Single-agent Trastuzumab Research Articles

Abstract P1-08-23: Potential biomarkers of long-term benefit from single-agent trastuzumab or lapatinib in HER2-positive metastatic breast cancer

Abstract Purpose: In 2009 we started a prospective, randomized Phase II trial to evaluate HER2-targeting without chemotherapy (CT) in HER2-positive (HER2+) metastatic breast cancer (MBC) patients (pts). Although the study was prematurely closed because of slow accrual, we decided to analyze the primary tumors in order to identify possible biomarkers that could identify, among the enrolled pts, those deriving the longest lasting benefit from HER2-targeting without CT. Experimental Design: In the HERLAP study (NCT00842998), pts with HER2+ MBC were randomized to trastuzumab or lapatinib as first-line therapy. Patients showing radiological signs of tumor regression after 8 weeks of treatment were allowed to continue on single agent anti-HER2 therapy until disease progression. CT was added to anti-HER-2 therapy in pts failing to achieve tumor regression at the 8-week evaluation and in those progressing at any time. Expression analysis of 105 selected genes was performed from formalin-fixed paraffin-embedded primary tumor samples. The research-based PAM50 intrinsic subtypes (Luminal A, Luminal B, HER2-enriched and Basal-like) and the normal breast-like group were also identified. Additionally, quantitative HER2 (H2T) and p95HER2 (p95) protein expression were evaluated using the HERmark® assay and the p95 VeraTag® assay, respectively. Potential predictors of persistence on protocol (PP, time from randomization to addition of chemotherapy to anti HER2-therapy or death from any cause) were studied by univariate and multivariate analysis. Results: Nineteen patients were enrolled. Median overall survival was 43 months and median PP was 3.8 months (0.8-38.8+) with 4 pts (21.1%) persisting on single agent T or L for longer than 12 months (14.9-38.8+ months). Seventeen pts were evaluable for PP. Gene expression analysis revealed that high expression of the 17q12-21 amplicon genes HER2 and GRB7, and the PAM50 HER2-enriched intrinsic profile, were significantly associated with longer PP. Conversely, high expression of luminal-related genes such as PGR, MDM2 and PIK3CA, or the PAM50 luminal intrinsic profile, were found associated with reduced PP. Quantitative H2T and p95 expression revealed that, increasing H2T/p95 ratio significantly associated with longer PP (HR 0.969, p = 0.010). When analyzed as a multivariable model, PAM50 intrinsic subtype and H2T/p95 ratio dichotomized around the median value independently predicted for longer PP (PAM50 non-luminal vs. Luminal A+B, HR 0.164, p = 0.078 and H2T/p95 ratio higher vs. lower/equal, HR 0.294, p = 0.062 respectively). Conclusions: Our data suggest that tumors belonging to the PAM50 “HER2-enriched” subtype tumors and/or with high H2T/p95 protein expression ratio are exquisitely sensitive to anti HER2-agents. MBC pts with these tumors may be candidates for studies aimed at establishing chemotherapy-free approaches. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-08-23.

Abstract P5-08-03: In vitro resistance to ERBB2-targeted therapies does not bestow cross-resistance to antibody dependent cellular cytotoxicity

