Biomedical subjects

Khê Hoang-Xuan

Publications and source records attributed to Khê Hoang-Xuan.

17 recordsLinked to original sources

PubMed2007

MGMT prognostic impact on glioblastoma is dependent on therapeutic modalities.

MGMT promoter methylation, which has been correlated with the response to alkylating agents, was investigated in a retrospective series of 219 glioblastomas (GBMs) treated with various modalities. MGMT methylation had no impact on survival for the whole group, but showed a significant advantage (17.1 months vs. 13.1) for patients treated with RT+ adjuvant chemotherapy (relative risk of death (RR) = 0.53; P = 0.041), particularly when patients received CT during the course of RT (MS = 19.9 months vs. 12.5 months; RR = 0.227, P = 0.001). This suggests that the prognostic impact of MGMT methylation is dependent on therapeutic modalities and schedules. MGMT methylation was not correlated with the main molecular alterations, such as 10q loss and p53 expression.

Adult↗

PubMed2006

MGMT methylation: a marker of response to temozolomide in low-grade gliomas.

The methylation status of the O6-methylguanine-methyltransferase promoter (MGMTP) was evaluated in 68 low-grade gliomas treated by neoadjuvant temozolomide. Methylated MGMTP was detected in 63 of 68 (92.6 %) patients and was a favorable predictor of progression-free survival as compared with unmethylated MGMTP tumors (p < 0.0001). Assessment of MGMTP status could help identifying low-grade gliomas patients more likely to respond to chemotherapy or to benefit from MGMT depletion strategies.

Adult↗

PubMed2005

A uniform activated B-cell-like immunophenotype might explain the poor prognosis of primary central nervous system lymphomas: analysis of 83 cases.

Most primary central nervous system lymphomas (PCNSLs) in immunocompetent patients are diffuse large B-cell lymphomas (DLBCLs), characterized by poor prognosis, compared with systemic forms. A germinal center B-cell-like (GCB) origin of PCNSL was hypothesized on the basis of BCL-6 expression and ongoing mutational activity. Our goal herein was to determine, for 83 PCNSLs, the percentages of GCB and activated B-cell-like (ABC) phenotypes and their prognostic significance. CD10, BCL-6, MUM1, BCL-2, and CD138 antigens were immunohistochemically labeled on paraffin-embedded sections; the first 4 were positive in 2.4%, 55.5%, 92.6%, and 55.5% of the tumors, respectively. None of the 56 tested samples expressed CD138. Among the 82 patients with complete information, 79 (96.3%) were classified as ABC; 42 (51.2%) expressed BCL-6+ MUM1+, suggesting an "activated GCB" origin; 33 (40.2%) were exclusively MUM1+, and the remaining 4 (4.9%) were negative for all markers tested. These findings provide new insights into interpreting the poor PCNSL prognostic, which may, in part, be due to biologic aggressiveness associated with its activated B-cell-like pattern. We postulate assigning PCNSL a histogenetic "time-slot," overlapping late GC and early post-GC, that could explain the predominant ABC phenotype observed.

Adult↗

PubMed2005

Chromosome 1p loss: a favorable prognostic factor in low-grade gliomas.

Search for loss of heterozygosity on chromosomes 1p, 9p, 10q, and 19q, epidermal growth factor receptor (EGFR) gene amplification, and p53 expression was performed in a series of 131 low-grade gliomas. The profile of molecular changes, clinical findings, and histology were subsequently correlated with the course of the disease, mainly progression-free survival. When these parameters were considered as candidate variables in a multivariate analysis, only loss of heterozygosity on chromosome 1p was associated with increased progression-free survival (hazard ratio, 0.521), indicating a major favorable prognostic role of this genetic alteration in low-grade gliomas.

Adolescent↗

PubMed2005

Two types of chromosome 1p losses with opposite significance in gliomas.

