Biomedical subjects

N Papadopoulos

Publications and source records attributed to N Papadopoulos.

At least 109 records · Page 6Linked to original sources

PubMed1997

Phase II trial of tirapazamine combined with cisplatin in chemotherapy of advanced malignant melanoma.

PURPOSE: A phase II study was undertaken to determine the efficacy of tirapazamine (TPZ) combined with cisplatin (cDDP) in patients with metastatic melanoma. PATIENTS AND METHODS: Between June 1994 and November 1995, 48 patients with metastatic melanoma were treated with TPZ (260 mg/m2, administered intravenously over two hours) followed in one-hour by cDDP (75 mg/m2 over one hour) every 21 days. Sixteen patients had received prior chemotherapy, and 13 of these had failed to respond to prior cDDP. None of the patients had symptomatic brain metastasis. RESULTS: Nine patients had partial responses, with an overall response rate of 19% (95% confidence interval (95% CI) of 9%-33%). The median duration of response was six months. None of the responders had received prior chemotherapy. Responses were seen in 8 (33%, confidence interval of 16%-55%) of 24 patients with primary cutaneous melanoma who had received no prior chemotherapy and in the only patient with previously untreated conjunctival melanoma. There were no responders among the seven patients with choroidal melanoma and 16 patients with previously treated cutaneous melanoma. Two patients with partial responses were rendered free of gross disease surgically three months after completing eight courses of TPZ-cDDP; they remain free of tumor recurrence. Responses were seen in lymph nodes (27%), lung (26%), skin (20%), adrenal gland (20%), soft tissues (17%) and liver (17%). Common toxicities included muscle cramps, fatigue, gastrointestinal effects and peripheral neuropathy. Fatigue, nausea, vomiting, anorexia, and muscle cramps were grade 3 or 4 in less than 10% of the courses. Neutropenia and thrombocytopenia were rare. CONCLUSION: The TPZ-cDDP combination has definite activity against chemotherapy-naïve patients with cutaneous melanoma and warrant further studies in combination with other cytotoxic agents.

Adult↗

PubMed1997

Critical analysis of the current American Joint Committee on Cancer staging system for cutaneous melanoma and proposal of a new staging system.

PURPOSE: To critically review the accuracy of the current American Joint Committee on Cancer (AJCC) staging system for cutaneous melanoma and propose a more useful staging system. METHODS: Retrospective evaluation of the published data as well as a reanalysis of the University of Alabama and Sydney Melanoma Unit (UAB/SMU) data bases (n = 4,568) for patients with primary melanoma was performed to examine specifically the impact of level of invasion and ulceration on the prognostic value of tumor thickness. In addition, an overlay graphic technique was used to compare the Kaplan-Meier survival curves of patients with local recurrences, satellites, in-transit metastases, and nodal metastases reported in the literature. RESULTS: Tumor thickness and ulceration remained the most powerful prognostic indicators in patients with stage I and II disease. Level of invasion provided statistically significant prognostic information only in the subgroup of patients with tumor thickness < or = 1 mm, but the absolute 10-year survival differences were small and inconsistent (level II, 95%; level III, 85%; level IV, 89%). The best statistical fit for tumor thickness cutoffs was at 1 versus 2 versus 4 mm. The overlay graphic technique showed that patients who developed satellite lesions or local recurrence had prognoses similar to those of patients with stage III disease. The most important prognostic factor for patients with nodal metastases was number of involved nodes rather than size. CONCLUSION: Our analysis showed that the current AJCC staging system has many inaccuracies that should be modified to conform to published data. On the basis of our analysis and review of the literature, we propose a new and more accurate staging system.

Humans↗

PubMed1997

Development and results of biochemotherapy in metastatic melanoma: the University of Texas M.D. Anderson Cancer Center experience.

