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Biomedical subjects

Bruce E Johnson

Publications and source records attributed to Bruce E Johnson.

At least 19 recordsLinked to original sources
PubMed2007

Phase II clinical trial of chemotherapy-naive patients > or = 70 years of age treated with erlotinib for advanced non-small-cell lung cancer.

PURPOSE: This is a phase II, multicenter, open-label study of chemotherapy-naïve patients with non-small-cell lung cancer (NSCLC) and age > or = 70 years who were treated with erlotinib and evaluated to determine the median, 1-year, and 2-year survival. The secondary end points include radiographic response rate, time to progression (TTP), toxicity, and symptom improvement. PATIENTS AND METHODS: Eligible patients with NSCLC were treated with erlotinib 150 mg/d until disease progression or significant toxicity. Tumor response was assessed every 8 weeks by computed tomography scan using Response Evaluation Criteria in Solid Tumors. Tumor samples were analyzed for the presence of somatic mutations in EGFR and KRAS. RESULTS: Eighty eligible patients initiated erlotinib therapy between March 2003 and May 2005. There were eight partial responses (10%), and an additional 33 patients (41%) had stable disease for 2 months or longer. The median TTP was 3.5 months (95% CI, 2.0 to 5.5 months). The median survival time was 10.9 months (95% CI, 7.8 to 14.6 months). The 1- and 2- year survival rates were 46% and 19%, respectively. The most common toxicities were acneiform rash (79%) and diarrhea (69%). Four patients developed interstitial lung disease of grade 3 or higher, with one treatment-related death. EGFR mutations were detected in nine of 43 patients studied. The presence of an EGFR mutation was strongly correlated with disease control, prolonged TTP, and survival. CONCLUSION: Erlotinib monotherapy is active and relatively well tolerated in chemotherapy-naïve elderly patients with advanced NSCLC. Erlotinib merits consideration for further investigation as a first-line therapeutic option in elderly patients.

Age Factors↗
PubMed2006

Allelic dilution obscures detection of a biologically significant resistance mutation in EGFR-amplified lung cancer.

EGFR is frequently mutated and amplified in lung adenocarcinomas sensitive to EGFR inhibitors gefitinib and erlotinib. A secondary mutation, T790M, has been associated with acquired resistance but has not been shown to be sufficient to render EGFR mutant/amplified lung cancers resistant to EGFR inhibitors. We created a model for studying acquired resistance to gefitinib by prolonged exposure of a gefitinib-sensitive lung carcinoma cell line (H3255; EGFR mutated and amplified) to gefitinib in vitro. The resulting resistant cell line acquired a T790M mutation in a small fraction of the amplified alleles that was undetected by direct sequencing and identified only by a highly sensitive HPLC-based technique. In gefitinib-sensitive lung cancer cells with EGFR mutations and amplifications, exogenous introduction of EGFR T790M effectively conferred resistance to gefitinib and continued ErbB-3/PI3K/Akt signaling when in cis to an activating mutation. Moreover, continued activation of PI3K signaling by the PIK3CA oncogenic mutant, p110alpha E545K, was sufficient to abrogate gefitinib-induced apoptosis. These findings suggest that allelic dilution of biologically significant resistance mutations may go undetected by direct sequencing in cancers with amplified oncogenes and that restoration of PI3K activation via either a T790M mutation or other mechanisms can provide resistance to gefitinib.

Alleles↗
PubMed2006

Epidermal growth factor receptor mutation testing in the care of lung cancer patients.

