'Lymphoid' blast crisis of chronic myeloid leukaemia is associated with distinct clinicohaematological features

Bi-lineage B- and T-lymphoid Extramedullary Blast Crisis at an Initial Presentation of Chronic Myeloid Leukemia: A Case Report and Literature Review of Extramedullary Blast Crisis

Chronic myeloid leukemia (CML) with BCR-ABL1-positive cells is a myeloproliferative neoplasm (MPN) characterized by a chromosomal translocation t(9,22)(q34.1;q11.2), which results in the formation of a Philadelphia (Ph) chromosome containing the BCR-ABL1 fusion gene. Extramedullary blast crisis (EBC) associated with bcr/abl-positive CML is a rare initial presentation. Here, we present and discuss the case of a 51-year-old man who presented with a weight loss history, cervical swelling, and left-sided abdominal pain. He had a white blood cell count of 147,910/mm3. The blood smear study revealed myelemia in 23% and 8% of blast-like cells. The bone marrow aspiration and biopsy showed a richly cellularized sample; the megakaryocytes were present; the granular neutrophil line was at 89% with blasts at 1%. The cytogenetic analysis revealed a complex karyotype with the presence of a Philadelphia chromosome t (9, 22) (q34, q11) associated with additional cytogenetic abnormalities (ACA). Molecular analysis (PCR) detected a BCR::ABL1 (p210) rearrangement. At this point, a diagnosis of CML in the chronic phase was confirmed, but a cervical lymph node biopsy analysis revealed a bi-phenotypic B/T-lymphoblastic lymphoma (LBL) and expressed at fluorescent in situ hybridization (FISH) analysis BCR::ABL1 rearrangement. These findings were consistent with the diagnosis of a bi-phenotypic B/T extramedullary blast crisis associated with CML.

Bilineal evolution of a U2AF1-mutated clone associated with acquisition of distinct secondary mutations

Rare hematologic malignancies display evidence of both myeloid and lymphoid differentiation. Here, we describe such a novel bilineal event discovered in an adult woman with B-lymphoblastic leukemia (BLL). At the time of BLL diagnosis, the patient had a normal karyotype and a bulk sequencing panel identified pathogenic variants in BCOR, EZH2, RUNX1, and U2AF1, a genotype more typical of myeloid neoplasia. Additionally, the patient was noted to have 3-year history of cytopenias, and morphologic dyspoiesis was noted on post-treatment samples, raising the possibility of an antecedent hematologic disorder. To investigate the clonal architecture of her disease, we performed targeted sequencing on fractionated samples enriched for either B-lymphoblasts or circulating granulocytes. These studies revealed a truncal founder mutation in the spliceosome gene U2AF1 in both fractions, while distinct secondary mutations were present only in B-lymphoblasts (BCOR, NRAS) or myeloid cells (ASXL1, EZH2, RUNX1). These results indicate that both processes evolved from a common U2AF1-mutated precursor, which then acquired additional mutations during a process of divergent evolution and bilineal differentiation. Our findings highlight novel mechanisms in BLL leukemogenesis and expand the spectrum of observed bilineal neoplasms.

Understanding and Monitoring Chronic Myeloid Leukemia Blast Crisis: How to Better Manage Patients

Chronic myeloid leukemia (CML) is triggered primarily by the t(9;22) (q34.13; q11.23) translocation. This reciprocal chromosomal translocation leads to the formation of the BCR-ABL fusion gene. Patients in the chronic phase (CP) experience a good curative effect with tyrosine kinase inhibitors. However, cases are treatment refractory, with a dismal prognosis, when the disease has progressed to the accelerated phase (AP) or blast phase (BP). Until now, few reports have provided a comprehensive description of the mechanisms involved at different molecular levels. Indeed, the underlying pathogenesis of CML evolution comprises genetic aberrations, chromosomal translocations (except for the Philadelphia chromosome), telomere biology, and epigenetic anomalies. Herein, we provide knowledge of the biology responsible for blast transformation of CML at several levels, such as genetics, telomere biology, and epigenetic anomalies. Because of the limited treatment options available and poor outcomes, only the therapeutic response is monitored regularly, which involves BCR-ABL transcript level assessment and immunologic surveillance, with the optimal treatment strategy for patients in CP adapted to evaluate disease recurrence or progression. Overall, selecting optimal treatment endpoints to predict survival and successful TFR improves the quality of life of patients. Thus, identifying risk factors and developing risk-adapted therapeutic options may contribute to a better outcome for advanced-phase patients.

