Safety of treatment of metastatic breast cancer with trastuzumab beyond disease progression.

PURPOSE: In a pivotal phase III trial, the addition of trastuzumab to chemotherapy significantly improved response rate, time to disease progression, and overall survival in women with HER2 overexpressing metastatic breast cancer. We conducted an extension study to this trial to obtain additional safety information and to provide trastuzumab following disease progression. PATIENTS AND METHODS: A total of 247 patients with documented disease progression received weekly intravenous trastuzumab in the extension study. Concurrent therapies were administered at the discretion of the treating physician. Patient groups were based on initial study treatment: chemotherapy alone (group 1, n=154) or chemotherapy plus trastuzumab (group 2, n=93). RESULTS: Sixty-eight percent of group 1 and 76% of group 2 received chemotherapy plus trastuzumab in the extension trial; the remainder received trastuzumab alone or combined with palliative radiotherapy or hormonal therapy. Seventy-six percent of group 1 and 55% of group 2 experienced at least one adverse event, similar to effects observed in the pivotal trial. Symptomatic or asymptomatic cardiac dysfunction occurred in 9% of group 1 and 2% of group 2 patients. Overall objective response rates were 14% in group 1 and 11% in group 2; median durations of response exceeded 6 months in both groups. CONCLUSION: Our results suggest that prolonged use of trastuzumab therapy is safe and well tolerated. Longer durations of therapy did not appear to increase the risk of cardiac dysfunction. Patients progressing on trastuzumab-containing therapy demonstrate some response to a second trastuzumab-containing regimen. The independent contribution of trastuzumab in this setting merits further study.     

Assessment of methods for tissue-based detection of the HER-2/neu alteration in human breast cancer: a direct comparison of fluorescence in situ hybridization and immunohistochemistry.

PURPOSE: To compare the efficacy of fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) in detecting the HER-2/neu alteration in human breast cancer. PATIENTS AND METHODS: Unselected stage I, II, and III breast cancer patients (N = 900) were tested for HER-2/neu gene amplification by FISH in paraffin-embedded, formalin-fixed archival material. Of these samples, 856 were tested for HER-2/neu overexpression by non-antigen-retrieval IHC with the polyclonal antibody R60, the sensitivity and specificity of which was preliminarily compared with the United States Food and Drug Administration-approved HercepTest (Dako Corp, Carpinteria, CA). Patient survival was analyzed in relation to the presence of the HER-2/neu alteration as determined by these two methodologies. RESULTS: A total of 189 (21%) of 900 patients were positive by FISH and 147 (17.2%) of 856 were positive by IHC. This discrepancy is consistent with expected loss of IHC sensitivity associated with tissue fixation/embedding. The HercepTest did not improve sensitivity and introduced false positives. Comparison of R60-based IHC with FISH demonstrates that patient survival is associated progressively to gene amplification level as determined by FISH, whereas for IHC an association is found only in the highest (3+) immunostaining group. Among FISH-negative tumors, 45 (6.6%) of 678 were IHC-positive, with a survival probability similar to that of FISH-negative/IHC-negative cases; FISH-positive/IHC-negative patients have a survival probability similar to that of FISH-positive/IHC-positive cases. CONCLUSION: IHC does not consistently discriminate patients likely to have a poor prognosis, whereas FISH provides superior prognostic information in segregating high-risk from lower-risk beast cancers. HER-2/neu protein overexpression in the absence of gene amplification occurs infrequently in breast cancer, in which case, patient outcome is similar to that of patients without the alteration.     

Retinoic-acid-resistant neuroblastoma cell lines show altered MYC regulation and high sensitivity to fenretinide

BACKGROUND: High-dose, pulse-13-cis-retinoic acid (13-cis-RA) given after intensive cytotoxic therapy improves event-free survival for high-risk neuroblastoma (NB), but more than 50% of patients have tumor recurrence. PROCEDURE: We conducted multistep selection for resistance to all-trans-retinoic acid (ATRA) in NB cell lines with (SMS-KCNR and LA-N-5) or without (SMS-LHN) MYCN genomic amplification. RESULTS: After 12 exposures to 10 microM ATRA, the two MYCN-amplified cell lines (KCNR 12X RR and LA-N-5 12X RR) showed partial resistance to the cytostatic/differentiation effects of ATRA; complete resistance was seen in LHN 12X RR. ATRA-selected cells showed general RA resistance (cross-resistance to 13-cis-RA). Transient (KCNR 12 X RR, LA-N-5 12X RR) or sustained (LHN 12X RR) novel overexpression of c-myc was associated with RA resistance. RA-insensitive overexpression of MYCN by transduction in SMS-LHN also conferred RA resistance. Both parental and RA-resistant lines showed 2-4 logs of cell kill in response to N-(4-hydroxyphenyl)retinamide (4- HPR, fenretinide). Compared to parental lines, 4-HPR achieved 1-3 log greater cell kills in RA-resistant LHN 12X RR, LA-N-5 12X RR, KCNR 12X RR, and MYCN-transduced SMS-LHN or SK-N-RA. NB cell lines (n = 26) from 21 different patients showed that 16 of 26 (62%) were sensitive to 4-HPR (LC(90) < 10 microM), including lines established at relapse after myeloablative and/or 13-cis-RA therapy. CONCLUSION: Thus, RA-resistant NB cell lines can be sensitive (and in some cases collaterally hypersensitive) to 4-HPR.     

