6, five developed clinical evidence of spread to the central nervous system (CNS). Neuroradiological examination showed cerebral deposits in three, in whom rapid symptomatic relief was obtained with radiotherapy. In two of these patients who developed solid intracranial deposits haematological remission could be reinduced or maintained; they were still alive 86 and 134 weeks later. When patients presented with spread to the CNS complicating generalised uncontrolled leukaemia they had short survivals. CNS infiltration may respond dramatically to appropriate treatment provided that it is not associated with generalised uncontrolled leukaemia, which has a poor prognosis. In view of this, routine "prophylaxis" of the CNS in adult acute myeloid leukaemia does not seem justified at present.     

Feedback regulation in a stem cell model with acute myeloid leukaemia

Background

The haematopoietic lineages with leukaemia lineages are considered in this paper. In particular, we mainly consider that haematopoietic lineages are tightly controlled by negative feedback inhibition of end-product. Actually, leukemia has been found 100 years ago. Up to now, the exact mechanism is still unknown, and many factors are thought to be associated with the pathogenesis of leukemia. Nevertheless, it is very necessary to continue the profound study of the pathogenesis of leukemia. Here, we propose a new mathematical model which include some negative feedback inhibition from the terminally differentiated cells of haematopoietic lineages to the haematopoietic stem cells and haematopoietic progenitor cells in order to describe the regulatory mechanisms mentioned above by a set of ordinary differential equations. Afterwards, we carried out detailed dynamical bifurcation analysis of the model, and obtained some meaningful results.

Results

In this work, we mainly perform the analysis of the mathematic model by bifurcation theory and numerical simulations. We have not only incorporated some new negative feedback mechanisms to the existing model, but also constructed our own model by using the modeling method of stem cell theory with probability method. Through a series of qualitative analysis and numerical simulations, we obtain that the weak negative feedback for differentiation probability is conducive to the cure of leukemia. However, with the strengthening of negative feedback, leukemia will be more difficult to be cured, and even induce death. In contrast, strong negative feedback for differentiation rate of progenitor cells can promote healthy haematopoiesis and suppress leukaemia.

Conclusions

These results demonstrate that healthy progenitor cells are bestowed a competitive advantage over leukaemia stem cells. Weak g₁, g₂, and h₁ enable the system stays in the healthy state. However, strong h₂ can promote healthy haematopoiesis and suppress leukaemia.

     

Microarray analysis of tumour antigen expression in presentation acute myeloid leukaemia

Acute myeloid leukaemia (AML) is a difficult to treat disease, especially for those patients who have no eligible haematopoietic stem cell (HSC) donor. One of the most promising treatment options for these patients is immunotherapy. To investigate the expression of known tumour antigens in AML, we analysed microarray data from 124 presentation AML patient samples and investigated the present/absent calls of 82 tumour-specific or -associated antigens. We found 11 antigens which were expressed in AML patient samples but not normal donors. Nine of these were cancer-testis (CT) antigens, previously shown to be expressed in tumour cells and immunologically protected sites and at very low levels, if at all, in normal tissues. Expression was confirmed using real-time PCR. We have identified a number of CT antigens with expression in presentation AML samples but not normal donor samples, which may provide effective targets for future immunotherapy treatments early in disease.     

Development of a whole cell vaccine for acute myeloid leukaemia

We describe the modification of tumour cells to enhance their capacity to act as antigen presenting cells with particular focus on the use of costimulatory molecules to do so. We have been involved in the genetic modification of tumour cells to prepare a whole cell vaccine for nearly a decade and we have a particular interest in acute myeloid leukaemia (AML). AML is an aggressive and difficult to treat disease, especially, for patients for whom haematopoietic stem cell (HSC) transplant is not an option. AML patients who have a suitable donor and meet HSC transplant fitness requirements, have a 5-year survival of 50%; however, for patients with no suitable donor or for who age is a factor, the prognosis is much worse. It is particularly poor prognosis patients, who are not eligible for HSC transplant, who are likely to benefit most from immunotherapy. It would be hoped that immunotherapy would be used to clear residual tumour cells in these patients in the first remission following standard chemotherapy treatments and this will extend the remission and reduce the risk of a second relapse associated with disease progression and poor mortality rates. In this symposia report, we will focus on whole cell vaccines as an immunotherapeutic option with particular reference to their use in the treatment of AML. We will aim to provide a brief overview of the latest data from our group and considerations for the use of this treatment modality in clinical trials for AML. This article is a symposium paper from the conference “Progress in Vaccination against Cancer 2004 (PIVAC 4)”, held in Freudenstadt-Lauterbad, Black Forest, Germany, on 22–25 September 2004     

Results in children of acute lymphoid leukaemia protocol ICIG-ALL 9 consisting of chemotherapy for only nine months followed by active immunotherapy

Summary Protocol ICIG-ALL 9 with only nine months' remission chemotherapy followed by active immunotherapy has given a proportion of about 50% of the patients on the plateau of the first remission curve, while 60% of the children are on the plateau of survival curve.These results do not differ from those of another protocol (ICIG-ALL 10) conducted on an identical population of patients and comprising a 25 month remission chemotherapy before immunotherapy.This observation, confirmed by a randomized trial of the EORTC Haemopathy Working Party, suggests that between the 9th and the 25th month, active immunotherapy is as efficient as maintenance chemotherapy.The overall results of this protocol with short chemotherapy followed by active immunotherapy have been compared with those of another prolonged maintenance chemotherapy before immunotherapy protocol (ICIG-ALL 11), and with published protocols comprising only long maintenance chemotherapy: protocol 9 is, as far as the first remission plateau and the survival plateau are concerned, superior to most of these protocols (if not all their branches).Lethal toxicity of active immunotherapy is nil, in contrast to the proportion of deaths (4–28%) occurring during remission in the patients submitted to maintenance chemotherapy.However, not all patients with so-called acute lymphoid leukaemias should be treated identically: our early prognosis parameters (WHO cytological types and volume of the tumour, in this study) allow us to distinguish a good prognosis group in which protocol 9 gave an 80% cure expectancy.The patients with a poor prognosis should be the object of further research for a more efficient therapy. Even if this should be more intensive, the risk is justified in this group, while it is not so for the good prognosis group.