Favourable outcome of de novo advanced phases of childhood chronic myeloid leukaemia

BACKGROUND

Chronic myeloid leukaemia (CML) is very rare in children. The aim of the study is to report the experience within the I-CML-Ped study in children and adolescents presenting at diagnosis with advanced phase disease and to describe their characteristics and outcomes.

METHODS

Of 479 children and adolescents enrolled in the international registry for childhood chronic myeloid leukaemia (I-CML-Ped Study; www.clinicaltrials.govNCT01281735), 36 children (7.5%) presented at initial diagnosis with CML in advanced phase according to the European LeukemiaNet criteria.

RESULTS

Nineteen (4%) patients were diagnosed in accelerated phase (CML-AP), and among the 17 patients (3.5%) diagnosed in blastic phase (CML-BP), 70% presented with lymphoid immunophenotype. Initial treatment of CML-AP/CML-BP consisted of tyrosine kinase inhibitors (TKIs) with or without chemotherapy, leading to complete haematologic response in 33 of 36 (92%) patients. Seventeen patients proceeded to haematopoietic stem cell transplantation. At the last follow-up, 18 of 19 patients with de novo CML-AP are alive in at least major molecular response (MMR) (n = 16), in progression (n = 1) or in molecular relapse (n = 1) and 13 of 17 patients with de novo CML-BP are alive in at least MMR. Five-year overall survival rates are 94% (95% confidence interval [CI]: 66%-99%) and 74% (95% CI: 44%-89%) for patients diagnosed in CML-AP and CML-BP, respectively.

CONCLUSION

Children with advanced phase at diagnosis of CML seem to have a better survival rate than that reported for advanced phases evolving under TKI treatment.

Precursor B cell lymphoid blast crisis of chronic myeloid leukemia with novel chromosomal abnormalities: A case report

Chronic myeloid leukemia (CML) is a clonal hematopoietic stem cell disorder. It is characterized by the presence of the Philadelphia (Ph) chromosome, t(9;22)(q34.1;q11.2), which carries the BCR-ABL1 fusion gene. Tyrosine kinase inhibitors (TKIs) have markedly changed the treatment approach of CML and have become the first-line agents for almost all CML patients. However, certain patients experience resistance to these medications, which occurs through several mechanisms, including the accumulation of TKI-resistant chromosomal abnormalities. The present study reports a case of a 27-year-old Saudi male with CML receiving TKI treatment, who presented with precursor B-cell lymphoblastic crisis demonstrating the presence of the novel combined chromosomal abnormalities; non-Ph der(22), i(9) and der(20), carrying the BCR-ABL1 fusion gene. This case report adds to the literature on novel TKI-resistance-conferring chromosomal abnormalities and links them to precursor B-cell lymphoblastic crisis.

Prognostic Factors, Response to Treatment, and Survival in Patients With Chronic Myeloid Leukemia in Blast Phase: A Single-Institution Survey

INTRODUCTION

Data from 51 patients (23 women) with chronic myeloid leukemia (CML) in blast phase (BP) were analyzed in order to identify prognostic factors for complete hematologic response (CHR) and survival.

PATIENTS AND METHODS

Forty-four patients experienced disease progression from chronic or accelerated phase, and 7 cases presented as CML-BP. Thirteen patients (25.5%) had extramedullary involvement at diagnosis, and 71% were myeloid BP. Clonal evolution was identified in 53% of the cases, and the abnormalities most frequently observed were isochromosome (17q), double Philadelphia chromosome, and trisomy 8. Forty-five patients received treatment: 60% chemotherapy (CT) alone and 40% CT plus tyrosine kinase inhibitors (TKI) or TKI alone; 42% of them experienced CHR.