Abstract Background: The advent of ERBB2-directed therapies, including trastuzumab and lapatinib, has changed the clinical management of ERBB2+ breast cancer and improved patient outcomes. However, both de novo and acquired resistance to ERBB2-targeting agents remain significant clinical problems; thus, it is important to understand the mechanisms that tumor cells use to resist and/ or escape ERBB2-directed therapeutic agents. A growing body of evidence supports the role of immune effector cells in trastuzumab-induced tumor cell lysis in vivo, which is hypothesized to occur through antibody dependent cellular cytotoxicity (ADCC) mediated by natural killer cells bearing FC gamma receptors. Existing in vitro models of trastuzumab and lapatinib resistance are limited in that they are most often generated by incubating tumor cells with drug alone, outside the context of the host immune system. Consequently, the impact of in vitro generated drug resistance on ADCC susceptibility has not been defined. In this study, we tested existing trastuzumab and lapatinib resistant breast cancer cell lines for ADCC sensitivity. Materials and Methods: The ERBB2 amplified breast cancer cell lines BT474 and SKBR3, which are sensitive to trastuzumab-mediated ADCC, were selected for trastuzumab and lapatinib resistance. Drug resistant cells were generated by serial culture in the presence of escalating doses of trastuzumab and/or lapatinib until complete tolerance was acquired at clinically achievable concentrations (100μg/ml trastuzumab and 2.6μM lapatinib). Drug sensitivity was assessed by Alamar Blue assay. Cell resistance to trastuzumab-mediated ADCC was measured by Calcein-AM release assay, using 1μg/ml antibody concentration and four different effector target ratios (20:1, 10:1, 5:1, and 1:1), with a minimum of five replicates. Human peripheral blood lymphocytes freshly isolated from buffy coat were used as effector cells. Results and Discussion: Neither BT474 nor SKBR3 cells with acquired resistance to single agent trastuzumab (HerR), lapatinib (LapR), or both in combination (DualR) demonstrated cross-resistance to effector cell-mediated ADCC at any of the E:T ratios tested. At the highest E:T ratio tested (20:1), trastuzumab-induced ADCC of control BT474 cells resulted in 61.92% cell lysis (95% CI = 3.97), compared to 64.97% lysis for BT-HerR cells (95% CI = 2.87, Student's t-test p > 0.1). Similarly, BT-LapR and DualR cell lysis was 58.13% and 63.66%, respectively (95% CI = 2.62 and 6.57, Student's t-test p > 0.1). Additionally, trastuzumab-induced ADCC of control SKBR3 cells resulted in 89.98% cell lysis (95% CI = 4.29), compared to 93.53% lysis for SK-HerR cells (95% CI = 0.81, Student's t-test p > 0.1). SK-LapR and DualR cell lysis was 94.81% and 92.09%, respectively (95% CI = 0.6 and 2.66, Student's t-test p > 0.1). Our results indicate the importance of incorporating immune effector cells to in vitro models of trastuzumab resistance. Accordingly, we have begun modeling ADCC resistance in vitro to further investigate the relationship between targeted antibody therapies, effector cell-mediated cytolysis, and mechanisms of tumor immune escape. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-08-03.

Abstract A112: Combined targeting of HER2 and HER3 inhibits tumor growth in both trastuzumab-sensitive and trastuzumab-resistant breast cancer models.

Abstract HER3 (ERBB3) is a tumor driver in divergent cancer types with high HRG levels or heightened EGFR or HER2 kinase activity via growth signal coupling to the PI3K-AKT pathway. HER3 lacks intrinsic tyrosine kinase activity but is capable of signaling after heterodimerizing with tyrosine kinase ERBB family members EGFR or HER2. Heterodimer formation is driven either by the binding of heregulin (NRG1/HRG) to HER3 (ligand dependent - LD), or alternatively, by overexpression of EGFR or HER2 (ligand-independent - LI). Preclinical evaluation of MEDI3379, a human IgG1 modified monoclonal anti-HER3 antibody that antagonizes both LD and LI signaling, demonstrated tumor growth inhibition in the HER2-expressing MDA-MB-361 breast cancer xenograft model. Anti-tumor activity of MEDI3379 in this model was increased in combination with the HER2-targeting drug trastuzumab to a greater extent than MEDI3379 when combined with either lapatinib or pertuzumab. Combined inhibition of HER2 and HER3 led to strong reduction in pHER3. Unexpectedly, co-administration of MEDI3379 together with trastuzumab in MDA-MB-361 tumor-bearing mice but not in naïve mice resulted in reduced serum levels of trastuzumab. A control antibody combined with trastuzumab in MDA-MB-361 tumor bearing mice did not have this effect. Furthermore, in the trastuzumab-resistant JIMT-1 breast cancer xenograft model which has high HRG and pHER3 levels MEDI3379 but not pertuzumab resensitized JIMT-1 tumors to trastuzumab resulting in synergistic anti-tumor activity and a reduction of pHER3. In vivo resistance to this regimen appeared with prolonged treatment of JIMT-1 tumors and was accompanied by a decrease in homogenous expression of HER2. In conclusion, the use of MEDI3379 in combination with trastuzumab in HER2-amplifed breast cancer cell lines has demonstrated additional tumor growth inhibition over single agent trastuzumab and overcoming trastuzumab-resistance mechanisms. This combination warrants further evaluation in preclinical and clinical studies. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A112. Citation Format: Philipp Steiner, Leslie Wetzel, Kevin Schifferli, Raymond Rothstein, Ravinder Tammali, Marlon Rebelatto, Zhan Xiao, Andrew Pierce, Robert Hollingsworth. Combined targeting of HER2 and HER3 inhibits tumor growth in both trastuzumab-sensitive and trastuzumab-resistant breast cancer models. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A112.

