The Treatment of Chronic Granulocytic Leukaemia

Cyclin-dependent kinase modulators and cancer therapy

The cell cycle of eukaryotic cells varies greatly from species to species and tissue to tissue. Since an erroneous control of the cell cycle can have disastrous consequences for cellular life, there are genetically programmed signals, so-called cell cycle checkpoints, which ensure that all events of each stage are completed before beginning the next phase. Among the numerous molecules involved in this process, the most important are the cyclin-dependent kinases (CDKs), proteins that are activated only when bound to cyclins (regulatory proteins with fluctuating concentrations). In general, more CDKs are overexpressed in cancer cells than in normal cells, which explains why cancer cells divide uncontrollably. Succeeding in modulating CDK activity with pharmacological agents could result in decreasing the abnormal proliferation rate of cancer cells. This review offers an overview of CDK-cyclin complexes in relation to different cell cycle phases, an analysis of CDK activation and inhibition of molecular mechanisms, and an extensive report, including clinical trials, regarding four new drugs acting as CDK modulators: alvocidib, P276-00, SNS-032 and seliciclib.

Cyclin-dependent kinase modulators and cancer therapy

The cell cycle of eukaryotic cells varies greatly from species to species and tissue to tissue. Since an erroneous control of the cell cycle can have disastrous consequences for cellular life, there are genetically programmed signals, so-called cell cycle checkpoints, which ensure that all events of each stage are completed before beginning the next phase. Among the numerous molecules involved in this process, the most important are the cyclin-dependent kinases (CDKs), proteins that are activated only when bound to cyclins (regulatory proteins with fluctuating concentrations). In general, more CDKs are overexpressed in cancer cells than in normal cells, which explains why cancer cells divide uncontrollably. Succeeding in modulating CDK activity with pharmacological agents could result in decreasing the abnormal proliferation rate of cancer cells. This review offers an overview of CDK-cyclin complexes in relation to different cell cycle phases, an analysis of CDK activation and inhibition of molecular mechanisms, and an extensive report, including clinical trials, regarding four new drugs acting as CDK modulators: alvocidib, P276-00, SNS-032 and seliciclib.

Induction of differentiation of myeloid leukemic cells by busulphan: in vivo and in vitro observations

Treatment of a 74 year old patient with chronic myelogenous leukemia (CML) with busulphan resulted in an abrupt and pronounced decrease of the white blood cell (WBC) count with restoration of normal peripheral blood cell morphology and regression of splenomegaly. The Philadelphia positive (Ph+) clone was however still detectable. The alterations in the WBC count and morphology were not preceded by marrow hypoplasia but correlated closely with a marked decrease in the serum levels of Transcobalamin I (TC I), a vitamin B12-binding protein derived from immature myeloid precursors and a reciprocal rise in serum TC III, a vitamin B12-binding protein originating from terminally differentiated mature granulocytes. Studies on the HL-60 cell line showed that busulphan is capable of inducing leukemic cells to differentiate into granulocyte-like cells. These observations, taken together, suggest that in addition to its potent myelosuppressive effects, busulphan may induce apparent clinical remissions in some CML patients by promoting terminal cell differentiation.

Pharmacokinetics of busulfan: correlation with veno-occlusive disease in patients undergoing bone marrow transplantation

Busulfan is an alkylating agent that is widely used in preparative regimens for bone marrow transplantation (BMT). We developed a high-performance liquid chromatographic (HPLC) assay for the determination of plasma busulfan concentrations in 30 patients who received oral doses of 1 mg/kg. Concentrations were fit by a one-compartment pharmacokinetic model with first-order absorption. The pattern of absorption and elimination varied widely between patients, with peak concentrations ranging from 1.2 to 10.4 mumol/l (mean, 4.25 +/- 2.49). The elimination half-life ranged from 58 to 433 min (harmonic mean, 140 min). The AUC contributed by a single oral dose ranged from 606 to 5,144 mumol-min/l (mean, 2,012 +/- 1,223). Patients were evaluated for the development of veno-occlusive disease (VOD), a treatment complication that occurs in 20% of patients undergoing BMT and causes 10% of transplantation-related deaths. All six patients who developed VOD had an AUC greater than the mean, and five of them had an AUC that was greater than 1 SD above the mean. The occurrence of VOD was highly correlated with an increased AUC (greater than 1 SD above the mean) (X2 = 18; P less than 0.0001). Using multivariate logistic regression, no other statistically significant pharmacokinetic predictor of VOD was found. The tenfold variability in the busulfan AUC and the statistical association of increased AUC with the development of VOD suggest a possible role for therapeutic monitoring in this setting.

