Suppression of clonal evolution in two chronic myelogenous leukaemia patients treated with leucocyte interferon

Interferon alfa-2b in acute- and chronic-phase chronic myelogenous leukaemia: initial response and long-term results in 54 patients

Fifty-four patients with Ph1-positive chronic myelogenous leukaemia (CML) (48 with chronic-phase and six acute-phase disease) were treated with interferon alfa-2b subcutaneously (s.c.). The starting dose was 4 million units (MU)/m2 body surface area daily. It was reduced in parallel with serially determined leucocyte counts, and minimal effective doses were given as maintenance after achieving remission. Haematological remissions were induced in 22 of the 48 patients (46%) with chronic-phase disease. Thirteen patients (27%) revealed partial haematological remission and another 13 no response to treatment. No complete remission could be induced, although minor or partial cytogenetic responses were seen in 16 patients (33%). Moreover, a bcr-abl reduction was detected on Southern blot analysis in two patients. In chronic-phase disease, results of treatment were influenced by elapsed time after diagnosis, extent of previous treatment and interferon dosage. No beneficial effects of interferon were detected in the six patients with acute-phase disease. Principal acute side effects were fever and flu-like symptoms at the beginning of the therapy, which usually subsided within 3-7 days. Chronic side effects, especially weakness and neuropathy, were less frequent but more severe and necessitated discontinuation of treatment in 10 patients. In summary, interferon alfa-2b seems to be an effective treatment in early chronic-phase CML. Long-term effects on the course of the disease, however, must be determined.

In vivo induction of HLA molecules in patients with myeloproliferative syndrome during IFN alpha treatment

Eighteen patients with myeloproliferative syndrome (14 with chronic myeloid leukemia, four with essential thrombocytosis) were investigated for modulation of HLA antigens on peripheral blood lymphocytes, monocytes, and hematopoietic precursors during IFN alpha therapy as a sign of potentially increased immune recognition of malignant cells. After 1 month of IFN alpha therapy, an increased number of monocytes and hematopoietic precursor cells, but not of lymphocytes, expressed HLA-DQ antigens. In addition, a strong induction of HLA class-I antigens was found on both hematopoietic progenitors and normal peripheral blood mononuclear cells. With daily injections of IFN in the first month of therapy stimulation continuously increased, suggested a major effect of IFN alpha on hematopoietic progenitors with sustained enhanced expression of HLA class-I antigens during differentiation of myelomonocytic cells. HLA class-I antigen expression was consistently augmented by IFN alpha in all patients, irrespective of their hematological response.

Interferon-gamma in vivo reverses the increased platelet levels of platelet-derived growth factor and transforming growth factor-beta in patients with myelofibrosis with myeloid metaplasia

We previously reported high platelet-derived growth factor (PDGF) and transforming growth factor beta (TGF-beta) levels in platelets from patients with myelofibrosis with myeloid metaplasia. We report here the effects of in vivo administration of recombinant human interferon-gamma on these growth factor levels. Of six patients who entered this study in our institution, four completed the 6-month therapy trial with interferon-gamma PDGF and TGF-beta levels in platelets were evaluated before and after treatment. PDGF levels were determined using a radioimmunoassay and TGF-beta activity was measured using an inhibition growth assay on CC164 cells. In these four patients, IFN-gamma therapy led to a reduction of the increased PDGF and TGF-beta levels in platelets towards the normal range. PDGF and TGF-beta values decreased by 25-45% and 32-46%, respectively. An acute deterioration was observed in one patient 5 months after the end of IFN-gamma therapy. In this patient, the deterioration of his clinical state correlated with an increase in intraplatelet PDGF and TGF-beta levels.

Impaired conversion of exogenous arachidonic acid by platelets to thromboxane B2 and correction of that deficiency by interferon-alpha

In the course of an investigation of cyclooxygenase and 12-lipoxygenase activity in platelets of patients with myeloproliferative syndrome receiving treatment with interferon-alpha 2 patients showed unusual results which have not been reported so far. Both patients had thrombocytosis, in one case associated with polycythaemia. In platelets of both patients, a reduced conversion of exogenous 14C arachidonic acid to TXB2 was observed accompanied by a shift in conversion to PGE2 and 12-HETE in one patient and to 12-HETE alone in the other before therapy. These findings were paradoxically associated with evidence of enhanced platelet activation in vivo. Treatment of both patients with interferon-alpha resulted in reversal of the biochemical abnormalities and in clinical remission.