Abstract C104: Preclinical sensitivity of low and high-HER2 expressing START-PDX breast models to T-DM1 and effects of HER3 expression on drug antitumor activity.

Abstract Background: Ado-trastuzumab emtansine (T-DM1), a recently approved antibody-drug conjugate (ADC), is comprised of the monoclonal antibody trastuzumab linked to the cytotoxic agent mertansine. Trastuzumab targets and inhibits growth of HER2/neu-receptor expressing tumors and mertansine enters and kills the cells by binding to tubulin. Trastuzumab alone is sufficient to effectively treat high (3+) HER2-expressing breast cancers; however, whether T-DM1 is effective in lower HER2-expressing cancers is unclear. To better understand how HER-2 expression correlates with activity of trastuzumab or T-DM1 we characterized HER2 expression in our START-PDX breast panel and screened trastuzumab and T-DM1 efficacy in each model. Study endpoints included tumor volume and time from treatment initiation. Reported results included tumor growth inhibition or delay and regression. Methods: Methods: START-PDX breast models were established in immune-deficient mice from primary or metastatic patient tissue and once established were confirmed by histologic comparative analysis and linked with patient treatment and outcome data. For each model, DNA was extracted and subjected to exon sequencing of 207 known oncogenes; growth factor receptor and ligand densities were interrogated using immunohistochemistry and quantitative RNA in situ hybridization. Drug sensitivity studies were performed evaluating sensitivity of models to single agent trastuzumab and T-DM1, administered for at least four weeks. Study endpoints included tumor volume and time from treatment initiation with tumor growth inhibition, delay and regression reported at study completion. Results: HER2 or HER3 and comparative heregulin expression occurred in 67% of models. EGFR expression was reported in 50% of models Efficacy studies revealed T-DM1 but not trastuzumab was active both in several high- and low-HER2 expressing models. Interestingly, models reporting higher T-DM1 sensitivity had no detectable HER3 expression. For example ST996 and ST910 showed similar HER2 and EGFR expression but ST996 (HER3 3+) was insensitive to T-DM1 whereas ST910 (HER3 0+) reported significant tumor growth inhibition compared with control. Conclusion: We have established a panel of breast PDX models and characterized mutation status, receptor and ligand density and drug sensitivity. We found T-DM1 active towards a number of breast PDX models even with low HER2 expression. HER3 co-expression may serve as a negative predictor for T-DM1 activity. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C104. Citation Format: Michael J. Wick, Jennifer Brown, Teresa L. Vaught, Justin Meade, Anthony W. Tolcher, Drew Rasco, Amita Patnaik, Amy Lang, Murali Beeram, Kyriakos P. Papadopoulos. Preclinical sensitivity of low and high-HER2 expressing START-PDX breast models to T-DM1 and effects of HER3 expression on drug antitumor activity. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C104.

Potential biomarkers of long-term benefit from single-agent trastuzumab or lapatinib in HER2-positive metastatic breast cancer

In 2009 a prospective, randomized Phase II trial (NCT00842998) was initiated to evaluate the activity of HER2-targeting agents without chemotherapy (CT) in HER2-positive metastatic breast cancer (MBC) patients. The primary tumors of the patients enrolled in this study offered a unique opportunity to identify biomarkers that could predict durable clinical benefit from CT-free anti-HER2 therapy.Patients with HER2-positive MBC were randomized to trastuzumab or lapatinib as first-line therapy. CT was added to anti-HER2 therapy in patients failing to achieve tumor regression at the 8-week evaluation and in those progressing at any time. Expression analysis of 105 selected genes was performed from formalin-fixed paraffin-embedded primary tumor samples. The research-based PAM50 intrinsic subtypes were also identified. Additionally, quantitative HER2 (H2T) and p95HER2 (p95) protein expression were evaluated by HERmark® and VeraTag® assay, respectively. Predictors of persistence on protocol (PP) were studied by Cox univariate and multivariate analysis.Nineteen patients were enrolled. Median overall survival was 43 months and median PP was 3.8 months (0.8–38.8+), with 4 patients (21.1%) persisting on single agent trastuzumab or lapatinib for longer than 12 mo (14.9–38.8 + mo). Seventeen patients were evaluable for PP. Gene expression analysis revealed that high expression of the 17q12-21 amplicon genes HER2 and GRB7, and the PAM50 HER2-enriched intrinsic profile, were significantly associated with longer PP. Conversely, high expression of luminal-related genes such as PGR, MDM2 or PIK3CA, or the PAM50 luminal intrinsic profile correlated with reduced PP. Moreover, increasing H2T/p95 ratio was found to be significantly associated with longer PP (HR 0.56 per 2-fold increase in H2T/p95, P = 0.0015).Our data suggest that patients belonging to the “HER2-enriched” subtype and/or having high H2T/p95 protein expression ratio are exquisitely sensitive to anti-HER2 agents. MBC patients with these tumors could be candidates for studies aimed at establishing chemotherapy-free regimens.