Transformation mediated by the human HER-2 gene independent of the epidermal growth factor receptor.

Amplification of the HER-2 (c-erbB-2) gene and overexpression of the p185HER-2 gene product is found in approximately one-third of primary human breast and ovarian cancers and is associated with a poor clinical outcome of early relapse and death. The HER-2 gene encodes a cell-surface growth factor receptor with intrinsic tyrosine kinase activity. Wild-type human HER-2 has been shown to act as a potent oncogene when over-expressed in mouse fibroblasts. Recent data suggest that the mechanism by which HER-2 mediates transformation requires the interaction of the epidermal growth factor (EGF) receptor. To test whether overexpression of normal human HER-2 can transform cells independently of the EGF receptor, we have introduced multiple copies of HER-2 into the EGF receptor-negative cell line, NR6, and have performed assays for both transformation and tumorigenicity. Engineered NR6 cells that overexpress the HER-2 gene product display a highly transformed and tumorigenic phenotype as compared with control cells. Additionally, a monoclonal antibody to the extracellular domain of the HER-2 receptor is able to inhibit the proliferation of the overexpressing cells in vitro as well as tumor growth in vivo. This study provides clear evidence that HER-2-mediated transformation can be achieved independently of the EGF receptor.     

Assessment of DNA damage in C6 glioma cells after antidepressant treatment using an alkaline comet assay

The effects of acute (24 h) exposure to the antidepressants amitriptyline, imipramine (both tricyclics), fluoxetine (a selective serotonin re-uptake inhibitor) and tranylcypromine (a monoamine oxidase inhibitor) on DNA damage in cultured C6 rat glioma cells were determined using an alkaline comet assay. The effects of manipulation of intracellular cyclic AMP by pretreatment with dibutyryl cyclic AMP (dBcAMP) and 3-isobutyl-1-methylxanthine (IBMX) were also studied. For fluoxetine, the effects of addition of exogenous glutathione (GSH) and pretreatment with L-buthionine sulfoximine (BSO) were also assessed. There were increases in DNA damage with increasing concentrations of antidepressants. IBMX pretreatment protected against antidepressant-induced DNA damage in C6 cells pretreated with dBcAMP. Addition of exogenous reduced GSH and BSO increased DNA damage after fluoxetine exposure. The data show that the antidepressants induce significant amounts DNA damage in C6 cells.     

HER-2/neu overexpression and in vitro chemosensitivity to CMF and FEC in primary breast cancer

Available clinical and experimental data on the effect of HER-2/neu overexpression on chemosensitivity are controversial. It was the purpose of this in vitro study to define the association between HER-2/neu overexpression and the sensitivity to the chemotherapeutic drug combinations of cyclophosphamide, methotrexate and 5-fluorouracil (CMF) and 5-fluorouracil, epirubicin and cyclophosphamide (FEC) of breast cancer cells derived from 140 chemotherapy-naïve patients at the time of primary surgery. Both drug combinations were tested at six different concentrations ranging from 6.25–200% peak plasma concentration (PPC). Immunohistochemical detection of HER-2/neu overexpression was performed with the HER-2/neu antibodies, CB11, TAB250 and AO485, in the same tumor specimens. Immunoreactions were determined as negative (0/1+), weakly positive (2+) and strongly positive (3+). However, the antibodies varied in their degrees of sensitivity. Breast cancer samples with strong (3+) HER-2/neu overexpression demonstrated 90% growth inhibition (IC₉₀) at significantly lower PPC values, using the CB11 (p=0.048), TAB250 (p=0.007) and AO485 (p0.01) antibodies, and showed 50% growth inhibition (IC₅₀) at significantly lower PPC values, using the CB11 antibody (p=0.01) compared to their counterparts with lower levels of HER-2/neu expression. When analyzing the group of patients with intermediate and strong HER-2/neu overexpression (2+ and 3+), an association between HER-2/neu overexpression and increased chemosensitivity was seen with the TAB250 (p=0.044) and AO485 (p=0.032) antibodies, but not with the CB11 antibody (p=0.8) at the IC₉₀ level. Differences in chemosensitivity between samples with strong HER-2/neu overexpression and those with lower levels were then analyzed separately for CMF and FEC. Both regimens achieved 90% tumor growth inhibition at lower PPC values in samples with strong HER-2/neu overexpression (3+) compared to their counterparts with lower expression levels (AO485 p=0.011 for CMF, and p=0.09 for FEC). Cumulative concentration-response plots of tumors responding in vitro with 90% tumor cell inhibition showed a stronger dose dependence for both CMF and FEC among tumor samples with strong HER-2/neu overexpression compared to those with lower levels of expression. In conclusion, the data show that HER-2/neu overexpression was not associated with in vitro drug resistance to CMF or FEC. In contrast, tumors with strong HER-2/neu overexpression demonstrated increased dose-dependent in vitro sensitivity to both the FEC and CMF regimens.     