Restoration of nonclonal hematopoiesis in chronic myelogenous leukemia with interferon alpha

Studies have shown that recombinant human alpha interferon (rIFN alpha) inhibits the growth of colonies of multipotential stem cells from human bone marrow. This report demonstrates that rIFN alpha inhibits the growth of such colonies from the bone marrow of patients with chronic myelogenous leukemia (CML) to a greater extent than from bone marrow of healthy individuals. It also shows that T lymphocyte colonies subcloned with interleukin 2 (IL-2) from CML mixed colonies were inhibited more by rIFN alpha than were similar colonies subcultured from normal mixed colonies. The report demonstrates that the Ph' chromosome is present in such T cell colonies subcultured from CML mixed colonies. When mixed colonies were grown from CML bone marrow in the presence of rIFN alpha, Ph' negative colonies were observed, whereas no such Ph' negative mixed colonies grew from a similar number of bone marrow cells incubated without rIFN alpha. These observations confirm that T lymphocytes derived from bone marrow stem cells are from the CML clone, and that the inhibition of growth of Ph' positive colonies, by rIFN alpha permits the growth of residual normal stem cells. The disappearance of the Ph-chromosome in subclones of T lymphocytes supports the notion of nonclonal hematopoiesis in patients with CML.

Recombinant interferon-alpha-2C in chronic myelogenous leukaemia: relationship of sensitivity of committed haematopoietic precursor cells in vitro (BFU-E, CFU-GM, CFU-Meg) and clinical response

In an ongoing phase-II trial we aimed to predict clinical responsiveness of Philadelphia chromosome positive (Ph1+) chronic myelogenous leukaemia (CML) to recombinant IFN-alpha-2C (rIFN-alpha-2C) by pretesting in vitro. From five normal controls and 14 CML patients in chronic phase, bone marrow samples were taken before treatment and tested for antiproliferative activity by rIFN-alpha-2C, using a microagar culture system for BFU-E, CFU-GM, and CFU-Meg. Light-density nucleated bone marrow cells were stimulated for BFU-E and CFU-Meg colony formation with Alpha medium containing 20% serum obtained from a patient with severe aplastic anaemia. CFU-GM growth was induced with conditioned medium from the cell line GCT. In normal controls BFU-E, CFU-GM and CFU-Meg colony formation was inhibited by rIFN-alpha-2C in a dose-dependent manner. BFU-E proved to be the most sensitive cell lineage (IC50: 65; range: 53-116 U/ml) whereas CFU-GM was about 20 times less sensitive (IC50: 643; range: 480-897 U/ml). The sensitivity of CFU-Meg ranged between these two colony types with 50% growth inhibition at an IFN concentration of 160 (range: 68-246 U/ml). A heterogeneous response to rIFN-alpha-2C in vitro was seen in CML patients. Three of the 14 patients were 'resistant' to rIFN-alpha-2C in vitro with IC50 values for BFU-E, CFU-GM and/or CFU-Meg colony formation greater than 10(4) U/ml. Patients were subsequently treated with a daily dose of rIFN-alpha-2C of 5 x 10(6) U. Four patients achieved a complete and six achieved a partial haematological response. Of the four non-responders three rapidly progressed into blastic crisis. Thus it was seen that treatment failure to interferon was accompanied by IFN-resistance in vitro of BFU-E, CFU-GM and/or CFU-Meg colony formation by bone marrow precursors (p less than 0.01). These results suggest a predictive value of IFN-sensitivity testing in vitro in Ph1 + CML.

Effect of interferon-alpha in patients with chronic myelogenous leukemia in the accelerated phase: cytogenetic and molecular studies

Human interferon-alpha (IFN-alpha) has been shown to be effective in the treatment of Philadelphia chromosome (Ph1)-positive chronic myelogenous leukemia (CML) in the benign stable phase. The present study indicates that IFN-alpha may have a suppressive effect on Ph1-positive clones not only in the early stable phase but also in the accelerated phase with additional chromosomal abnormalities in some patients. In this study, in addition to 5 benign-phase patients, 3 patients with CML in the accelerated phase who had additional chromosomal abnormalities were treated with IFN-alpha. The presence of the Ph1-positive clone was estimated by chromosomal analysis and by Southern analysis at the DNA level using a 3' breakpoint cluster region (bcr) probe. Hematological remission and the suppression of proliferation of Ph1-positive clone to various extents were achieved by IFN-alpha treatment in 2 benign-phase patients and 3 patients with additional chromosomal abnormalities. Interestingly, in one of the latter three patients, Ph1-positive clones with or without additional chromosomal abnormalities were completely suppressed judging from chromosomal analysis and from the disappearance of bcr gene rearrangements.

