Effects of chemotherapy (busulfan-hydroxyurea) and interferon-alfa on bone marrow morphologic features in chronic myelogenous leukemia. Histochemical and morphometric study on sequential trephine biopsy specimens with special emphasis on dynamic features

Entrapment of a Cytotoxic Drug into the Crystal Structure of Calcite for Targeted Drug Delivery

Controlled drug release and targeted drug delivery can reduce systemic toxicity of chemotherapeutics by restricting drugs to the target organ and increasing the local concentration. As tumors and inflamed tissue are often surrounded by an acidic microenvironment, pH-responsive calcium carbonates (CaCO₃) are promising vehicles for controlled drug delivery applications. The aim of this study was to evaluate the loading efficacy and release of a chemotherapeutic drug, Hydroxyurea (HU), into the crystal structure of calcite. Incorporation of HU did not alter the crystallinity, crystal size, or morphology of precipitated calcite crystals, as assessed by XRD and SEM. The amount of HU was quantified by High-Pressure Liquid Chromatography (HPLC) and showed that 6.7 ± 0.7 µg of HU could be for each milligram of calcite (0.016 mol% ± 0.002). In cell media, the optimal pH for controlled release was 5 (0.1 mg/mL released after 1 h). However, in vitro, pH below 6.5 was cytotoxic to human breast cancer cells (MCF-7). Direct contact studies, where particles were incubated with MCF-7 cells, showed that the amount of HU release from calcite was not high enough to kill the cell or arrest growth at pH 6.5. Pre-dissolved release studies, where the particles were pre-dissolved in acidic media to simulate complete drug release in vivo, pH neutralized, and exposed to the cells, showed that the amount of loaded HU reduced the survival/proliferation of MCF7. In conclusion, it is possible to integrate HU into the crystal structure of a calcite crystal and release the drug in vitro at concentrations that can slow the growth of cancer cells, without affecting calcite morphology and crystallinity. Further research is needed to investigate the in vivo behavior of the particles and whether the actual tumor pH is low enough to achieve complete drug release in vivo.

Morphological Changes in Bone Marrow Post Imatinib Therapy in Chronic Phase CML: A Follow up Study on Sequential Bone Marrow Aspirates and Biopsies

INTRODUCTION

Imatinib mesylate is used extensively for first line treatment of Chronic Myeloid Leukemia (CML). However, not many studies have documented morphological changes in bone marrow biopsies produced during Imatinib therapy with reference to myelofibrosis.

AIM

To document the morphological changes produced in the bone marrow during Imatinib therapy.

MATERIALS AND METHODS

This longitudinal study followed up 75 Philadelphia Chromosome Positive Chronic Myeloid Leukemia with chronic phase(Ph+ CML- CP) patients sequentially, receiving 400-600mg Imatinib over a period of 12 or more months. Haematologic parameters were measured at admission, 2 weeks, 1 month, 3 months, 6 months and 12 or more months. Morphologic changes in bone marrow aspirate and biopsy were evaluated at admission, 6 months and ≥12 months of treatment in accordance with National Comprehensive Cancer Network(NCCN) guidelines.

RESULTS

Complete Haematologic Response (CHR) was seen in 47.1%, 80%, 85.4%, 90.4% at ≥1 month, 3 months, 6 months and 12 months respectively after therapy. It was noted that patients not showing CHR by 3 months were less likely to show CHR at 6 months and beyond. Bone marrow aspirates and biopsies showed reduction in cellularity and myeloid precursors with regeneration of erythroid precursors in 70-83% at ≥12 months. A significant decrease in myelofibrosis (p-value< 0.04) was noted as early as 6 months. Mild to moderate hypoplasia was noted in 31.8% of biopsies within 6 months. Pseudo gaucher cells and benign lymphoid nodules were also seen.

CONCLUSION

Sequential analysis showed that Imatinib reduced the grade of myelofibrosis significantly (p-value< 0.04). It also prevented development of myelofibrosis in patients who did not have it at presentation. Hence Imatinib is effective when used early in the course of CML-CP.

Therapy Effect: Impact on Bone Marrow Morphology

This article highlights the most common morphologic features identified in the bone marrow after chemotherapy for hematologic malignancies, growth-stimulating agents, and specific targeted therapies. The key is to be aware of these changes while reviewing post-therapeutic bone marrow biopsies and to not mistake reactive patterns for neoplastic processes. In addition, given the development and prevalent use of targeted therapy, such as tyrosine kinase inhibitors and immune modulators, knowledge of drug-specific morphologic changes is required for proper bone marrow interpretation and diagnosis.

