Substrate-dependent bidirectional modulation of P-glycoprotein-mediated drug resistance by erlotinib

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR‐TKIs) inhibit the function of certain adenosine triphosphate (ATP)‐binding cassette transporters, including P‐glycoprotein/ABCB1 and breast cancer resistance protein (BCRP)/ABCG2. We previously reported an antagonistic activity of gefitinib towards BCRP. We have now analyzed the effects of erlotinib, another EGFR‐TKI, on P‐glycoprotein and BCRP. As with gefitinib, erlotinib effectively reversed BCRP‐mediated resistance to SN‐38 (7‐ethyl‐10‐hydroxycamptothecin) and mitoxantrone. In contrast, we found that erlotinib effectively suppressed P‐glycoprotein‐mediated resistance to vincristine and paclitaxel, but did not suppress resistance to mitoxantrone and doxorubicin. Conversely, erlotinib appeared to enhance P‐glycoprotein‐mediated resistance to mitoxantrone in K562/MDR cells. This bidirectional activity of erlotinib was not observed with verapamil, a typical P‐glycoprotein inhibitor. Flow cytometric analysis showed that erlotinib co‐treatment restored intracellular accumulation of mitoxantrone in K562 cells expressing BCRP, but not in cells expressing P‐glycoprotein. Consistently, erlotinib did not inhibit mitoxantrone efflux in K562/MDR cells although it did vincristine efflux in K562/MDR cells and mitoxantrone efflux in K562/BCRP cells. Intravesicular transport assay showed that erlotinib inhibited both P‐glycoprotein‐mediated vincristine transport and BCRP‐mediated estrone 3‐sulfate transport. Intriguingly, Lineweaver‐Burk plot suggested that the inhibitory mode of erlotinib was a mixed type for P‐glycoprotein‐mediated vincristine transport whereas it was a competitive type for BCRP‐mediated estrone 3‐sulfate transport. Collectively, these observations indicate that the pharmacological activity of erlotinib on P‐glycoprotein‐mediated drug resistance is dependent upon the transporter substrate. These findings will be useful in understanding the pharmacological interactions of erlotinib used in combinational chemotherapy. (Cancer Sci 2009; 100: 1701–1707)     

Impairment of decision-making cognition in a case of frontotemporal lobar degeneration (FTLD) presenting with pathologic gambling and hoarding as the initial symptoms.

OBJECTIVE: The aim of this study was to use the Iowa Gambling Task (IGT) to examine decision-making cognition in a patient with mild frontal variant of frontotemporal dementia (fv-FTD). BACKGROUND: Although fv-FTD may present with bizarre and dramatic behavioral changes, traditional executive tasks are sometimes preserved in patients with mild fv-FTD. Some evidence suggests that tasks assessing decision-making cognition, such as the IGT, may be sensitive to detect cognitive dysfunction in patients with mild fv-FTD. Here, we report a patient with fv-FTD who presented with bizarre behavior including hoarding, pathologic gambling, and abnormal sexual behavior. METHODS: A 54-year-old man who had been diagnosed as having fv-FTD was examined using a behavioral assessment, a wide range of neuropsychologic tasks, and the IGT. Brain magnetic resonance imaging and brain 99mTc-ethylcysteinate dimer single-photon emission computed tomography examinations were also performed. RESULTS: Although the patient's cognitive abilities were almost fully preserved for a number of traditional neuropsychologic tasks (memory, executive function), the IGT suggested that his decision-making cognition was impaired. The 99mTc-ethylcysteinate dimer single-photon emission computed tomography examination revealed hypometabolism in bilateral medial frontal and orbitofrontal regions of the cerebral cortex, and also in the cingulate gyri. CONCLUSIONS: Our findings suggest that the IGT may be a sensitive tool for assessing patients with mild fv-FTD before the development of severe dementia. We speculate that the deficit in decision-making cognition observed in the present case was associated with hypometabolism in the neural networks of the frontal lobe and involving both the bilateral medial frontal and orbitofrontal regions of the cerebral cortex.     

Elevation of plasma D-dimer is closely associated with venous thrombosis produced by double-lumen catheter in pre-dialysis patients.

