Efficacy Of Trastuzumab In Patients Research Articles

The Visualization of Protein-Protein Interactions in Breast Cancer: Deployment Study in Pathological Examination.

The therapeutic strategy is determined by protein expression using immunohistochemistry of estrogen receptor (ER), progesterone receptor, and human epidermal growth factor receptor 2 (HER2) in formalin-fixed paraffin-embedded (FFPE) breast cancer tissues. However, few proteins function independently, and many of them functions due to protein-protein interactions (PPIs) with other proteins. Therefore, it is important to focus on PPIs. This review summarizes the PPIs of ER and HER2 in breast cancer, especially those using a proximity ligation assay that can visualize PPIs in FFPE tissues. In particular, assessing the interaction of CEACAM6 with HER2 may serve as a surrogate marker for the efficacy of trastuzumab in patients with breast cancer. Therefore, in this review, the technique used to detect the interaction of CEACAM6 and HER2 in routinely processed pathological specimens will be applied to the clinical practice of drug selection. We showed the possibility as a novel pathological examination method using PPIs.

P002 - Evaluation of the efficacy of Trastuzumab in patients with HER2 positive small (pT1mi/a) breast cancers. A multicenter retrospective study on 100 patients

P002 - Evaluation of the efficacy of Trastuzumab in patients with HER2 positive small (pT1mi/a) breast cancers. A multicenter retrospective study on 100 patients

Abstract P4-10-32: Commensal gut microbiota influences efficacy of trastuzumab in patients with HER2-positive breast carcinoma

Abstract Although the clinical benefit of trastuzumab for the management of HER2-positive breast carcinomas (BCs) has been largely demonstrated, many women, even those reported to have tumors potentially most sensitive to trastuzumab (e.g., HER2-enriched by PAM50 and with infiltrating immune cells) do not respond to this agent. The relevance of immunity in the cytotoxic mechanism of action of trastuzumab supports the notion that the anti-tumor effect of this monoclonal antibody depends on host immune system activity. Since gut commensal bacteria reportedly contribute to the development and maintenance of the immune system and have immunomodulatory effects, we investigated whether a relationship between gut microbiota composition and the response to trastuzumab exists in patients with HER2-positive BC. Stool samples were collected from 18 patients with primary HER2-positive BCs before the outset of neoadjuvant trastuzumab-based chemotherapy and analyzed by 16S rRNA gene profiling using Illumina Miseq platform. Gut microbiota β-diversity analysis by UniFrac algorithm revealed a heterogeneous microbiota composition mainly due to differences in the relative abundance of Bacteroides, Faecalibacterium and a genus belonging to Ruminococcaceae family. Unsupervised analysis identified two microbiota clusters that significantly discriminated patients according to pathological complete response (pCR) (p=0.0128, by Fisher test). No association between microbiota clusters and PAM50 molecular classification of tumor biopsies, as evaluated by gene expression, was observed. Moreover, HER2-enriched cases were distributed in the two microbiota clusters based on trastuzumab response. Differences in the intestinal microbiota between responsive (R) and non-responsive (NR) patients were assessed by LEfSe analysis: a significant higher and lower abundance of Clostridiales taxonomic order and Bacteroides taxonomic genus, respectively, was foundin R as compared to NR patients. Immune genes expressed in tumor biopsies that were found significantly correlated with these bacteria mainly belong to innate and adaptive immune response and cellular response to tumor necrosis factor pathways. To investigate the causal role of gut microbiota in trastuzumab benefit, FVB mice bearing syngeneic mammary carcinoma overexpressing human HER2 were transplanted with fecal material from R and NR patients after intestinal flora depletion by the use of an antibiotic cocktail. The mouse response to trastuzumab treatment recapitulated the response observed in patients from which stool derived. The obtained results support the contribution of gut microbiota in trastuzumab activity by influencing tumor immune microenvironment, independently of tumor intrinsic molecular characteristics. These data represent the proof-of-concept that manipulating gut microbes in resistant patients could be a new strategy to improve the response to trastuzumab. Supported by AIRC Citation Format: Elda Tagliabue, Martina Di Modica, Giorgio Gargari, Viola Regondi, Arianna Bonizzi, Stefania Arioli, Fabio Corsi, Simone Guglielmetti, Tiziana Triulzi. Commensal gut microbiota influences efficacy of trastuzumab in patients with HER2-positive breast carcinoma [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-10-32.