RESULTS

Median overall survival (OS) in patients whose disease responded to treatment was 7 months (95% confidence interval, 1.7-6.2 months), with a median disease-free survival of 5 months (95% confidence interval, 2.8-5.8 months). One out of 3 patients who underwent hematopoietic stem-cell transplantation remains alive. Multivariate analysis revealed that lymphoid BP and TKI therapy had a statistically significant positive impact as prognostic factors for CHR. In the multivariate analysis, age > 60 years, hemoglobin < 10 g/dL, and complex karyotype were statistically significant negative prognostic factors for OS. There was no statistical significant difference in OS between patients who received only CT (1988-2002) with those treated with CT plus TKI (2003-2013).

CONCLUSION

This is the first study in Mexico to report prognostic factors associated with CHR and OS in patients with CML-BP.

Clinical observations on chemotherapy curable malignancies: unique genetic events, frozen development and enduring apoptotic potential

BACKGROUND

A select number of relatively rare metastatic malignancies comprising trophoblast tumours, the rare childhood cancers, germ cells tumours, leukemias and lymphomas have been routinely curable with chemotherapy for more than 30 years. However for the more common metastatic malignancies chemotherapy treatment frequently brings clinical benefits but cure is not expected. Clinically this clear divide in outcome between the tumour types can appear at odds with the classical theories of chemotherapy sensitivity and resistance that include rates of proliferation, genetic development of drug resistance and drug efflux pumps. We have looked at the clinical characteristics of the chemotherapy curable malignancies to see if they have any common factors that could explain this extreme differential sensitivity to chemotherapy.

DISCUSSION

It has previously been noted how the onset of malignancy can leave malignant cells fixed with some key cellular functions remaining frozen at the point in development at which malignant transformation occurred. In the chemotherapy curable malignancies the onset of malignancy is in each case closely linked to one of the unique genetic events of; nuclear fusion for molar pregnancies, choriocarcinoma and placental site trophoblast tumours, gastrulation for the childhood cancers, meiosis for testicular cancer and ovarian germ cell tumours and VDJ rearrangement and somatic hypermutation for acute leukemia and lymphoma. These processes are all linked to natural periods of supra-physiological apoptotic potential and it appears that the malignant cells arising from them usually retain this heightened sensitivity to DNA damage. To investigate this hypothesis we have examined the natural history of the healthy cells during these processes and the chemotherapy sensitivity of malignancies arising before, during and after the events. To add to the debate on chemotherapy resistance and sensitivity, we would argue that malignancies can be functionally divided into 2 groups. Firstly those that arise in cells with naturally heightened apoptotic potential as a result of their proximity to the unique genetic events, where the malignancies are generally chemotherapy curable and then the more common malignancies that arise in cells of standard apoptotic potential that are not curable with classical cytotoxic drugs.

Clinical and Hematological Features of 335 Patients of Chronic Myelogenous Leukemia Diagnosed at Single Centre in Northern Pakistan

There are no studies regarding analysis of clinical and haematological features of chronic myelogenous leukemia (CML) from Pakistan. This study analyzes the data of patients suffering from CML, reporting to a major referral Institute in Northern Pakistan in the past 6 years and 3 months. CML constitutes approximately 80% of all myeloproliferative disorders, with a peak incidence between 21-50 years of age, and a male:female ratio of 2:1. Anaemia and massive splenomegaly were the main clinical features found in 92% and 47% patients respectively. There was significant correlation between anaemia and WBC counts with degree of splenomegaly. Three percent of all CML patients presented as de novo accelerated phase, and another 3% presented as blast crises without any previous history of chronic phase. The ratio of myeloid and lymphoid blast crisis was 2:1. Median duration of chronic phase in patients on hydroxyurea treatment was 6 years. Thirty six percent of patients in chronic phase of CML belonged to intermediate and high risk according to Sokal and Hasford scoring systems. In contrast to the Caucasian populations where the peak incidence of the disease is in 6th to 7th decade, CML occurs in Pakistan in a much younger population, with a broad peak between 21-50 years of age. Patients present in fairly advanced disease because of poor access to health care facilities, due to non-affordability and lack of health insurance coverage.

