Liposomal cytarabine for treatment of myeloid central nervous system relapse in chronic myeloid leukaemia occurring during imatinib therapy

Leukostasis With Isolated Central Nervous System Involvement in Chronic Phase of Chronic Myelogenous Leukemia

Chronic myelogenous leukemia (CML) is a hematologic malignancy with unique significance to the field of hematology and oncology, specifically due to the development of tyrosine kinase inhibitors (TKIs). CML often presents with nonspecific symptoms, and the quality of life in patients with CML has drastically improved as a result of TKIs. However, complications of CML including the risk of transforming into life-threatening blast crises continue to exist. Further, as most patients are asymptomatic in the chronic phase, patients often present with serious complications associated with noncompliance to TKIs. For example, central nervous system (CNS) manifestations of CML have been reported, both as the initial presentation of undiagnosed CML and as known complication of uncontrolled CML. Hyperleukocytosis is a manifestation of uncontrolled CML and leukostasis is a complication, occurring in cases of acute myeloid leukemia (AML). Here we present a rare case of leukostasis in a patient with known CML presenting on computed tomography (CT) as intracranial masses in the chronic phase. Our goal is to discuss this rare case of leukostasis in adult CML and describe its management.

CNS Involvement in a Patient with Chronic Myeloid Leukemia

Inspite of medication compliance, some chronic myeloid leukemia (CML) patients will relapse/progress into an accelerated phase or blast crisis. Central nervous system (CNS) involvement is a rare manifestation of such a relapse. Here, we report a case of 23-year-old female who was diagnosed with CML in the accelerated phase and subsequently treated with imatinib. She developed early relapse in her CNS, and her treatment was switched to dasatinib and intrathecal chemotherapy with cytarabine and methotrexate. Her CNS disease went into remission, and she underwent matched unrelated donor (MUD) hematopoietic stem cell transplant (HSCT). We discuss various mechanisms of treatment failure, importance of vigilance for symptoms and signs of treatment failure/relapse, indications for use of different tyrosine kinase inhibitors (TKIs), and management of blast crises in CML.

Organic Nanoparticles as Drug Delivery Systems and Their Potential Role in the Treatment of Chronic Myeloid Leukemia

Chronic myeloid leukemia is a myeloproliferative neoplasm that occurs more prominently in the older population, with a peak incidence at ages 45 to 85 years and a median age at diagnosis of 65 years. This disease comprises roughly 15% of all leukemias in adults. It is a clonal stem cell disorder of myeloid cells characterized by the presence of t(9;22) chromosomal translocation, also known as the Philadelphia chromosome, or its byproducts BCR-ABL fusion protein/messenger RNA, leading to the expression of a protein with enhanced tyrosine kinase activity. This fusion protein has become the main therapeutic target in chronic myeloid leukemia therapy, with imatinib displaying superior antileukemic effects, placing it at the forefront of current treatment protocols and displaying great efficacy. Alternatively, nanomedicine and employing nanoparticles as drug delivery systems may represent new approaches in future anticancer therapy. This review focuses primarily on the use of organic nanoparticles aimed at chronic myeloid leukemia therapy in both in vitro and in vivo settings, by going through a thorough survey of published literature. After a brief introduction on the pathogenesis of chronic myeloid leukemia, a description of conventional, first- and second-line, treatment modalities of chronic myeloid leukemia is presented. Finally, some of the general applications of nanostrategies in medicine are presented, with a detailed focus on organic nanocarriers and their constituents used in chronic myeloid leukemia treatment from the literature.

Isolated central nervous system relapse in chronic myeloid leukemia

Chronic myeloid leukemia is a myeloproliferative disorder that has three distinguished phases: chronic, accelerated, and blastic. In extremely rare cases, the blast phase can affect the central nervous system without concomitant bone marrow involvement. We report the case of a patient with chronic myeloid leukemia who, despite having achieved complete cytogenetic remission in the bone marrow for several years, experienced a blast crisis of the central nervous system following an episode of infectious meningoencephalitis.

Brain-targeted delivery of trans-activating transcriptor-conjugated magnetic PLGA/lipid nanoparticles

Magnetic poly (D,L-lactide-co-glycolide) (PLGA)/lipid nanoparticles (MPLs) were fabricated from PLGA, L-α-phosphatidylethanolamine (DOPE), 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-amino (polyethylene glycol) (DSPE-PEG-NH₂), and magnetic nanoparticles (NPs), and then conjugated to trans-activating transcriptor (TAT) peptide. The TAT-MPLs were designed to target the brain by magnetic guidance and TAT conjugation. The drugs hesperidin (HES), naringin (NAR), and glutathione (GSH) were encapsulated in MPLs with drug loading capacity (>10%) and drug encapsulation efficiency (>90%). The therapeutic efficacy of the drug-loaded TAT-MPLs in bEnd.3 cells was compared with that of drug-loaded MPLs. The cells accumulated higher levels of TAT-MPLs than MPLs. In addition, the accumulation of QD-loaded fluorescein isothiocyanate (FITC)-labeled TAT-MPLs in bEnd.3 cells was dose and time dependent. Our results show that TAT-conjugated MPLs may function as an effective drug delivery system that crosses the blood brain barrier to the brain.