Juvenile chronic myelogenous leukaemia: report of a case with an unusually long period of survival

A case of juvenile chronic myelogenous leukaemia is presented. The clinical and haematological responses to courses of cytosine arabinoside, 6-mercaptopurine and prednisolone are described. Although there was some satisfactory response to the treatment and remission lasting over an unusually long period of time, the patient died of a rapidly progressive hypersplenism with severe sequestration of transfused blood and platelets. The nonaggressive and easily administered regimen of drugs described here is recommended for children with this disease where bone marrow transplant facilities are unavailable.

Cytogenetically distinct leukemic cell lines displaying in vitro specific proliferative and differentiation capacities may account for early disease relapse in the blast phase of CML

The cytogenetic features and the proliferative and differentiation capabilities of blast cell fractions purified on a density gradient were studied in one patient with chronic myeloid leukemia (CML) in blast crisis, both at the emergence and at relapse of the disease. The results show that relapse was due to the appearance of a new leukemic cell line that was characterized by peculiar chromosomal, growth, and differentiation features, which seemingly accounted for early refractoriness to therapy and disease progression.

Treatment of the blastic transformation of chronic granulocytic leukemia using high dose BCNU chemotherapy and cryopreserved autologous peripheral blood stem cells

Seven nonsplenectomized patients with blastic CGL have received high dose BCNU chemotherapy followed by cryopreserved peripheral blood stem cells (PBSC). The PBSC obtained at diagnosis were stored in the vapor phase of liquid nitrogen in 10% dimethyl sulfoxide for 11-46 months prior to use. Patients received 2.9 X 10(8) (1.9-7.8) thawed washed mononuclear cells/kg over 30 minutes with minimal morbidity. One patient was not rendered pancytopenic and died with blastic leukemia at 4 months. One patient, previously treated with daily busulfan, died of progressive hepatic failure 2 months after high dose BCNU. Restoration of the chronic phase of CGL was observed in the remaining five patients. Peripheral blood counts returned to normal ranges after a median of 19 days. Median survival for all patients is 11 months. Cytogenetic studies revealed elimination of acquired aneuploid cell lines in four of seven patients with persistence of Ph1. We conclude that: 1) frozen PBSC retain their viability for up to 4 years after cryopreservation and 2) the use of autologous PBSC following ablative chemotherapy may be associated with both symptomatic and karyotypic improvement in patients with blastic CGL.

Autopsy and clinical findings in acute leukemia and chronic myeloproliferative diseases--an evaluation of 104 patients

In acute myeloid leukemia (AML-46 patients) and various entities of chronic myeloproliferative diseases (CMPD-58 patients) an evaluation and comparison of clinical and postmortem findings has been performed. This study included also aspirates and core biopsies of the bone marrow which were initially taken on admission of those patients. Classification of CMPD was done following the concept of Georgii et al. (1984) into CGL -24-, CMGM-6-, E-MS-13- and MS/OMS-15 cases. There was a significant increase in blastic crisis in CGL compared with the other entities and in the latter a prolongation of the total course of disease due to a long period between symptoms--clinical diagnosis. As revealed by the autopsies causes of death were mostly infections (pneumonia, septicemia-50%) and lethal hemorrhages (gastrointestinal and cerebral--about 30%) in both AML and CMGM patients. Rare causes comprised fatal pulmonary embolism due to a peripheral thrombocytosis in CMPD, acute rupture of the spleen and extensive leukemic infiltrates of the myocard in AML. In addition to the well known giant enlargement of the spleen in MS/OMS, the relatively high frequency of a meningeal involvement (meningeosis leukemica) in AML (about 35%) and during an acute transformation in CMPD (up to 30%) was conspicuous. The examination of the bone marrow at various sites became feasible during the postmortem procedure and thus provided the opportunity to investigate the development and extent of a myelosclerosis evolving in CMPD. In contrast to the a- or hypoplasia and regeneration of the hematopoiesis following chemotherapy, the evolution of myelosclerotic lesions showed a very uniform pattern throughout the skeleton and obviously no reversal of a manifest MS/OMS after cytotoxic treatment.