Deletion of the short arm of chromosome 1 (1p) is considered a favorable prognostic factor in glial tumors. High-density array-comparative genomic hybridization analysis of 108 gliomas shows two distinct types of 1p deletions. Complete hemizygous losses of 1p, which are tightly associated with 19q loss and oligodendroglial phenotype, and partial 1p deletions mainly observed in astrocytic tumors and not associated with 19q loss. Whereas the first type predicts longer overall and progression-free survival (p < 0.0001), the second type has a pejorative prognostic value. Complete 1p-arm evaluation therefore is required to appreciate the real clinical significance of 1p loss in gliomas.

Adult↗

PubMed2005

Leptomeningeal metastases from solid malignancy: a review.

Leptomeningeal metastases (LMM) consist of diffuse involvement of the leptomeninges by infiltrating cancer cells. In solid tumors, the most frequent primary sites are lung and breast cancers, two tumors where the incidence of LMM is apparently increasing. Careful neurological examination is required to demonstrate multifocal involvement of the central nervous system (CNS), cranial nerves, and spinal roots, which constitute the clinical hallmark of the disease. Cerebro-spinal fluid (CSF) analysis is almost always abnormal but only a positive cytology or demonstration of intrathecal synthesis of tumor markers is diagnostic. T1-weighted gadolinium-enhanced sequence of the entire neuraxis (brain and spine) plays an important role in supporting the diagnosis, demonstrating the involved sites and guiding treatment. Radionuclide CSF flow studies detect CSF compartmentalization and are useful for treatment planning. Standard therapy relies mainly on focal irradiation and intrathecal or systemic chemotherapy. Studies using other therapeutic approaches such as new biological or cytotoxic compounds are ongoing. The overall prognosis remains grim and quality of life should remain the priority when deciding which treatment option to apply. However, a sub-group of patients, tentatively defined here, may benefit from an aggressive treatment.

Breast Neoplasms↗

PubMed2005

New treatment approaches in primary central nervous system lymphoma.

A major advance in the treatment of primary central nervous system lymphoma (PCNSL) was made when the addition of chemotherapy to radiotherapy was shown to improve patient survival significantly. However, few chemotherapeutic agents are able to cross the blood-brain barrier. New therapeutic approaches in PCNSL are based on: the treatment of systemic non-Hodgkin's lymphomas with monoclonal antibodies and intensive chemotherapy followed by hematopoietic stem cell rescue, new chemotherapeutic agents with central nervous system penetration, or blood-brain barrier disruption to enhance drug delivery to the brain. This article discusses the rationale and results of these innovative approaches.

Blood-Brain Barrier↗

PubMed2005

[Towards a molecular classification of gliomas].

Several molecular genetic alterations have been characterized in gliomas in the past years. Molecular profiles have been associated with specific histologic and prognostic tumor subgroups, contributing to improve the classification of gliomas. At least two alternative molecular pathways have been suggested in the astrocytoma progression involving TP53 inactivation (secondary glioblastomas) and EGFR amplification (de novo glioblastomas) respectively. Oligodendroglial tumors have demonstrated recurrent combined loss of chromosome 1p/19q, which represent a favorable prognosis marker and probably a predictor of a good chemosensitivity of the tumor. This review discusses recent molecular advances and clinical implications with special focus on oligodendroglial tumors.

Astrocytoma↗

PubMed2004

Frequent epigenetic inactivation of RASSF1A and BLU genes located within the critical 3p21.3 region in gliomas.