Bone marrow histopathology in the diagnosis of chronic myeloproliferative disorders: A forgotten pearl

Histopathology of bone marrow (BM) biopsies plays a crucial role in the interdisciplinary approach to diagnosis and classification of chronic myeloproliferative disorders (CMPDs). Based on careful clinicopathologic studies, BM features are critical determinants that help to predict overall prognosis, to detect complications such as progression to myelofibrosis and blast crisis, and to assess therapy-related changes. A systematic evaluation of BM histopathology allows an objective identification of cases of (true) essential thrombocythemia (ET) and their separation from (false) ET, which often is the prodromal stage of chronic idiopathic myelofibrosis (CIMF). By follow-up examinations that include BM biopsies, the progression of the disease process is unveiled, which is especially important for patients with initial (early) polycythemia vera and prefibrotic CIMF that may require a different therapeutic approach than the full-blown stages. In conclusion, BM biopsy should be considered as major diagnostic tool for evaluation and follow-up of patients enrolled in prospective studies.

Hematologic aspects of myeloablative therapy and bone marrow transplantation

The transplantation of bone marrow cells or isolated hematopoietic stem cells from the bone marrow or peripheral blood is a widely utilized form of therapy for patients with incurable diseases of the hematopoietic and immune systems. Successful engraftment of the transplanted stem cells in an adequately prepared recipient normally leads to bone marrow reconstitution over a period of several weeks, accompanied by more gradual reconstitution of the immune system. Since the recipient is profoundly ill during the initial treatment period, laboratory data is critical for monitoring engraftment, detecting residual/recurrent disease, and identifying problems that may delay bone marrow reconstitution or lead to other medical complications. Accurate blood cell counts are imperative, and most bone marrow transplantation patients undergo periodic monitoring with bone marrow aspirates and biopsies with cytogenetic, molecular, and multiparametric flow cytometric studies. The potential complications of bone marrow transplantation include engraftment failure and delayed engraftment, infection, residual bone marrow disease, acute and chronic graft versus host disease, myelofibrosis, therapy-related acute leukemia, post-transplant lympho-proliferative disorders, and toxic myelopathy.

Marrow fibrosis, indicator of therapy failure in chronic myeloid leukemia - prospective long-term results from a randomized-controlled trial

Marrow fibrosis (MF) has rarely been considered in therapy studies on chronic myeloid leukemia (CML), and there is a lack of long-term observations on the basis of sequential bone marrow biopsies (BMBs) taken prospectively during the course of disease. A total of 848 BMBs from 400 patients with Ph(+) CML recruited in the German randomized CML study I were examined for MF before and during therapy. In total, 110 patients had been randomized to receive interferon (IFN)-alpha, and 290 to receive chemotherapy (hydroxyurea (HU): 154, busulfan: 136). During IFN-alpha and HU medication, MF was reduced or did not increase for about 2 years. Evolving or progressive MF was an independent and early predictor of therapy failure about 2 years earlier than indicated by changes in the peripheral blood, spleen size, marrow blast count and cytogenetics (P<0.00005), resulting in a significant shortening of the survival times of patients independent of the type of therapy applied including allografting (multivariate analyses; P<0.00005). The analyzed long-term observations strongly indicate that MF is an independent poor prognostic complication of CML, allowing an early prediction of therapy failure. Consideration of the fiber content in marrow may therefore significantly improve the prediction of therapy efficacy and outcome of disease.

Reversal of bone marrow angiogenesis in chronic myeloid leukemia following imatinib mesylate (STI571) therapy

The effect of imatinib mesylate (imatinib) therapy on angiogenesis and myelofibrosis was investigated and compared with interferon (IFN) and hydroxyurea (HU) in 98 patients with newly diagnosed Philadelphia chromosome-positive/BCR-ABL(+) (Ph(+)/BCR-ABL(+)) chronic myeloid leukemia in first chronic phase and no other pretreatment. By means of immunostaining (CD34) and morphometry, a relationship between microvessel frequency and fiber density was detectable in initial bone marrow (BM) biopsies and sequential examinations after at least 8 months of therapy. First-line monotherapy with imatinib induced a significant reduction (normalization in comparison with controls) of microvessels and reticulin fibers. In most patients, decrease in BM vascularity was associated with a complete cytogenetic response. A significant anti-angiogenic effect was also observed after HU treatment, contrasting with IFN administration or combination regimens (IFN plus HU). In conclusion, our data support the anti-angiogenic capacity of imatinib by normalization of vascularity. In contrast, hematologic response following IFN treatment is independent from BM angiogenesis.

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.