Comparison of in vitro and in vivo effects of vincristine and vindesine on leukemic cells from patients with chronic granulocytic leukemia in blast crisis

We employed a liquid culture system to examine the in vitro effects of vincristine and vindesine on cellular incorporation of 35SO4 into leukemic cells obtained from 5 patients with chronic granulocytic leukemia in blast crisis. The per cent of 35SO4 into drug-treated as compared to saline-treated leukemic cells was compared to the clinical outcome of patients treated with these agents. A good or partial clinical response to vincristine or vindesine was seen in patients whose leukemic cells incorporated less than 50% 35SO4 when exposed to vincristine or vindesine in vitro, compared with control saline-treated cells. No clinical response was observed following treatment with vincristine or vindesine if the 35SO4 incorporation of drug treated leukemic cells was greater than 50% of saline-treated cells. These data suggest that the in vitro effects of vincristine or vindesine on 35SO4 incorporation into leukemic cells of patients in blast crisis may parallel the clinical outcome of patients treated with these agents in vivo.

Characterization and Treatment of the Non-Lymphoblastic Crisis of Chronic Myelogenous Leukemia

Fifty-six consecutive patients affected by the non-lymphoblastic-like crisis of chronic myelogenous leukemia were the subjects of this study. The cytologic and cytochemical features, together with the extension of clinical involvement, were investigated in all the patients. The most frequent cytologic variant was the « myeloid » one (60% of the patients). All the patients received a standard treatment (hydroxyurea, 6-mercaptopurine ± prednisone). The overall median survival was 5.1 months; however, 22% of the patients survived for one year or more. The length of survival was independent of the cytologic variety and clinical conditions (previous splenectomy, organomegalies, etc.). There was no correlation between drug dosage and length of survival, whereas the disappearance of blast cells from the peripheral blood appeared to be directly correlated with a longer survival. The treatment was well tolerated (slight hematologic and hepatic toxicity) and allowed a reasonably good quality of life: most of the patients were treated on an out-patient basis.

Total body irradiation in chronic myeloid leukemia

Total body irradiation (TBI), given as 10 rad daily for five days a week for a total dose of 150 rad has been used in an attempt to control the chronic phase of chronic myeloid leukemia (CML). Thirteen patients with CML received fractionated TBI leading to rapid and good control of WBC count without any adverse reaction. The chronic phase of CML could also be controlled with TBI, even in three patients who were resistant to busulfan. Following TBI, WBC count remained under control for a period of 32 weeks as compared to 40 weeks following busulfan alone. Repeat TBI was also well tolerated with good response. It appears that TBI is an effective and safe therapy for controlling the chronic phase of CML.

The in vitro effects of vincristine on peripheral blood leukocyte progenitor cells (CFU-C) in patients in blast crisis of chronic granulocytic leukemia: correlation with clinical response

The in vitro sensitivity of circulating progenitor cells (CFU-C) of 20 patients in blast crisis of chronic granulocytic leukemia (CGL) to vincristine was correlated with the clinical response to vincristine in vivo. Eleven patients who achieved either a good or partial clinical response displayed a reduction in the number of colonies or clusters formed by their peripheral blood leukocytes in a double layer agar culture assay following incubation with vincristine. The CFU-C of five of six patients who failed to respond clinically to vincristine and prednisone were not suppressed following incubation with up to 12 microM vincristine. Three additional patients were not evaluable due to early post-treatment deaths. In vitro assay of the effects of vincristine on CFU-C appears to have predictive value for in vivo response in blast crisis of CGL.