As the literature about epidermal growth factor receptor (EGFR) mutations grows and screening for mutations becomes increasingly integrated into clinical care, it is important to examine how best to do somatic mutational analyses and how best to use the test results in clinical decision making. We began offering mutation screening by comprehensive direct sequence analysis of exons 18 to 24 of the tyrosine kinase domain of EGFR in August 2004 as part of clinical cancer care and protocol therapy at our institutions. All identified potential mutations are confirmed with three to five independent PCRs of the original genomic DNA sample and, if not previously noted in the literature, are compared with the patient's germ-line DNA to ensure the finding is somatic. We formally analyzed the first 100 patients to undergo EGFR sequence analysis and found that testing was feasible and significantly affected the treatment of patients with non-small cell lung cancer (NSCLC). Patients harboring EGFR mutations were significantly more likely to receive recommendations for therapy with EGFR tyrosine kinase inhibitors (i.e., gefitinib or erlotinib) than patients without mutations. However, negative EGFR test results did not prevent physicians from administering these agents to selected patients. Ideally, a standardized technique for mutation testing could be developed, with demonstrated reproducibility and validity. Clinical trials incorporating molecular diagnostics are ongoing to assess the efficacy of EGFR tyrosine kinase inhibitors as first-line therapy for metastatic NSCLC and as adjuvant therapy for early-stage resected NSCLC. It is likely that mutation testing and other molecular analyses will be most useful in these two clinical situations.

Carcinoma, Non-Small-Cell Lung↗
PubMed2006

Effect of epidermal growth factor receptor tyrosine kinase domain mutations on the outcome of patients with non-small cell lung cancer treated with epidermal growth factor receptor tyrosine kinase inhibitors.

Somatic mutations in the epidermal growth factor receptor (EGFR) have been identified in patients with advanced non-small cell lung cancer who achieve dramatic clinical and radiographic response to the EGFR tyrosine kinase inhibitors (TKI) gefitinib and erlotinib. These mutations in EGFR are found more frequently in patients with adenocarcinomas, nonsmokers, patients of Asian ethnicity, and in females: the same populations that are the most likely to have a clinical response when treated with EGFR TKIs. Retrospective studies comparing the outcomes of patients with and without EGFR mutations treated with EGFR TKIs show a significant clinical benefit of EGFR TKIs in patients with EGFR mutations. These findings suggest that for patients with advanced non-small cell lung cancer bearing EGFR mutations, treatment with an EGFR TKI should be incorporated as at least part of their initial therapy. These approaches are being studied in ongoing clinical trials and will spur the development of additional technology for EGFR mutation detection.

Carcinoma, Non-Small-Cell Lung↗
PubMed2006

Rationale for a phase II trial of pertuzumab, a HER-2 dimerization inhibitor, in patients with non-small cell lung cancer.

BACKGROUND AND RATIONALE: In non-small cell lung cancer (NSCLC) HER-2 gene amplification and 3+ staining by immunohistochemistry are present in only 2% to 5% of the tumors. Therefore, relatively few patients with lung cancer are likely to benefit from treatment with trastuzumab, the humanized monoclonal antibody that is effective in the 20% of patients with breast cancer and HER-2 gene amplification and/or 3+ staining by immunohistochemistry. Pertuzumab (rhuMAb 2C4), a humanized HER2 antibody, represents a new class of targeted therapeutics that inhibit dimerization of HER2 with ligand-activated EGFR (HER1), HER3, and HER-4. Pertuzumab can have antitumor activity in patients with HER-2 present on the tumor without gene amplification or 3+ staining by immunohistochemistry. Preclinical xenograft studies have shown efficacy of pertuzumab in treating NSCLC. Therefore, a trial was undertaken for patients with relapsed NSCLC. MATERIALS AND METHODS: Subjects with advanced or recurrent NSCLC treated previously with chemotherapy were treated with pertuzumab (840 mg i.v. loading dose then 420 mg every 3 weeks). Mandatory fresh tumor biopsies before treatment were obtained for biomarker analysis including HER-2 phosphorylation. Computed tomography scans were obtained every two cycles to assess tumor response. Tumor response (response evaluation criteria in solid tumors criteria) was the primary end point. RESULTS: As reported in a previous abstract, none of the 33 patients with NSCLC and evaluable disease had a response to the treatment. CONCLUSIONS: Pertuzumab has an appropriate rationale for therapeutic use in patients with NSCLC. A phase II trial in patients with NSCLC has completed enrollment, and the details of the trial will be presented in a future publication. This article will review the preclinical rationale for undertaking a study of pertuzumab for patients with relapsed NSCLC.

Antibodies, Monoclonal↗
PubMed2006

Exon 19 deletion mutations of epidermal growth factor receptor are associated with prolonged survival in non-small cell lung cancer patients treated with gefitinib or erlotinib.

