Long-term efficacy and safety of cladribine (2-CdA) in adult patients with mastocytosis.

Mastocytosis (M) is a clonal myeloid-disabling disorder for which no curative therapy is currently available. Cladribine (2-chlorodeoxyadenosine [2-CdA]) is a synthetic purine analog cytoreductive treatment, for which efficacy is mostly reported in advanced M. Here we report, with a long-term follow-up period (>10 years) efficacy and safety in 68 adult patients with M (36 [53%] had indolent M and 32 [47%] had advanced M) treated by 2-CdA (0.14 mg/kg in infusion or subcutaneously, days 1-5; repeated at 4-12 weeks until 1 to 9 courses). Median 2-CdA courses number was 3.7 (1-9). The overall response rate was 72% (complete remission [R]/major/partial R: 0%/47%/25%) and according to indolent/advanced M was 92% (major/partial R: 56%/36%) and 50% (major/partial R: 37.5%/12.5%), respectively. Clinical improvement was observed for 10 of 11 mediator release and 6 of 7 mast cell infiltration-related symptoms including urticaria pigmentosa and organomegaly (P < .02). Serum tryptase levels decreased (P = .01). Median durations of response were 3.71 (0.1-8) and 2.47 (0.5-8.6) years for indolent and aggressive M, respectively. The most frequent grade 3/4 toxicities were lymphopenia (82%), neutropenia (47%), and opportunistic infections (13%). 2-CdA appears to provide a significant efficacy with some toxicity in various M subtypes, mostly in indolent M, refractory to multiple symptomatic therapies.

Characteristic pattern of chromosomal imbalances in posttransplantation lymphoproliferative disorders: correlation with histopathological subcategories and EBV status.

BACKGROUND: Posttransplantation lymphoproliferative disorders (PTLDs) are a spectrum of lymphoid proliferations, occurring in immunosuppressed organ transplant recipients. They comprise early lesions, polymorphic (P-PTLD), monomorphic (M-PTLD), and Hodgkin/Hodgkin-like lymphoma PTLD (HL-PTLD) lesions. Most of them are associated with Epstein-Barr virus (EBV). Little is known about their genetic changes. MATERIALS AND METHODS: We have studied 35 PTLDs[7 P-PTLDs (3/7 polyclonal IgH), 26 M-PTLDs (22 B-cell PTLD, 4 T-cell PTLD), 2 HL-PTLDs], using comparative genomic hybridization (CGH), a DNA-based technique allowing a screening of chromosomal imbalances without needing cultured cells. RESULTS.: Overall incidence of chromosomal imbalances: 51.5 %. The most frequent gains involved 8q24, 3q27 [4 cases each]; 2p24p25, 5p, 9q22q34, 11, 12q22q24, 14q32, 17q, 18q21 [2 cases each]. Nonrandom losses were 17p13 [4 cases]; 1p36, 4q [3 cases each]; 17q23q25, Xp [2 cases each]. Three high-level amplifications were detected: 4p16, 9p22p24, 18q21q23. In this latter imbalance, involvement of Bcl2 has been confirmed by FISH. The nonrandom CGH imbalances occurring in M-PTLD are usually described in lymphomas of immunocompetent patients and contain genes known to be involved in lymphomagenesis, while genomic abnormalities detected in half cases of EBV positive P-PTLD are mostly unknown. CONCLUSION: This study reported nonrandom chromosomal imbalances in PTLD and also identified early genomic alterations in EBV positive P-PTLD. These results raise two questions: the role of such lesions in the development and progression of those EBV induced-lymphoproliferations and their clinical significance especially in P-PTLD.

Liquid chromatography-tandem mass spectrometry assay for therapeutic drug monitoring of the tyrosine kinase inhibitor, midostaurin, in plasma from patients with advanced systemic mastocytosis.

We developed and validated quantitative bioanalytical liquid chromatography-tandem mass spectrometry assay for the protein kinase inhibitor, midostaurin. Plasma samples were pre-treated using a protein precipitation with methanol containing midostaurin-d5 as an internal standard. After centrifugation, 5µL of the supernatant was injected into the chromatographic system. The system consisted of a 3.5µm particle bonded octadecyl silica column, with gradient elution using a mixture of 0.1% (v/v) formic acid in acetonitrile and 10mM ammonium formate in water with 0.1% formic acid. The analyte was quantified using the selected reaction-monitoring mode of a triple quadrupole mass spectrometer equipped with a heated electrospray interface. The assay was validated in a 75-2500ng/mL calibration range. For quality control, within-day and between-day precisions were 1.2-2.8%, and 1.2-6.9%, respectively. The ß-expectation tolerance limit (accuracy) met the limits of acceptance ±15% (±20% for the LLQ). The drug was sufficiently stable under all relevant analytical conditions. The assay has successfully been used to assess drug levels for therapeutic drug monitoring in patients presenting advanced systemic mastocytosis and treated with the promising midostaurin.

Bone complications of mastocytosis: a link between clinical and biological characteristics.

OBJECTIVES: Mastocytosis is a heterogeneous group of clonal mast cell disorders in which bone manifestations are frequently seen, but poorly understood. In this study, we analyzed correlation of clinical findings in mastocytosis patients with bone mineral density and bone turnover markers. METHODS: Serum levels of bone turnover markers were measured in mastocytosis patients and healthy volunteers. Bone disease was evaluated using radiographic imaging, and measurement of bone mineral density. RESULTS: Of 45 adult mastocytosis patients, bone abnormalities were detected in 34 (75%). Bone lesions were documented on radiographic imaging in 16 patients (36%), and bone mineral density in 24 patients (53%), of which 9 patients (20%) had osteoporosis and 15 (33%) had osteopenia. Serum levels of bone turnover markers that evaluate bone resorption (C-telopeptide, deoxypyridinoline), bone formation (bone-specific alkaline phosphatase), and bone remodeling (osteoprotegerin) were significantly higher in the patient population than in the control population (n=28). Levels of C-telopeptide and osteoprotegerin were higher in patients with advanced systemic mastocytosis than in patients with cutaneous or indolent systemic mastocytosis. Moreover, C-telopeptide and osteoprotegerin levels were significantly correlated with those of serum tryptase, a diagnostic marker of mastocytosis. CONCLUSION: The observed bone turnover markers variations indicate a complex process of bone turnover in mastocytosis-related bone manifestations. The highly significant correlation between serum tryptase and serum bone turnover markers levels, and the positive correlation of levels of bone turnover markers with advanced disease, support the existence of a link between bone remodeling and mast cell burden.