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Biomedical subjects

P A Bunn

Publications and source records attributed to P A Bunn.

At least 19 recordsLinked to original sources
PubMed1997

Overview of chemotherapy for small cell lung cancer.

Small cell lung cancer (SCLC) accounts for 20% to 25% of all lung cancer cases in developing countries. The incidence of and mortality from SCLC continues to increase in these countries, especially in females. Small cell lung cancer is different from other lung cancer histologic types in that it has neuroendocrine features, grows more rapidly, spreads earlier, is more responsive to chemotherapy and radiotherapy, and has a lower cure rate. Because of the propensity to metastasize early, the lack of screening modalities, and the sensitivity to chemotherapy, the cornerstone of treatment is combination chemotherapy, which is indicated in all SCLC patients able to tolerate any therapy. Patients with extensive-stage SCLC generally receive combination chemotherapy alone. Most patients with limited-stage SCLC should be treated with combined modality therapy consisting of chemotherapy and chest radiotherapy. In the rare patient with stage I SCLC and no involved lymph nodes, surgical resection with chemotherapy provides a high rate of long-term survival. Several combinations are used routinely, including the two-drug combination of etoposide with cisplatin or carboplatin, which is used most frequently in the United States. There is no proven role for any type of maintenance therapy, for intensive chemotherapy, or for biological therapies. There have been no major advances in therapy in the last decade, although the recent advent of new active agents, including gemcitabine, provides hope for more effective therapies in future years. This report will review the past literature on SCLC therapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1997

Systemic investigational therapies as adjuvants to surgery in patients with operable lung cancer.

Early resection of lung cancers confined to the chest remains the best means of curing patients. Nonetheless, cure rates for resected patients are less than 50% overall, primarily due to the presence of occult distant metastases at the time of resection that subsequently manifest as relapse at distant sites. In approximately 20% of patients, local failure occurs within the chest. Chest radiotherapy reduces and nearly eliminates local failure, but does not improve survival or cure rates. Effective systemic chemotherapy is the cornerstone to improving survival and cure rates for early stage lung cancer. Recent studies showed that the preoperative use of cisplatin-based chemotherapy improved survival and 3-year disease-free survival in stage IIIA non-small cell lung cancer. New drugs such as paclitaxel and gemcitabine appear to improve survival in stages IIIB and IV non-small cell lung cancer. These agents will be tested in the surgical setting in the near future.

Carcinoma, Small Cell↗
PubMed1996

Paclitaxel enhances in vitro radiosensitivity of squamous carcinoma cell lines of the head and neck.

Squamous cell carcinoma of the head and neck is the fourth most common cancer in the United States, and therapy for very advanced cases is relatively ineffective. Paclitaxel has activity against cancers of the breast, lung, prostate, cervix, and ovary. The activity of paclitaxel for squamous cell carcinoma of the head and neck is less certain, and results of its radiosensitization properties have been variable. The radiation responses of two squamous carcinomas, SCC-9 (oropharynx) and HEP-2 (larynx), were examined to determine the radiosensitizing potential of paclitaxel. In vitro exposures for 24 and 48 h with paclitaxel concentrations of 10(-4) to 6 x 10(-2) microg/ml were followed by irradiation of 0.1-10 Gy. Percent survival was calculated by colony count, and the paclitaxel-radiation interaction was quantitated by the median effect principle and the combination index method of Chou and Talalay. The paclitaxel-radiation combination resulted in multiphasic interactions in both 24 and 48 h paclitaxel pretreatment in SCC-9 and HEP-2 cell lines. In general there was slight synergism [combination index (CI) <1] at low dose-low effect levels (e.g., at a paclitaxel concentration of 0.002 microg/ml or lower and radiation of 0.1-0.3 Gy), moderate antagonism (CI >1) at median dose ranges and strong synergism (CI <<1) at high dose ranges (e.g., at a paclitaxel concentration of 0.012-0.06 microg/ml and radiation doses of 3-10 Gy), especially at a surviving fraction of <0.1, which is therapeutically relevant. The median effect principle and combination index method provided a simple way to quantitate the synergism or antagonism of a paclitaxel-radiation interaction under various conditions. This analysis demonstrated that paclitaxel-radiation synergy exists at doses that are readily achievable in the clinical scenario for both agents and that greater synergy occurred at high dose-high effect levels. These results suggest that the combination of both therapies should be explored further in clinical trials assessing the treatment of squamous cell carcinomas of the head and neck.

Antineoplastic Agents, Phytogenic↗
PubMed1996

Neutral endopeptidase: variable expression in human lung, inactivation in lung cancer, and modulation of peptide-induced calcium flux.

