Recombinant Humanized anti-HER2 Monoclonal Antibody Research Articles

A Phase I Clinical Study Comparing the Pharmacokinetics, Safety, and Immunogenicity of GB221 Injection and Trastuzumab (Herceptin®) in Healthy Chinese Adults.

GB221 is a recombinant humanized anti-HER2 monoclonal antibody. The purpose of this study was to evaluate the pharmacokinetic, safety, and immunogenicity of GB221 in healthy Chinese adults in comparisontotrastuzumab (Herceptin®). In this randomized, double-blind, parallel-group phase I clinical trial, 88 subjects were randomized 1:1 to receive a single intravenous infusion (90-100 min) of GB221 or trastuzumab (6 mg/kg). The primary pharmacokinetic parameters-maximum observed serum concentration (Cmax), area under the serum concentration-time curve from zero to the last quantifiable concentration at time t (AUC0-t), and area under the serum concentration-time curve from time zero to infinity (AUC0-∞)-of GB221 and trastuzumab were compared to establish whether the 90% confidence interval (CI) attained the 80-125% bioequivalence standard. Safety and immunogenicity were also evaluated. The GB221 group (n=43) and the trastuzumab group (n=44) showed similar pharmacokinetic characteristics. The geometric mean ratios (90% CI) of Cmax, AUC0-t, and AUC0-∞ between the two groups were 107.53% (102.25-113.07%), 108.31% (103.57-113.26%), and 108.34% (103.57-113.33%), respectively. The incidence of treatment-emergent adverse events (TEAEs) was 83.7% (36/43) of the subjects in the GB221 group and 95.5% (42/44) of the subjects in the trastuzumab group. No subjects withdrew from the trial due to TEAEs, and there were no occurrences of serious adverse events. All subjects tested negative for antidrug antibodies (ADA). GB221 demonstrated similar pharmacokinetics to trastuzumab and comparable safety and immunogenicity in healthy Chinese adults.

Abstract 6581: DX126-262 combined with chemotherapy (Cisplatin and 5-Fu) demonstrates promising antitumor efficacy in HER2-positive gastric cancer

Abstract Gastric cancer is a common malignant tumor of the digestive system, and its morbidity and mortality rank among the top five in the world. Although significant progress has been made in cytotoxic chemotherapy, immunotherapy and targeted therapy in recent years, the long-term prognosis of patients with advanced or metastatic gastric cancer is still poor. Trastuzumab combined with chemotherapy is the first-line standard of care (SOC) for HER2-positive advanced or metastatic gastric cancer. Two ADC drugs targeting HER2, DS-8201 and RC-48, have also been approved for the treatment of gastric cancer. However, their limited clinical benefits and occurrence of adverse events still present a significant challenge. Therefore, minimizing the off-target toxicity and collateral damage while achieving significant chemotherapy efficacy has become the focus of gastric cancer treatment. DX126-262 is a novel HER2-targeting antibody-drug conjugate (ADC), generated by conjugating a Tubulysin B analogue to a recombinant humanized anti-HER2 monoclonal antibody through a linker containing branched hydrophilic polyethylene glycol, using thiol-maleimide chemistry to achieve drug antibody ratio (DAR) of 3.8. Previous studies have confirmed that DX126-262 monotherapy showed excellent efficacy in HER2-positive gastric cancer NCI-N87 cells in vitro and in vivo. And the efficacy has also been demonstrated in clinical trials (now in phase II, CTR20211871). Based on above results, we intended to further explore whether combination therapy of DX126-262 with Cisplatin and 5-FU can improve the anti-tumor efficacy compared with SOC (Herceptin plus Cisplatin and 5-FU) or DS-8201 monotherapy. The triple-drug combination therapy demonstrated much better therapeutic efficacy than single drug (DX126-262, Cisplatin, 5-FU, Herceptin, or DS-8201) or double-drug combination (Cisplatin plus 5-FU) or SOC (Herceptin plus Cisplatin and 5-FU) on human gastric cancer cells in vitro and in vivo. Meanwhile, triple-drug combination therapy did not exhibit superimposed toxicity, judging by the body weight of mice and hemal biochemistry assays. These results suggested that DX126-262 plus Cisplatin and 5-FU might be a promising strategy for treatment of HER2-positive advanced or metastatic gastric cancer in clinic. Citation Format: Xiaobo Cai, Min Cao, Huihui Guo, Qingliang Yang, Xiangfei Kong, Yong Du, Zhicang Ye, Zhixiang Guo, Lingli Zhang, Lu Bai, Junxiang Jia, Yunxia Zheng, Yongxiang Chen, Miaomiao Chen, Wei Zheng, Jun Zheng, Wenjun Li, Yuanyuan Huang, Mengmeng Liu, Zhongliang Fan, Hangbo Ye, Yifang Xu, Binbin Chen, Meng Dai, Robert Y. Zhao. DX126-262 combined with chemotherapy (Cisplatin and 5-Fu) demonstrates promising antitumor efficacy in HER2-positive gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6581.