Survivin expression in the progression of chronic myeloid leukemia: A sequential study in 16 patients

An increase in the proliferation and resistance to apoptosis of leukemic cells has been found in chronic myeloid leukemia (CML) as the disease evolves from the chronic phase to blast crisis (BC). To contribute to a better knowledge of the molecular mechanisms involved in such biological abnormality, the expression of the survivin gene was studied by quantitative real-time polymerase chain reaction (PCR) in the chronic phase of CML and at BC in 16 patients in whom sequential RNA samples from the 2 phases of the disease were available. Survivin was significantly overexpressed in both the chronic phase and BC as compared with granulocytes from controls. In BC, survivin expression was 7-fold higher than in the chronic phase, with such an increase being more pronounced in the myeloid (17-fold) than in the lymphoid cases (3-fold) (P = 0.03). Cell proliferation was significantly increased at BC, with Ki-67 expression being 2.8-fold higher than in the chronic phase. Despite the overexpression of both survivin and Ki-67 at BC, no significant correlation between their expression levels was observed. These data support a possible role for survivin overexpression in the pathogenesis of the progression of CML. However, further studies are required to elucidate the possible prognostic importance of such biological findings in this disease.

The spectrum of adult B-lymphoid leukemias with BCR-ABL: molecular diagnostic, cytogenetic, and clinical laboratory perspectives

The Philadelphia (Ph) chromosome is characteristic of chronic myelogenous leukemia (CML), but it is also the most frequent cytogenetic abnormality in precursor B-lymphoblastic leukemia (ALL) of adults. The vast majority of CML patients have a BCR-ABL translocation that yields a 210 kD (p210) oncoprotein, whereas adult Ph-positive ALL cases can present with either a p190 or a p210 oncoprotein, or both. Considering that 30% of the patients with CML that progress to blast crisis will have a lymphoblastic presentation, adults presenting with a p210 ALL may have either a de novo ALL or CML presenting for the first time in lymphoblastic phase. To identify the distinguishing features, cases of p190-ALL, p210-ALL, and lymphoblastic CML were compared. In spite of significant overlap between the three entities, a number of features were found to aid in their differentiation. p210-ALL patients present at a younger age with blasts that frequently show loss of expression of CD34, whereas p190-ALL patients present with marked increase in peripheral blast percentage. Interestingly, bone marrow findings characteristic of a myeloproliferative disorder are specific, but are not sensitive for lymphoblastic CML. This study suggests that despite the similarities between these leukemias, p190-ALL, p210-ALL, and lymphoblastic phase CML likely represent three distinct diseases.

Blastic phase of chronic myelogenous leukemia

Chronic myelogenous leukemia (CML), also known as chronic myelocytic or chronic myeloid leukemia, is a clonal disorder of hematopoiesis that arises in a hematopoietic stem cell or early progenitor cell. This is characterized by the dysregulated production of mature nonlymphoid cells with normal differentiation. Eventually, in spite of the term chronic, there is progression to acute leukemia, usually of the myeloid variety, which is highly resistant to current therapies. Despite recent improvements in the treatment of early-stage disease, CML blast crisis (CMLBC) remains a therapeutic challenge. CMLBC is highly refractory to standard induction chemotherapy, with a response rate in myeloid blast crisis of less than 30%. Conventional chemotherapy has been much less successful in this disease compared with de novo acute leukemia, with a mean survival after diagnosis of blast crisis of only 2 to 4 months for nonresponders. Many regimens of chemotherapies have been tried in CMLBC, with minor success. Although imatinib was evaluated in patients with CMLBC, most CMLBC cases today arise in patients already on imatinib-based therapy and developing blastic phase on that therapy; thus there is no standard therapy for patients with CMLBC. Further studies of the mechanisms of transformation of chronic-phase CMLBC at a molecular level, and methods to target these molecular abnormalities, will determine the future direction of new treatment modalities. The prognosis of CML in blast crisis remains disappointing, despite great efforts. Currently, the most successful strategy for improving survival in CML is by prolonging the chronic phase and delaying the onset of blast crisis.