Neutral endopeptidase (NEP; CALLA, CD10, EC 3.4.24.11) is a cell surface endopeptidase that hydrolyses bioactive peptides, including the bombesin-like peptides, as well as other neuropeptides. Bombesin-like peptides and other neuropeptides are autocrine growth factors for both small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). Low expression of NEP has been reported in SCLC and NSCLC cell lines. NEP inhibition has been shown to increase proliferation in one cell line. To date, NEP expression has not been quantitatively evaluated in normal adult lung, SCLC or NSCLC tumors, paired uninvolved lung from the same patient, or in other pulmonary neoplasms such as mesotheliomas and carcinoids. We examined the expression of NEP in these tissues and human cell lines using immunohistochemistry, flow cytometry, enzyme activity, ELISA, Western blot, and reverse transcription (RT)-PCR. Uninvolved lung tissue from different individuals displayed considerable variation in NEP activity and protein. By immunohistochemistry, NEP expression was detectable in alveolar and airway epithelium, fibroblasts of normal lung, and in mesotheliomas, whereas it was undetectable in most SCLC, adenocarcinoma, squamous cell carcinoma, and carcinoid tumors of the lung. NEP activity and protein levels were lower in all SCLC and adenocarcinoma tumors when compared to adjacent uninvolved lung, often at levels consistent with expression derived from contaminating stroma. NEP expression and activity were reduced or undetectable in most SCLC and lung adenocarcinoma cell lines. NEP mRNA by RT-PCR was not expressed or was in low abundance in the majority of lung cancer cell lines. The majority of lung tumors did not express NEP by RT-PCR as compared with normal adjacent lung. In addition, recombinant NEP abolished, whereas an NEP inhibitor potentiated, the calcium flux generated by neuropeptides in some lung cancer cell lines, demonstrating potential physiological significance for low NEP expression. NEP, therefore, is a signal transduction and possibly a growth modulator for both SCLC and NSCLC, emphasizing the role of neuropeptides in the pathogenesis of the major histological forms of lung cancer.

Adenocarcinoma↗
PubMed1996

Discordant signal transduction and growth inhibition of small cell lung carcinomas induced by expression of GTPase-deficient G alpha 16.

Small cell lung carcinoma (SCLC) accounts for 20-25% of primary lung cancers and is rapidly growing, widely metastatic, and rarely curable. Autocrine stimulation of multiple G protein-coupled neuropeptide receptor systems contributes to the transformed growth of SCLC. The ability of neuropeptide receptors to stimulate phospholipase C and mobilize intracellular Ca2+ indicates that Gq family members of heterotrimeric G proteins are a convergence point mediating autocrine signaling by multiple neuropeptides in SCLC. Expression of a GTPase-deficient, constitutive active form of an alpha q family member, alpha 16Q212L, in SCLC markedly inhibited growth of the cells in soft agar and tumor formation in nude mice. SCLC lines expressing alpha 16Q212L exhibited 2-4-fold elevated basal phospholipase C activity, but neuropeptide and hormone-regulated intracellular Ca2+ mobilization was nearly abolished. The data suggest that Ca2+ mobilization is an obligatory signal in neuropeptide-stimulated growth of SCLC. In addition, the proline-directed c-Jun NH2-terminal kinases/stress-activated protein kinases, which are members of the mitogen-activated protein kinase family, were stimulated approximately 2-fold in parental SCLC in response to exogenous neuropeptides and muscarinic agonists and were constitutively activated to the same degree in alpha 16Q212L-expressing SCLC. Thus, alpha 16Q212L expression induced desensitizaton of neuropeptide-stimulated Ca2+ signaling and persistent activation of the c-Jun NH2-terminal kinase/stress-activated protein kinase pathway. We propose that the induction of discordant signaling by selective perturbation of receptor-regulated effector systems leads to the inhibition of SCLC cell growth.

Amino Acid Sequence↗
PubMed1996

T-cell lymphoma cell lines (HUT102 and HUT78) established at the National Cancer Institute: history and importance to understanding the biology, clinical features, and therapy of cutaneous T-cell lymphomas (CTCL) and adult T-cell leukemia-lymphomas (ATLL).

