Yoon Choi

The role of peripheral N-methyl-D-aspartate receptors in Freund's complete adjuvant induced mechanical hyperalgesia in rats.

We investigated the role of excitatory amino acid receptors in mechanical hyperalgesia induced by subcutaneous injection of Freunds complete adjuvant (FCA) into the rat hind paw. In normal rats, an intraplantar (i.pl.) injection of L-glutamate, but not of D-glutamate (3 pmol/0.1 ml each) produced a mechanical hyperalgesia in the hind paw with a lowered paw-withdrawal threshold to pressure. In rats that developed mechanical hyperalgesia associated with inflammation in the hind paw following i.pl. injection of FCA (0.15 ml), the injection of N-methyl-D-aspartate (NMDA) receptor antagonist, MK-801 (1 pmol/0.1 ml) into the inflamed paw increased the paw pressure threshold. On the other hand, the injection of non-NMDA receptor antagonist, 6-cyano-7-nitroqiunoxaline-2,3-dione (CNQX, 10 pmol/0.1 ml) into the inflamed paw had no effect on FCA-induced lowering of the paw pressure threshold. The results suggest that NMDA, but not non-NMDA receptors play a substantial role in mediating the development of mechanical hyperalgesia induced in the inflamed paw following i.pl. FCA injection.

Clinical outcomes and prognostic factors in patients with breast diffuse large B cell lymphoma; Consortium for Improving Survival of Lymphoma (CISL) study

BackgroundThe breast is a rare extranodal site of non-Hodgkin lymphoma, and primary breast lymphoma (PBL) has been arbitrarily defined as disease localized to one or both breasts with or without regional lymph nodes involvement. The aim of this study was to evaluate the clinical outcomes in patients with diffuse large B cell lymphoma (DLBCL) and breast involvement, and to find the criteria of PBL reflecting the outcome and prognosis.MethodsWe retrospectively analyzed data from 68 patients, newly diagnosed with DLBCL and breast involvement at 16 Korean institutions between January 1994 and June 2009.ResultsMedian age at diagnosis was 48 years (range, 20-83 years). Forty-three (63.2%) patients were PBL according to previous arbitrary criteria, sixteen (23.5%) patients were high-intermediate to high risk of international prognostic index. The patients with one extranodal disease in the breast (OED) with or without nodal disease were 49 (72.1%), and those with multiple extranodal disease (MED) were 19 (27.9%). During median follow-up of 41.5 months (range, 2.4-186.0 months), estimated 5-year progression-free survival (PFS) was 53.7 ± 7.6%, and overall survival (OS) was 60.3 ± 7.2%. The 5-year PFS and OS was significantly higher for patients with the OED group than those with the MED group (5-year PFS, 64.9 ± 8.9% vs. 27.5 ± 11.4%, p = 0.001; 5-year OS, 74.3 ± 7.6% vs. 24.5 ± 13.0%, p < 0.001). In multivariate analysis, MED (hazard ratio [HR], 3.61; 95% confidence interval [CI], 1.07-12.2) and fewer than four cycles of systemic chemotherapy with or without local treatments (HR, 4.47; 95% CI, 1.54-12.96) were independent prognostic factors for worse OS. Twenty-five (36.8%) patients experienced progression, and the cumulative incidence of progression in multiple extranodal sites or other than breasts and central nervous system was significantly different between the OED group and the MED group (5-year cumulative incidence, 9.7 ± 5.4% vs. 49.0 ± 15.1%, p = 0.001).ConclusionsOur results show that the patients included in OED group, reflecting different treatment outcome, prognosis and pattern of progression, should be considered as PBL in the future trial. Further studies are warranted to validate our suggested criteria.

Association Between Age at Diagnosis and the Presence of EGFR Mutations in Female Patients with Resected Non-small Cell Lung Cancer

Background: Our previous report showed an association between age and outcome in gefitinib-treated female patients with non-small cell lung cancer (NSCLC). Only limited numbers of molecular studies have been performed with respect to the presence of epidermal growth factor receptor (EGFR) mutations according to age. This retrospective study was performed to evaluate a possible association between age at the time diagnosis and the presence of EGFR mutations in female patients with NSCLC. Methods: Tumor specimens were collected retrospectively from paraffin blocks of 98 female patients with primary NSCLC who underwent surgical resection between January 1992 and December 2002 at the Korea Cancer Center Hospital. To detect EGFR mutations, a Scorpion Amplified Refractory Mutation System was used. Results: Most of the study population comprised never smokers (84%) and patients with adenocarcinoma (82%). The age at the time of diagnosis ranged from 34 to 74 years (median, 57 years). When the median age was used as a cutoff value, older patients were more likely to have EGFR mutations than younger patients (70 versus 39%; p = 0.004). After controlling for the effects of histology, smoking history, and stage, age remained a significant predictor for EGFR mutations (odds ratio, 4.03; 95% confidence interval, 1.61–10.09; p = 0.003). Conclusions: Our data suggest that age at the time of diagnosis in female patients with NSCLC may be associated with the frequency of EGFR mutations, a strong indicator for favorable outcomes.