Our Takeaways from the San Antonio Breast Cancer Symposium

Our Takeaways from the San Antonio Breast Cancer Symposium

Epithelial-to-mesenchymal transition (EMT) confers primary resistance to trastuzumab (Herceptin)

The rate of inherent resistance to single-agent trastuzumab in HER2-overexpressing metastatic breast carcinomas is impressive at above 70%. Unfortunately, little is known regarding the distinctive genetic signatures that could predict trastuzumab refractoriness ab initio. The epithelial-to-mesenchymal transition (EMT) molecular features, HER2 expression status and primary responses to trastuzumab were explored in the public Lawrence Berkeley Laboratory (LBL) Breast Cancer Collection. Lentivirus-delivered small hairpin RNAs were employed to reduce specifically and stably the expression of EMT transcription factors in trastuzumab-refractory basal/HER2+ cells. Cell proliferation assays and pre-clinical nude mice xenograft-based studies were performed to assess the contribution of specific EMT transcription factors to inherent trastuzumab resistance. Primary sensitivity to trastuzumab was restricted to the SLUG/SNAIL2-negative subset of luminal/HER2+ cell lines, whereas all of the SLUG/SNAIL2-positive basal/HER2+ cell lines exhibited an inherent resistance to trastuzumab. The specific knockdown of SLUG/SNAIL2 suppressed the stem-related CD44+CD24-/low mesenchymal immunophenotype by transcriptionally upregulating the luminal epithelial marker CD24 in basal/HER2+ cells. Basal/HER2+ cells gained sensitivity to the growth-inhibitory effects of trastuzumab following SLUG/SNAIL2 gene depletion, which induced the expression of the mesenchymal-to-epithelial transition (MET) genes involved in promoting an epithelial phenotype. The isolation of CD44+CD24-/low mesenchymal cells by magnetic-activated cell sorting (MACS) confirmed their intrinsic unresponsiveness to trastuzumab. A reduction in tumor growth and dramatic gain in sensitivity to trastuzumab in vivo were confirmed when the SLUG/SNAIL2 knockdown basal/HER2+ cells were injected into nude mice. HER2 overexpression in a basal, rather than in a luminal molecular background, results in a basal/HER2+ breast cancer subtype that is intrinsically resistant to trastuzumab. EMT transcription factors might induce an enhanced phenotypic plasticity that would allow basal/HER2+ breast cancer cells to “enter” into and “exit” dynamically from trastuzumab-responsive stem cell-like states. The systematic determination of SLUG/SNAIL2 as a stem/CD44+CD24-/low cell-associated protein may improve the therapeutic management of HER2+ breast carcinomas.

AJ-3 - HER2-Neu in Breast Cancer: History and Future Directions

ABSTRACT Shortly after discovery of epidermal growth factor receptor (EGFR) as an inducer of increased cell growth [1], Weinberg et al. characterized Neu oncogene in rat neuro/glioblastomas [2,3] and later its human homolog was called Human Epidermal growth factor Receptor 2 (HER2) [4]. Then amplification was shown in human breast carcinoma cell lines [5] (Figure 1). Slamon et al. identified that 30% of patients with primary breast cancers harbored HER2 amplification which negatively correlated with survival [6]. In early 1990s, a humanized monoclonal antibody against domain IV of HER2 (trastuzumab, Herceptin®) was developed and it was found to be safe and active in HER+ breast cancer patients. Soon the Chemotherapy and Antibody Response Evaluation (CARE) trial of trastuzumab in combination with chemotherapy was launched for metastatic breast cancer (MBC). This randomized study showed significant improvement in median time to progression (TTP) in combination with trastuzumab and chemotherapy arm compared with chemotherapy alone arm (4.6–7.4 months) [7]. Based on the results of this randomized phase III trial and a single-arm single agent trastuzumab study [8], trastuzumab was approved in HER + MBC in combination with paclitaxel in first and as single agent in second-line setting, respectively. The clear additional benefit of trastuzumab to chemotherapy was also shown in neo-adjuvant [9], and adjuvant settings [10,11]. Laptinib, a dual tyrosine kinase inhibitor (inh) against EGFR and HER2, is the second agent that has been approved by FDA for HER+ patients with MBC in combination with capecitabine [12,13] or letrozole [14]. The additional benefit of laptinib to trastuzumab in heavily pretreated HER2+ MBC improved PFS from 8.1 to 12 months [15]. Homo- and heterodimerization of HER receptors are essential for the signaling and HER2-HER3 heterodimer is the most potent pair in downstream signaling [16]. Pertuzumab is a humanized monoclonal antibody against domain II of HER2 that inhibits HER2 dimerization and the activation of the signaling pathway [16]. CLEOPATRA was a randomized phase III study that launched to test the efficacy of adding pertuzumab to trastuzumab plus chemotherapy (docetaxel) in first-line setting and the results clearly showed the significant improved median progression-free survival (PFS) (18.5 versus 12.4 months) in HER2+ MBC patients [17]. Despite this progress in the treatment of HER2+ breast cancer, the median PFS in CLEOPATRA study was reported to be 18.5 months, which means that half of the patients in