Immunotherapy of human leukemia with antibody to pluripotential K-562 stem cells

Gamma (gamma) globulin was fractionated from the serum of a goat immunized with the pluripotential leukemia cell line K-562. The lyophilized gamma-globulin preparation, termed leukoglobulin, contained about 50% immune IgG and suppressed the proliferation of heterotransplanted leukemia and lymphoma cells of human origin. The main aims of this study were to evaluate the potential therapeutic value of leukoglobulin and to determine its toxicity in humans with terminal leukemia and patients whose disease was unresponsive to current therapy. Two patients with CML, one with AMML, four with ALL, and one with AML were treated once a week for up to 5 weeks with leukoglobulin intravenously at doses ranging from 2 to 29 mg/kg. Leukoglobulin was well tolerated with minimal adverse effects and produced an initial mobilization of blasts from the bone marrow, spleen, and other organs with a parallel increase in the number of blasts in the systemic circulation. Subsequent injections of leukoglobulin led to a sharp decrease and the eventual eradication of blasts from the peripheral blood and bone marrow. Except in patients with CML, immature cells other than blasts also markedly diminished. The results of the clinical trials indicated a synergism with or potentiation of most chemotherapeutic agents used. Two possible uses for a combination of leukoglobulin and antileukemic drugs are indicated by the results we report here; drug-antibody synergism for cases showing no response to chemotherapy alone or leukoglobulin given immediately after chemotherapy is administered to eliminate residual leukemia cells. Alternatively, leukoglobulin can be given as a single therapeutic agent during the induction or maintenance phases of treatment to patients with leukemia resistant to other therapeutic combinations.

Chromosomal, morphological and clinical correlations in blastic crisis of chronic myeloid leukaemia: a study of 69 cases

The karyotypic pattern in 69 patients with Ph1-positive chronic myeloid leukaemia (CML) was investigated during the blastic phase (BC) and correlated with survival and certain parameters of potential prognostic significance, including blast morphology, basophilia and thrombocytopenia. There was no difference in median survival in BC between patients with and without aberrations in addition to the Ph1. Nor were there any differences in this respect among patients with the specific aberrations +Ph1, +8, iso(17q), or other abnormalities. There was no correlation between the incidence of thrombocytopenia and any particular karyotypic change. However, the incidence of basophilia was a characteristic feature for patients with an iso(17q). The survival time in BC was considerably longer in patients with a lymphoid morphology of the blastic cells compared to the myeloid varieties, and within the myeloid varieties the survival in BC was longer in patients with granular differentiated blasts than in those with granular atypical blast cells. No obvious correlation was apparent between blast morphology and karyotypic pattern. However, a pattern was discernible regarding survival and certain chromosomal changes within some morphologic groups: in patients with granular differentiated and lymphoid morphology, the median survival in BC was considerably longer when the bone marrow cells had a Ph1 as the sle abnormality compared to patients who had additional aberrations.

Plasma fucosyltransferase as an indicator of imminent blastic crisis

Plasma fucosyltransferase activity was evaluated as an indicator of an impending blastic transformation in 25 patients with chronic granulocytic leukemia (CGL). Fifteen age-and sex-matched controls were also studied. The level of enzyme activity was significantly higher in the plasma of patients with blastic transformation (1,630 +/- 570 units) compared with steady chronic granulocytic leukemia (509 +/- 110 units) and normal controls (354 +/- 57 units). In three patients with CGL, a rise in fucosyltransferase activity preceded any other clinical or laboratory parameter of blastic transformation by 16-20 weeks.