PURPOSE: Systemic therapy for metastatic melanoma includes chemotherapy, either with dacarbazine alone or a multiagent combination regimen, and biologic therapy with recombinant interferon-alpha and/or recombinant interleukin-2. However, neither of these treatment options has produced long-term control of disease except on rare occasions. We have therefore developed a combined biochemotherapy program in an effort to improve long-term control of metastatic melanoma. PATIENTS AND METHODS: Between October 1990 and October 1993, we treated 115 patients with a triple-drug chemotherapy regimen--CVD (cisplatin, vinblastine, dacarbazine)--in combination with biotherapy using recombinant interleukin-2 and recombinant interferon-alpha. This program of biochemotherapy has evolved from an initial protocol of sequential use of CVD followed by biotherapy, called sequential biochemotherapy, to a more recent protocol of concurrent administration of all five drugs, called concurrent biochemotherapy. Sixty-two patients have been treated with the sequential regimen and 53 patients with the concurrent regimen. RESULTS: Among the 114 evaluable patients, we have observed 24 complete responses (21%) and 45 partial responses (39%) for an overall response rate of 60%. From the group of 24 complete responders, 12 patients (10% of the total) have achieved long-term remissions and have remained disease free for periods of time ranging from 4+ to 6+ years. CONCLUSION: Although the overall results of sequential versus concurrent biochemotherapy are similar, the toxicity appears to be less severe in patients treated with the concurrent regimen. The overall median survival of patients treated with biochemotherapy appears to be longer compared with our previous experience with CVD chemotherapy used alone (12 vs 9 months). Based on the encouraging results obtained with biochemotherapy, phase III studies have been initiated to compare prospectively biochemotherapy with chemotherapy (CVD regimen) alone.

Adolescent↗

PubMed1996

APC mutations in colorectal tumors with mismatch repair deficiency.

We have investigated the influence of genetic instability [replication error (RER) phenotype] on APC (adenomatous polyposis coli), a gene thought to initiate colorectal tumorigenesis. The prevalence of APC mutations was similar in RER and non-RER tumors, indicating that both tumor types share this step in neoplastic transformation. However, in a total of 101 sequenced mutations, we noted a substantial excess of APC frameshift mutations in the RER cases (70% in RER tumors versus 47% in non-RER tumors, P < 0.04). These frameshifts were characteristic of mutations arising in cells deficient in DNA mismatch repair, with a predilection for mononucleotide repeats in the RER tumors (P < 0.0002), particularly (A)n tracts (P < 0.00007). These findings suggest that the genetic instability that is reflected by the RER phenotype precedes, and is responsible for, APC mutation in RER large bowel tumors and have important implications for understanding the very earliest stages of neoplasia in patients with tumors deficient in mismatch repair.

Adenomatous Polyposis Coli↗

PubMed1996

Analysis of mismatch repair genes in hereditary non-polyposis colorectal cancer patients.

Hereditary non-polyposis colorectal cancer (HNPCC) is an autosomal dominant disorder characterized by the early onset of colorectal cancer and linked to germline defects in at least four mismatch repair genes. Although much has been learned about the molecular pathogenesis of this disease, questions related to effective presymptomatic diagnosis are largely unanswered because of its genetic complexity. In this study, we evaluated tumors from 74 HNPCC kindreds for genomic instability characteristic of a mismatch repair deficiency and found such instability in 92% of the kindreds. The entire coding regions of the five known human mismatch repair genes were evaluated in 48 kindreds with instability, and mutations were identified in 70%. This study demonstrates that a combination of techniques can be used to genetically diagnose tumor susceptibility in the majority of HNPCC kindreds and lays the foundation for genetic testing of this relatively common disease.

Base Sequence↗

PubMed1996

Treatment of metastatic melanoma with combined chemotherapy containing cisplatin, vinblastine and dacarbazine (CVD) and biotherapy using interleukin-2 and interferon-alpha.