Efforts at the National Cancer Institute to generate continuous in vitro cultures from patients with mycosis fungoides and the Sezary syndrome, neoplasms with a mature T-helper phenotype, led to the establishment of two cell lines, HUT78 and HUT102. Further characterization of these cell lines led to the identification of the first human retrovirus, HTLV-1, in the HUT102 cells, and the clinical description of the syndrome of HTLV-1 associated acute T-cell leukemia/lymphoma; the serum antibody test to screen for this virus was developed from the serum of the patient from whom the cell line was derived. The HUT78 cell line was pivotal in the identification and characterization of the HIV retrovirus in that a subclone, H9, proved to be permissive for replication of HIV in vitro. Propagation of HIV in vitro in H9 cells allowed for the development of immunological reagents to screen blood supplies for the presence of the virus. Further biologic and molecular studies of these lines have led not only to a better understanding of the underlying diseases but also to the development of rational therapeutic approaches.

Adult↗
PubMed1996

NCI-Navy Medical Oncology Branch cell line data base.

The cell line data base described in this paper includes both clinical information about the patients from whom the cell lines were derived and information about the in vitro analyses performed of the cell lines. The cell line data base has evolved as a part of a systematic effort by a research group at the NCI since 1976 to generate human cell lines as biological tools to study cancer and other diseases. The cell lines were generated from clinical specimens obtained as part of a series of Institutional Review Board-approved clinical protocols. The preponderance of the data is on lung cancer cell lines, though a broad range of other cancers are represented. A bank of over 300 human cell lines including cancer cell and in some instances autologous B-lymphoblastoid cells from the NCI-VA and NCI-Navy Medical Oncology Branch are reposited at the American Type Culture Collection. The cell lines are available for the research community. The entire data base is available on the American Type Culture Collection Web Site (WWW:http:@www.atcc.org/).

Biological Specimen Banks↗
PubMed1996

Expansion of bronchial epithelial cell populations by in vitro culture of explants from dysplastic and histologically normal sites.

The genetic and phenotypic properties of cells which ultimately give rise to carcinoma of the lung are not well defined in part because of unavailability of preneoplastic cells from well-characterized dysplastic sites. In order to expand bronchial epithelial cell populations from patients at high risk for lung cancer, endobronchial biopsy specimens were explanted onto collagen- and fibronectin-coated dishes and cultured in serum-free, chemically defined media. One hundred forty-nine biopsy pairs were obtained from smokers and from healthy volunteers for culture and histologic evaluation. The histologic appearances of mucosa adjacent to the site of the cultured biopsies ranged from normal through varying degrees of noninvasive squamous dysplasia to invasive carcinoma. Confluent monolayers of pure epithelial cells were obtained from 68% of the cultured explants. Sites exhibiting high-grade dysplasia were 51% more likely to yield successful cultures than sites exhibiting normal histology (13 of 14 cultures successful versus 52 of 83 cultures successful, P < 0.02). Cultures had a maximum proliferative life span of 81 days and none of the cultures spontaneously became immortalized. Immunolabeling studies revealed that all cultured epithelial cells, regardless of the in situ histologic appearances of the mucosa at the biopsy site, strongly expressed keratin and epidermal growth factor receptor, weakly expressed transferrin receptor and human folate receptor, and were negative for neural cell adhesion molecule and human leukocyte antigen DR (HLADR). Ploidy and karyotypic analyses were performed in a limited number of explants from normal and dysplastic sites and all were found to be diploid without karyotypic abnormality. We conclude that pure bronchial epithelial cell populations can be routinely expanded from histologically normal and dysplastic sites by tissue culture of biopsy explants and that the expanded cell populations may represent a library of normal and preneoplastic cells which are suitable for immunophenotypic, ploidy, genetic, or functional analyses.

Bronchi↗
PubMed1996

Combination paclitaxel and platinum in the treatment of lung cancer: US experience.

Despite marked improvements in the treatment options available for patients with lung cancers, more than 85% of patients ultimately relapse and die of their disease. Among the most auspicious of new agents available to treat lung cancers, paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) also has been the most extensively studied. The US experience with this promising new agent is reviewed here. It is concluded that paclitaxel, both as a single agent and in combination therapies, is as active as other available agents in the treatment of stages III and IV small cell and non-small cell lung cancer, whether given as a 24- or a 1- to 3-hour infusion. In combination therapy, paclitaxel/cisplatin has been shown to be superior to etoposide/cisplatin in the treatment of non-small cell lung cancer. Further study is needed to clarify the optimal role of paclitaxel in combination therapy and to define its optimal dose and schedule in therapy for lung cancers.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

Phase I study of cisplatin, etoposide, and paclitaxel in patients with extensive-stage small cell lung cancer: a University of Colorado Cancer Center study.