Blastic mantle cell lymphoma developing concurrently in a patient with chronic myelogenous leukemia and a review of the literature

Non-Hodgkin's lymphoma (NHL) occurring as a synchronous malignancy with chronic myelogenous leukemia (CML) is rare. To our knowledge, this is the first case reported of a patient who developed mantle cell lymphoma (MCL) after therapy with imatinib mesylate for CML. After a 3-year history of CML, the patient developed a lymphocytosis associated with diarrhea, anorexia, and weight loss. Imaging studies revealed abdominal adenopathy and extensive lymphomatous infiltration of the liver, stomach, pancreas, and kidneys. Flow cytometric and cytogenetic studies were consistent with MCL. Fluorescence in situ hybridization (FISH) of the bone marrow revealed a genetically distinct lymphoid neoplasm rather than an extramedullary blast crisis of CML. The development of lung cancer, prostate cancer, CML and MCL in this patient suggests a genetic predisposition, although other factors, including environmental exposures and therapy with imatinib mesylate could have had a contributory or synergistic role in the development of MCL.

Pathology of the myeloproliferative diseases

The classification of myeloid neoplasms now includes CMPD, mixed CMPD/ MDS, MDS, and acute myeloid leukemias. CMPD and CMPD/MDS, both clonal stem cell diseases, share myeloproliferative features, including typical hypercellular marrows, organomegaly, and cell lineage maturation. The CMPD generally differ by which myeloid cell lineage dominates hematopoiesis, and the main diseases include CML, PV, ET, and CIM. The mixed CMPD/MDS disorders also show dysplastic features and variable amounts of effective hematopoiesis; these disorders include CMML, JMML, and atypical CML. Given the overlap in morphology among these diseases, correlation with clinical, hematologic, and cytogenetic/molecular genetic findings is imperative for precise classification.

Genomic p16 abnormalities in the progression of chronic myeloid leukemia into blast crisis: a sequential study in 42 patients

OBJECTIVE

The molecular abnormalities involved in the progression of chronic myeloid leukemia (CML) are poorly understood. Genetic alterations of the INK4A/ARF locus have been implicated in the lymphoid blast crisis (BC), but sequential studies are not available. The aim of this study was to contribute to a better knowledge of the status of such locus in the different phases of CML and to analyze the prognostic significance of its inactivation.

MATERIALS AND METHODS

Sequential assessment by quantitative real-time polymerase chain reaction (PCR) and conventional semiquantitative PCR of p16 exon 2 deletions was performed in 42 CML patients in whom paired DNA samples from the chronic phase and the BC were available. Samples of 10 healthy donors and 30 patients with nonleukemic myeloproliferative syndromes served as controls. The methylation status of the promoter region of the p16 gene was also studied by methylation-specific PCR.

RESULTS

The concordance rate between the two PCR techniques was 97.8% (87/89). By real-time PCR, homozygous p16 deletions were found in 6 of 21 patients (29%) with lymphoid BC, whereas they were not observed in chronic-phase CML nor in 21 myeloid BC patients. Hypermethylation of the p16 gene was not detected in any of the lymphoid BC. No specific clinical profile was associated with homozygous p16 deletions. Therapeutic response and survival did not significantly differ in p16-deleted and p16 germline lymphoid BC patients.