BACKGROUND: Metastatic melanoma is commonly treated with chemotherapy and/or biological agents used separately. In this study we have investigated the efficacy of combined chemotherapy using cisplatin, vinblastine, DTIC (CVD) and biological therapy using interleukin-2 (IL-2) and interferon-alpha (IFN-alpha) in patients with metastatic melanoma. PATIENTS AND METHODS: All patients had advanced, inoperable melanoma without prior treatment with chemotherapy or biotherapy, a performance status of ECOG 0-2 and no evidence of symptomatic brain metastases. The CVD regimen consisted of cisplatin 20 mg/m2/d x 4, vinblastine 1.6 mg/m2/d x 5 and DTIC 800 mg/m2 x 1, repeated at 21-day intervals. The biotherapy regimen included IL-2, 9 x 10(6) IU/ m2/d x 4 days and IFN-alpha 5 x 10(6) U/m2/d SC x 5 days. The CVD and biotherapy regimens were integrated initially, in an alternating manner at 6-week intervals and subsequently, in a sequential fashion where patients were randomized to receive either CVD immediately followed by biotherapy (CVD/Bio) or the reverse sequence (Bio/CVD). Patients were admitted to the hospital for IL-2 administration and for monitoring and treatment of IL-2 induced side effects. The phase II results of the integrated therapy (biochemotherapy) studies were retrospectively compared to our previously reported results with the CVD regimen used alone. RESULTS: The alternating biochemotherapy program was used in 40 patients and the sequential biochemotherapy was used in 62 patients. The alternating regimen produced 2 CRs and 11 PRs for an overall response rate of 33% among 39 evaluable patients. The sequential biochemotherapy produced 14 CRs and 23 PRs for an overall response rate of 60% (95% CI, 47% to 72%). The sequence of CVD/Bio resulted in a higher response rate (11 CRs + 11 PRs (69%)) compared to the Bio/CVD sequence (3 CRs + 12 PRs (50%)). Although the duration of PRs was short (median, 8 months), the median duration of CRs was 3+years and 10 of 16 CRs are currently disease free for periods of 3+ to 6+ years. The median survival of patients receiving sequential biochemotherapy was 13 months compared to 9 months for the CVD treated group (P = 0.04). Treatment with biochemotherapy was associated with severe toxicity including intense myelosuppression, infections, IL-2 induced constitutional toxicity and hypotension. However, the IL-2 induced toxicities were generally manageable on a regular ward, except for 15% of the patients who required transfer to an intensive care unit for treatment of complications associated with the treatment. CONCLUSIONS: The sequential combination of CVD with IL-2 + IFN-alpha appears to have produced an increase in the number of durable responses in patients with metastatic melanoma. The toxicity of this program, although severe, was manageable. The biochemotherapy regimen produced an apparent increase in the median survival compared to that observed with the CVD regimen. However, a prospective comparison of these two regimens will be required to confirm these observations.

Adult↗

PubMed1996

DNA measurement in pituitary adenomas assessed on imprints by image analysis.

OBJECTIVE: To determine the DNA content and S-phase fraction (SPF) of pituitary adenomas by image analysis and to correlate them with clinical and morphologic parameters. STUDY DESIGN: The study group consisted of 26 prospectively collected cases of operated pituitary adenomas (3 microadenomas and 23 macroadenomas). The tumors were classified by histology, immunocytochemistry and electron microscopy. DNA measurement was performed on imprints from fresh pituitary tissue. Samples of nontumorous adenohypophysial parenchyma served as normal controls. RESULTS: Overall, 31% of adenomas, all but one functioning one, were aneuploid. The remaining nonfunctioning aneuploid tumor was a null cell adenoma with glycoprotein differentiation. All aneuploid tumors were macroadenomas, mostly at advanced stages, III and IV. Dural invasion, although frequent in macroadenomas (78%), was not correlated with DNA ploidy and SPF. An increased number of hyperpentaploid aneuploid cells was noted primarily in aneuploid tumors. The mean SPF was < 2.50%, with a statistically significant difference between aneuploid and diploid adenomas (3.60% vs. 1.70%). CONCLUSION: The results suggest that quantitative assessment of DNA content may provide important information, particularly in functioning adenomas. In addition, fresh tissue imprints represent excellent material for optimum cytometric measurements by image analysis systems, even for microadenomas.

