***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: Background Trastuzumab , an anti-HER2/neu monoclonal antibody , is thought to promote HER2/neu receptor internalization and /or turnover . This study was design ed to investigate the kinetics of trastuzumab treatment on tumor cells with varying levels of HER2/neu expression and to determine the effect of trastuzumab on HER2/neu-specific cytotoxic T lymphocyte – mediated lysis . Methods Three cell lines with varying levels of HER2/neu expression were incubated with varying doses of trastuzumab at multiple time points . Trastuzumab binding and HER2/neu expression were determined . Peripheral blood mononuclear cells from three HLA-A2 + healthy donors and four E75 peptide – vaccinated patients were stimulated with HER2/neu-derived peptides and tested in st and ard chromium release cytotoxicity assays with HER2/neu+ tumor cells pretreated with trastuzumab . Results Treatment of tumor cells with 10 μg/mL of trastuzumab in an overnight incubation result ed in saturation of cell-surface HER2/neu receptors . At higher doses , trastuzumab staining and HER2/neu expression decreased in a time-dependent manner . Pretreatment of tumor cells with trastuzumab result ed in increases in specific cytotoxicity by peptide-stimulated cytotoxic T lymphocytes from HLA-A2 + donors over untreated cells by an average of 5.6 % and 15.3 % ( P = .0002 ) for doses of 10 and 50 μg/mL , respectively . In similar experiments involving peripheral blood mononuclear cells obtained from immunized patients , the average specific cytotoxicity for untreated cells was 34.2 % ± 1.3 % vs. 40.6 % ± 2.5 % ( P = .035 ) and 40.7 % ± 1.6 % ( P = .0005 ) for those treated with 10 and 50 μg/mL , respectively . Conclusions Our data suggest that pretreatment of breast cancer cells  with trastuzumab induces turnover of the HER2/neu protein and enhanced killing by HER2/neu peptide – stimulated CTLs . This increased lysis occurs regardless of the degree of HER2/neu expression and seems more pronounced in vaccinated patients . These findings support further investigation into the use of combination immunotherapy with trastuzumab and HER2/neu peptide – based vaccines Purpose : HER2/neu , a source of immunogenic peptides , is expressed in > 75 % of breast cancer patients . We have conducted clinical trials with the HER2/neu E75 peptide vaccine in breast cancer patients with varying levels of HER2/neu expression . Vaccine response based on HER2/neu expression level was analyzed . Experimental Design : Patients were stratified by HER2/neu expression . Low expressors ( n = 100 ) were defined as HER2/neu immunohistochemistry ( IHC ) 1 + to 2 + or fluorescence in situ hybridization < 2.0 . Overexpressors ( n = 51 ) were defined as IHC 3 + or fluorescence in situ hybridization ≥ 2.0 . Additional analyses were done stratifying by IHC status ( 0 - 3 + ) . St and ard clinocopathlogic factors , immunologic response ( in vivo delayed-type hypersensitivity reactions ; ex vivo human leukocyte antigen A2:immunoglobulin G dimer assay ) , and clinical responses ( recurrence ; mortality ) were assessed . Results : Low-expressor ( control , 44 ; vaccinated , 56 ) versus overexpressor patients ( control , 22 ; vaccinated , 29 ) were assessed . Low expressors , overexpressors , and most IHC-status vaccinated groups responded immunologically . Vaccinated low-expressor patients had larger maximum immunologic responses compared with overexpressor patients ( P = 0.04 ) , and vaccinated IHC 1 + patients had increased long-term immune response ( P = 0.08 ) . More importantly , compared with controls , low-expressor patients had a mortality reduction ( P = 0.08 ) . The largest decrease in mortality was seen in IHC 1 + patients ( P = 0.05 ) . In addition , a subset of overexpressor patients ( n = 7 ) received trastuzumab before vaccination , and this combination seems safe and immunologically beneficial . Conclusions : Most patients with various levels of HER2/neu expression responded immunologically and seemed to benefit from vaccination . The low expressors , specifically IHC 1 + patients , had more robust immunologic responses and may derive the greatest clinical benefit from the E75 vaccine Ideally , vaccines should be design ed to elicit long-lived immunity . The goal of this study was to determine whether HER-2/neu peptide-specific CD8 + T-cell immunity could be elicited using an immunodominant HER-2/neu-derived HLA-A2 peptide alone in the absence of exogenous help . Granulocyte macrophage colony-stimulating factor ( GM-CSF ) was used as adjuvant . Six HLA-A2 patients with HER-2/neu-overexpressing cancers received 6 monthly vaccinations with a vaccine preparation consisting of 500 microg of HER-2/neu peptide , p369 - 377 , admixed with 100 microg of GM-CSF .  The patients had either stage III or IV breast or ovarian cancer .  Immune responses to the p369 - 377 were examined using an IFN-gamma enzyme-linked immunosorbent spot assay . Before vaccination , the median precursor frequency ( range ) , defined as precursors per 10(6 ) peripheral blood mononuclear cell , to p369 - 377 was 0 ( no range ) . After vaccination , the median precursor frequency to p369 - 377 in four evaluable patients was 0 ( 0 - 116 ) . Overall , HER-2/neu peptide-specific precursors developed to p369 - 377 in two of four evaluable subjects . The responses were short-lived and not detectable at 5 months after the final vaccination . Immunocompetence was evident , because patients had detectable enzyme-linked immunosorbent spot responses to tetanus toxoid and influenza . These results demonstrate that HER-2/neu MHC class I epitopes can induce HER-2/neu peptide-specific IFN-gamma-producing CD8 + T cells . However , the magnitude of the responses were low , as well as short-lived , suggesting that CD4 + T-cell help is required for lasting immunity to this epitope E75 , a HER‐2/neu‐derived peptide , was administered as a preventive vaccine with granulocyte‐macrophage – colony‐stimulating factor ( GM‐CSF ) in disease‐free lymph node‐positive ( NP ) and lymph node‐negative ( NN ) breast cancer ( BCa ) patients . The optimal biologic dose ( OBD ) was determined based on toxicity and immunologic response PURPOSE E75 is an immunogenic peptide from the HER2/neu protein that is highly expressed in breast cancer . We are conducting a clinical trial of an E75 + granulocyte-macrophage colony-stimulating factor vaccine to assess safety , immunologic response , and the prevention of clinical recurrences in patients with disease-free , node-positive breast cancer ( NPBC ) . PATIENTS AND METHODS Fifty-three patients with NPBC were enrolled and HLA typed . HLA-A2 + patients ( n = 24 ) were vaccinated , and HLA-A2- patients ( n = 29 ) are observed prospect ively as clinical controls . Local/systemic toxicities , immunologic responses , and time to recurrence are being measured . RESULTS Only minor toxicities have occurred ( one grade 3 [ 4 % ] ) . All patients have demonstrated clonal expansion of E75-specific CD8+T cells that lysed HER2/neu-expressing tumor cells . An optimal dosage and schedule have been established . Patients have developed delayed-type hypersensitivity reactions to E75 postvaccination compared with controls ( 33 v 7 mm ; P < .01 ) . HLA-A2 + patients have been found to have larger , more poorly differentiated , and more hormonally insensitive tumors compared to HLA-A2- patients . Despite this , the only two deaths have occurred in the control group . The disease-free survival in the vaccinated group is 85.7 % compared to 59.8 % in the controls at 22 months ' median follow-up with a recurrence rate of 8 % compared to 21 % , respectively ( P < .19 ) . Median time to recurrence in the vaccinated patients was prolonged ( 11 v 8 months ) , and recurrence correlated with a weak delayed-type hypersensitivity response . CONCLUSION This