Chronic Myeloid Leukemia: A Perspective of the Clinical and Biologic Issues of the Chronic Phase

Monitoring your patients with chronic myeloid leukemia

PURPOSE

Chronic myeloid leukemia (CML), a hematopoietic stem cell disorder, which sometimes presents with fatigue, hepato-splenomegaly, and weight loss but is sometimes asymptomatic, is discussed.

SUMMARY

Diagnosis is suspected on the observation of an increased white blood cell count and is confirmed by the presence of the Philadelphia (Ph) chromosome. CML progresses through a series of three defined stages with survival times of 3-5 years if untreated. The chromosomal translocation creating the Ph chromosome creates the BCR-ABL fusion protein, which is the initiating factor for CML. BCR-ABL is a constitutively active tyrosine kinase, which transforms hematopoietic stem cells through dysregulation of proliferation, apoptosis, differentiation, and cell adhesion. The transformation process is then accelerated by the accumulation of additional translocations. This fusion protein has been used clinically as a therapeutic target and a sensitive marker for measuring residual disease. Techniques, such as cytogenetic analysis of chromosomes, allow for the visualization of the Ph chromosome and additional translocations and abnormalities. The more sensitive fluorescent in situ hybridization assay can directly visualize the bcr-abl translocation through merged fluorescent tags. Polymerase chain reaction, the most sensitive of the assays, can be used to detect minute amounts of bcr-abl mRNA and this has made it possible to monitor and detect minimal residual disease recurrence and disease progression, thus greatly enhancing patient care.

CONCLUSION

A variety of monitoring techniques can be employed during CML therapy, providing degrees of quantifying disease burden or absence of disease.

An in vivo and in vitro comparison of the effects of b2-a2 and b3-a2 p210BCR-ABL splice variants on murine 32D cells

The Philadelphia (Ph) chromosome, a characteristic cytogenetic marker of chronic myeloid leukaemia (CML), is caused by a reciprocal translocation juxtaposing the 3' region of the ABL gene onto the 5' region of the BCR gene. Due to conservation of the reading frame, but depending on the site of the breakpoint in the BCR gene, two alternatively spliced variants of the p210BCR-ABL mRNA (known as b2-a2 and b3-a2) are produced. To investigate whether there are any biological differences between these splice variants we have transfected the b3-a2 or b2-a2 cDNA into a murine myeloid cell line, 32D. We have also included the previously prepared 32Dp210 cell line (which expresses the b3-a2 transcript) in all of our comparisons. RT-PCR analysis indicated that transcription levels were comparable between the variants. Morphological examination of the cells expressing either of the BCR-ABL transcripts indicated that these cells were more mature with increased cytoplasm:nuclear ratios compared to the 32D parental and 32Dneo vector control cells. However, the 32Dp210 cells had a very different appearance from the other panel members and flow karyotyping indicated a clonal evolution and cytogenetic instability in these cells alone. At 10(6) and 10(7) cell doses all 32D cells expressing BCR-ABL caused ill health and tissue infiltration in SCID mice with such rapidity that statistical analysis was not informative. However, at the 10(5) and 10(4) dosage levels there were similar survival rates between mice injected with 32Db2-a2 or 32Db3-a2 while mice injected with 32Dp210 had a significantly shorter survival time. The study of this 32D cell line panel indicated that there were no overt differences in the biological properties conferred by the b3-a2 or b2-a2 transcripts to the 32D cells although these transcripts were able to confer in vitro and in vivo biological effects. This panel of BCR-ABL expressing 32D cells provides a useful model for CML disease progression studies.

Two consecutive spontaneous regressions to chronic phase in a patient with blastic transformation of chronic myelogenous leukemia

In this report, we present a patient with chronic myeloid leukemia (CML) in blastic phase who had two consecutive episodes of spontaneous regression back to chronic phase without chemotherapy. Although, spontaneous remission (SR) is well documented in acute leukemia, SR in CML blastic phase is extremely rare and to the best of our knowledge only one case has been reported in the world literature. The factors possibly related to this phenomenon are discussed.