Adenoma↗

PubMed1995

Genomic organization of the human PMS2 gene family.

The hPMS2 gene (HGMW-approved symbol PMS2) encodes a mutL homolog that causes hereditary non-polyposis colon cancer (HNPCC) when inherited in mutant form. We have here characterized the genomic structure of the hPMS2 gene to facilitate its analysis in HNPCC kindreds. The hPMS2 genomic locus was found to encompass 16 kb and consist of 15 exons. During its analysis, we identified a family of hPMS2-related genes located on chromosome 7 at bands 7p12-p13, 7q11, and 7q22. Exons 1 through 5 of these homologs shared a high degree of identity with hPMS2. We present the sequence of seven novel genes that represent the hPMSR (hPMS2-related) gene family. The similarity and number of these genes made specific amplification of hPMS2 problematic, but knowledge of them aided the successful design of oligonucleotides for this purpose.

Adenosine Triphosphatases↗

PubMed1995

Treatment of uveal melanoma metastatic to the liver: a review of the M. D. Anderson Cancer Center experience and prognostic factors.

BACKGROUND: Liver metastasis develops in approximately two-thirds of patients with recurrent uveal melanoma. Despite therapy, the median survival of those with liver metastasis is 5 to 7 months. The recognition of a grave prognosis associated with liver metastasis has led to evaluation of new modalities of therapy, including the use of regional therapies such as intrahepatic arterial chemotherapy and either embolization or chemoembolization of hepatic metastases. In this study, the results of an institutional experience over the past 2 decades are reviewed and prognostic factors that affect survival from the time the liver metastasis is diagnosed are assessed. METHODS: In this study of 201 patients with uveal melanoma involving the liver who were treated at M. D. Anderson Cancer Center between 1968 and 1991, the authors restrospectively reviewed the cases and compared the results of systemic therapies, hepatic intra-arterial chemotherapies, and chemoembolization of liver metastases. Cox's multivariate analysis and stepwise logistic regression were then computed to determine significant prognostic variables. RESULTS: The systemic therapies produced a response rate of less than 1%. Chemoembolization was the most effective treatment, inducing responses in 36% of patients. Survival curves were calculated using the life-table method of Kaplan and Meier. Patient- and tumor-related characteristics were examined and their relation to on survival from the time of diagnosis of liver metastasis was determined. Levels of serum alkaline phosphatase, total bilirubin, and lactic dehydrogenase plus response to treatment showed a strong relation to survival. In contrast, univariate analysis showed that patient age and gender, metastasis free interval, presence of extrahepatic metastasis, and type of therapy for liver metastasis did not influence survival. Multivariate stepwise regression analysis identified serum alkaline phosphatase and metastasis free interval as the main independent prognostic factors for survival after liver metastasis diagnosis. CONCLUSIONS: Of the three modalities of therapy used for choroidal melanoma metastatic to the liver, only chemoembolization using cisplatin-based regimens produced a meaningful response rate. Information from this analysis can be used to predict the outcome of patients with uveal melanoma metastatic to the liver. Patients with metastatic ocular melanoma confined to the liver should be treated with chemoembolization and should not be included in chemotherapy trials designed for cutaneous melanoma.

Adult↗

PubMed1995

Mutations of GTBP in genetically unstable cells.

The molecular defects responsible for tumor cell hypermutability in humans have not yet been fully identified. Here the gene encoding a G/T mismatch-binding protein (GTBP) was localized to within 1 megabase of the related hMSH2 gene on chromosome 2 and was found to be inactivated in three hypermutable cell lines. Unlike cells defective in other mismatch repair genes, which display widespread alterations in mononucleotide, dinucleotide, and other simple repeated sequences, the GTBP-deficient cells showed alterations primarily in mononucleotide tracts. These results suggest that GTBP is important for maintaining the integrity of the human genome and document molecular defects accounting for variation in mutator phenotype.