CONCLUSION

P16 gene deletions are detected in a substantial proportion of lymphoid BC of CML by quantitative real-time PCR analysis, but this is not associated with any clinico-hematological feature other than lymphoid phenotype and does not influence the patients' outcome. Such technique is simple and reliable to assess the p16 gene status.

Intensive chemotherapy in patients with chronic myelogenous leukaemia (CML) in accelerated or blastic phase--a report from the Swedish CML Group

In attempting to restore the chronic phase (CP) of chronic myelogenous leukaemia (CML), the Swedish CML group utilized an intensive chemotherapy protocol for 83 patients (aged 16-79 years) in accelerated (AP, n = 22) or blastic phase (BC, n = 61). Most patients received a combination of mitoxantrone (12 mg/m2/d) and etoposide (100 mg/m2/d) together with cytosine arabinoside (1 g/m2 b.i.d) for 4 d. Overall, 39 patients (47%) achieved a second CP (CP2)/partial remission (PR). Responding patients < 65 years were eligible for ablative chemotherapy followed by an allogeneic (SCT) or a double autologous stem cell transplant (ASCT). Seventeen of 34 responders < 65 years failed to proceed to transplantation as a result of early disease progression (n = 15) or disease-related complications (n = 2). The remaining 17 patients underwent SCT (n = 9; including four unrelated donor SCT) or ASCT (n = 8). Only one of the eight ASCT patients had a second ASCT; the remaining seven failed because of progression (n = 5) or hypoplasia (n = 2). The median duration of CP2/PR was 6 months (range 1-72 months). Five patients achieved a longer CP2/PR than CP1. The 1 year survival was 70% for SCT/ASCT patients (median survival 21 months), 50% for responding patients overall, but only 7% for non-responders (P < 0.001). Three SCT/ASCT patients are long-term survivors (65+, 66+ and 73+ months). In conclusion, approximately half of the patients achieved a CP2/PR after intensive chemotherapy, with a clear survival advantage for responders vs non-responders. Subsequent SCT/ASCT was feasible for half of the responders (< 65 years), and one individual underwent double ASCT. Novel therapeutic options for CML patients in AP/BP are needed.

Molecular cytogenetic characterization of a novel additional chromosomal aberration in blast crisis of a Ph-positive chronic myeloid leukemia

We describe a novel chromosomal aberration acquired in blast crisis (BC) in a patient affected by Philadelphia-positive chronic myeloid leukemia (CML). Conventional cytogenetic studies at onset showed a classic t(9;22)(q34;q11.2) in all bone marrow cells, confirmed by fluorescence in situ hybridization and reverse transcription-polymerase chain reaction (b3a2) analysis. In BC, the malignant clone developed a new additional cytogenetic abnormality consisting of a deletion of chromosome 21. To our knowledge, this is the first case of del(21) reported in literature associated with BC CML. The use of an appropriate set of BAC/PAC clones restricted the breakpoint to an interval of approximately 100 kb. Sequence analysis did not reveal any known gene in this interval. Oncosuppressor genes distal to the breakpoint could be hypothesized to be involved in the progression of disease toward BC. Identification of new chromosome abnormalities in CML may allow further understanding of specific molecular events leading to disease evolution.

Response to therapy is independently associated with survival prolongation in chronic myelogenous leukemia in the blastic phase

BACKGROUND

Achievement of minimal tumor burden, such as complete response, has been accepted as a surrogate marker for improved survival in many solid and hematologic carcinomas. Several new agents have been approved recently for orphan disease indications or unmet medical needs, based on response analyses. This has not been the case for chronic myelogenous leukemia in the blastic phase (CML-BP), despite its poor prognosis, because response has not been proven to be a valuable endpoint for survival prolongation. The purpose of this study was to analyze the effect of response in CML-BP on survival prolongation. STUDY GROUP AND METHODS In total, 328 patients with CML-BP referred from 1989 to 1999 were studied; 311 patients received therapy for CML-BP, and 275 were evaluable for response. Blastic phase CML was defined by the presence of 30% or more blasts in the blood or bone marrow, or extramedullary disease. Treatment responses were reviewed and categorized as proposed in previous large studies. Four categoric response groups were defined further based on significant differences in outcome: cytogenetic response, hematologic response, bone marrow improvement, and failure. The association of treatment response with survival was evaluated by multivariate and landmark analyses.