A phase 1 study of weekly dosing of trastuzumab emtansine (T‐DM1) in patients with advanced human epidermal growth factor 2–positive breast cancer

We conducted a phase 1, multicenter, open-label, dose-escalation study (TDM3569g) to assess the safety, tolerability, and pharmacokinetics of single-agent trastuzumab emtansine (T-DM1) administered weekly and once every 3 weeks in patients with HER2-positive metastatic breast cancer previously treated with trastuzumab. The weekly dose results are described here. Patients were administered escalating doses of T-DM1 weekly, starting at 1.2 mg/kg. Additional patients were enrolled at the maximum tolerated dose (MTD) to better characterize tolerability and pharmacokinetics. Twenty-eight patients received weekly T-DM1, and the MTD was determined to be 2.4 mg/kg. In general, T-DM1 was well tolerated, requiring few dose modifications or discontinuations because of adverse events (AEs). Grade ≥ 3 AEs were reported in 19 patients (67.9%); treatment-related AEs occurred in 25 (89.3%) patients. Exposure to weekly T-DM1 was dose-proportional at ≥ 1.2 mg/kg, and accumulation of T-DM1 and total trastuzumab was observed. Objective partial tumor responses were reported in 13 (46.4%) patients; the median duration of response was 18.6 months, and the 6-month clinical benefit rate was 57.1%. The results suggest that a weekly dose of T-DM1 2.4 mg/kg has antitumor activity and is well tolerated in patients with HER2-positive metastatic breast cancer.

Abstract 3867: Dual blockade of HER2 in HER2-overexpressing tumor cells does not eliminate HER3 function completely: Clinical implications

Abstract There is mounting evidence that the most efficacious approach to treat HER2+ breast cancer is dual blockade with HER2 inhibitors such as the monoclonal antibody trastuzumab and the tyrosine kinase inhibitor lapatinib. We examined what effect dual blockade had on HER3 protein levels. The combination of lapatinib and trastuzumab treatment increased both cell-surface and total HER3 protein levels in BT474, SKBR3, and MDA453 cells. Treatment with the HER3 neutralizing antibody U3-1287 decreased HER3 levels starting at 1 h and continuing through 24 h in these cell lines. Moreover, adding U3-1287 to lapatinib and trastuzumab reversed the upregulation of cell surface and total HER3. Addition of the HER3 antibody to lapatinib and trastuzumab treatment improved the action of lapatinib and trastuzumab as assessed by the TUNEL apoptosis assay, three-dimensional matrigel growth and two-dimensional crystal violet growth assays. We next examined the effect of dual blockade of HER2 in combination with the HER3 antibody in cells with acquired resistance to trastuzumab. Treatment with U3-1287 blocked the upregulation of HER3 that followed therapy with lapatinib and trastuzumab. In mice bearing trastuzumab resistant xenografts, there was a reduction in tumor volume of mice treated with U3-1287 and trastuzumab compared to mice treated with single agent trastuzumab, U3-1287, or vehicle. We next hypothesized that inhibition of HER3 combined with dual HER2 blockade would result in decreased tumor recurrence in vivo. Mice bearing BT474 xenografts were treated with either lapatinib and trastuzumab (L+T) or lapatinib, trastuzumab and U3-1287 (L+T+U) for 3 weeks. After 3 weeks of treatment mice from both groups exhibited almost complete tumor regressions. At 7 weeks post-treatment 5 of 10 mice (50%) in the L+T group exhibited tumor re-growth (defined as a tumor larger than 200 mm3), whereas only 1 of 12 mice (8.3%) in the L+T+U group did so (p= 0.043, fisher's exact test). We are additionally performing studies in a transgenic mouse model with conditional ablation of HER3 to further examine if lapatinib and trastuzumab do not completely eliminate HER3 function. Finally we are comparing genetic inhibition of HER3 via stable inducible shRNA to pharmacological inhibition of HER3 to determine the most efficacious approach to inhibit HER3. In summary, a HER3 inhibitor prevents the upregulation of HER3 observed with lapatinib and trastuzumab treatment and sensitizes breast cancer cells to lapatinib and trastuzumab. Moreover, lapatinib and trastuzumab in combination with a HER3 inhibitor prevent tumor recurrence better than lapatinib and trastuzumab. These data suggest dual blockade of HER2 may only be partially effective in some instances due to maintenance of active HER3 Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3867. doi:1538-7445.AM2012-3867