HER2/neu ( E75 ) vaccine is safe and effective in eliciting a peptide-specific immune response in vivo . Induced HER2/neu immunity seems to reduce the recurrence rate in patients with NPBC The authors conducted exploratory phase 1‐2 clinical trials  vaccinating breast cancer patients with E75 , a human leukocyte antigen ( HLA ) A2/A3–restricted HER‐2/neu ( HER2 ) peptide , and granulocyte‐macrophage colony‐stimulating factor . The vaccine is given as adjuvant therapy to prevent disease recurrence . They previously reported that the vaccine is safe and effective in stimulating expansion of E75‐specific cytotoxic T cells . Here , they report 24‐month l and mark analyses of disease‐free survival ( DFS ) Background E75 , a HER2/neu immunogenic peptide , is expressed in breast cancer ( BCa ) . We have performed clinical trials of E75 + GM-CSF vaccine in disease-free , node-positive and node-negative BCa patients at high recurrence risk and recurrences were noted in both control and vaccine groups . Methods Among the 186 BCa patients enrolled , 177 completed the study . Patients were HLA typed ; the HLA-A2+/A3 + patients were vaccinated ; HLA-A2−/A3− patients were followed as controls . St and ard clinicopathological factors , immunologic response to the vaccine , and recurrences were collected and assessed . Results The control group recurrence rate was 14.8 and 8.3 % in the vaccinated group ( P = 0.17 ) . Comparing the 8 vaccinated recurrences ( V-R ) to the 88 vaccinated nonrecurrent patients ( V-NR ) , the V-R group had higher nodal stage ( ≥N2 : 75 vs. 5 % , P = 0.0001 ) and higher grade tumors ( % grade 3 : 88 vs. 31 % , P = 0.003 ) . The V-R group did not fail to respond immunologically as noted by equivalent dimer responses and post-DTH responses . Compared to control recurrent patients ( C-R ) , V-R patients trended toward higher- grade tumors and hormone-receptor negativity . C-R patients had 50 % bone-only recurrences , compared to V-R patients with no bone-only recurrences ( P = 0.05 ) . Lastly , V-R mortality rate was 12.5 % compared with 41.7 % for the C-R group ( P = 0.3 ) . Conclusions The vaccinated patients who recurred had more aggressive disease compared to V-NR patients . V-R patients had no difference in immune response to the vaccine either in vitro or in vivo . V-R patients , when compared to C-R patients , trended towards more aggressive disease , decreased recurrence rates , decreased mortality , and no bone-only recurrences We used the Luminex assay to compare serum cytokine profiles of breast cancer patients ( BCa ) to healthy controls , node-positive ( NP ) patients to node-negative ( NN ) , and pre- and post-vaccination serum of BCa vaccinated with a HER2/neu E75 peptide vaccine .  Sera from 36 pre- and post-vaccination BCa , ( 12 NP and 24 NN ) and 13 healthy , female donors , were evaluated using Luminex technology . Levels of 22 cytokines consisting of interleukin (IL)-1alpha , -1beta , -2 , -4 , -5 , -6 , -7 , -8 , -10 , -12 , -13 , -15 , -17 , IFN-gamma , G-CSF , GM-CSF , TNF-alpha , IP-10 , MIP-1alpha , RANTES , eotaxin and monocyte chemotactic protein-1 ( MCP-1 ) were assessed . Six of 22 cytokines showed significant differences between BCa and healthy controls . MCP-1 , eotaxin , RANTES and GM-CSF levels were significantly elevated in BCa ( P<0.009 ) and IL-1alpha and IL-4 levels were significantly decreased in BCa ( P<0.015 ) . Cytokine levels were generally elev 
    Output:
    
Meta‐ analysis of delayed‐type hypersensitivity)DTH ( reactions and CD8+‐T cell levels , as immune responses , displayed the significant differences in the vaccinated groups compared to their non‐vaccinated counterparts .
In addition , the recurrence , and the overall and the disease‐free survival were significantly different in the vaccinated subjects versus the control .
Evaluation of the local and systemic toxicity of the E75 peptide vaccine demonstrated the minimal side effects .