Effect of cyclin E overexpression on resistance to trastuzumab and phosphorylation of SMAD3 in HER2+ breast cancer.

e12006 Background: Trastuzumab, an effective treatment for HER2+ breast cancer, can be limited by development of resistance. Cyclin E (CCNE) overexpression was implicated in trastuzumab resistance, though the association is not well understood. We sought to explore a potential mechanism focusing on altered phosphorylation of the TGFβ signaling protein, SMAD3, in CCNE overexpressing HER2+ breast cancer cells, leading to trastuzumab resistance. Methods: A transcriptional activity cell array (TRACER) was used to examine the relationship between specific transcription factors and trastuzumab resistance in BT474 HER2+ human breast cancer cells. Immunoblotting examined phosphorylation patterns of SMAD3 in trastuzumab sensitive and resistant conditions. Effects of blocking CCNE overexpression with a CDK2 inhibitor were measured. To test the relative influence of SMAD3 and SMAD3 linker region phosphorylation on cell proliferation, BT474R2 cell lines were created overexpressing SMAD3 (BT474R2-SMAD3), a mutant construct blocking CCNE-mediated SMAD3 linker region phosphorylation (BT474R2-5M), and a control (BT474R2-Blank). In vitro and in vivo studies measured response to trastuzumab. Results: Resistance to trastuzumab was confirmed for BT474R2 cells, showing a markedly increased resistance to treatment when compared to the parental line. Network analysis of TRACER data identified decreased SMAD3 activity was central to resistance. Immunoblotting showed SMAD3 expression was significantly downregulated in BT474R2 cells (p < 0.01). Noncanonical phosphorylation of SMAD3 was increased in CCNE-overexpressing cells. Blocking CCNE mediated noncanonical phosphorylation of SMAD3 with CDK2 inhibition resulted in decreased proliferation of BT474R2 cells. In vitro studies examining response to trastuzumab showed an increased sensitivity for BT474R2-5M cells. Findings were validated in NSG mice inoculated with BT474R2-5M cells that developed significantly lower tumor volumes (p < 0.001) when treated with trastuzumab. Conclusions: These results identified a mechanism of CCNE-mediated trastuzumab resistance, regulated through noncanonical SMAD3 phosphorylation, which may be effectively treated with CDK2 inhibition to help enhance the efficacy of trastuzumab for patients with HER2+ breast cancer.

Clinical impact of intratumoral HER2 heterogeneity on trastuzumab efficacy in patients with HER2-positive gastric cancer

BackgroundThere is growing interest in the clinical significance of intratumoral HER2 heterogeneity. Its prognostic and predictive impacts on trastuzumab efficacy were demonstrated in breast cancer. However, its clinical significance in gastric cancer is still unclear.MethodsTwenty-eight HER2-positive gastric cancer patients who had gastrectomy prior to trastuzumab-based chemotherapy were consecutively enrolled. Intratumoral HER heterogeneity was evaluated using whole-tissue sections by immunohistochemistry. When all tumor cells overexpressed HER2 protein, the tumor was defined as homogeneously HER2 (Homo-HER2)-positive group. The others were defined as heterogeneously HER2 (Hetero-HER2)-positive group.ResultsThere was no significant difference in clinicopathological features between the two groups. The median progression-free survival (PFS) and overall survival (OS) in the Homo-HER2-positive group were significantly longer than those in the Hetero-HER2-positive group (PFS; 20.0 months [95% CI 17.8–22.2] vs. 6.0 months [95% CI 2.3–9.7]; HR 0.11; 95% CI 0.03–0.41; p < 0.001, OS; not reached vs. 14.0 months [95% CI 11.9–16.1]; HR 0.18; 95% CI 0.06–0.61; p = 0.003). In the multivariate analysis, these associations remained significant both in PFS (HR 0.12; 95% CI 0.03–0.46, p = 0.002) and OS (HR 0.21; 95% CI 0.06–0.72, p = 0.013). With respect to response rate, no statistical difference was found between two groups. However, deeper tumor shrinkage was obtained in the Homo-HER2-positive group compared with the Hetero-HER2-positive group (p = 0.046).ConclusionsIntratumoral HER2 heterogeneity may have robust clinical impact on trastuzumab efficacy in patients with HER2-positive gastric cancer. These findings should be validated by larger independent cohorts and further molecular correlative analyses are warranted.