Marked Response to Single Agent Trastuzumab in a Patient with Metastatic HER-2 Gene Amplified Rectal Cancer

Overexpression or HER-2 gene amplification occurs in approximately 25% of invasive breast cancers and predicts response to the targeting therapeutic antibody trastuzumab (). In this report, trastuzumab was used in the treatment of a patient with metastatic colorectal cancer harboring HER-2 gene amplification and overexpression. There was a marked radiographic response to the trastuzumab. If a larger series confirms the efficacy of trastuzumab use in patients with colorectal cancers with HER-2 gene amplification, trastuzumab could help improve the outlook for patients with this unusual colorectal cancer variant.

Safety and efficacy of single-agent adjuvant trastzumab in older women with breast cancer.

TPS109 Background: Trastuzumab is a humanized monoclonal antibody targeting the extracellular domain of the human epidermal growth factor receptor 2 (HER2) protein. The addition of trastuzumab to adjuvant chemotherapy, either concomitant or sequential, leads to better outcomes for women with HER2-positive breast cancer and in the setting of metastatic disease, single agent trastuzumab is effective and extremely well tolerated. The main adverse effect of trastuzumab is cardiotoxicity, which necessitated discontinuation prior to the planned one year of therapy in 17% of women on adjuvant trials. Since age is a risk factor for the cardiotoxicity of trastuzumab, and women ≥ 65 years were under-represented in trastuzumab clinical trials, determination of the safety and efficacy of trastuzumab in this patient population is lacking. This study is designed to define the risk-benefit profile of adjuvant single-agent trastuzumab in older women. Methods: This open label, single arm, multi-center, phase II study will include 124 women with stage I-III, HER2+ (defined as either 3+ by immunohistochemistry or gene amplified by fluorescent in situ hybridization), breast cancer who undergo primary surgery (mastectomy or lumpectomy) with at least a sentinel lymph node dissection, and are unwilling to undergo or are unable to tolerate adjuvant chemotherapy. Trastuzumab will be given, at 8mg/kg IV loading dose followed by 6mg/kg IV every three weeks, for 52 weeks. Patients will be followed prospectively for five years or until death, whichever comes first. The primary objective of the study is to evaluate the three-year cumulative incidence of cardiac events. Secondary objectives include i) the three-year cumulative incidence of asymptomatic decline in Left Ventricular Ejection Fraction; ii) the five-year cumulative incidence of cardiac events; iii) three-year disease-free and overall survival; iv) identification of correlative biomarkers of cardiac events (troponin-I, N-terminal brain natriuretic protein, and pro-inflammatory cytokines); and v) the longitudinal changes in Health-related Quality of Life, functional, cognitive, and mental status. Ten patients have been enrolled thus far.

Randomized Phase II Study Comparing Efficacy and Safety of Combination-Therapy Trastuzumab and Docetaxel vs. Sequential Therapy of Trastuzumab Followed by Docetaxel Alone at Progression As First-Line Chemotherapy in Patients with HER2 + Metastatic Breast Cancer: HERTAX Trial