Differential antinociceptive effect of transcutaneous electrical stimulation on pain behavior sensitive or insensitive to phentolamine in neuropathic rats.

The effects of transcutaneous electrical stimulation and systemic injection of phentolamine, a non-specific alpha-adrenergic antagonist, on the behavioral signs of mechanical allodynia and cold hyperalgesia in rats with nerve injury were investigated. Mechanical allodynia and cold hyperalgesia were evaluated by measuring the paw withdrawal frequency (PWF) resulting from repetitive application of a von Frey hair and the paw lift duration (PLD) at a cold temperature, respectively. After a unilateral nerve injury, both PWF and PLD increased in the injured hind paw. Application of low-frequency, high-intensity transcutaneous electrical stimulation (LFHI-TES) to the injured hind paw depressed the injury-induced increased PWF, whereas it had no effect on the injury-induced increased PLD. Naloxone reversed the LFHI-TES produced depression of PWF. Intraperitoneal administration of phentolamine depressed the injury-induced increased PLD without affecting the injury-induced increased PWF. Our results suggest that LFHI-TES, which activates the endogenous opioid systems, produces an antinociceptive effect that appears to be related to whether or not the pain is mediated by sympathetic activity.

Tissue microarray-based study of patients with lymph node-negative breast cancer shows that HER2/neu overexpression is an important predictive marker of poor prognosis

BACKGROUND Despite good prognosis in most cases of lymph node (LN)-negative breast cancer, individual patients may have markedly different clinical outcomes. Here, we investigated the prognostic significance of HER2/neu overexpression in these tumors. MATERIALS AND METHODS We employed a tissue microarray to examine HER2/neu overexpression by immunohistochemical staining in 359 consecutive patients diagnosed with LN-negative breast cancer, who underwent surgery from January 1993 to December 1998. RESULTS HER2/neu overexpression was detected in 81 of 359 (23.1%) patients. The 10-year disease-free survival (DFS) values (81.2% versus 61.8%, P value 0.000) and overall survival (OS) rates (85.7% versus 63.9%, P value 0.000) were significantly different between cases with HER2/neu-negative or HER2/neu-positive tumors. After multivariate analysis, HER2/neu status and tumor size were identified as independent prognostic factors for 10-year OS. Moreover, HER2/neu overexpression was significantly associated with poorer clinical outcomes in an intermediate-risk group identified by the St Gallen classification (10-year DFS, 79.6% versus 61.8%, P value 0.000; 10-year OS, 84.7% versus 63.9%, P value 0.000). CONCLUSIONS Our results show that HER2/neu overexpression is an important independent prognostic factor for LN-negative breast cancer cases and support the theory that more intensive adjuvant chemotherapy is required in the population with HER2/neu overexpression.

A Phase II study of clinical outcomes of 3-week cycles of irinotecan and S-1 in patients with previously untreated metastatic colorectal cancer: influence of the UGT1A1 and CYP2A6 polymorphisms on clinical activity.

Objectives: We investigated the efficacy and safety of the combination of irinotecan (CPT-11) and S-1 (IRIS regimen) as a first-line treatment in patients with metastatic colorectal cancer. We also evaluated the association between UGT1A1 and CYP2A6 polymorphisms and clinical phenotypes. Methods: The patients received CPT-11 (225 mg/m2) on day 1 and S-1 (80 mg/m2) on days 1–14 every 3 weeks. The association of the UGT1A1 (*6 and *28) and CYP2A6(*4, *7, *9, and *10) polymorphisms with toxicities and efficacy were analyzed. Results: Thirty patients were treated. The overall response rate was 66.7% (95% CI 48.7–84.6). The median time to progression was 7.6 months (95% CI 5.8–9.5). The most common grade 3/4 hematologic and non-hematologic toxicity were neutropenia (53.4%) and diarrhea (16.7%), respectively. The allele frequencies of UGT1A1*6 and *28 were 15.5 and 10.3%, respectively. The frequencies of CYP2A6*4, *7, *9, and *10 were 15.5, 8.6, 29.3, and 3.5%, respectively. Stratification of patients according to the number of UGT1A1*28 and *6 alleles showed a significant correlation between the number of defective alleles and the incidence of grade 3/4 neutropenia. Conclusions: Our results indicate that IRIS is a promising first-line regimen in patients with metastatic colorectal cancer. Severe neutropenia may be associated with interindividual variations in UGT1A1 polymorphisms.

An analysis of drug interaction between morphine and neostigmine in rats with nerve-ligation injury.