Molecular Follow-Up of Disease Progression and Interferon Therapy in Chronic Myelocytic Leukemia

We previously reported that the abl promoter (Pa) undergoes de novo DNA methylation in the course of chronic myelocytic leukemia (CML). The clinical implications of this finding are the subject of the present study in which samples of CML patients, including a group treated with interferon α (IFNα) were surveyed. The methylation status of the abl promoter was monitored by polymerase chain reaction (PCR) amplification of the Pa region after digestion with several site-methylation sensitive restriction enzymes. Some 74% of the DNA samples from blood and marrow drawn in the chronic phase were nonmethylated, similar to control samples from non-CML patients. The remaining 26% were partially methylated in the abl Pa region. The latter samples were derived from patients who were indistinguishable from the others on the basis of clinical presentation. Methylated samples were mostly derived from patients known to have a disease of longer duration (26 months v 7.5 months, P = .01). Samples of 30 IFNα-treated patients were sequentially analyzed in the course of treatment. Fifteen patients with no evidence of Pa methylation before treatment remained methylation-free. The remainder, who displayed Pa methylation before treatment, reverted to the methylation-free status. The outcome is attributed to IFNα therapy, as the Pa methylation status was not reversed in any of the patients treated with hydroxyurea. Methylation of the abl promoter indicates a disease of long-standing, most likely associated with a higher probability of imminent blastic transformation. It appears to predict the outcome of IFNα therapy far better than the cytogenetic response.

Molecular Follow-Up of Disease Progression and Interferon Therapy in Chronic Myelocytic Leukemia

We previously reported that the abl promoter (Pa) undergoes de novo DNA methylation in the course of chronic myelocytic leukemia (CML). The clinical implications of this finding are the subject of the present study in which samples of CML patients, including a group treated with interferon α (IFNα) were surveyed. The methylation status of the abl promoter was monitored by polymerase chain reaction (PCR) amplification of the Pa region after digestion with several site-methylation sensitive restriction enzymes. Some 74% of the DNA samples from blood and marrow drawn in the chronic phase were nonmethylated, similar to control samples from non-CML patients. The remaining 26% were partially methylated in the abl Pa region. The latter samples were derived from patients who were indistinguishable from the others on the basis of clinical presentation. Methylated samples were mostly derived from patients known to have a disease of longer duration (26 months v 7.5 months, P = .01). Samples of 30 IFNα-treated patients were sequentially analyzed in the course of treatment. Fifteen patients with no evidence of Pa methylation before treatment remained methylation-free. The remainder, who displayed Pa methylation before treatment, reverted to the methylation-free status. The outcome is attributed to IFNα therapy, as the Pa methylation status was not reversed in any of the patients treated with hydroxyurea. Methylation of the abl promoter indicates a disease of long-standing, most likely associated with a higher probability of imminent blastic transformation. It appears to predict the outcome of IFNα therapy far better than the cytogenetic response.

Splenectomy in the accelerated or blastic phase of chronic myelogenous leukemia: a single-institution, 25-year experience

BACKGROUND

Patients in the accelerated or blastic phases of chronic myelogenous leukemia (CML) often have painful splenomegaly and secondary thrombocytopenia. We tested the hypothesis that splenectomy can be performed with minimal complications in advanced CML, thereby alleviating pain, reversing thrombocytopenia, and minimizing transfusion requirements.

METHODS

We reviewed the records of 53 patients in the accelerated or blastic phases of CML who underwent splenectomy between 1970 and 1995 at the U. T. M. D. Anderson Cancer Center.

RESULTS

Twenty-eight patients were in accelerated phase and 25 in blastic phase at the time of splenectomy. The most common indications for splenectomy were symptomatic splenomegaly (median splenic weight, 1000 gm; range, 120 to 6700 gm) or thrombocytopenia (platelet count less than 100,000/microliter) or both. There was 1 death within 30 days of splenectomy. The preoperative platelet count increased 3.72-fold +/- 0.53-fold (mean +/- SEM) by postoperative day 7 (p < 0.001; paired t test). Patients with transfusion-dependent thrombocytopenia had significantly fewer platelet and red blood cell transfusions in the 6 months after splenectomy than in the 6 months before splenectomy (p = 0.016; sign test).