This phase I study investigated the maximum tolerated dose of cisplatin, etoposide, and paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) in 18 patients with advanced small cell lung cancer. Cisplatin (80 mg/m2) and etoposide (50 or 80 mg/m2 intravenously and 100 or 160 mg/m2 orally) were infused concomitantly 30 minutes after a 3-hour infusion of paclitaxel (135, 175, or 200 mg/m2). This order of administration was known to cause less toxicity than the reverse order. Granulocyte colony-stimulating factor was given as necessary. Overall, complete responses were observed in 33% of evaluable patients and partial responses were seen in 67%. No patient progressed during therapy. Median survival exceeded 12 months, with 53% of patients alive at 1 year. Untreated patients in similar health survive approximately 6 to 16 weeks. Hematologic toxicities were seen most frequently, and neutropenia was seen most often and was the most severe. Febrile neutropenia occurred in one patient; grade 4 thrombocytopenia did not occur at all. Nonhematologic toxicity was mild. Nausea and vomiting generally were well controlled, and there were no instances of severe allergic reaction. Although the maximum tolerated dose has not yet been defined, one of two patients in the group receiving the highest doses encountered a dose-limiting toxicity. Thus, we expect to recommend the following dosages for further study: cisplatin 80 mg/m2, etoposide 80 mg/m2, and paclitaxel 175 mg/m2. All patients had an objective response and one third had a complete response, compared with 10% of patients in most series. We conclude that paclitaxel can be added safely to full doses of cisplatin and etoposide with encouraging efficacy, and recommend a randomized trial be undertaken to compare the two-drug regimen with the three-drug regimen.

Antineoplastic Agents, Phytogenic↗
PubMed1996

The North American experience with paclitaxel combined with cisplatin or carboplatin in lung cancer.

Paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) is a new cytotoxic chemotherapeutic agent with a novel mechanism of action. Single-agent paclitaxel studies have shown promising activity in both small cell and non-small cell lung cancers. In non-small cell lung cancer, response rates of 22% to 26% and 1-year survival rates of 40% were reported with both 3-hour and 24-hour infusions of paclitaxel. In small cell lung cancer, 24-hour infusions produced response rates of 61%. These data indicate that paclitaxel is one of the most active agents for all lung cancer patients. Combination studies demonstrated that paclitaxel could be combined with either cisplatin or carboplatin at full doses using either a 3-hour or a 24-hour infusion schedule. Response rates with these combinations have been high, usually 40% to 50%, which are higher than with any of the drugs used alone. Neutropenia is the most frequent toxicity and occurs less frequently with the 3-hour infusion. Thrombocytopenia occurred less frequently than expected. One completed randomized study showed that the paclitaxel/cisplatin regimen was superior to the etoposide/cisplatin regimen with respect to response rate and survival. Additional randomized studies are necessary to determine whether the combinations are superior to single-agent paclitaxel, to define the optimal dose with the 3-hour infusion schedule, to define the optimal schedule (3 hours v 24 hours), and to determine whether paclitaxel can be combined with other new agents.

Antineoplastic Agents, Phytogenic↗
PubMed1995

Role of recombinant interferon alfa-2a maintenance in patients with limited-stage small-cell lung cancer responding to concurrent chemoradiation: a Southwest Oncology Group study.

PURPOSE: This study was designed to determine if recombinant interferon alfa-2a (rIFN alpha-2a) could prolong remission duration and/or survival in patients with limited-stage small-cell lung cancer (SCLC) who achieved an objective response to chemoradiotherapy. A secondary end point was to assess the toxicity of chronic IFN administration. PATIENTS AND METHODS: One hundred seventy-one of 215 eligible patients achieved an objective response and were eligible to receive rIFN alpha-2a (3 million units [MU]/m2 subcutaneously three times per week escalated to 9 MU/m2 as tolerated) or observation for 2 years. RESULTS: One hundred thirty-two of 140 registered patients were eligible. Sixty-four patients were randomized to receive IFN and 68 to observation alone. The median time from randomization to progression was 9 months on the IFN arm and 10 months on the observation arm (P = .72). The overall median survival time was 16 months on the observation arm versus 13 months on the IFN arm (P = .77). Significant toxicities occurred in the rIFN alpha-2a arm. Grade 3 or higher toxicities included malaise, fatigue, and/or lethargy (30%), leukopenia (14%), neutropenia (13%), dyspnea (13%), nausea (11%), and respiratory infection (6%). Forty-three patients discontinued treatment due to intolerable side effects. CONCLUSION: rIFN alpha-2a in the dose and schedule used in this study failed to prolong response duration or survival in patients with limited-stage SCLC who had previously responded to an induction chemoradiotherapy program. Failure may have been partly related to poor tolerance and inability to complete therapy.

Adult↗