PURPOSE: Somatic mutations in the epidermal growth factor receptor (EGFR) have been detected in patients with non-small cell lung cancer (NSCLC) and are associated with sensitivity to treatment with gefitinib or erlotinib. Our study explored the relationship between the two most common types of somatic EGFR mutations, exon 19 deletions and the L858R point mutation, and outcomes of patients following treatment with gefitinib or erlotinib. EXPERIMENTAL DESIGN: Tumor specimens obtained before treatment with gefitinib or erlotinib were analyzed for EGFR mutations. Patients with exon 19 deletion or L858R mutations were identified. The response rate, time to progression, and overall survival were determined for the two groups. RESULTS: We identified 36 patients with NSCLC and an EGFR mutation who were treated with gefitinib or erlotinib. Patients with an exon 19 deletion had a significantly longer overall survival compared with patients with an L858R mutation (38 versus 17 months; P = 0.04). There were also trends toward higher response rate (73% versus 50%) and improved time to progression (24 versus 10 months) for the patients with an exon 19 deletion, although these were not independently significant in a multivariate analysis. A difference in response rate for patients treated with gefitinib compared with erlotinib was also noted [18 of 23 (78%) versus 3 of 9 (33%); P = 0.04]. No obvious difference in time to progression or overall survival was noted between gefitinib- and erlotinib-treated patients. CONCLUSIONS: Patients with NSCLC and EGFR exon 19 deletions have a longer survival following treatment with gefitinib or erlotinib compared with those with the L858R mutation. Pooling of greater numbers of patients and completion of prospective trials are needed to further define the predictive and prognostic roles of different EGFR mutations with respect to treatment with gefitinib, erlotinib, and other EGFR inhibitors.

Adult↗
PubMed2006

The impact of human EGFR kinase domain mutations on lung tumorigenesis and in vivo sensitivity to EGFR-targeted therapies.

To understand the role of human epidermal growth factor receptor (hEGFR) kinase domain mutations in lung tumorigenesis and response to EGFR-targeted therapies, we generated bitransgenic mice with inducible expression in type II pneumocytes of two common hEGFR mutants seen in human lung cancer. Both bitransgenic lines developed lung adenocarcinoma after sustained hEGFR mutant expression, confirming their oncogenic potential. Maintenance of these lung tumors was dependent on continued expression of the EGFR mutants. Treatment with small molecule inhibitors (erlotinib or HKI-272) as well as prolonged treatment with a humanized anti-hEGFR antibody (cetuximab) led to dramatic tumor regression. These data suggest that persistent EGFR signaling is required for tumor maintenance in human lung adenocarcinomas expressing EGFR mutants.

Adenocarcinoma↗
PubMed2006

A metabolic study of patients with lung cancer and hyponatremia of malignancy.

PURPOSE: One-third of patients with lung cancer and hyponatremia have no evidence of ectopic arginine vasopressin (AVP) production and the cause of their hyponatremia is not conclusively established. We sought to distinguish patients with hyponatremia caused by elevated AVP versus those with ectopic atrial natriuretic peptide (ANP) via this detailed metabolic study. EXPERIMENTAL DESIGN: We enrolled 24 patients recently diagnosed with lung cancer in a metabolic study in which patients were placed on sodium and fluid restriction for 4 days. Serum electrolytes, osmolality, urine electrolytes and osmolality, plasma AVP, ANP, aldosterone, urinary cyclic AMP and cyclic guanosine 3',5'-monophosphate were measured daily and tumor tissue was obtained to measure ectopic hormone production. We attempted to characterize the pathophysiology of hyponatremia caused by ectopic ANP production in patients with small cell lung cancer (SCLC) and to determine its effect on the aldosterone axis. RESULTS: Seven of the nine patients with SCLC presented with hyponatremia and three had elevated ANP levels at presentation without elevation of AVP. All three patients who presented with hyponatremia and elevated ANP showed a decline in serum sodium following fluid restriction, whereas two patients with SCLC and elevated AVP had normalized serum sodium levels. The combination of hyponatremia and elevated ANP was associated with a persistent natriuresis and inappropriately low aldosterone levels despite sodium restriction, suggesting ANP suppression of the aldosterone axis. CONCLUSIONS: Management of patients with hyponatremia and SCLC should be guided by the knowledge that some patients with SCLC have ectopic production of ANP as the cause of their hyponatremia.