Heterogeneous blast cell crises in Philadelphia negative chronic granulocytic leukaemia

A case of Philadelphia negative chronic granulocytic leukaemia (Ph1-CGL) is described showing features only previously demonstrated in Ph1+ disease. These features include: (1) lymphoid blast crisis, determined by morphology and immunological marker analysis; (2) dual blast cell populations that can be distinguished both morphologically and by immunological markers; (3) clonal evolution, as shown by the emergence of chromosome markers and in one of the cell lines a change in membrane phenotype. These changes were apparently associated with the emergence of a relatively drug resistant subclone of leukaemic cells. This study demonstrates that the lymphoid blast crisis of CGL, and its sequelae, can occur in Ph1- cases. It is similar in respect to morphology, enzyme, and membrane markers and responsiveness to vincristine and prednisolone therapy to the lymphoid blast crisis seen in Ph1+ CGL. This suggests that the Philadelphia chromosome is a clonal marker only, and its presence is not directly related to the subsequent clinical course of the disease.

Relation of "lymphoid" phenotype and response to chemotherapy incorporating vincristine-prednisolone in the acute phase of Ph1 positive leukemia

Forty-four patients with Ph positive leukemia (36 developing blast crisis after chronic phase and eight presenting in acute leukemia) were classified into subgroups on the basis of reactivity of blasts with an anti-serum made against non-T,non-B acute lymphoid leukemia (ALL+), levels of terminal transferase enzyme (TdT+) and morphology. Positivity with anti-ALL serum was the most sensitive and reliable marker, and TdT was an important aid. The presence of "lymphoid" blasts in blast crisis of CML was related to the response to chemotherapy incorporating Vincristine and Prednisolone (VP). Patients with ALL+ blasts frequently (14 of 15 cases) responded to therapy while 21 of 25 patients who had no ALL+ blasts failed to respond. The clinical course of the ALL+ patients was variable: eight patients remitted with return to the appearances of the chronic phase; four patients demonstrated elimination of the Ph1 positive clone with hypoplasia and this was followed by normal (Ph1 negative) marrow regeneration in two. Subsequent relapse was of either the ALL+ "lymphoid" or the ALL-myeloid type. A regimen incorporating VP should be the treatment of choice in "lymphoid" blast crisis of CML.

Remission induction in chronic granulocytic leukaemia using intermittent high-dose busulphan

In a series of 19 patients, the pre-blastic phase of chronic granulocytic leukaemia was controlled with busulphan given as single doses of 50-100 mg at 2-weekly intervals. Although there was no significant increase in the incidence of Ph1-negative cells in the bone marrow, remissions of a better haematological quality were attained more rapidly than with conventional therapy.

Chronic myelogenous leukemia

Chronic myelogenous leukemia (CML) is a relatively rare disease, with a number of features that make it especially suitable for observations on leukemogenesis in man. These include known etiologic agents, often a prolonged preclinical and active stage, cells with identifiable morphological and histochemical characteristics and the presence of the unique Ph' chromosome. The transition of CML to blast crisis is a catastrophic event; however, recent clinical and biochemical studies have raised important questions as to the nature and origin of blast cells in this disease. During the past 10 years, we have followed 113 cases olf CML throughout their course and results of observations on the clinical, hematological and other apsects of the disease are presented in this communication.

Lymphoblastic transformation of Ph1-positive chronic myeloid leukaemia: therapeutic implications and relevance to haemopoietic stem cell theory

A proportion of patients with blast crisis of CML have blast cells identical to those found in common non-T, non-B all, and whilst this disease is often referred to as lymphoid blast crisis (LBC), evidence is presented that it may in fact arise from a prelymphoid, pre-myeloid (pluripotential) stem cell. Recently developed membrane and enzyme markers (anti-ALL antiserum, TdT assay) have provided convenient diagnostic tests for the detection of LBC. The clinical and haematological features of LBC are reviewed: patients with LBC show a higher response rate to therapy with vincristine and prednisolone, and their survival may be significantly prolonged. The frequent occurrence of meningeal leukaemia suggests the need for prophylactic CNS therapy in LBC patients achieving remission.