Cytogenetics in patients with chronic myelogenous leukemia treated with bone marrow transplantation

Cytogenetic data are reported from 16 patients with Philadelphia chromosome (Ph) positive chronic myelogenous leukemia (CML) treated with bone marrow transplantation (BMT). The usefulness of cytogenetic investigations for the assessment of marrow engraftment is stressed. The significance of persistence or reappearance of Ph after BMT, possibly due to a defective leukemic clone eradication by the conditioning regimen, is also discussed. Generally, Ph-positive cells are damaged and disappear within the first year of BMT. Sometimes, however, the cells may repair the damage and proliferate again, resulting in disease relapse. Rarely, clinical and hematologic relapse does not follow Ph-positive clone expansion although leukemic cells represent more than 50% of marrow metaphases examined. Finally, the effect of interferon on Ph-positive clones after BMT and random chromosome changes, that appear transiently after BMT and are of uncertain significance, are discussed.

Hypothesis: a possible role for interferon in the treatment of idiopathic myelofibrosis

It is proposed that interferon may be an active agent in the treatment of patients with idiopathic myelofibrosis. In this disorder the megakaryocyte cell lineage plays a major role in the deposition of bone marrow collagen by the release of growth promoting factors, including platelet-derived growth factor, which are mitogenic for fibroblast proliferation. Interferon reduces collagen deposition in the bone marrow by suppressing the activity of the proto-oncogene, which is involved in the production of growth factors from abnormal megakaryocytes and platelets. A direct myeloid cytoreductive effect of interferon upon the megakaryocyte proliferation contributes to reducing growth factor activity in the bone marrow. Finally, interferon induces monocytoid differentiation, thereby increasing bone marrow collagenase-activity. Thus, interferon has several actions, which in concert might reduce bone marrow collagen in myelofibrosis.

[Detection of nephrotoxicity of human alpha 2b interferon with special reference to the analysis of urine enzymes in patients with chronic myeloid leukemia]

The nephrotoxic potential of alpha-interferon (IFN alpha-2b) was analysed in 21 patients with chronic myeloid leukemia. As particularly sensitive parameters in the detection of subclinical renal injury we measured the excretion of the following urinary enzymes: lactate dehydrogenase (LDH), gamma-glutamyltransferase (GGT), leucine arylaminidase (LAP), beta-galactosidase (GAL) and N-acetyl-beta-glucosaminidase (NAG). Additionally, protein excretion and urinary sediment were analysed. In 18 of 21 patients a significant increase in the excretion of LDH, LAP, GGT and NAG was found, in 6 patients there was an additional rise in the output of GAL. Eleven patients developed proteinuria up to 2 g/l, one patient excreted up to 9 g/l. Enzymuria and protein excretion decreased in all patients after reduction of the IFN alpha-2b dosage and disappeared in two patients following cessation of therapy. The high incidence of nephrotoxic events in patients with CML during IFN alpha-2b therapy might be mostly due to immunological or substance-specific effects.

Hematologic remission and cytogenetic improvement induced by recombinant human interferon alpha A in chronic myelogenous leukemia

We treated 17 patients who had Philadelphia-chromosome-positive chronic myelogenous leukemia (4 of whom had not received therapy and 13 of whom had been treated with hydroxyurea or busulfan for less than six months) with recombinant human interferon alpha A (Roferon-A). The interferon was given as 5 X 10(6) units per square meter of body-surface area per day intramuscularly during induction therapy. Fourteen patients responded to the treatment, of whom 13 had a hematologic remission and 1 had a partial hematologic remission. The median number of white cells in those patients declined from 60.9 X 10(3) to 3.4 X 10(3) per microliter, and the median number of platelets decreased from 476 X 10(3) to 231 X 10(3) per microliter. Among the five responding patients who had splenomegaly before treatment, the spleen size returned to normal in four and decreased by 75 percent in one, although it remained enlarged. Bone marrow cellularity declined from a median of 92.5 percent to a median of 57.5 percent. In six of the patients with hematologic remission, complete suppression of Philadelphia cells was observed on at least one examination. Of the 14 patients who responded, 11 have received the interferon therapy for 9 to 15 months. One patient relapsed during the treatment, and the treatment has been temporarily interrupted in two patients because of toxicity. These data are preliminary and will need further confirmation, but they suggest that recombinant human interferon alpha A is effective in inducing hematologic remission in most patients with benign-phase chronic myelogenous leukemia and in suppressing the Philadelphia chromosome in some of these patients.

The technique of premature chromosome condensation to study the leukemic process: review and speculations

The technique of premature chromosome condensation involves the fusion of mitotic cells with interphase cells resulting in the immediate condensation of the interphase chromatin into discrete chromosome units, the prematurely condensed chromosomes (PCC). The ability to visualize the interphase chromosomes of bone marrow and blood cells by this technique has proved useful in the study of human leukemia. This article describes how the PCC technique has been used to predict clinical outcome as well as gain insight into the biology of leukemia.