RASSF1A is a major tumor suppressor gene located at 3p21.3. We investigated the role of aberrant promoter region hypermethylation of RASSF1A in a large series of adult gliomas. RASSF1A was frequently methylated in both primary tumors (36/63; 57%) and tumor cell lines (7/7; 100%). Hypermethylation of RASSF1A in glioma cell lines correlated with loss of expression and treatment with a demethylating agent-reactivated RASSF1A gene expression. Furthermore, re-expression of RASSF1A suppressed the growth of glioma cell line H4 in vitro. Next, we investigated whether other members of the RASSF gene family were also inactivated by methylation. NORE1B and RASSF3 were not methylated in gliomas, while NORE1A and RASSF5/AD037 demonstrated methylation in glioma cell lines but not in primary tumors. We then investigated the methylation status of three other candidate 3p21.3 tumor suppressor genes. CACNA2D2 and SEMA3B were not frequently methylated, but the BLU gene located just centromeric to RASSF1 was frequently methylated in glioma cell lines (7/7) and in 80% (35/44) of glioma tumors. In these tumor cell lines, BLU expression was restored after treatment with a demethylating agent. Loss of BLU gene expression in glioma tumors correlated with BLU methylation. There was no association between RASSF1A and BLU methylation. RASSF1A methylation increased with tumor grade, while BLU methylation was seen at similar frequencies in all grades. Our data implicate RASSF1A and BLU promoter methylation in the pathogenesis of adult gliomas, while other RASSF family members and CACNA2D2 and SEMA3B appear to have only minor roles. In addition, RASSF1A and BLU methylation appear to be independent and specific events and not due to region-wide changes in DNA methylation.

Adaptor Proteins, Signal Transducing↗

PubMed2004

Analysis of the bHLH transcription factors Olig1 and Olig2 in brain tumors.

In the absence of specific markers, the histological diagnosis of oligodendroglial tumors is based on subjective qualitative criteria and remains controversial. Recently, two bHLH transcription factors involved in oligodendroglial specification, Olig1 and Olig2 have been proposed as potential markers of oligodendrogliomas. Expression of Olig1/2 was analyzed by in situ hybridization on 78 samples including 47 glial, 29 non-glial tumors, and two non-tumoral brain tissues. Both genes had a similar pattern of expression. Olig1 and Olig2 were expressed in 26/30 (87%) and 28/30 (93%) of oligodendroglial tumors respectively but in only 9% of glioblastomas (1/11). Olig genes were also expressed in the low-grade fibrillary astrocytomas (4/4) and anaplastic astrocytomas (2/2). No expression was found in non-glial tumors, except for one primary cerebral lymphoma. Double staining with PLP, NFH, GFAP showed that olig genes were expressed by mature, non-tumoral oligodendrocytes, but not by normal astrocytes or neurones. This study indicates that Olig1/2 expression clearly distinguishes pure Olig-negative glioblastomas from a wide spectrum of Olig-positive tumors including traditional oligodendrogliomas and oligoastrocytomas, glioblastomas with an oligodendroglial component (GBMO), and WHO grade 2 and 3 astrocytomas. Because Olig genes have a crucial role in oligodendroglial determination, our data could be of help in defining the real spectrum of oligodendroglial tumors.

Astrocytes↗

PubMed2004

Molecular changes in gliomas.

PURPOSE OF REVIEW: Despite optimal clinical treatment, the prognosis for gliomas remains poor, and little progress has been observed during the last few years. Meanwhile, understanding of glioma oncogenesis has improved greatly. This review focuses on recent advances in molecular biology of glial tumors, with particular emphasis on lineage markers, genetic mechanisms underlying tumor progression, new diagnostic and prognostic markers, and potential therapeutic targets. RECENT FINDINGS: The question of the cell of origin, illustrated by the evidence of tumor-derived multipotent progenitors, by the animal models of gliomas, and by lineage markers such as Olig1/2 markers, remains unsolved. Genotype/phenotype correlation studies have identified early and late genetic alterations related either to astrocytic or oligodendroglial phenotype. They complement the existing World Health Organization morphologic classification and provide additional prognostic markers such as 1p/19q deletion in oligodendrogliomas. Most of these genetic alterations result in the disruption of three main cellular systems: RB1, P53, and tyrosine kinase receptor pathways. New gene alterations have also been identified in glioma, promoting mitotic signal transduction, cell cycle regulation, apoptosis, angiogenesis, or invasion. Gene and protein profiling has been correlated with outcome. SUMMARY: Management of gliomas, especially oligodendrogliomas with 1p19q deletion, benefits from advances in molecular genetics. A better understanding of the molecular pathogenesis and cellular lineage of gliomas will improve tumor classification and define more reliable prognostic markers. There is a hope that it will also lead to novel targets for therapy.