Background Because chemotherapy for metastatic breast cancer (MBC) is associated with relevant toxicity, sequential monotherapy trastuzumab followed by cytotoxic therapy at disease progression might be an attractive approach. Methods In a multicenter phase II trial, 101 patients with overexpression of human epidermal growth factor receptor 2 (HER2 +) MBC were randomized between combination-therapy trastuzumab (Herceptin) plus docetaxel (H+D) and sequential therapy of single-agent trastuzumab followed at disease progression by docetaxel alone (H→D) as first-line chemotherapy for metastatic disease. The primary endpoint was progression-free survival (PFS) after completed sequential or combination therapy. Results For the H+D group the median PFS was 9.4 vs. 9.9 months for the H→D group and 1-year PFS rates were 44% vs. 35%, respectively. However the overall response rates (ORRs) were 79% vs. 53%, respectively ( P = .016), and overall survival was 30.5 vs. 19.7 months, respectively ( P = .11). In the H→D group, response rates to monotherapy trastuzumab and subsequent docetaxel were 34% and 39%, respectively, with a median PFS during single-agent trastuzumab of 3.9 months. The incidence and severity of neuropathy were significantly higher in the H+D group. Retrospective analysis of trastuzumab treatment beyond progression (applied in 46% of patients in the H+D group and 37% in the H→D group) showed a correlation with longer overall survival in both treatment arms (36.0 vs. 18.0 months and 30.3 vs. 18.6 months, respectively). Conclusion First-line treatment in patients with MBC with H→D resulted in a similar PFS compared with H+D, but the response rate was lower and the overall survival nonsignificantly shorter.

Severe thrombocytopenia related to trastuzumab infusion

SummaryBackgroundTrastuzumab is a humanized, monoclonal antibody that interferes with the HER2/neu receptor and binds selectively to the HERB2 protein which causes uncontrolled proliferation of malignant breast cells.Case ReportWe report a case of severe thrombocytopenia related to trastuzumab administration. Three days after the first dose of single-agent trastuzumab, the patient was admitted to the hospital with nose bleeding, petechiae and platelet counts of 5×109/L.ConclusionsThe patient showed a self-limiting trastuzumab-related thrombocytopenia. Among the reported cases of trastuzumab-induced severe thrombocytopenia, this patient is the only one who did not interrupt trastuzumab treatment. It is possible that our patient showed progressive reduction of immune-mediated thrombocytopenia caused by trastuzumab administration.

Abstract P4-11-12: Neurocognitive Function and Quality of Life of Patients Treated within a Prospective Randomised Clinical Trial Testing the Role of Prophylactic Cranial Radiotherapy (PCI) in Patients Treated with Trastuzumab (Herceptin®) for Metastatic Breast Cancer. The Anglo Celtic VII Trial

Abstract Background. Various authors have reported a relatively high incidence of CNS metastases in patients with HER2 positive tumours receiving Trastuzumab based therapy for metastatic breast cancer. There has been concern with regard to the possible neuropsychological sequelae of PCI, although data from two prospective randomised trials assessing toxicity and quality of life after PCI for small cell lung cancer (UK02 and PCI 85) have failed to confirm this. Methods. The HER-PCI trial was a prospective randomised trial of PCI in patients with HER2 positive breast cancer who had progressive systemic disease and had Trastuzumab therapy + chemotherapy as planned treatment. Patients had a screening MRI or CT of the brain after randomisation with a view to excluding those with sub-clinical CNS disease. Neurocognitive function was assessed at baseline, 3,6 and 9 months from randomisation using EORTC QLQC30, EORTC neurological sub-scale BN20, Hospital anxiety and depression score (HADS) and the Addenbrookes Cognitive Examination (ACE-R). Patients were randomised 1:1 to no PCI or PCI delivered at around 6 weeks after the start of their systemic treatment for metastatic disease. The PCI dose was 30Gy in 10 fractions, a fraction deferred if due on a day of planned chemotherapy. Results. 51 patients entered the randomisation between March 2007 and March 2010. 25 received PCI and 26 did not. 46 (90%) of patients received Trastuzumab + chemotherapy and 5 patients single agent Trastuzumab. The mean age was 54 years. Results of the neurcognitive testing and QOL will be presented Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-11-12.

Phase II trial of trastuzumab in women with advanced or recurrent, HER2-positive endometrial carcinoma: A Gynecologic Oncology Group study