Base Sequence↗

PubMed1995

The molecular basis of Turcot's syndrome.

BACKGROUND: Turcot's syndrome is characterized clinically by the concurrence of a primary brain tumor and multiple colorectal adenomas. We attempted to define the syndrome at the molecular level. METHODS: Fourteen families with Turcot's syndrome identified in two registries and the family originally described by Turcot and colleagues were studied. Germ-line mutations in the adenomatous polyposis coli (APC) gene characteristic of familial adenomatous polyposis were evaluated, as well as DNA replication errors and germline mutations in nucleotide mismatch-repair genes characteristic of hereditary nonpolyposis colorectal cancer. In addition, a formal risk analysis for brain tumors in familial adenomatous polyposis was performed with a registry data base. RESULTS: Genetic abnormalities were identified in 13 of the 14 registry families. Germ-line APC mutations were detected in 10. The predominant brain tumor in these 10 families was medulloblastoma (11 of 14 patients, or 79 percent), and the relative risk of cerebellar medulloblastoma in patients with familial adenomatous polyposis was 92 times that in the general population (95 percent confidence interval, 29 to 269; P < 0.001). In contrast, the type of brain tumor in the other four families was glioblastoma multiforme. The glioblastomas and colorectal tumors in three of these families and in the original family studied by Turcot had replication errors characteristic of hereditary nonpolyposis colorectal cancer. In addition, germ-line mutations in the mismatch-repair genes hMLH1 or hPMS2 were found in two families. CONCLUSIONS: The association between brain tumors and multiple colorectal adenomas can result from two distinct types of germ-line defects: mutation of the APC gene or mutation of a mismatch-repair gene. Molecular diagnosis may contribute to the appropriate care of affected patients.

Adenomatous Polyposis Coli↗

PubMed1995

Assignment of the human p27Kip1 gene to 12p13 and its analysis in leukemias.

The p27Kip1 (p27) gene encodes an inducible inhibitor of cyclin-dependent kinase activity. Using a murine p27 cDNA as probe, we obtained a human cDNA clone and subsequently used it to isolate a genomic clone of this gene. The coding region of the human p27 gene was contained in two exons. Both the amino acid sequence and intron-exon organization of p27 were similar to those previously found for the related cyclin-dependent kinase inhibitor p21Waf1 (p21). The p27 gene was localized to chromosome band 12p13 by a combination of somatic cell hybrid and fluorescence in situ hybridization analyses. The p27 gene product is thought to control the leukocyte cell cycle and the 12p13 chromosomal band is known to be deleted in leukemias, suggesting that the p27 gene may act as a tumor suppressor gene in leukemias. Although p27 was found to reside in the minimal region of chromosomal loss in hematological malignancies, no mutations of p27 were observed in leukemia samples. Haploinsufficiency of p27 may confer a growth advantage to leukemia cells.

Base Sequence↗

PubMed1995

Common occurrence of APC and K-ras gene mutations in the spectrum of colitis-associated neoplasias.

BACKGROUND/AIMS: Chronic colitis is associated with an increased risk of colorectal neoplasia, creating a need for early diagnosis in this population. Little is yet known of the genetic changes of early lesions. Cases of colitis-associated neoplasia were analyzed for APC and K-ras mutations with special emphasis given to the spectrum of noninvasive lesions. METHODS: Ten patients were studied. APC mutations were screened by an in vitro synthesized protein assay, and K-ras mutations were screened by a ligation assay. RESULTS: APC mutations were found in 5 patients, including dysplasias. K-ras mutations were present in 5 patients and in all classes of lesions, including 5 of 14 lesions indefinite for dysplasia. In only 2 patients were no mutations found. CONCLUSIONS: Mutations of APC and K-ras are common in colitis-associated neoplasia and can occur early in neoplastic progression. Serrated lesions and lesions indefinite for dysplasia may harbor genetic changes and thus are clonal, highlighting the importance of distinguishing them histologically. Assays for APC and K-ras mutations are promising as adjuncts to surveillance programs. Care will be needed in their application because the confident diagnosis of early lesions presumed to be of lesser clinical importance will raise new issues concerning prudent patient management.