Antineoplastic Agents↗

PubMed2004

Recent advances in primary CNS lymphoma.

PURPOSE OF REVIEW: This review highlights the recent advances in the pathogenesis and treatment of primary CNS lymphoma (PCNSL) in the immunocompetent population. RECENT FINDINGS: High-dose methotrexate (MTX)-based chemotherapy followed by whole brain radiotherapy represents the standard treatment. However, combined treatment exposes the patients to the risk of delayed neurotoxicity. Although this complication is less frequent and severe in young patients (less than 60 years) than in the elderly, neuropsychometric evaluation suggests that it is underestimated in this population. Recent trials, adding further to previous studies, suggest that high-dose MTX-based chemotherapy with deferred radiotherapy allows comparable results to those reported after combined chemoradiotherapy, with much better neurocognitive preservation. Intensive chemotherapy with autologous stem cell transplantation has shown a promising activity in relapsed or refractory PCNSL, but its value as first-line treatment compared with conventional treatment remains questionable. New therapeutic agents such as temozolomide, topotecan, or intrathecal rituximab (anti-CD20 monoclonal antibody) have demonstrated a modest but true activity as single-agent therapy in relapsed PCNSL and are of interest, in terms of their good safety profile, for inclusion in new polychemotherapy regimen as primary treatment. SUMMARY: In the elderly, MTX-based chemotherapy seems to be the best approach to achieve effective tumor control without compromising patient quality of life. Future trials should first analyze the value of radiotherapy as consolidation treatment in young patients (less than 60 years) who have achieved a remission after induction chemotherapy in a randomized study. Other trials are needed to further evaluate intensive chemotherapy with autologous stem cell transplantation both as primary and salvage therapy; and to investigate new drug combinations with high-dose MTX.

Antimetabolites, Antineoplastic↗

PubMed2004

[Results of intensive chemotherapy followed by hematopoietic stem-cell rescue in 22 patients with refractory or recurrent primary CNS lymphoma or intraocular lymphoma].

Rescue therapies for relapsing/refractory primary central nervous system lymphoma (PCNSL) and intraocular lymphoma (IOL) remain a challenging problem for clinicians. In 2001, we published encouraging results for 22 patients treated at relapse with a CYVE regimen combining high doses of Ara-C (50 mg/m(2)/d in 12 hours infusion dl through d5; 2 g/m(2)/d d2 through d5) and VP16 (200 mg/m(2)/d d2 through d5), followed by intensive chemotherapy based on high doses of thiotepa (250 mg/m(2)/d d-9 through d-7), busulfan (10 mg/kg total dose d-6 through d-4) and cyclophosphamide (60 mg/kg/d, d-3 and d-2 with hematopoietic cell rescue at d0. Patients were enrolled onto the study for a relapse (n = 10; 2 IOL, 3 CSF, 5 brain lesion) or for a refractory disease (n = 12; 9 IOL, 3 brain lesion). CYVE rescue was not administered to patients with refractory IOL who had previously received high doses of methotrexate and Ara-C as part of their first-line treatment. Twenty patients received the intensive chemotherapy and hematopoietic cells rescue. We updated our results in March 2003. Seven patients had neurologic adverse events during the entire procedure. With a median follow up of 6.2 years, the median overall survival is 91 months, and the median survival after intensive chemotherapy has not been reached.

Adult↗

PubMed2003

Radiotherapy and chemotherapy with or without carbogen and nicotinamide in inoperable biopsy-proven glioblastoma multiforme.