P-glycoprotein (MDR1/ABCB1) and breast cancer resistance protein (BCRP/ABCG2) restrict brain accumulation of the JAK1/2 inhibitor, CYT387

CYT387 is an orally bioavailable, small molecule inhibitor of Janus family of tyrosine kinases (JAK) 1 and 2. It is currently undergoing Phase I/II clinical trials for the treatment of myelofibrosis and myeloproliferative neoplasms. We aimed to establish whether the multidrug efflux transporters P-glycoprotein (P-gp; MDR1; ABCB1) and breast cancer resistance protein (BCRP;ABCG2) restrict oral availability and brain penetration of CYT387. In vitro, CYT387 was efficiently transported by both human MDR1 and BCRP, and very efficiently by mouse Bcrp1 and its transport could be inhibited by specific MDR1 inhibitor, zosuquidar and/or specific BCRP inhibitor, Ko143. CYT387 (10 mg/kg) was orally administered to wild-type (WT), Bcrp1(-/-), Mdr1a/1b(-/-) and Bcrp1;Mdr1a/1b(-/-) mice and plasma and brain concentrations were analyzed. Over 8h, systemic exposure of CYT387 was similar between all the strains, indicating that these transporters do not substantially limit oral availability of CYT387. Despite the similar systemic exposure, brain accumulation of CYT387 was increased 10.5- and 56-fold in the Bcrp1;Mdr1a/1b(-/-) mice compared to the WT strain at 2 and 8h after CYT387 administration, respectively. In single Bcrp1(-/-) mice, brain accumulation of CYT387 was more substantially increased than in Mdr1a/1b(-/-) mice, suggesting that CYT387 is a slightly better substrate of Bcrp1 than of Mdr1a at the blood-brain barrier. These results indicate a marked and additive role of Bcrp1 and Mdr1a/1b in restricting brain penetration of CYT387, potentially limiting efficacy of this compound against brain (micro) metastases positioned behind a functional blood-brain barrier.

Dasatinib maintenance therapy after allogeneic hematopoietic stem cell transplantation for an isolated central nervous system blast crisis in chronic myelogenous leukemia

A 22-year-old male with Ph-positive chronic myelogenous leukemia (CML) was started on treatment with imatinib. After 12 months of therapy, he achieved a complete cytogenetic response (CCyR). Although the CCyR persisted in his bone marrow, he developed an isolated CML blast crisis in his central nervous system (CNS) after 29 months of therapy. He underwent allogeneic hematopoietic stem cell transplantation (HSCT) following combination therapy with dasatinib, intrathecal chemotherapy and cranial irradiation. Subsequently, 168 days after allogeneic HSCT, he was started on dasatinib maintenance therapy to prevent a CNS relapse. Thirty-eight months after allogeneic HSCT, he has sustained a complete molecular response in both bone marrow and CNS. We believe dasatinib has the potential to prevent CNS relapse if used for maintenance therapy after allogeneic HSCT.

c-Abl inhibition delays motor neuron degeneration in the G93A mouse, an animal model of amyotrophic lateral sclerosis

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive death of motor neurons. Although the pathogenesis of ALS remains unclear, several cellular processes are known to be involved, including apoptosis. A previous study revealed the apoptosis-related gene c-Abl to be upregulated in sporadic ALS motor neurons.

METHODOLOGY/FINDINGS

We investigated the possibility that c-Abl activation is involved in the progression of ALS and that c-Abl inhibition is potentially a therapeutic strategy for ALS. Using a mouse motor neuron cell line, we found that mutation of Cu/Zn-superoxide dismutase-1 (SOD1), which is one of the causative genes of familial ALS, induced the upregulation of c-Abl and decreased cell viability, and that the c-Abl inhibitor dasatinib inhibited cytotoxicity. Activation of c-Abl with a concomitant increase in activated caspase-3 was observed in the lumbar spine of G93A-SOD1 transgenic mice (G93A mice), a widely used model of ALS. The survival of G93A mice was improved by oral administration of dasatinib, which also decreased c-Abl phosphorylation, inactivated caspase-3, and improved the innervation status of neuromuscular junctions. In addition, c-Abl expression in postmortem spinal cord tissues from sporadic ALS patients was increased by 3-fold compared with non-ALS patients.