Pleiotrophin mediates hematopoietic regeneration via activation of RAS

Hematopoietic stem cells (HSCs) are highly susceptible to ionizing radiation–mediated death via induction of ROS, DNA double-strand breaks, and apoptotic pathways. The development of therapeutics capable of mitigating ionizing radiation–induced hematopoietic toxicity could benefit both victims of acute radiation sickness and patients undergoing hematopoietic cell transplantation. Unfortunately, therapies capable of accelerating hematopoietic reconstitution following lethal radiation exposure have remained elusive. Here, we found that systemic administration of pleiotrophin (PTN), a protein that is secreted by BM-derived endothelial cells, substantially increased the survival of mice following radiation exposure and after myeloablative BM transplantation. In both models, PTN increased survival by accelerating the recovery of BM hematopoietic stem and progenitor cells in vivo. PTN treatment promoted HSC regeneration via activation of the RAS pathway in mice that expressed protein tyrosine phosphatase receptor-zeta (PTPRZ), whereas PTN treatment did not induce RAS signaling in PTPRZ-deficient mice, suggesting that PTN-mediated activation of RAS was dependent upon signaling through PTPRZ. PTN strongly inhibited HSC cycling following irradiation, whereas RAS inhibition abrogated PTN-mediated induction of HSC quiescence, blocked PTN-mediated recovery of hematopoietic stem and progenitor cells, and abolished PTN-mediated survival of irradiated mice. These studies demonstrate the therapeutic potential of PTN to improve survival after myeloablation and suggest that PTN-mediated hematopoietic regeneration occurs in a RAS-dependent manner.     

Heterotransplantation of human breast carcinomas in nude mice. Correlation between successful heterotransplants, poor prognosis and amplification of the HER-2/neu oncogene

Four hundred and thirty-three human breast carcinomas and 23 cell lines derived from human breast carcinomas were heterotransplanted in nude mice. Twenty-eight tumors and 13 cell lines took and could be serially transplanted. Their human origin was established by isozyme analysis performed on successive passages. Sixteen primary infiltrating duct-cell carcinomas (PIDC) took, from a total of 262 transplanted (6.1%). This is in striking contrast to the greater than 50% rate of takes of most major cancers of epithelial origin. All 16 PIDC growing in nude mice were highly cellular and lacked desmoplastic hyperplasia. The clinical prognosis of the PIDC patients whose tumors were successfully transplanted was poor. Ten of 16 (63%) died of their disease within 3 years, compared to only 49 (20%) of the 246 PIDC patients whose tumors did not take in nude mice. This could not be attributed to later stage disease of the tumors that took, because only 15% of these patients had 4 or more positive axillary lymph nodes as opposed to 28% of the patients whose tumors did not take. Sixty-four percent of the breast carcinomas growing in nude mice exhibited amplification of the HER-2/neu oncogene which is also correlated with poor prognosis in human breast cancer. It is possible that the nude mouse is more susceptible to a population of highly invasive and lethal breast carcinomas.     

Knockdown of ovarian cancer amplification target ADRM1 leads to downregulation of GIPC1 and upregulation of RECK

Approximately 25,000 ovarian cancers are diagnosed in the United States annually, and 75% of cases are in the advanced stage when they are largely incurable. There is a critical need for improved early detection tools and development of novel treatments. Recently, we showed that among 20q13-amplified genes in ovarian cancer, ADRM1 overexpression was the most highly correlated with amplification and was significantly upregulated with respect to stage, recurrence, and metastasis. In addition, overexpression of ADRM1 correlated significantly with shorter time to recurrence and overall survival. Herein, array-CGH and microarray expression of ovarian cancer cell lines provides evidence consistent with the primary tumor data that ADRM1 is a 20q13 amplification target. Knockdown of ADRM1 in amplified ovarian cell-line OAW42 results in downregulation of growth factor GIPC1 and upregulation of tumor-suppressor RECK RNA and protein. In our dataset of 141 ovarian primary tumors, ADRM1 overexpression significantly correlates with GIPC1 overexpression. In addition, there is a significant anticorrelation between ADRM1 overexpression and RECK expression. Further research is necessary to determine whether targeting knockdown of ADRM1 in 20q13-amplified ovarian cancers results in growth inhibition and tumor suppression via downstream targets GIPC1 and RECK.