BACKGROUND: Nicotinamide and carbogen have been shown to enhance the radiation effect in tumour models. PURPOSE: Prospective evaluation of the toxicity and efficacy of carbogen and nicotinamide with external beam radiotherapy in the management of inoperable glioblastoma. PATIENTS AND METHODS: From April 1995 to December 1997, 33 patients with inoperable biopsy-proven glioblastoma multiforme (GBM) were enrolled in a phase II trial, to undergo radiotherapy (59.4 Gy in 1.8 Gy/fraction), intra-arterial cerebral chemotherapy (ACNU 100 mg/m(2), three cycles), carbogen breathing (15 l/min), and nicotinamide (85 mg/kg). This experimental group was compared to a control group of 38 patients with inoperable GBM treated with radiotherapy and three cycles of nitrosourea-based chemotherapy from January 1990 to March 1995, in our institution. RESULTS: In the experimental group, carbogen breathing was well tolerated, but only 51.5% of patients completed daily nicotinamide over the 6.5-week treatment period. Nausea and vomiting were the most frequent side effects of nicotinamide. No significant difference in overall survival was observed among the two treatment groups: median survival times were 36.7 and 35.3 weeks for patients treated with carbogen and nicotinamide, and for those treated in the control group, respectively. CONCLUSION: The association of carbogen and nicotinamide with radiotherapy is feasible, but tolerable only in 51.5% of patients with GBM. Carbogen and nicotinamide did not appear to modify the evolution of glioblastoma.

Adult↗

PubMed2003

Treatment of primary central nervous system lymphoma in the elderly.

Although the incidence of primary central nervous system lymphoma has recently declined among people with acquired immunodeficiency syndrome, the incidence of primary central nervous system lymphoma remains high among the immunocompetent population >/=60 years of age. Elderly patients represent an important subgroup that accounts for approximately half of primary central nervous system lymphoma cases. Radiotherapy (RT) alone has produced disappointing results in the elderly. Improved clinical outcomes have been achieved with high-dose methotrexate-based chemotherapy regimens in combination with whole-brain RT. Unfortunately, combination therapy exposes elderly patients to a high risk of severe delayed neurotoxicity in up to 80%. Chemotherapy alone may be the best approach for treating elderly patients and appears to be more effective than RT, while considerably reducing the risk of neurotoxicity. Clinical studies are needed to define the optimal chemotherapy regimen for the elderly in an effort to delay or completely avoid the need for RT.

Age Factors↗

PubMed2002

Preferential loss of paternal 19q, but not 1p, alleles in oligodendrogliomas.

Portions of chromosomes 1p and 19q, which are frequently deleted in oligodendrogliomas, are subject to genomic imprinting, suggesting that the putative tumor suppressor genes could be monoallelically expressed. The parental origins of 1p and 19q allele losses were determined in 6 cases of pure oligodendroglioma. An equilibrated parental loss (3 maternal and 3 paternal) was found for 1p deletions. In contrast, 19q deletions always occurred on the paternal copy (p = 0.015). In this setting, a cloning strategy based on a search for homozygous deletion or mutation of the remaining allele would be appropriate for identifying the tumor suppressor gene located on 1p but inappropriate for identifying the presumably monoallelically expressed tumor suppressor gene located on 19q.

Alleles↗

PubMed2002

Analysis of loss of chromosome 10q, DMBT1 homozygous deletions, and PTEN mutations in oligodendrogliomas.

OBJECT: Chromosomal deletions of 10q and candidate genes such as PTEN and DMBT1 have been thoroughly investigated in glioblastomas but few data specifically address oligodendrogliomas. METHODS: In this study, 39 pure oligodendrogliomas were investigated for loss of heterozygosity (LOH) on 10q, PTEN mutations, and DMBT1 homozygous deletions. The LOH on 10q was found in 19 (48%) of 39 oligodendrogliomas and was closely related to anaplasia (p = 0.02), shorter time to progression (p = 0.0005), and poorer survival (p = 0.035). The DMBT1 homozygous deletions were found in 10 (26%) of 39 oligodendrogliomas but only one PTEN mutation was detected. The LOH on 10q is a strong predictor of survival and could be a valuable prognostic marker in oligodendrogliomas. CONCLUSIONS: Frequent inactivation of DMBT1 contrasting with rare mutations of PTEN may indicate that DMBT1 is preferentially involved in oligodendrogliomas. Nevertheless, the absence of a correlation with survival makes the role of DMBT1 in tumorigenesis still questionable and warrants further investigation.

Agglutinins↗