CONCLUSIONS/SIGNIFICANCE

The present results suggest that c-Abl is a potential therapeutic target for ALS and that the c-Abl inhibitor dasatinib has neuroprotective properties in vitro and in vivo.

Reduced mast cell and basophil numbers and function in Cpa3-Cre; Mcl-1fl/fl mice

It has been reported that the intracellular antiapoptotic factor myeloid cell leukemia sequence 1 (Mcl-1) is required for mast cell survival in vitro, and that genetic manipulation of Mcl-1 can be used to delete individual hematopoietic cell populations in vivo. In the present study, we report the generation of C57BL/6 mice in which Cre recombinase is expressed under the control of a segment of the carboxypeptidase A3 (Cpa3) promoter. C57BL/6-Cpa3-Cre; Mcl-1(fl/fl) mice are severely deficient in mast cells (92%-100% reduced in various tissues analyzed) and also have a marked deficiency in basophils (58%-78% reduced in the compartments analyzed), whereas the numbers of other hematopoietic cell populations exhibit little or no changes. Moreover, Cpa3-Cre; Mcl-1(fl/fl) mice exhibited marked reductions in the tissue swelling and leukocyte infiltration that are associated with both mast cell- and IgE-dependent passive cutaneous anaphylaxis (except at sites engrafted with in vitro-derived mast cells) and a basophil- and IgE-dependent model of chronic allergic inflammation, and do not develop IgE-dependent passive systemic anaphylaxis. Our findings support the conclusion that Mcl-1 is required for normal mast cell and basophil development/survival in vivo in mice, and also suggest that Cpa3-Cre; Mcl-1(fl/fl) mice may be useful in analyzing the roles of mast cells and basophils in health and disease.

Liposomal cytarabine is effective and tolerable in the treatment of central nervous system relapse of acute lymphoblastic leukemia and very aggressive lymphoma

BACKGROUND

Treatment of central nervous system relapse in adult acute lymphoblastic leukemia is a challenge and outcome is poor. Liposomal cytarabine has a prolonged half-life and, given intrathecally, has produced high response rates in patients with central nervous system relapse of non-Hodgkin's lymphoma. The aim of this study was to evaluate the efficacy and tolerability of liposomal cytarabine in central nervous system relapse of acute lymphoblastic leukemia or Burkitt's lymphoma/leukemia.

DESIGN AND METHODS

Liposomal cytarabine (50 mg) was given intrathecally together with systemic or intrathecal dexamethasone once every 2 weeks in a phase II European trial. The primary end-point, cytological response in the cerebrospinal fluid after one or two cycles, was evaluated at the time of next treatment.

RESULTS

Nineteen heavily pretreated patients (median age, 53 years; range 24-76 years) were evaluable: 14 with acute lymphoblastic leukemia and 5 with Burkitt's lymphoma/leukemia). Complete cytological remission as best response after two cycles of liposomal cytarabine was confirmed in 74% of the patients: 86% of those with acute lymphoblastic leukemia and 40% of those with Burkitt's lymphoma/leukemia). Nine of the 14 patients who achieved complete remission relapsed after a median of 7 months. The median overall survival was 11 months. Adverse events were observed in 89% of the patients (57% of cycles). Grade III-IV events with potential correlation to liposomal cytarabine occurred in 32% of the patients. The most frequent adverse event was headache. One patient developed severe neurological complications with loss of vision and a conus syndrome.

CONCLUSIONS

Overall, liposomal cytarabine showed excellent antileukemic activity. Toxicity was acceptable but appeared to increase with the number of cycles. Future evaluation in prophylaxis is of interest.

Standard treatment of Ph+ CML in 2010: how, when and where not to use what BCR/ABL1 kinase inhibitor?

Chronic myeloid leukaemia (CML) is a haematopoietic neoplasm characterised by the BCR/ABL1 oncoprotein. In chronic phase CML, the neoplastic clone exhibits multilineage differentiation and maturation capacity. The BCR/ABL1 kinase blocker imatinib shows major antileukaemic effects in most patients and is considered standard frontline therapy. However, not all patients have a long-lasting response to imatinib. Notably, resistance to imatinib has been recognised as an emerging problem and challenge in CML. Whereas CML stem cells are considered to exhibit intrinsic resistance, acquired resistance may, in addition, develop in subclones over time, resulting in an overt relapse. A key trigger of resistance in subclones are BCR/ABL1 mutations. For such patients, novel multikinase inhibitors such as nilotinib, dasatinib, bosutinib or bafetinib, which block the kinase activity of various BCR/ABL1 mutants, have been developed and reportedly exert antileukaemic effects in drug-resistant cells. For highly resistant patients, haematopoietic stem cell transplantation is an alternative option. Treatment decisions and the selection of drugs are based on the presence and type of BCR/ABL1 mutation(s), phase of disease, other disease-related variables and patient-related factors including age, compliance and co-morbidity. The current review provides an overview on standards in the diagnosis and therapy in CML, with special reference to novel BCR/ABL1 inhibitors.

