Navitoclax (ABT-263) and bendamustine ± rituximab induce enhanced killing of non-Hodgkin's lymphoma tumours in vivo

BACKGROUND AND PURPOSE

Bendamustine with or without rituximab provides an effective and more tolerable alternative to the polytherapy cyclophosphamide-doxorubicin-vincristine-prednisolone (CHOP) in the treatment of haematological tumours and is currently approved for the treatment of many haematological malignancies. Navitoclax (ABT-263) is a potent inhibitor of Bcl-2, Bcl-x(L) and Bcl-w, which has demonstrated efficacy in haematological tumours alone and in combination with other agents. This paper describes the in vivo efficacy of combining either bendamustine or bendamustine plus rituximab (BR) with navitoclax in xenograft models of non-Hodgkin's lymphoma

EXPERIMENTAL APPROACH

Activity was tested in xenograft models of diffuse large B-cell lymphoma (DoHH-2, SuDHL-4), mantle cell lymphoma (Granta 519) and Burkitt's lymphoma (RAMOS). Activity was also monitored in a systemic model of Granta 519.

KEY RESULTS

Navitoclax potentiated bendamustine activity in all cell lines tested. Bendamustine activated p53 in Granta 519 tumours, concurrent with activation of caspase 3. Navitoclax also improved responses to bendamustine-rituximab (BR) in a subset of tumours.

CONCLUSIONS AND IMPLICATIONS

Navitoclax in combination with bendamustine and BR is a viable combination strategy for use in the clinic and demonstrated superior efficacy compared with previously reported data for navitoclax plus CHOP and rituximab-CHOP.

Lesions and identification of crystalline precipitates of glycoprotein IIb-IIIa antagonists in the rat kidney

Two glycoprotein IIb-IIIa antagonists (xemilofiban, SC-54684A, and orbofiban, SC-57099B), which are platelet aggregation inhibitors, caused crystalline precipitates in the kidney tubules of rats at high dosages. Dogs were not affected. Depending on the degree of the precipitation, which was dosage dependent, and the location, which differed somewhat between the two compounds, the lesions varied from acute obstruction with tubule cell necrosis, nephron dilation, and sudden death with no inflammation to severe chronic pyogranulomatous inflammation. In order to understand the relevance of the lesions, it was important to identify the precipitates. This was technically challenging because the crystals were water soluble (dissolving in routine fixing and staining techniques) and were present in insufficient quantity to physically isolate. Techniques were devised to evaluate the crystals in situ in unstained frozen sections prepared without directly embedding the tissues in supporting medium, which interfered with the analyses. The crystals were analyzed in situ by infrared and Raman spectroscopy and time-of-flight secondary ion mass spectroscopy (TOF-SIMS). Uroliths found in the renal pelvis of one animal were analyzed by liquid chromatography/mass spectrometry. The resulting spectra showed that the crystals were the de-esterified acids of the parent compounds. This knowledge allowed us to predict that the crystalline precipitates would not be a hazard to humans because of the large multiples of the human dosage at which they occurred and because of differences in renal physiology between rats, dogs, and humans.

Multiple neuromuscular abnormalities in a paranoid schizophrenic

A broad range of skeletal muscle fiber abnormalities has been reported previously in muscle biopsy specimens from psychotic patients. In our experience, individual patients manifest only a few types of lesions; but we now have studied a paranoid schizophrenic patient whose skeletal muscle fibers show virtually the entire range of morphologic abnormalities. In addition to the morphologic abnormalities of skeletal muscle fibers, we also noted increased branching of subterminal motor nerves with enlarged endplates and chronic elevations of serum creatine phosphokinase activity. Despite this, the patient had minimal clinical evidence of neuromuscular dysfunction. The variety of types of neuromuscular dysfunctions found in this patient suggests their etiology may be related.

Mean serum creatine kinase activity in patients with functional psychoses

Increased serum creatine kinase (CPK) activity has been reported to be present during acute exacerbations of psychosis in the majority of patients with the major "functional" psychoses. It has also been demonstrated that mean serum CPK activity, ie, average daily serum CPK activity, is under genetic control. In this report, we present evidence for an association between the presence of a transient elevation of serum CPK activity beyond the upper limit of normal during psychotic episodes and relatively high mean serum CPK levels during the rest of hospitalization. The magnitude of the transient serum CPK elevation was correlated with mean serum CPK activity in psychotic patients. The mean serum CPK level was also correlated with the terminal innervation ratio, an indication of alpha motor neuron dysfunction. The incidence of serum CPK elevations in first-degree relatives of psychotic patients was significantly greater in patients with high mean serum CPK activity than in those with low mean serum CPK activity. High mean serum CPK activity may be an indication of an increase in permeability of the muscle cell membrane, which in turn may be due to some defect in the neurotrophic regulation of muscle physiology or an independent expression of muscle abnormalities.