Exploring the clinical outcomes and safety profile of inetetamab treatment in metastatic breast cancer patients: A multicenter assessment of a Chinese-origin recombinant Anti-HER2 monoclonal antibody

BackgroundInetetamab is a novel recombinant humanized anti-HER2 monoclonal antibody. This study aimed to evaluate the efficacy and safety of inetetamab and predictive factors for response in HER2-positive metastatic breast cancer (MBC) patients. MethodsA cohort of HER2-positive MBC patients who received inetetamab-based therapy between June 2020 and August 2021 was evaluated. The primary endpoint was progression-free survival (PFS), and the secondary endpoints included objective response rate (ORR) and disease control rate (DCR). Adverse events (AEs) were graded according to the National Cancer Institute Common Toxicity Criteria. ResultsA total of 141 patients were included in the final analysis. The median PFS of the entire cohort was 7.1 months. The median number of treatment lines administered was three. The ORR was 36.9 %, and the DCR was 80.9 %. The most frequently employed treatment strategy was inetetamab + chemotherapy (49/141, 34.8 %), followed by inetetamab + HER2-tyrosine kinase inhibitors (HER2-TKIs) + chemotherapy, inetetamab + pertuzumab + chemotherapy, inetetamab + endocrine treatment and inetetamab + HER2-TKIs. Cox multivariate analysis revealed that PFS was associated with liver metastasis (hazard ratio [HR] 2.112, 95 % confidence interval [CI] 1.334–3.343, p = 0.001), previous HER2-TKI treatment (HR 2.019, 95 % CI 1.133–3.597, p = 0.017) and estrogen receptor positivity (HR 0.587, 95 % CI 0.370–0.934, p = 0.024). The toxicity was tolerable, with neutropenia being the most common treatment-related grade 3/4 AE (14.9 %). ConclusionInetetamab demonstrates effectiveness with a manageable safety profile, offering a promising therapeutic option for HER2-positive breast cancer patients who have shown resistance to prior anti-HER2 treatments.

Safety and efficacy of inetetamab in combination with pyrotinib in HER2 mutant patients with non-small cell lung cancer (NSCLC): An open-label, phase Ib trial.

9105 Background: Currently, limited targeted therapies are available for HER2 mutant NSCLC patients. Previous studies have shown the antitumor activity of pyrotinib in advanced NSCLC patients with HER2 mutations. Inetetamab is a recombinant humanized anti-HER2 monoclonal antibody. Whether inetetamab combined with pyrotinib could show manageable safety and more active antitumor activity remains unknown. This study was designed to evaluate the safety and efficacy of inetetamab in combination with pyrotinib in HER2 mutant patients with advanced NSCLC. Methods: This study was an open-label, phase Ib study. The HER2 mutant patients with locally advanced or metastatic NSCLC were assigned to receive inetetamab combined with pyrotinib. The study consisted of dose-escalation part and dose-expansion part. During dose-escalation period, the parallel "3+3" dose-escalation design was used to determine the dose-limiting toxicity (DLT). Inetetamab was administered every 3 weeks (8 mg/kg loading dose for cycle 1, followed by 6 mg/kg in subsequent cycles) with pyrotinib (dose-escalation part, 240mg QD, 320mg QD; dose-expansion part, 320mg QD). Primary endpoint of the study was DLT dosage and safety. The DLT was assessed during the 21-day DLT evaluation period after the first dose. Secondary endpoints included objective response rate (ORR), disease control rate (DCR), progression free survival and overall survival. Results: Between August 6, 2021, and August 25, 2022, 48 patients were enrolled. No DLT occurred during pyrotinib 240mg and 320mg escalation period. Therefore, pyrotinib 320mg was chosen as expansion dose. The most common treatment-related adverse events (TRAEs) were diarrhea (66.7% [2/3] in pyrotinib 240mg group, 95.6% [43/45] in pyrotinib 320mg group), rash (66.7% [2/3] in pyrotinib 240mg group, 22.2% [10/45] in pyrotinib 320mg group) and vomiting (0 in pyrotinib 240mg group, 24.4% [11/45] in pyrotinib 320mg group). TRAEs were generally Grade (G) 1-2. Only 7 patients reported G3 TRAE (1 in pyrotinib 240mg group, 6 in pyrotinib 320mg group). The preliminary efficacy was shown in the table below. The ORR and DCR of group receiving inetetamab with pyrotinib 240mg were 0% and 66.7%, respectively. The ORR and DCR of inetetamab with pyrotinib 320mg group were 36.6% and 85.4% respectively. The relationship between different mutation subtypes or co-mutations and efficacy will be updated during the conference reports. Conclusions: The preliminary data of inetetamab in combination with pyrotinib showed manageable safety and compelling antitumor activity in advanced NSCLC patients harboring HER2 mutations. Clinical trial information: NCT05016544 . [Table: see text]

Multinational Study of the Efficacy and Safety of Humanized Anti-HER2 Monoclonal Antibody in Women Who Have HER2-Overexpressing Metastatic Breast Cancer That Has Progressed After Chemotherapy for Metastatic Disease.