CONCLUSIONS

Splenectomy can be performed with minimal morbidity and mortality in advanced CML, thereby relieving symptomatic splenomegaly, reversing thrombocytopenia, and minimizing transfusion requirements.

p53 mutations, methylation and genomic instability in the progression of chronic myeloid leukaemia

In chronic myeloid leukaemia (CML), as with other tumour types, mutations of the p53 gene are associated with disease progression. Changes in regional methylation of DNA with CML tumour development have also been demonstrated. Methylation is one mechanism by which gene expression is controlled and the CpG sites, which are the targets of DNA methylation, are also the sites of a number of the mutations found in the p53 gene. Cells harbouring mutant p53 have been shown to accumulate further genomic and genetic aberrations and methylation which alters the conformation of DNA is also believed to play a role in genomic stability. There appears to be an interplay between p53 deregulation and changing methylation patterns with the progression of CML. The cause and effect of changes in both of these critical gene regulating, DNA repair and genomic stability factors and their deviation during the progression of CML will be discussed.

A substantive theory of quality of life of adults with chronic leukaemia

The person with chronic leukaemia is living with a chronic and life-threatening disease. The aims of this study were to gain a deeper understanding of what individuals with chronic leukaemia consider QOL to be and to give the concept of QOL a theoretical and empirical significance relevant to nursing care. Fifteen adults with different forms of diagnosed chronic leukaemia have been interviewed about their experience of QOL. Verbatim transcripts were analysed using constant comparative analysis. The emerging core category was life satisfaction. Under this construct there were four categories; self-esteem, interpersonal relationships, performance ability and social ability. Changed QOL was described in two ways. First, coping was the core category for living with chronic leukaemia. The strategies were action, denial and hope. Second, QOL was seen as individual perception, experience of a positive attitude to life and self-contemplation.

Mosaicicm in bcr-abl protein expression in B cells in chronic myelogenous leukemia

Chronic myelogenous leukemia is a disease of the pluripotent stem cell that involves the myeloid and, to a varying degree, the lymphoid compartment. We studied the involvement of B cells in chronic myelogenous leukemia at diagnosis and during treatment. B lymphocytes were immortalized by infection with Epstein-Barr virus. B-lymphoid cell lines could be established from 25 patients suffering from Philadelphia-chromosome (Ph1)-positive chronic myelogenous leukemia. The cell lines were tested for expression of the typical 210-kDa fusion protein, p210, using Western-blot analysis, and/or for mRNA expression of bcr-abl fusion genes, using reverse transcriptase polymerase chain reaction analysis. At diagnosis, mosaicism of B cells was demonstrated in every patient. During treatment with interferon alpha, p210-expressing B-lymphoid cell lines could not be established from 8 of 8 patients. Following discontinuation of IFN-alpha therapy, p210-positive cell lines were found early, even before cytogenetic recurrence. Resistance to IFN-alpha therapy and progression of the disease were both associated with the appearance of p210-positive cell lines. Cell lines established from 3 healthy individuals and from patients suffering from Ph1-negative diseases did not show p210 expression in Western blots. Our data suggest that B lymphocytes are involved early in the disease, and that B-cell mosaicism may be a sensitive marker for resistance to IFN-alpha therapy and disease progression.

Increasing methylation of the calcitonin gene during disease progression in sequential samples from CML patients

In chronic myeloid leukaemia (CML), disease progression from the initial chronic phase to the acute phase or blast crisis has previously been shown to be correlated with progressive increases in hyper-methylation of the calcitonin gene, located at chromosome 11p15. However, sequential studies of individual patients were not performed in these investigations. We have analysed 44 samples from nine patients with typical Philadelphia chromosome positive CML throughout their disease progression to determine the methylation state of the calcitonin gene at these time points. Densitometry was used to quantitate the ratio of the normal 2.0 kb Hpa II fragments, indicating normal methylation status of the gene, compared to the intensity of the abnormal, hyper-methylated, 2.6-3.1 kb Hpa II fragments. We found a gradual increase in the ratio of methylated:unmethylated calcitonin gene during chronic phase with a dramatic rise at blast crisis. Further, the ratio of the abnormal hypermethylated 3.1 kb fragments to the methylated 2.6 kb fragment resulted in the identification of a clonal expansion of abnormally methylated cells. This expansion of cells with hypermethylation of the calcitonin gene during chronic phase was shown to coincide with the presence of a mutation in the p53 gene. The data presented in this study would suggest that an increased methylation status of the calcitonin gene during disease progression may indicate the expansion of abnormal blast cell populations and subsequent progression to blast crisis.