FcγRIIA and IIIA polymorphisms predict clinical outcome of trastuzumab-treated metastatic gastric cancer.

Trastuzumab has substantial antitumor activity in metastatic gastric cancer. One such mechanism by which it exerts its antitumor activity is antibody-dependent cell-mediated cytotoxicity, which has been reported to be influenced by FcγRIIA and IIIA polymorphisms. This study is the first to assess their impact on trastuzumab efficacy in patients with metastatic gastric cancer. We retrospectively examined 42 Her-2-positive patients receiving fluorouracil and platinum-based chemotherapy and trastuzumab, and 68 Her-2-negative patients receiving fluorouracil and platinum-based chemotherapy only as the first-line treatment. FcγRIIA and IIIA polymorphisms were assessed, and their associations with efficacy in both settings were analyzed. In patients treated with trastuzumab, the FcγRIIA H/H genotype was associated with significantly superior progression-free survival (PFS) (hazard ratio [HR] [95% CI]: 0.36 [0.16–0.82], adjusted HR [95% CI]: 0.18 [0.07–0.48], P=0.001). When combining FcγRIIA and IIIA polymorphisms, the FcγRIIA H/H or FcγRIIIA V/V genotype was associated with a significantly improved disease control rate (P=0.04) and PFS (HR [95% CI]: 0.29 [0.13–0.67], adjusted HR [95% CI]: 0.17 [0.07–0.45], P<0.001). As expected, no association of FcγRIIA and IIIA polymorphisms with efficacy was found in patients receiving chemotherapy only. We concluded that FcγRIIA and IIIA polymorphisms might predict disease control rate and PFS in metastatic gastric cancer patients receiving trastuzumab treatment.

CD55 and CD59 expression protects HER2-overexpressing breast cancer cells from trastuzumab-induced complement-dependent cytotoxicity

A large proportion (40–60%) of patients with human epidermal growth factor receptor 2 (HER2)-overexpressing breast cancer do not benefit from trastuzumab treatment, potentially due to the lack of complement-dependent cytotoxicity (CDC) activation. In the present study, the effect of complement decay-accelerating factor (CD55) and CD59 glycoprotein precursor (CD59) expression on trastuzumab-induced CDC in HER2-positive breast cancer cell lines was investigated. The CD55 and CD59-overexpressing and HER2-positive cell lines SK-BR-3 and BT474 were selected for subsequent experiments. Blocking CD55 and CD59 function using targeting monoclonal antibodies significantly enhanced the cell lysis of SK-BR-3 and BT474 cells following treatment with trastuzumab. In addition, following treatment with 0.1 U/ml phosphatidylinositol-specific phospholipase C (PI-PLC) for 1 h, CD55 and CD59 surface expression was significantly decreased, and the cell lysis rate was further enhanced. Treatment of SK-BR-3 cells with short hairpin RNA (shRNA) targeting CD55 and CD59 downregulated CD55 and CD59 expression at the mRNA and protein levels, and resulted in significantly enhanced trastuzumab-induced CDC-dependent lysis. The data from the present study suggested that CD55 and CD59 serve roles in blocking trastuzumab-induced CDC, therefore strategies targeting CD55 and CD59 may overcome breast cancer cell resistance to trastuzumab. The results from the present study may provide a basis for developing suitable, personalized treatment strategies to improve the clinical efficacy of trastuzumab for patients with HER2-positive breast cancer.