Adult↗
PubMed2006

A rapid and sensitive enzymatic method for epidermal growth factor receptor mutation screening.

PURPOSE: Mutations in the epidermal growth factor receptor (EGFR) are associated with clinical and radiographic responses to EGFR tyrosine kinase inhibitors gefitinib and erlotinib. Currently available methods of EGFR mutation detection rely on direct DNA sequencing, which requires isolation of DNA from a relatively pure population of tumor cells, cannot be done on small diagnostic specimens, and lack sensitivity. Here we describe the use of a sensitive screening method that overcomes many of these limitations. EXPERIMENTAL DESIGN: We screened 178 non-small cell lung cancer specimens for mutations in exons 18 to 21 of EGFR using a DNA endonuclease, SURVEYOR, which cleaves mismatched heteroduplexed DNA. Samples were analyzed by high-performance liquid chromatography on the Transgenomic WAVE HS system. Selected specimens that produced digestion products using SURVEYOR were subsequently reanalyzed by size separation or under partially denaturing conditions, followed by fractionation and sequencing. The specimens included DNA isolated from frozen tumor specimens, dissected formalin-fixed, paraffin-embedded tumor specimens undergoing clinical sequencing, and undissected formalin-fixed, paraffin-embedded specimens. One hundred sixty specimens were independently analyzed using direct DNA sequencing in a blinded fashion. RESULTS: EGFR mutations were detected in 16 of 61 fresh frozen tumor specimens, 24 of 91 dissected formalin-fixed, paraffin-embedded tumor specimens, and 11 of 26 undissected formalin-fixed, paraffin-embedded tumor specimens. Compared with sequencing, the sensitivity and specificity of the present method were 100% and 87%. The positive and negative predictive values were 74% and 100%, respectively. SURVEYOR analysis detected 7 (4%) mutations that were not previously detected by direct sequencing. CONCLUSIONS: SURVEYOR analysis provides a rapid method for EGFR mutation screening with 100% sensitivity and negative predictive value. This unbiased scanning technique is superior to direct sequencing when used with undissected formalin-fixed, paraffin-embedded specimens.

Carcinoma, Non-Small-Cell Lung↗
PubMed2006

Paraneoplastic syndromes associated with small cell lung cancer.

Small cell lung cancer (SCLC) is the most frequent cancer histology associated with paraneoplastic syndromes. These syndromes are typically caused by ectopic hormone production or immune-mediated tissue destruction caused by neural antigen expression from cancer cells. This antigen expression induces the production of antibodies that cross-react with neural tissue. This article discusses the most common ectopic hormone and neurologic paraneoplastic syndromes and emphasizes the relationships among antigens, clinical syndromes, and outcomes. Although ectopic hormone production has been associated with extensive-stage disease and a poorer outcome, the antibody-mediated paraneoplastic syndromes are prognostic factors associated with more favorable outcomes. Both have the potential for improvement with cancer treatment.

Carcinoma, Small Cell↗
PubMed2005

Clinical Cancer Advances 2005: major research advances in cancer treatment, prevention, and screening--a report from the American Society of Clinical Oncology.

This year, for the first time, the American Society of Clinical Oncology (ASCO) is publishing Clinical Cancer Advances 2005: Major Research Advances in Cancer Treatment, Prevention, and Screening, an annual review of the most significant clinical research presented or published over the past year across all cancer types. ASCO embarked on this project to provide the public, patients, policymakers, and physicians with an accessible summary of the year's most important research advances. While not intended to serve as a comprehensive review, this report provides a year-end snapshot of research that will have the greatest impact on patient care. As you will read, there is much good news from the front lines of cancer research. These pages report on new chemotherapy regimens that sharply reduce the risk of recurrence for very common cancers; the "coming of age" of targeted cancer therapies; promising studies of drugs to prevent cancer; and improvements in quality of life for people living with the disease, among many other advances. Survival rates for cancer are on the rise, increasing from 50% to 64% over the last 30 years. Cancer still exacts an enormous toll, however. Nearly 1.4 million Americans will be diagnosed this year, and some 570,000 will die of the disease. Clearly, more research is needed to find effective therapies for the most stubborn cancer types and stages. We need to know more about the long-term effects of newer, more targeted cancer therapies, some of which need to be taken over long periods of time. And we need to devote far greater attention to tracking and improving the care of the nearly 10 million cancer survivors in the United States today. Despite these and other challenges, the message of this report is one of hope. Through the dedicated, persistent pursuit of clinical research and participation in clinical trials by people with cancer, we steadily uncover new and better ways of treating, diagnosing, and preventing a disease that touches the lives of so many. I want to thank the Editorial Board members, the Specialty Editors, and the ASCO Cancer Communications Committee for their dedicated work to develop this report, and I hope you find it useful.