Characterization of a complex translocation [t(4;9;22)(p16;q34;q11)] in chronic myelogenous leukemia by fluorescence in situ hybridization technique

A patient was referred with a high leukocyte count and diagnosed with chronic myelogenous leukemia (CML). Although practically asymptomatic since the time of diagnosis, he had a variable and inconsistent response to treatment. All of his bone marrow cells had a complex, three-way translocation, involving chromosomes 4, 9 and 22. Translocation of chromosome 4 to chromosome 9 was undetectable by routine cytogenetic techniques; however, by the fluorescence in situ hybridization technique, a three-way translocation was identified, 46,XY,t(4;9;22)(p16;q34;q11). Although, other chromosomes are frequently involved in complex or variant translocations with chromosome 9 and 22, participation of chromosome 4 is a very rare event. So far, two previous cases have been described in the literature with translocations involving chromosome 4p16. We present a third case of CML having similar break points whose clinical presentation is unusual.

Chronic myelogenous leukemia: a review

Chronic myelogenous leukemia (CML) is a chronic myeloproliferative disorder with an initially chronic course lasting for 3-5 years. It eventually transforms into accelerated and blastic phases, which are generally fatal. CML was one of the first diseases in which a specific chromosomal abnormality was identified, a t(9;22)(q34;q11) or Philadelphia chromosome. CML had been traditionally treated with conventional chemotherapy with hydroxyurea or busulfan. Although these agents can achieve hematologic remissions in most patients, no evidence of sustained disappearance of the chromosomal abnormality was evident. Interferon alpha (IFN-alpha) has been able to achieve hematologic and cytogenic remissions in a significant number of patients, and recent studies show a survival advantage for patients treated with IFN-alpha compared with those treated with conventional chemotherapy. The results of these studies are discussed, and the reasons for discordance among different investigators analyzed in this review. Allogeneic bone marrow transplantation (BMT) may be curative in some patients with CML. The benefits and limitations of this approach in the treatment of CML are also discussed and the results of different alternatives compared. Other alternatives of therapy, including newer chemotherapeutic agents, combinations of IFN-alpha with other agents, and autologous BMT, are presented. The availability of very sensitive techniques for detection of the Philadelphia chromosome at the molecular level has allowed the detection of minimal residual disease. The information available on these measurements is also analyzed. Finally, we discuss the alternatives for patients with accelerated and blastic phase CML, as well as the clinical characteristics and prognosis for patients with Philadelphia-chromosome-negative CML.

Chronic myeloid leukemia (CML): prognostic factors and survival analysis

The prognostic value of different factors upon diagnosis of CML was analysed in 45 Philadelphia (Ph1)-positive patients. The median survival was 48 months. Univariate analysis showed 5 poor prognostic factors (male sex, under 45 years-old, bone marrow blasts greater than or equal to 10 percent, blood basophils greater than or equal to 6 percent and blood eosinophils greater than or equal to 6 percent) which provided for the development of a clinical staging system: Stage I with none or one factor and a two-year survival rate of 100 percent; Stage II with two or three factors and two-year survival of 72.2 percent; and Stage III with four or five factors and two-year survival of 0 percent (p = 0.00016). Multivariate survival analysis showed that combination of blood basophilia and bone marrow blasts had the strongest predictive relationship to survival time. We conclude that a combination of pretreatment factors identifies different risk subcategories in CML patients and is helpful in assessing the overall prognosis and the treatment approach.

v-Abl-mediated apoptotic suppression is associated with SHC phosphorylation without concomitant mitogen-activated protein kinase activation