641P - FcγR IIA and IIIA polymorphisms predict clinical outcome of trastuzumab treated metastatic gastric cancer

Trastuzumab has substantial anti-tumor activity in metastatic gastric cancer, and one mechanism is antibody-dependent cell-mediated cytotoxicity (ADCC), which has been reported to be influenced by FcγR II A and III A polymorphisms. This retrospective study is the first to assess their impact on trastuzumab efficacy in patients with metastatic gastric cancer. We retrospectively included 42 Her-2 positive patients receiving fluorouracil and platinum based chemotherapy and trastuzumab, and 68 Her-2 negative patients receiving fluorouracil and platinum based chemotherapy only as first line treatment. FcγR II A and III A polymorphisms were assessed and their associations with efficacy in both settings were analyzed. In patients treated with trastuzumab, FcγR II A H/H genotype was associated with significantly superior progression-free survival (PFS) (hazard ratio (HR) and 95% confidence interval (CI): 0.36 (0.16-0.82), adjusted HR and 95% CI: 0.18 (0.07-0.48), P = 0.001). Combining FcγR II A and III A polymorphisms, FcγR II A H/H or FcγRIII A V/V genotype was associated with significantly improved disease control rate (DCR) (P = 0.04) and PFS (HR and 95% CI: 0.29 (0.13-0.67), adjusted HR and 95% CI: 0.17 (0.07-0.45), P < 0.001). As expected, no association of FcγR II A and III A polymorphisms with efficacy was identified in patients receiving chemotherapy only. FcγR II A and III A polymorphisms might predict DCR and PFS in metastatic gastric cancer receiving trastuzumab treatment.

Abstract A33: Physical intimacy of breast cancer cells with mesenchymal stem cells elicits trastuzumab resistance through Src activation

Abstract The development of resistance to trastuzumab is a major obstacle for lasting effective treatment of patients with ErbB2-overexpressing tumors. Here, we demonstrate that the physical contact of breast cancer cells with mesenchymal stem cells (MSCs) is a potential modulator of trastuzumab response by activation of nonreceptor tyrosine kinase c-SRC (Src) and down regulation of phosphatase and tensin homolog (PTEN). In this study we demonstrate a method for controlling breast cancer cells adhesion on polyelectrolyte multilayer (PEM) films without the aid of adhesive proteins/ligands to study the role of tumor and stromal cell interaction on cancer biology. Numerous studies have explored engineering co-culture of tumor and stromal cells predominantly using transwell co-culture of stromal cells cultured onto cover slips that were subsequently added to tumor cell cultures. However, these systems imposed an artificial boundary that precluded cell-cell interactions. To our knowledge this is the first demonstration of patterned co-culture of tumor cells and stromal cells that captures the temporal changes in the miRNA signature as the breast tumor develops through various stages. In this study we utilized cancer cells derived from two different tumor stages and two different stromal cells to effectively model heterogeneous tumor microenvironment and emulate various tumor stages. The co-culture model mimics the proliferative index (Ki67 expression) and tumor aggressiveness (HER-2 expression) akin to those observed in clinical tumor samples. We also demonstrated that our patterned co-culture model captures the temporal changes in the miRNA-21 and miRNA-34 signature as the breast tumor develops through various stages. Using our patterned breast cancer/MSC co-culture model, we find that the presence of MSCs results in Src activation that is missing in cancer cells monoculture, transwell co-culture, and cells treated with MSCs conditioned media. Interestingly, the co-culture model also results in PTEN loss and activation of PI3K/AKT pathway that has been demonstrated as fundamental proliferative and survival pathways in clinical settings. In addition, breast cancer cells in co-culture with MSCs conferred trastuzumab resistance in vitro as observed in the lack of inhibition of proliferative and migrative properties of the cancer cells. Our findings show that MSCs are potent mediators of resistance to trastuzumab and might reveal targets to enhance trastuzumab efficacy in patients. The engineered co-culture platform lays groundwork towards precision medicine wherein patient-derived tumor cells can be incorporated within our in vitro models to identify potential pathways and drug treatment regimens for individual patients. Citation Format: Srivatsan Kidambi. Physical intimacy of breast cancer cells with mesenchymal stem cells elicits trastuzumab resistance through Src activation. [abstract]. In: Proceedings of the AACR Special Conference: Function of Tumor Microenvironment in Cancer Progression; 2016 Jan 7–10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2016;76(15 Suppl):Abstract nr A33.