Central nervous system is a sanctuary site for chronic myelogenous leukaemia treated with imatinib mesylate

Imatinib mesylate (IM) is currently used as the first therapeutic choice against chronic myelogenous leukaemia (CML). Because IM poorly penetrates the blood-brain barrier, IM-treated CML patients may have a potential risk of central nervous system (CNS) involvement. Here we report a case with lymphoid blast crisis isolated only in CNS after bacterial meningitis, although the patient achieved and maintained complete cytogenetic response by IM therapy. It is important to consider isolated CNS blast crisis as a possible event in IM-treated CML patients.

Characterisation of extramedullary relapse in patients with chronic myeloid leukemia in advanced disease after allogeneic stem cell transplantation

Recently, higher extramedullary relapse rates following allogeneic stem cell transplantation (SCT) in myeloid malignancies were reported e.g. because of selection of poor-risk patients. We analysed five consecutive patients with post-transplant extramedullary relapse of chronic myeloid leukemia (CML) out of a total of 24 patients (21%) undergoing allo-SCT. All five patients with extramedullary relapse had clonal evolution and a history of blast phase (BP). In particular, 56% of the patients in BP had extramedullary relapse with no extramedullary relapse in patients with chronic/accelerated phase. Most frequent manifestation sites were the skeletal system, the muscles/subcutaneous tissue and the central nervous system. In one case chloroma was mimicking myositis of the lower limbs. Combined approaches were performed including irradiation (n = 4), chemotherapy (n = 2), IM (n = 2), dasatinib (n = 4), nilotinib (n = 1), a novel aurora-kinase-inhibitor (n = 1), donor lymphocytes (n = 2) or a second allo-SCT (n = 2). Transient response was achieved in one case, stable partial remissions in two cases, whereas two cases were refractory. Research should focus on prospective studies aiming to improve treatment of extramedullary relapse in stem cell recipients with CML with a special focus on the role of second generation tyrosine kinase inhibitors.

Management of the advanced phases of chronic myelogenous leukemia in the era of tyrosine kinase inhibitors

Imatinib has revolutionised the management of chronic phase chronic myelogenous leukemia (CML). Unfortunately it has had less of an impact on the management of the advanced phases of CML. These historically difficult-to-treat phases of disease remain largely resistant to therapy. Even when responses are obtained with the tyrosine kinase inhibitors, they are brief, particularly in blast phase (BP) disease. Allogeneic stem cell transplantation is the only curative option for these patients and should be considered early as an integral part of the treatment plan. But transplant outcomes are dependent on cytogenetic and gross disease burden at the time of transplant. This review will compare and contrast the various tyrosine kinase- and non-tyrosine kinase inhibitor-based treatments for accelerated and BP CML before allogeneic transplantation.

Emerging stem cell concepts for imatinib-resistant chronic myeloid leukaemia: implications for the biology, management, and therapy of the disease

Chronic myeloid leukaemia (CML) is a myeloid neoplasm defined by the BCR/ABL oncoprotein that is considered essential for leukaemogenesis and accumulation of neoplastic cells. The BCR/ABL kinase inhibitor imatinib is an effective agent in most patients and can now be regarded as front-line therapy. Hence, intrinsic and acquired resistance to imatinib has been described and is an emerging challenge in clinical practice. While CML stem cells display primary resistance, stem cell subclones may, in addition, acquire imatinib-resistant mutants of BCR/ABL. Other factors that are considered to contribute to stem cell resistance include the genetic background, clonal evolution, additional biological features of subclones, gene amplifications, silencing of tumour suppressor genes and specific pharmacological aspects. In this article, mechanisms of resistance of CML (stem) cells against imatinib and other BCR/ABL inhibitors are discussed, together with strategies to overcome and/or to prevent resistance with available drugs or novel anti-leukaemic approaches.

Treatment of lymphomatous and leukemic meningitis with liposomal encapsulated cytarabine

Liposomal encapsulated cytarabine (DepoCyte, Mundipharma GmbH, Limburg/Lahn, Germany) is a slow-release formulation of conventional cytarabine. It is licensed for intrathecal use in patients with lymphomatous and leukemic meningitis. DepoCyte obtained superior response rates, improved patient quality of life and improved the time to neurological progression in a randomized albeit small clinical trial. In this review we briefly summarize the clinical data and discuss them in light of clinical problems and possible treatment scenarios.