UNLABELLED Intrathecal neostigmine reverses mechanical allodynia in humans and animals. The efficacy of morphine in a neuropathic pain state is still controversial. This study examines the antiallodynic interaction between morphine and neostigmine in a rat model of neuropathic pain. Rats were prepared with tight ligation of left L5-6 (fifth and sixth lumbar) spinal nerves and chronic intrathecal catheter implantation. Mechanical allodynia was measured by using application of von Frey hairs to the left hindpaw. Morphine (1, 3, 10, and 30 microg) and neostigmine (0.3, 1, 3, and 10 microg) were administered intrathecally to obtain the dose-response curves and the 50% effective dose (ED(50)) for each drug. ED(50) values and fractions of the ED(50) values (1/2, 1/4, and 1/8) were administered intrathecally in an equal dose ratio to establish the ED(50). Isobolographic and fractional analyses for the drug interaction were performed. Intrathecal morphine produced a moderate antagonism of the tactile allodynia. A morphine-neostigmine combination produced a dose-dependent increase in withdrawal threshold of the lesioned hind paw with reduced side effects. Both analyses revealed a synergistic interaction after the coadministration of morphine and neostigmine. These experiments suggest that the antiallodynic action of a morphine-neostigmine combination is synergistic at the spinal level. IMPLICATIONS This study indicates that, by using both isobolographic and fractional analyses, the antiallodynic effect of intrathecal morphine and neostigmine is synergistic when coadministered intrathecally. In a rat model of neuropathic pain, the intrathecal morphine produced a moderate antagonism on touch-evoked allodynia at the spinal level.

Conduction block by clonidine is not mediated by α2-adrenergic receptors in rat sciatic nerve fibers☆

Background and Objectives Clonidine, an α 2-adrenergic agonist, has been shown to prolong local anesthesia. It appears that clonidine by itself produces conduction block by acting on peripheral nerves. However, whether clonidine-induced conduction block is mediated through α 2-adrenergic receptors remains unclear. The purpose of this study was to see if clonidine’s nerve-blocking action was through α 2-adrenergic receptors by examining clonidine’s action in the presence of α 2-adrenergic antagonists. Methods The compound action potentials (CAPs) evoked by electrical stimuli were recorded from the isolated rat sciatic nerve in a recording chamber. Conduction block was examined by analyzing CAPs with regard to peak amplitude and time-to-peak in the presence of clonidine alone or clonidine plus α 2-adrenergic antagonist yohimbine or idazoxan. Results Both clonidine and yohimbine produced concentration-dependent, reversible, conduction block. Based on concentration-response relationships, the 50% of effective concentration (EC50) were estimated to be 1.61 ± 0.51 mmol/L (mean ± SD) for clonidine and 51.4 ± 27.2 μmol/L for yohimbine. A mixture of equal volumes of 2.07 mmol/L clonidine and 55.6 μmol/L yohimbine produced conduction block to a level close to the mean value between conduction blocks induced by 2.07 mmol/L clonidine alone and 55.6 μmol/L yohimbine alone. Addition of idazoxan, a more specific α 2-adrenergic antagonist than yohimbine, to clonidine was without effect on clonidine-induced conduction block. Conclusions The results indicated that the mixture of clonidine and yohimbine, in which either drug inhibited impulse conduction, produced conduction block in an additive manner, and that clonidine-induced conduction block was not reversed by coapplication with a specific α 2-adrenergic antagonist idazoxan. These data suggest that clonidine’s effects likely depend on mechanisms not mediated by α 2-adrenergic receptors.

Two Lung Masses with Different Responses to Pemetrexed

We described here a patient who had two lung masses. Although the two masses had the same histology and a similar good response to initial chemotherapy with gemcitabine and carboplatin, the response to pemetrexed as a second-line treatment was different after re-growth of the tumors. These two lung masses could have originated from different clones or they could have progressed through different paths of molecular pathogenesis after metastasis, which would lead to different tumor characteristics, including their chemosensitivity. Regardless of their pathogenetic mechanisms, it seems important to recognize that tumors with the same histology that develop in one patient can have different responses to drugs.

A Randomized, Open-Label, Phase II Study Comparing Pemetrexed Plus Cisplatin Followed by Maintenance Pemetrexed versus Pemetrexed Alone in Patients with Epidermal Growth Factor Receptor (EGFR)-Mutant Non-small Cell Lung Cancer after Failure of First-Line EGFR Tyrosine Kinase Inhibitor: KCSG-LU12-13

Purpose The optimal cytotoxic regimens have not been established for patients with non-small cell lung cancer (NSCLC) who develop disease progression on first-line epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI). Materials and Methods We conducted a multi-center randomized phase II trial to compare the clinical outcomes between pemetrexed plus cisplatin combination therapy followed by maintenance pemetrexed (PC) and pemetrexed monotherapy (P) after failure of first-line EGFR-TKI. The primary objective was progression-free survival (PFS), and secondary objectives included overall response rate (ORR), overall survival (OS), health-related quality of life (HRQOL), and safety and toxicity profiles. Results A total of 96 patientswere randomized, and 91 patientswere treated at 14 centers in Korea. The ORR was 34.8% (16/46) for the PC arm and 17.8% (8/45) for the P arm (p=0.066). With 23.4 months of follow-up, the median PFS was 5.4 months in the PC arm and 6.4 months in the P arm (p=0.114). The median OS was 17.9 months and 15.7 months in PC and P arms, respectively (p=0.787). Adverse events ≥ grade 3 were reported in 12 patients (26.1%) in the PC arm and nine patients (20.0%) in the P arm (p=0.491). The overall time trends of HRQOL were not significantly different between the two arms. Conclusion The outcomes of pemetrexed therapy in NSCLC patients with disease progression after firstline EGFR-TKI might not be improved by adding cisplatin.