Breast Neoplasms↗
PubMed2005

Inhibition of the met receptor in mesothelioma.

BACKGROUND: Expression of the Met receptor and its ligand, hepatocyte growth factor (HGF), has been observed in 74% to 100% and 40% to 85% of malignant pleural mesothelioma (MPM) specimens, respectively. HGF stimulation has been shown to enhance MPM cell proliferation, migration, cell scattering, and invasiveness. EXPERIMENTAL DESIGN: To investigate a potential therapeutic role for the Met receptor in MPM, we examined the effects of PHA-665752, a specific small-molecule inhibitor of the Met receptor tyrosine kinase, in a panel of 10 MPM cell lines. RESULTS: Two of the cell lines, H2461 and JMN-1B, exhibited autocrine HGF production as measured by ELISA (3.9 and 10.5 ng/mL, respectively, versus <0.05 ng/mL in other cell lines). Evaluation of PHA-665752 across the 10 MPM cell lines indicated that despite Met expression in all cell lines, only in cell lines that exhibited a Met/HGF autocrine loop, H2461 and JMN-1B, did PHA-665752 inhibit growth with an IC(50) of 1 and 2 micromol/L, respectively. No activating mutations in Met were detected in any of the cell lines. Consistent with observed growth inhibition, PHA-665752 caused cell cycle arrest at G(1)-S boundary accompanied by a dose-dependent decrease in phosphorylation of Met, p70S6K, Akt, and extracellular signal-regulated kinase 1/2. Growth of H2461 cells was also inhibited by neutralizing antibodies to HGF and by RNA interference knockdown of the Met receptor, confirming that growth inhibition observed was through a Met-dependent mechanism. PHA-665752 also reduced MPM in vitro cell migration and invasion. CONCLUSIONS: Taken together, these findings suggest that inhibition of the Met receptor may be an effective therapeutic strategy for patients with MPM and provides a mechanism, the presence of a HGF/Met autocrine loop, by which to select patients for PHA-665752 treatment.

Antibodies↗
PubMed2005

Epidermal growth factor receptor mutations in patients with non-small cell lung cancer.

A year has passed since mutations of the tyrosine kinase domain of the epidermal growth factor receptor (EGFR) were discovered in patients with non-small cell lung cancer (NSCLC) who had dramatic clinical responses to treatment with gefitinib. Additional laboratory and clinical studies have provided further insight into the biological impact of EGFR mutations in cell culture experiments and in patients with NSCLC. In vitro characterizations of NSCLC cell lines and host cell lines transfected with these mutant and wild-type EGFR show that most cell lines with mutated EGFR are growth-inhibited by 10- to 100-fold lower concentrations of gefitinib and erlotinib compared with wild-type EGFR. NSCLC lines with mutations of the EGFR treated with concentrations of gefitinib and erlotinib that are achievable in the plasma undergo apoptosis rather than growth arrest. Retrospective studies of patients with NSCLC-treated gefitinib have reported a close association between EGFR mutations, increased chance of clinical response and longer survival. This review will provide information on the impact of EGFR mutations on gefitinib and erlotinib treatment by in vitro experiments, the outcome of NSCLC patients with these mutations when treated with gefitinib and erlotinib, and the subsets of patients with NSCLC in whom these mutations arise.

Carcinoma, Non-Small-Cell Lung↗