L-ASN depletion after a first exposure to standard doses of Erwinase or medac is obtained in virtually all patients. No differences are seen between the I.M. or I.V. administration routes but the medac product is associated with a significantly higher enzyme activity in respect of Erwinase. L-ASN levels may be undetectable also in patients with L-ASE trough activity levels < 50 mU/ml, challenging the current opinion that an activity level of 100 mU/ml is needed to obtain L-ASN depletion.
We selected a 4-stain immunopanel including thyroid transcription factor (7ITF)-], cytokeratin (CK)7, 34betaE12, and CD56/neural cell adhesion molecule(NCAM) to subclassify a series of 45 pulmonary large cell carcinomas (LCCs) on bronchial biopsy. All cases consisted of a large tumor cell proliferation with abundant cytoplasm, vesicular nuclei, and prominent nucleoli. Immunohistochemically, 27 tumors (60%)were subclassified as adenocarcinoma (7TF-1 +/CK7+,24; CK7+ only, 3), 10 (22%) as squamous cell carcinoma (34betaE12+ only), and 4 (9%) as LCC with neuroendocrine differentiation (CD56+, variably stained with TTF-I and CK7, 34betaE12-). In 4 cases, the tumors coexpressed CK7 and 34betaE12 (3 cases) or were completely unstained (I case). Surgically resected tumors matched exactly with the corresponding original biopsy specimens in 21 of 23 cases; consistent CD56 expression was a reliable marker in confirming a diagnosis of large cell neuroendocrine carcinoma even on biopsy. Our results suggest that the proposed 4-stainset of commercially available markers might help subclassify LCC even in small biopsy material, validating expression-profiling studies aimed at lung cancer classification and permitting more consistent patient enrollment for trials with targeted treatments.
Intrathecal chemotherapy with antineoplastic agents is mainly utilised in children with leukaemia and lymphoma, and in selected brain tumours. In these diseases, intrathecal use is restricted to methotrexate (MTX), cytosine arabinoside (Ara-C) and corticosteroids. A number of other agents are, at the present time, under evaluation. Intrathecal MTX administered sequentially with systemic high dose MTX infusion prolongs therapeutic cerebral spinal fluid (CSF) levels of the drug. Prolonged therapeutic CSF levels can also be achieved by giving repeated small intrathecal doses of MTX over an extended period in selected patients, with an implanted Ommaya reservoir. In the CSF, the metabolic inactivation of Ara-C is significantly lower than in plasma with a CSF clearance similar to the rate of CSF bulk flow. A slow-release formulation of Ara-C may be given intrathecally, resulting in a prolonged cytotoxic concentration in the CSF. CNS relapse and neurotoxicity in patients with acute lymphoblastic leukaemia, especially younger children, may be reduced by using age-related dosing of intrathecal MTX and Ara-C. Hydrocortisone is used in combination with MTX and Ara-C for so-called 'triple intrathecal chemotherapy' in the treatment of meningeal leukaemia. Intrathecal thiotepa does not appear to be advantageous over systemic administration in patients with brain and meningeal leukaemia. Monoclonal antibodies, reactive with tumour-associated antigens, can be used as delivery systems for chemotherapeutic agents and radionuclides. However, the development of this new approach is currently under evaluation in larger clinical studies. Neurological adverse effects may be expected with intrathecal chemotherapy and are increased by high dose systemic therapy, concomitant cranial radiotherapy or meningeal infiltration by neoplastic cells. Inadvertant intrathecal administration of antineoplastic agents that are indicated for systemic administration only, is dangerous and may result in a fatal outcome.
Immunostaining for glial fibrillary acidic protein (GFAP) identifies a minor subpopulation of immunoreactive myoepithelial cells in the normal resting human breast. The GFAP-immunoreactive cells also express a panel of myoepithelial cell markers, including cytokeratin 14 (CK 14), vimentin, smooth-muscle-specific actin isoforms, nerve growth factor receptor (NGFR) and common acute lymphoblastic leukaemia antigen (CALLA). The percentage of GFAP-immunoreactive myoepithelial cells is greatly increased in various neoplastic and non-neoplastic diseases of the breast, being highest in adenomyoepitheliomas. Furthermore, in all the instances of fibroadenoma, phyllodes tumour, epitheliosis and gynaecomastia, a variable number of epithelial cells also acquires immunoreactivity for GFAP, vimentin, CK 14, NGFR and, to a lesser extent, for CALLA. Conversely, GFAP immunoreactivity has never been encountered in the malignant cells of the different types of breast carcinoma. These findings suggest that the expression of GFAP might be a (possibly transient) feature of proliferating epithelial and myoepithelial cells in breast diseases other than carcinomas.
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