Abstract P3-07-34: Predictive role of stromal tumor infiltrating lymphocytes (TILs) in patients with metastatic HER2-positive breast cancer (BC) treated with trastuzumab

Abstract Background:Prognostic significance of stromal TILs in metastatic BC has been suggested in various BC subtypes. However, predictive role of stromal TILs for the efficacy of trastuzumab has not been established in patients with HER2-positive BC. This study was performed to evaluate whether the stromal TILs are associated with the efficacy of trastuzumab in patients with metastatic HER2-positve BC. Method:Between June 2006 and March 2013, a total of 60 women with recurrent or metastatic HER2-positive BC treated with trastuzumab were included in this retrospective analysis. In these patients, trastuzumab was administered either as single agent or combination with taxanes. Stromal TILs were assessed using immunohistochemistry in surgical specimen (n=39, 65%) and biopsy specimen of metastatic lesion (n=21, 35%) by the academic pathologist (HJL). Primary endpoint of this study was progression-free survival (PFS), and secondary endpoints were response rate and overall survival (OS). Result:Median age was 54 year old (range, 36-76), and all patients had invasive ductal carcinoma. Hormone receptor was positive in 34 patients (57%) and 18 patients (30%) initially presented with metastatic disease. Nine patients (15%) received cytotoxic chemotherapy without trastuzumab before the administration of trastuzumab. Patients were grouped according to the TILs (&amp;lt; 10% [n=50] and &amp;gt;10% [n=10]), and there was no significant difference in age (p=0.68), histologic grade (p=1.00), metastatic sites (p&amp;gt;0.05), and number of lines of chemotherapy before the administration of trastuzumab(p=0.33) among patients with low and high stromal TILs. High TILs were more common in hormone receptor (HR)-negative tumor compared with HR–positive tumor (31% vs 6%; p=0.02). In overall, median PFS and OS were 15.0 months (95% CI, 9.7-20.2) and 35.0 months (95% CI, 29.8-40.2), respectively. Median PFS in patients with high stromal TILs were numerically longer than that in those with low TILs (22.0 months [95% CI, 9.6-34.4] vs 14.0 months [95% CI, 9.6-18.4]; p=0.057). There was no difference in response rates (p=0.43) and OS (p=0.94) according to the stromal TILs. FcR genotype was not significantly correlated with objective response rate, PFS and OS. Conclusion:This study suggests that the stromal TILs might be associated with the clinical outcomes of HER2-targeted therapy in patients with metastatic HER2-positive BC. Our finding should be validated in future studies based on a large sample size. Keywords: Breast cancer, tumor infiltrating lymphocyte. Trastzumab, HER2. Citation Format: Yoon JA, Yoo C, Lee HJ, Kim K-P, Kim J, Ahn J-H, Jung KH, Gong G, Kim S-B. Predictive role of stromal tumor infiltrating lymphocytes (TILs) in patients with metastatic HER2-positive breast cancer (BC) treated with trastuzumab. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-07-34.

Physical Intimacy of Breast Cancer Cells with Mesenchymal Stem Cells Elicits Trastuzumab Resistance through Src Activation.