BACKGROUND: A double-lumen catheter (DLC) is used as a temporary blood access in emergency haemodialysis and continuous haemodialysis. There are various reports concerning thrombosis related to use of DLC and other catheters. The objective of this study is to assess the incidence of venous thrombosis when using DLC in patients undergoing blood purification. Method. Forty-eight Japanese patients, hospitalized in the Saitama Medical University hospital from December 2004 to April 2005, who had DLC insertion as a temporary blood access for blood purification. The existence of a thrombus was determined using ultrasonography, before catheter insertion, and every 2 days after insertion up to 3 weeks. At the time of DLC insertion, general blood tests including plasma D-dimer, and serum C-reactive protein (CRP) were performed. When DLC was removed, plasma D-dimer and serum CRP were measured. RESULTS: In 30 of 48 (62.5%) patients with DLC insertion as a temporary blood access for haemodialysis, venous thrombi with diameters>1.1 mm were detected by venous ultrasonography. No predictive factors were recognized except an increase in plasma D-dimer that was significantly higher in the patients with venous thrombus. The changes in plasma D-dimer were 3.54 (SE 0.8) microg/dl in patient with thrombus, and 0.29 (0.30) microg/dl in patient without thrombus (P=0.004). CONCLUSIONS: The study suggests that changes in plasma D-dimer after the insertion of the catheter may be used to predict thrombus formation and is more accurate than baseline measurements, and easier than other new markers.     

Progress reports on immune gene therapy for stage IV renal cell cancer using lethally irradiated granulocyte-macrophage colony-stimulating factor-transduced autologous renal cancer cells

There is no effective treatment for patients with stage IV renal cell cancer (RCC), although the introduction of new therapy is imminent. Cancer gene therapy is currently considered to be one of the most promising therapeutic modalities in the field of cancer treatment. Based on the results of animal studies, vaccination using autologous granulocyte-macrophage colony-stimulating factor-transduced renal cancer cells appears promising. Before initiating a clinical study using an ex vivo gene-transduced autologous cell vaccine-based immunogene therapy for RCC in Japan, in 1992 we initially planned a Japanese version of a clinical protocol in collaboration with a US group. In 1993, the original protocol was refined. We performed five preclinical qualification studies using RCC nephrectomy specimens from patients in 1997, and the results showed that preparation of RCC cells for autologous vaccines at the Clinical Cell Technology Facility, Research Hospital of the Institute of Medical Science, University of Tokyo, was feasible. Subsequently in August 1998, the Ministry of Health and Welfare and the Ministry of Education, Science, Culture, and Sport approved our clinical protocol. We have recruited two patients with stage IV RCC to our study so far. Here we report the background to the initiation of cancer gene therapy in Japan.     

Acquisition rate of antibody to hepatitis B surface antigen among medical and dental students in Japan after three-dose hepatitis B vaccination

Background

Health care workers (HCWs) are at high risk of contracting blood-borne infections including hepatitis B virus (HBV) infection. In Japan, all HCWs are required to receive HB vaccination before beginning work. This study aimed to investigate the dynamics of the HB surface antibody (anti-HBs) titer after a three-dose HB vaccination in HCWs and to determine effective scheduling of HB vaccination for non-responders.

Phase I/II Study of Cisplatin plus Nab‐Paclitaxel with Concurrent Thoracic Radiotherapy for Patients with Locally Advanced Non‐Small Cell Lung Cancer

Lessons Learned

• The combination of cisplatin plus nab‐paclitaxel with concurrent thoracic radiotherapy in unresectable stage III non‐small cell lung cancer is a promising therapeutic strategy.
• Further investigation is warranted.

BackgroundWe conducted a phase I/II trial of cisplatin plus nab‐paclitaxel with concurrent thoracic radiotherapy for locally advanced non‐small cell lung cancer (NSCLC) to determine the recommended dose (RD) of nab‐paclitaxel and to evaluate the safety and efficacy of this regimen.MethodsIn the phase I study, escalating doses of weekly nab‐paclitaxel were administered together with cisplatin at 75 mg/m² every 3 weeks and concurrent radiotherapy. In the phase II study, nab‐paclitaxel was administered at the RD.ResultsIn the phase I study, whereas no dose‐limiting toxicity (DLT) was observed with nab‐paclitaxel at 50 or 60 mg/m², one of six patients experienced DLT (esophagitis of grade 3) at 70 mg/m², determined as the RD. Twenty‐four patients at RD were evaluable for safety and efficacy in phase II. Common toxicities included esophagitis (87.5%) and leukopenia (79.2%). Pneumonitis and treatment‐related deaths were not observed, but 20 patients (83.3%) experienced radiation pneumonitis, with one case of grade 3 and four of grade 2, after completion of concurrent chemoradiotherapy. The 2‐year overall survival and progression‐free survival rates were 73.9% and 56.5% (95% confidence interval [CI], 34.3%–74.7%), respectively.ConclusionConcurrent chemoradiation with nab‐paclitaxel at 70 mg/m² and cisplatin at 75 mg/m² every 3 weeks showed encouraging feasibility and activity for locally advanced NSCLC.