A temperature-sensitive mutant of the v-Abl protein has previously been shown to exhibit tyrosine protein kinase activity in Interleukin 3 (IL-3)-dependent IC.DP cells grown at the permissive temperature (32 degrees C) but not at the restrictive temperature (39 degrees C). These IC.DP cells are dependent on IL-3 for suppression of apoptosis at 39 degrees C, but at 32 degrees C cells will survive without added growth factor. Both IL-3 and v-Abl stimulated the tyrosine phosphorylation of SHC and GTPase-activating protein. However, while IL-3 stimulated similar levels of tyrosine phosphorylation in p46shc and p52shc, v-Abl preferentially phosphorylated p52shc, an event that occurred within 1 h of temperature switch. v-Abl also differentially associated with p46shc in a temperature-independent manner. In contrast, only IL-3 stimulated detectable increases in both myelin basic protein kinase and mitogen-activated protein (MAP) kinase kinase in in vitro assays, although in more specific MAP kinase activity assays a very slight increase in the activity of this enzyme was observed after 6 h at the permissive temperature. Time course studies suggest that phosphorylation and association of SHC with v-Abl is insufficient to lead to significant activation of MAP kinase and that activation of the MAP kinase kinase/MAP kinase pathway is not required for apoptotic suppression.

What is the contribution of molecular studies to the diagnosis of BCR-ABL-positive disease in adult acute leukemia?

The detection of BCR-ABL transcripts by polymerase chain reaction and hybridization protection assay was investigated in 59 adults with acute leukemia in whom the Philadelphia chromosome (Ph) abnormality was not documented by cytogenetic analysis. These included 35 patients with acute lymphocytic leukemia (ALL) and 24 with acute myelogenous leukemia (AML). Overall, three patients were found to have Ph-related molecular abnormalities; one had p190 and two had p210 disease. All three patients had ALL and were among 16 patients with insufficient metaphases by cytogenetic analysis, yielding an incidence of 19% in the latter category. Based on a 32% incidence of insufficient metaphases in our adult ALL population, we project an additional detection rate of 6% Ph-positive ALL by molecular studies and an overall incidence of 20% (14% + 6%) Ph-positive or BCR-ABL-positive ALL. None of the remaining patients with ALL and none of the 24 patients with AML investigated had BCR-ABL-positive disease. We conclude that molecular studies are useful in detecting BCR-ABL-positive disease in a subset of patients with Ph-positive ALL who are not identified by cytogenetic analysis because of insufficient metaphases.

Interferon alfa activates a lytic mechanism in ovarian and cervical carcinoma cells

OBJECTIVE

Our purpose was to examine the in vitro cytolytic potential of interferon alfa for human cervical and ovarian carcinoma cell lines.

STUDY DESIGN

The lytic potential of interferon alfa alone and in the presence the protein synthesis inhibitors actinomycin D and emetine was determined in the human cervical carcinoma cell lines ME-180, MS751, SiHa, HT-3, and C-33A and the ovarian carcinoma cell lines Caov-3, NIH:OVCAR-3, SK-OV-3 carcinoma cell lines by means of an 18-hour chromium 51 release assay.

RESULTS

Exposure of these cell lines to interferon alfa alone did not result in lysis. Similarly, when cells were simultaneously exposed to interferon alfa and either actinomycin D or emetine there was no additional increase in lysis above that seen with actinomycin D or emetine alone. Pretreatment of cells with interferon alfa (10(3), 10(4), or 10(5) U/ml) followed by protein synthesis inhibition by actinomycin D or emetine resulted in a synergistic increase in lysis.

CONCLUSION

The ability to reveal the lytic potential of interferon alfa when protein synthesis is subsequently inhibited could have practical applications for the treatment of gynecologic malignancies.

Atypical chronic myelogenous leukemia in a patient with trisomy 8 mosaicism syndrome

A 17-year-old woman was admitted for bone marrow transplantation with the diagnosis of atypical Philadelphia-negative chronic myelogenous leukemia (aCML), cytogenetically characterized by trisomy 8 as the sole chromosome aberration. A striking feature was a congenital opacity of the right cornea. Chromosomal analysis of skin fibroblasts were performed and revealed a mosaic for trisomy 8. Commonly, a distinct clinical picture leads to the diagnosis of trisomy 8 mosaicism syndrome (T8ms), but an extreme phenotypic variability has been observed. To our knowledge the development of an aCML in a patient with T8ms has not been reported. A review of the literature revealed that an association to other hematological disorders had been described in two cases. The question of whether our patient's aCML was a random event or not is discussed. The patient is now 24 months post transplant and shows no evidence of disease. Her Karnofsky score is 100%. We conclude that it might be worthwhile to look for an associated constitutional trisomy 8 mosaicism in all patients with trisomy 8 leukemia.