Hematopathologic and cytogenetic findings in imatinib mesylate-treated chronic myelogenous leukemia patients: 14 months' experience

Imatinib mesylate, an Abl kinase inhibitor, produces sustained complete hematologic responses (CHRs) in chronic myelogenous leukemia (CML) patients, but the sequence and timing of morphologic and cytogenetic changes in CML patients during prolonged imatinib mesylate treatment has not been described. In this report, we document sequential hematologic and bone marrow findings in 19 interferon-refractory/interferon-intolerant chronic phase CML patients on imatinib mesylate for at least 14 months. Patients treated at an effective oral dose (300 to 600 mg per day) were followed with peripheral blood (PB) counts, marrow examination, and cytogenetic studies at 0, 2, 5, 8, 11, and 14 months. By 2 months, 17 of 19 patients achieved CHR; 1 reached CHR by 5 months, and 1 at 11 months. Five of 19 patients developed cytopenias requiring treatment interruption and/or dose reduction, but all were able to continue in CHR on study. In contrast to interferon-alfa treatment, imatinib mesylate-treated CML patients achieved not only CHR but complete morphologic marrow response. Normalization of marrow lagged behind PB response; however, by 8 months, all marrows showed normal or reduced cellularity without morphologic evidence of CML. Eighteen of 19 patients continued in CHR and morphologic marrow remission at 14 months; 1 patient relapsed with chronic phase CML. Although hematologic and marrow responses were uniform, cytogenetic responses were variable. Complete cytogenetic responses occurred in 6 patients, with 4 also in remission by fluorescent in situ hybridization and/or reverse-transcription-polymerase chain reaction. Six of 19 had partial and 7 of 19 no cytogenetic response. Several patients acquired additional clonal cytogenetic abnormalities during therapy, a finding with significant implications for prognosis and laboratory monitoring in imatinib mesylate-treated CML patients.

Gene expression profiling in chronic myeloid leukemia patients treated with hydroxyurea

Using array technology that allows the simultaneous detection of gene expression of hundreds of genes, four patients with chronic myeloid leukemia (CML) were investigated at diagnosis and after starting administration of hydroxyurea. To detect the gene expression of peripheral blood mononuclears and granulocytes Human Cancer cDNA Array (CLONTECH) with 588 gene probes was used. Gene expression mononuclear and granulocyte profiles of patients at diagnosis were compared with the control profiles. The significant expression changes observed in most patients seemed to be important. Increased expression of c-jun N-terminal kinase 2 (JNK2), integrin alpha E, MMP-8, MMP-9 was detected in both fractions of most patients. In some samples PCNA, HDGF, MAPK p38, CD59 increased expressions were found. Significant down-regulation of expression in patients was detected in genes CDK4 inhibitor A, PURA, notch1 in mononuclears; STAT2, STAT5, RAR-alpha, MCL-1, junB, caspase 4 in granulocytes; CDK6, GADD153, ERBB-3, cadherin 5 in both fractions. Expression profiles detected in patients at diagnosis did not differ markedly from those after one-week treatment with hydroxyurea. Only in a few genes were significant changes after hydroxyurea administration observed and inter-individual expression differences were rather common.

Comparative effects of interferon and hydroxyurea on bone marrow fibrosis in chronic myelogenous leukemia

Therapy-related changes of the bone marrow fiber content remain a controversial issue in hematopathology. This conflict of opinion firstly depends on difficulties to determine the quantity of fibers exactly (semiquantitative grading, morphometry, reference to cellularity). Secondly, the appropriate selection of patients with specific monotherapies including hydroxyurea (HU) and interferon-alpha (IFN) seems to present some problems. Finally, assessment of myelofibrosis is further biased by the different endpoints of sequential examinations. The latter shortcoming can be improved upon by the calculation of the myelofibrosis progression/regression index which describes the ratio between difference of fiber density and observation time. Using strictly defined therapeutic regimens and intervals between sequential trephine biopsies a stimulating effect of IFN administration on bone marrow fibrosis in Ph1+-chronic myelogenous leukemia (CML) has been found. This result is comparable with the failure of this agent to improve myelofibrosis (and splenomegaly) in a considerable number of patients with allied subtypes of chronic myeloproliferative disorders. This is in contrast to the effect HU exerts which is a more fibrolytic or even stabilizing influence on bone marrow fibrosis. This phenomenon is readily demonstrable by the assessment of dynamic features (myelofibrosis progression index). In addition, patients showing a rapid progression of myelofibrosis during IFN and HU treatment of Ph1+-CML are generally associated with a poor risk outcome and a significant worsening of survival.