RESULTS

The association of response with survival was analyzed among the 275 patients who had evaluable responses, and follow-up information was documented. Univariate analysis of pretreatment characteristics found performance status, hemoglobin levels, platelet counts, peripheral blasts, additional chromosomal abnormalities, and blastic phase morphology as showing significant associations with survival (P < 0.1). A multivariate analysis found platelet counts and blastic morphology as independent significant factors associated with survival (P < 0.05). A landmark analysis conducted at 8 weeks from start of therapy showed the beneficial effect of achieving response on survival prolongation (P < 0.001). A repeat multivariate at the 8-week landmark time in the 240 patients alive at that time, which included pretreatment characteristics and treatment response, confirmed the independent significant association of morphology (P = 0.003), platelet counts (P = 0.04), and response (P < 0.001) with survival.

CONCLUSIONS

Response to therapy is a significant independent factor associated with survival prolongation and maybe an acceptable therapeutic endpoint for approving new treatments in CML-BP.

Hypercalcemia as the presenting feature of t-cell lymphoid blast crisis of ph-positive chronic myeloid leukemia

Hypercalcemia is a rare complication of chronic myeloid leukemia (CML), usually seen in the accelerated or blastic phases of the disease and associated with a poor prognosis. T-cell lymphoid phenotype is also an infrequent finding in the blast crisis (BC) of CML. A CML patient who had hypercalcemia as the presenting feature of a T-cell BC is reported. She was a 78 year-old woman who, at four months of CML diagnosis, developed weakness, bone pain, and mental confusion, with hypercalcemia being subsequently found. Although the peripheral blood and bone marrow were consistent with the chronic phase of CML, mediastinal enlargement, a soft tissue mass adjacent to the iliac bone, and multiple osteolytic lesions were seen. Serum levels of parathyroid hormone (PTH) and PTH-related peptide were normal, whereas the search for a second neoplasm was negative. The hypercalcemia initially responded to conventional treatment, but it reappeared two weeks later. Coincidentally, a high proportion of blast cells of T-cell origin at the cortical thymocyte stage were observed in the patient's peripheral blood and bone marrow, and she died shortly afterwards.

Extramedullary T cell lymphoblastic transformation of chronic myeloid leukaemia successfully treated with matched unrelated donor bone marrow transplantation

Chronic myeloid leukaemia (CML) inevitably terminates in blast crisis (BC) which is of myeloid phenotype in approximately two-thirds and B-lymphoid in one-third of patients. T cell BC is rare and associated with poor prognosis. We describe the case of a 48-year-old woman with extramedullary T cell lymphoblastic transformation. After treatment with combination chemotherapy she achieved a second chronic phase and underwent an allogeneic BMT from an HLA-matched unrelated donor. At 30 months follow-up she is still in complete molecular remission and in good clinical condition. We conclude that unrelated donor BMT should be considered as a therapeutic option for patients with extramedullary BC.

Therapy-related changes of CD20+ and CD45RO+ lymphocyte subsets in chronic myeloid leukemia (CML): an immunohistochemical and morphometric study on sequential trephine biopsies of the bone marrow