The development of resistance to trastuzumab is a major obstacle for lasting effective treatment of patients with ErbB2-overexpressing tumors. Here, we demonstrate that the physical contact of breast cancer cells with mesenchymal stem cells (MSCs) is a potential modulator of trastuzumab response by activation of nonreceptor tyrosine kinase c-Src and down regulation of phosphatase and tensin homolog (PTEN). Using an in vitro patterned breast cancer/MSC co-culture model, we find that the presence of MSCs results in Src activation that is missing in cancer cells monoculture, transwell co-culture, and cells treated with MSCs conditioned media. Interestingly, the co-culture model also results in PTEN loss and activation of PI3K/AKT pathway that has been demonstrated as fundamental proliferative and survival pathways in clinical settings. To our knowledge, this is the first report that showed PTEN loss without the use of chemical inhibitors, matrix stiffness, or silencing RNAs. In addition, breast cancer cells in co-culture with MSCs conferred trastuzumab resistance in vitro as observed in the lack of inhibition of proliferative and migrative properties of the cancer cells. Our findings show that MSCs are potent mediators of resistance to trastuzumab and might reveal targets to enhance trastuzumab efficacy in patients.

1966 Study of the impact of Charlson comorbidity index on the efficacy of adjuvant trastuzumab in patients with HER2-positive early breast cancer

1966 Study of the impact of Charlson comorbidity index on the efficacy of adjuvant trastuzumab in patients with HER2-positive early breast cancer

Exploratory analysis to investigate clinical factors that may influence trastsuzumab efficacy in patients with HER2-positive gastric cancer.

169 Background: ToGA study showed significant survival benefit of trastuzumab in patients with HER2 positive gastric cancer (GC); however, clinical factors which can impact its efficacy prior to treatment are still unknown. Hence, we conducted this exploratory analysis whether clinical factors could influence trastuzumab efficacy in patients with HER2 positive GC. Methods: Thirty-three HER2 positive GC patients, who were treated by trastuzumab with chemotherapy in our institute from 2011 March to 2012 December, were enrolled. Clinical factors according to ToGA study and tumor markers were examined. We retrospectively analyzed whether these clinical factors were associated with progression-free survival (PFS) and overall survival (OS). These endpoints were estimated using by Kaplan-Meier methods and compared by the log-rank test. The Cox regression analysis including only clinical factors of which p-value was less than 0.02 was done. Results: Median follow-up period was 10.8 months. Median age was 63 y.o. and 64% of the patients were male. PS 0-1, GEJ cancer, visceral metastasis (lung or liver), previous gastorectomy, previous chemotherapy, number of metastatic site (1-2), and number of metastatic lesion (1-4) were found in 97%, 27%, 58%, 36%, 21%, 76%, and 27% of the patients, respectively. Sixty-seven% and 94% of the patients were differentiated type and HER2 3+ by IHC, respectively. Baseline median CEA and CA19-9 levels were 5.2 ng/ml and 109.4 U/ml, respectively. Median PFS was 9.5 months (95% CI: 5.5-13.5) and median OS was not reached. Overall response rate by RECIST was 71.4%. Lower CA19-9 levels were associated with longer PFS in univariate analysis. Patients who had lower CA 19-9 levels showed a median PFS of 12.2 months vs. 6.9 months for patients who had higher CA19-9 levels (HR: 0.41 [95%CI: 0.17-1.00], p=0.042), however this result was not conserved in multivariate analysis. No clinical factors were associated with OS. Conclusions: Lower CA19-9 levels were associated with favorable PFS in the patients with HER2 positive GC upon when treated by trastuzunab. External clinical validations and further molecular analyses are needed to validate this result.

Abstract 4065: Regulation of luminal breast cancer stem cells by HER2 does not require gene amplification providing a potential molecular explanation for the efficacy of adjuvant trastuzumab in patients with “clinically HER2-negative” breast cancer.