The relationship between the location of the breakpoint within the M-bcr and clinical parameters

The Philadelphia chromosome (t9;22)(q34;q11) is a characteristic abnormality in chronic myeloid leukemia. In greater than 95% of the cases, the breakpoint occurs with the M-bcr region of the BCR gene on chromosome 22. Several studies have attempted to correlate the location of the breakpoint within the M-bcr with a clinical parameter. The majority of studies have examined the relationship between the site of breakpoint and the median chronic phase duration (CPD). Some studies have reported a correlation, with 5' breakpoint patients who have a longer median CPD than patients with a 3' breakpoint. However, other groups have reported that no correlation exists. Furthermore, data from some of the latter groups have suggested that a correlation may exist with the lineage of blast crisis which developed and 3' breakpoint patients had a higher than expected number of lymphoid blast crisis. A correlation between high platelet counts at diagnosis and patients with a 3' breakpoint or those who expressed a b3-a2 BCR-ABL mRNA has also been described. No consistent conclusion from any of these studies can be drawn. This may due, in part, to some degree of patient and sample selection, although environmental, genetic or life-style factors may also contribute.

Disappearance of a highly unusual clone, 46,XY,del(7)(p12),t(9;22)(q34;q11) in chronic myeloid leukemia after treatment with recombinant interferon and cytosine arabinoside

A patient with the typical features of the stable phase of chronic myeloid leukemia (CML) displayed two karyotypically related subclones. In addition to the t(9;22), cells from one clone contained a deletion of the short arm of chromosome 7, del(7)(p12), [46,XY,del(7)(p12),t(9;22)(q34;q11)]; the other contained only the standard translocation [46,XY,t(9;22)(q34;q11)]. Cells with a deletion of the short arm of chromosome 7 at band p12 as the only additional abnormality have not been observed previously in CML. Conventional chemotherapy with hydroxyurea and then with recombinant interferon-alpha (rIFN-alpha) did not reduce the population of either subclone. However, after treatment with a combination of rIFN-alpha and low-dose cytosine arabinoside (LoDac) continuously infused subcutaneously (s.c.), cells from the clone with the deleted chromosome 7 disappeared and normal metaphases were demonstrable.

Several new approaches to improvement of alpha interferon therapy in chronic myelogenous leukaemia

Several basic experimental and clinical studies were carried out in an attempt to improve the efficacy of alpha interferon therapy for chronic myelogenous leukaemia (CML). First, the combined use of hydroxyurea (HU) and interferon (500-1000 mg daily) in interferon-resistant cases facilitated maintenance of reduced leucocyte production, or a reduction in the dose of interferon, although suppression of Philadelphia chromosome (Ph1)-positive clones was not observed in most cases. In order to try and decrease the rate of lymphoblastic crisis during the course of interferon therapy, we recently added methotrexate (MTX) (10-15 mg, weekly) to the treatment protocol. Since then, no lymphoblastic crisis has been observed. Second, the in vitro expression of alpha interferon-stimulated gene (ISG) mRNA was shown to be markedly decreased in granulocytes of one representative interferon-resistant case, compared to that in granulocytes of the three interferon-sensitive cases. Interestingly, it was found that the transcriptional activity in this case became almost normal when the blood granulocytes were controlled by the addition of HU. These findings suggest that the in vitro transcriptional assay of ISG mRNA may be clinically useful for predicting alpha interferon efficacy. Third, when genetically manipulated, alpha interferon-producing NIH/3T3 cells were co-transplanted using diffusion chambers into nude mice bearing a CML cell line, KU812, the CML tumour growth was shown to be markedly suppressed. This experimental model for alpha interferon replacement gene therapy suggests some directions for future studies on interferon therapy.