Little information exists about the amount of CD45RO+-T- and CD20+-B-lymphocytes in the bone marrow of patients with Philadelphia chromosome-positive chronic myelogenous leukemia (Ph1+-CML) at presentation or regarding corresponding changes during therapy. On the other hand, quantification of this cell compartment seems to be imperative for two reasons: first, the presumed association of immunocompetent lymphocyte subsets in the expansion of the leukemic cell clone; and second, a speculated relationship with the complex generation of myelofibrosis. Therefore, an immunohistological and morphometric study was performed on 219 representative trephine biopsies of the bone marrow derived from 70 patients with repeated examinations during the course of Ph1+-CML. For the identification of the different lymphocyte populations, the monoclonal antibodies UCHL-1 (CD45RO) and L26 (CD20) were applied on formaldehyde-fixed and decalcified specimens. In comparison to a control group and calculated per hematopoietic cells, the CML bone marrow showed about a 50% decrease in the total amount of lymphocytes. Determination of CD45RO+ and CD20+ subsets revealed a significant enhancement during treatment. Because of the different intervals (range, 10 to 25 mo) between first and last biopsy in the various therapeutic groups, results had to be modified by considering dynamic features. This calculation included changes of the lymphocyte subpopulations related to time. Contrasting the CD45RO+ lymphocytes, a relevant increase in the CD20+ subset could be observed after interferon-a treatment or corresponding combination regimens. No significant correlations were found between fiber density at onset (first biopsy) or development of fibrosis and lymphocyte proliferations in the course of CML. Our results are in keeping with the finding that a proper immune response consistent with an increased lymphocyte growth seems to be associated with a regression of the clonally-transformed cell population. Opposed to a repeatedly discussed pathomechanism, we failed to demonstrate any quantitative relationships between the extent of lymphocyte proliferations and occurrence or progression of myelofibrosis.

CD7 expression on CD34+ cells from chronic myeloid leukaemia in chronic phase

Thirty-seven patients with chronic phase chronic myeloid leukaemia and fourteen healthy controls have been evaluated for lineage differentiation with immunological markers on purified bone marrow CD34 positive cells by multiparameter flow cytometry. The myeloid-associated antigen CD33 and the stem cell factor receptor (CD117, c-kit) was expressed by 82.3% and 73.5% on CP-CML patients and by 57% and 57.5% on healthy donors, respectively (P < 0.005). CD34+/CD19+ or CD34+/CD10+ B-lymphoid cell population represented 9. 1% and 10.7% of the CD34+ cells in CML whereas in normal controls this subpopulation was expressed by 27.9% and 30.4% of the CD34+ cells, respectively (P< 0.005). The T-lineage associated markers (CD7 and CD2) were detected on a minor population of CD34+ BM cells of healthy controls (mean, 3.6% and 4.6%, respectively). The CD2 positive cells represented 1.5% of the CD34+ cells in CML patients. CP-CML patients co-expressed the CD7 antigen on a mean of 32.6% of the CD34+ BM cells. Moreover, 93% of this CD34/CD7 double positive subpopulation co-expressed CD33 antigen in CML patients. Co-expression of CD7 on CD34+ cells was induced to decrease significantly after short-term in vitro culture with the differentiation-inducing agent phorbol ester (PMA) and with a combination of cytokines (stem-cell factor, interleukin-3 and granulocyte colony-stimulating factor). In conclusion, a high co-expression of CD7 antigen is demonstrated on CD34+ cells of chronic phase-chronic myeloid leukaemia patients. The loss of CD7 marker following incubation with PMA and cytokines suggests that this antigen is expressed transiently in early myeloid leukaemic CML haemopoiesis.

Chronic myelogenous leukemia

Over the past year, new information has been reported on the biology and treatment of chronic myelogenous leukemia (CML). Chronic myelogenous leukemia is characterized by the breakpoint cluster region (BCR-ABL) chimeric gene, the product of which is p210BCR-ABL, a tyrosine kinase that gives hematopoietic cells the characteristics of excessive proliferation, resistance to physiologic apoptotic signals, and resistance to chemotherapy. Recently, investigators have attempted to 1) elucidate the mechanisms by which the BCR-ABL gene and its product initiate and maintain the malignant phenotype, 2) improve the use of the BCR-ABL gene as a diagnostic marker of disease, and 3) inhibit the expression of this gene as a therapeutic maneuver. Other investigators have tried to explain interferon's mechanism of action in the treatment of CML and to improve the safety and applicability of stem cell transplantation (SCT) as a therapy for CML.