Adult↗

PubMed1995

Monoallelic mutation analysis (MAMA) for identifying germline mutations.

Dissection of germline mutations in a sensitive and specific manner presents a continuing challenge. In dominantly inherited diseases, mutations occur in only one allele and are often masked by the normal allele. Here we report the development of a sensitive and specific diagnostic strategy based on somatic cell hybridization termed MAMA (monoallelic mutation analysis). We have demonstrated the utility of this strategy in two different hereditary colorectal cancer syndromes, one caused by a defective tumour suppressor gene on chromosome 5 (familial adenomatous polyposis, FAP) and the other caused by a defective mismatch repair gene on chromosome 2 (hereditary non-polyposis colorectal cancer, HNPCC).

Alleles↗

PubMed1995

Genetic instability occurs in the majority of young patients with colorectal cancer.

Replication errors (RER) associated with genetic instability have been found in cancers of several different types and particularly in the tumours of patients with hereditary non-polyposis colorectal cancer (HNPCC). We have here determined the prevalence of such instability in relation to age among patients without HNPCC. Colorectal cancers (CRCs) in the majority of patients 35 years of age or younger exhibited instability (58% of 31 patients), whereas CRCs from patients older than 35 uncommonly did (12% of 158, p < 0.0001). Twelve of the patients under 35 with instability were evaluated for alterations of mismatch repair genes, and five were found to harbour germline mutations. These data suggest that the mechanisms underlying tumour development in young CRC patients differ from those in most older patients, regardless of HNPCC status. The results have important implications for genetic testing and management of young CRC patients and their families.

Adult↗

PubMed1995

Introduction to positional cloning.

The most common procedure for isolating genes that predispose to a certain disease is positional cloning. This process is initiated by mapping the responsible gene to its location on a chromosome linked to the disease. Successive cloning of the region results in the isolation of candidate genes. Finally, identification of mutations by mutational analysis points to the correct gene.

Chromosome Mapping↗

PubMed1994

Deletion of p16 and p15 genes in brain tumors.

We have used molecular genetic methods to examine the status of cell cycle-inhibitory genes in human brain tumors. We found that p16 and a neighboring gene, p15, were often homozygously deleted in glioblastoma multiformes but not in medulloblastomas or ependymomas. The deletions occurred in both primary tumors and their derived xenografts, but no intragenic mutations in either of the two genes were found. The p15 gene was expressed in a more widespread pattern in normal tissues than p16, but the products of both genes had similar capacities to bind to cyclin D-dependent kinases 4 and 6. These data suggest that the target of deletion in glioblastoma multiforme includes both p15 and p16 genes. The reason that homozygous deletions, rather than intragenic mutations, are so common in these tumors may be that deletion is a more efficient mechanism for simultaneous inactivation of both genes.

Animals↗

PubMed1994

Molecular determinants of dysplasia in colorectal lesions.

One hallmark of malignant potential is dysplasia, the disruption of normal morphology. While it is generally recognized that cancer is the result of a series of genetic changes, the relationship of these alterations and their timing to the advent of dysplasia remains obscure. To address this issue, 54 small benign colorectal lesions of various malignant potential were analyzed for APC and K-RAS mutations, two alterations which have been implicated in the early stages of colorectal tumorigenesis. APC mutations were closely associated with dysplasia. In contrast, K-RAS mutations were found to be remarkably common in small nondysplastic lesions which apparently have a limited potential to progress to larger tumors. These results provide evidence that the nature and order of genetic changes can have a specific impact on both tumor morphology (e.g., dysplasia) and the likelihood of tumor progression.

Base Sequence↗