Abstract Although current breast treatment guidelines limit the use of HER2 blocking agents such as trastuzumab to women whose tumors display HER2 gene amplification, recent retrospective analysis by several groups have suggested that in the adjuvant setting a wider group of patients whose tumors do not display HER2 amplification may also benefit from this therapy. We hypothesized that these unanticipated results might be explained by the cancer stem cell (CSC) hypothesis. We previously demonstrated that HER2 was an important regulator of CSCs in HER2 amplified breast cancers. We now utilize breast cancer cell lines, mouse xenograft and matched human primary and metastatic tumor samples to demonstrate that HER2 is selectively expressed in and regulates the self-renewal of CSC populations in ER-positive luminal breast cancers which do not display HER2 amplification. In luminal MCF7 and ZR-75-1 breast cancer cells, as well as in primary human tumors, we demonstrate an association between cells which express HER2 and the stem cell marker aldehyde dehydrogenase (ALDH1). In vitro trastuzumab reduced the CSC population as assessed by tumorsphere formation or ALDH expression while no such effects were scene in basal/claudin-low MDA-MB-231 and SUM159 cells. In mouse luminal tumor xenografts, the effects of trastuzumab were highly dependent on the timing of administration. While the effects of trastuzumab on established tumors were limited to those with HER2 amplification, trastuzumab administration begun immediately after tumor inoculation blocked the growth of luminal tumors which did not display HER2 amplification. HER2 expression was increased in luminal tumors grown in mouse bone xenografts, as well as in bone metastasis from patients with luminal breast cancer compared to matched primary tumors. Furthermore, this increase in HER2 protein expression was not due to gene amplification, but rather was mediated by RANK ligand in the bone microenvironment. These studies suggest that the clinical efficacy of adjuvant trastuzumab may relate to the ability of this agent to target the CSC population in a process that does not require HER2 gene amplification. Furthermore, these studies support a CSC model in which maximal clinical benefit is achieved when CSC targeting agents are administered in the adjuvant setting. Citation Format: Korkaya Hasan, Fayaz Malik, Kathleen C. Day, Suthinee Ithimakin, April Davis, Ahmed A. Quraishi, Nader Tawakkol, Kathleen Woods Ignatoski, Dafydd Thomas, Shawn G. Clouthier, Max S. Wicha. Regulation of luminal breast cancer stem cells by HER2 does not require gene amplification providing a potential molecular explanation for the efficacy of adjuvant trastuzumab in patients with “clinically HER2-negative” breast cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4065. doi:10.1158/1538-7445.AM2013-4065

Trastuzumab for Patients With Axillary-Node–Positive Breast Cancer: Results of the FNCLCC-PACS 04 Trial

To evaluate the efficacy of trastuzumab in patients with node-positive breast cancer treated with surgery, adjuvant chemotherapy, radiotherapy, and hormone therapy if applicable. Three thousand ten patients with operable node-positive breast cancer were randomly assigned to receive adjuvant anthracycline-based chemotherapy with or without docetaxel. Patients who presented human epidermal growth factor receptor 2 (HER2) -overexpressing tumors were secondary randomly assigned to either a sequential regimen of trastuzumab (6 mg/kg every 3 weeks) for 1 year or observation. The primary end point was disease-free survival (DFS). Overall 528 patients were randomly assigned between trastuzumab (n = 260) and observation (n = 268) arm. Of the 234 patients (90%) who received at least one administration of trastuzumab, 196 (84%) received at least 6 months of treatment, and 41 (18%) discontinued treatment due to cardiac events (any grade). At the date of analysis (October 2007), 129 DFS events were recorded. Random assignment to the trastuzumab arm was associated with a nonsignificant 14% reduction in the risk of relapse (hazard ratio, 0.86; 95% CI, 0.61 to 1.22; P = .41, log-rank stratified on pathologic node involvement). Three-year DFS rates were 78% (95% CI, 72.3 to 82.5) and 81% (95% CI, 75.3 to 85.4) in the observation and trastuzumab arms, respectively. After a 47-month median follow-up, 1 year of trastuzumab given sequentially after adjuvant chemotherapy was not associated with a statistically significant decrease in the risk of relapse.