Purpose This study evaluated efficacy of single-agent trastuzumab against advanced or recurrent HER2-positive endometrial carcinoma (EC), and explored predictors for HER2 amplification. Patients and methods Eligible patients had measurable stage III, IV, or recurrent EC. There was no limit on prior therapy although total prior doxorubicin dose was limited to 320 mg/m 2. Tumors were required to have HER2 overexpression (2+ or 3+ immunohistochemical staining) or HER2 amplification (FISH HER2/CEP 17 ratio > 2.0). Trastuzumab was administered intravenously at a dose of 4 mg/kg in week 1, then 2 mg/kg weekly until disease progression. The primary endpoint was tumor response. Results Of the 286 tumors centrally screened by LabCorp, 33 (11.5%) were HER2-amplified. Three of 8 clear (38%) cell carcinomas and 7 of 25 serous carcinomas (28%) screened exhibited HER2 amplification compared with 7% (2/29) of endometrioid adenocarcinomas. HER2 overexpression was correlated with HER2 amplification ( r = 0.459; p < 0.0001). Thirty-four women were enrolled; 1 was excluded (refused treatment); and 18 had tumors with known HER2 amplification. No major tumor responses were observed. Twelve women experienced stable disease, 18 had increasing disease, and 3 were indeterminate for tumor response. Neither HER2 overexpression nor HER2 amplification appeared to be associated with progression-free survival or overall survival. Conclusion Trastuzumab as a single agent did not demonstrate activity against endometrial carcinomas with HER2 overexpression or HER2 amplification, although full planned accrual of women with HER2 amplified tumors was not achieved due to slow recruitment. Serous and clear cell endometrial carcinomas appear to be more likely to demonstrate HER2 amplification.

Perspectives and Attitudes on the Use of Adjuvant Chemotherapy and Trastuzumab in Older Adults with HER-2+ Breast Cancer: A Survey of Oncologists

Substantial evidence supports the use of adjuvant trastuzumab with chemotherapy for patients with human epidermal growth factor receptor (HER)-2(+) breast cancer; however, a lesser amount of data is available to guide use of this therapy in older patients and in those with significant medical comorbidities. The goal of the current study was to understand how patient age and health status impact oncologists' decisions to recommend adjuvant therapy in older women with HER-2(+) breast cancer. Medical oncologists (n = 151) participated in an online survey regarding treatment recommendations for a hypothetical patient of varying age and health status with tumor stage 2, nodal stage 2, estrogen receptor-negative, HER-2(+) breast cancer. Survey respondents recommended either chemotherapy plus trastuzumab, chemotherapy alone, trastuzumab alone, or no therapy. The effect of age and health status on therapeutic recommendations was assessed. As the hypothetical patient's age increased or health status deteriorated, oncologists were less likely to recommend a combination of chemotherapy plus trastuzumab. In contrast, oncologists were more likely to recommend either trastuzumab alone or no therapy for patients with advanced age and deteriorating health status. Chemotherapy alone was recommended by only 7.5% of respondents, on average. With limited evidence-based data for the treatment of older women with early-stage HER-2(+) breast cancer, medical oncologists recommend a diverse array of therapeutic approaches. With increasing age and declining health status they were less likely to recommend chemotherapy plus trastuzumab and more likely to recommend single-agent trastuzumab or no therapy.

The role of trastuzumab in the management of HER2-positive metastatic breast cancer: an updated review

Currently, trastuzumab is one of the key drugs in the treatment strategy for HER2-positive breast cancer. Although metastatic breast cancer is unlikely to be cured, some HER2-positive patients have survived for a long time with complete response to trastuzumab therapy. In HER2-positive metastatic breast cancer, single agent trastuzumab is effective and less toxic. Combination of trastuzumab with cytotoxic drugs is also effective. Therefore, major guidelines recommend using trastuzumab as a key drug in the management of HER2-positive metastatic breast cancer. However, many clinical questions still need to be solved. In this article, recent evidence was reviewed to find some answers about these issues.

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.

Cross-Talk Between the ErbB/HER Family and the Type I Insulin-Like Growth Factor Receptor Signaling Pathway in Breast Cancer

Understanding the molecular mechanisms involved in tumorigenesis and their influence on clinical outcome is providing specific molecular markers for targeted therapy. Activation of tyrosine kinase receptors from the human epidermal growth factor receptor family (EGFR, HER2, HER3, HER4) and the insulin-like growth factor receptor I (IGF-IR) plays a key role in the initiation and progression of breast cancer. HER2 overexpression is a validated therapeutic target, as shown by the clinical efficacy of trastuzumab and lapatinib. However, only 25-30% of patients with HER2-overexpressing tumors respond to single-agent trastuzumab or lapatinib, and resistance develops even in responding patients. Therefore, to optimize therapeutic efficacy, it is urgent to elucidate the complex network of signaling pathways that develop in breast cancer cells. Signaling interactions have been reported between ErbB/HER family members and IGF-IR. As increased IGF-IR signaling has been implicated in trastuzumab resistance, agents targeting HER2, and IGF-IR could be potential therapeutic tools in breast cancers that develop resistance to HER2-directed therapy.