Immunoglobulin G fragment C gamma receptor (FcGR) polymorphisms and efficacy of single-agent trastuzumab in patients treated with metastatic breast cancer.

Abstract Abstract #6073 Background: Antibody-dependent cell-mediated cytotoxicity (ADCC) may be involved in antitumor effect of therapeutic monoclonal antibodies and their effector functions are induced following the interactions of IgG with FcGR. Studies have shown that FcGRIIIa-V158F and FcGRIIa-H131R polymorphisms may predict response to retuximab, cetuximab in patients with follicular lymphoma, colorectal cancer, and recently, trastuzumab-combined chemotherapy in breast cancer patients (J Clin Oncol 25; 1789, 2008). We tested the hypothesis of whether these two polymorphisms are associated with clinical outcome in metastatic breast cancer patients treated with single-agent trastuzumab treatment.&amp;#x2028; Patients and Methods: Patients with HER2-positive (HercepTest (3+) or (2+) with gene amplification either in primary or metastatic site) metastatic breast cancer were enrolled onto this prospective study. Eligible patients were hormone receptor negative or endocrine therapy resistant, and had received no prior chemotherapy for metastatic disease. Study patients received single agent trastuzumab at a loading dose of 4 mg/kg followed by 2 mg/kg per week until disease progression. The first clinical response was assessed at 8 week. FcGRIIIA-V158F and FcGRIIA-H131R genotypes were assessed from genomic DNA extracted from peripheral blood samples. The present study has been approved by the institutional review boards of National Cancer Center and Shikoku Cancer Center Hospital and all registered patients have given written consent to participate in this study.&amp;#x2028; Results: To date, 33 patients have been enrolled. The frequency of FcGRIIIa-V158F genotypes were V/V 48%, V/F45%, F/F 6%, and that of FcGRIIA-H131R genotypes were H/H 59%, H/R38%, R/R 3% , respectively. 8-wk response could be evaluated in 29 patients (CR 1, PR 4, SD 13, PD 11). Clinical benefit was observed in 13 patients (CR 1, PR 6, SD&amp;gt;6months 6). FcGRIIIa-158V/V genotype was significantly correlated with 8-wk response (p=.017) and clinical benefit (p=0.02) of single-agent trastuzumab, while there was no significant difference in clinical response to trastuzumab by FcGRIIA-H131R polymorphism.&amp;#x2028; Conclusion: Although still preliminary, these data support the previous finding that FcGRIIIa-V158F polymorphisms play an important role in the clinical activity of trastuzumab. Updated results will be presented at the 31st annual San Antonio Breast Cancer Symposium. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6073.

Overexpression of the HER-2/neu oncogene in pancreatic adenocarcinoma.

Novel systemic treatments are needed in pancreatic cancer. The authors sought to establish the frequency of overexpression of the HER-2/neu oncogene in patients with pancreatic adenocarcinoma to determine the potential role of trastuzumab (Herceptin) as a therapeutic agent in this disease. Tumor specimens from patients with pancreatic adenocarcinoma were analyzed by staining for p185HER2 protein using the DAKO immunohistochemical assay. Patients with and without HER-2/neu overexpression by immunohistochemistry were compared with respect to clinical and pathologic characteristics. HER-2/neu gene amplification was also evaluated by fluorescence in situ hybridization (FISH). Thirty-two of 154 patients (21%) had pancreatic adenocarcinoma that demonstrated HER-2/neu overexpression by immunohistochemistry. At initial diagnosis, 16% of resectable cancers, 17% of locally advanced cancers, and 26% of metastatic cancers were determined to have HER-2/neu overexpression. Three of 11 (27%) patients with HER-2/neu overexpression by immunohistochemistry had gene amplification by FISH. HER-2/neu overexpression occurs in a subset of pancreatic cancer. Evaluation of the efficacy of trastuzumab for patients with pancreatic cancer who overexpress HER-2/neu appears indicated.