Overexpression of the HER2 protein occurs in 25% to 30% of human breast cancers and leads to a particularly aggressive form of the disease. Efficacy and safety of recombinant humanized anti-HER2 monoclonal antibody as a single agent was evaluated in women with HER2-overexpressing metastatic breast cancer that had progressed after chemotherapy for metastatic disease. Two hundred twenty-two women, with HER2-overexpressing metastatic breast cancer that had progressed after one or two chemotherapy regimens, were enrolled. Patients received a loading dose of 4 mg/kg intravenously, followed by a 2-mg/kg maintenance dose at weekly intervals. Study patients had advanced metastatic disease and had received extensive prior therapy. A blinded, independent response evaluation committee identified eight complete and 26 partial responses, for an objective response rate of 15% in the intent-to-treat population (95% confidence interval, 11% to 21%). The median duration of response was 9.1 months; the median duration of survival was 13 months. The most common adverse events, which occurred in approximately 40% of patients, were infusion-associated fever and/or chills that usually occurred only during the first infusion, and were of mild to moderate severity. These symptoms were treated successfully with acetaminophen and/or diphenhydramine. The most clinically significant adverse event was cardiac dysfunction, which occurred in 4.7% of patients. Only 1% of patients discontinued the study because of treatment-related adverse events. Recombinant humanized anti-HER2 monoclonal antibody, administered as a single agent, produces durable objective responses and is well tolerated by women with HER2-overexpressing metastatic breast cancer that has progressed after chemotherapy for metastatic disease. Side effects that are commonly observed with chemotherapy, such as alopecia, mucositis, and neutropenia, are rarely seen.

Selenium inhibits growth of trastuzumab-resistant human breast cancer cells via downregulation of Akt and beclin-1.

The response rate to treatment with trastuzumab (Tz), a recombinant humanized anti-HER2 monoclonal antibody, is only 12–34% despite demonstrated effectiveness on improving the survival of patients with HER2-positive breast cancers. Selenium has an antitumor effect against cancer cells and can play a cytoprotective role on normal cells. This study investigated the effect of selenium on HER2-positive breast cancer cells and the mechanism in relation to the response of the cells to Tz. HER2-positive breast cancer cell lines, SK-BR-3 as trastuzumab-sensitive cells, and JIMT-1 as Tz-resistant cells were treated with Tz and sodium selenite (selenite). Cell survival rates and expression of Her2, Akt, and autophagy-related proteins, including LC3B and beclin 1, in both cell lines 72 h after treatment were evaluated. Significant cell death was induced at different concentrations of selenite in both cell lines. A combined effect of selenite and Tz at 72 h was similar to or significantly greater than each drug alone. The expression of phosphorylated Akt (p-Akt) was decreased in JIMT-1 after combination treatment compared to that after only Tz treatment, while p-Akt expression was increased in SK-BR-3. The expression of beclin1 increased particularly in JIMT-1 after only Tz treatment and was downregulated by combination treatment. These results showed that combination of Tz and selenite had an antitumor effect in Tz-resistant breast cancer cells through downregulation of phosphorylated Akt and beclin1-related autophagy. Selenite might be a potent drug to treat Tz-resistant breast cancer by several mechanisms.

Phase I study of the recombinant humanized anti-HER2 monoclonal antibody\u2013MMAE conjugate RC48-ADC in patients with HER2-positive advanced solid tumors

PurposeRC48 contains the novel humanized anti-HER2 antibody hertuzumab conjugated to MMAE via a cleavable linker. A phase I study was initiated to evaluate the toxicity, MTD, PK, and antitumor activity of RC48 in patients with HER2-overexpressing locally advanced or metastatic solid carcinomas, particularly gastric cancer.Patients and methodsThis was a 2-part phase I study. Successive cohorts of patients received escalating doses of RC48 (0.1 mg/kg, 0.5 mg/kg, 1.0 mg/kg, 2.0 mg/kg, 2.5 mg/kg, and 3.0 mg/kg). Dose expansion proceeded at the dose of 2.0 mg/kg Q2W. The efficacy and safety set included all patients who received at least one dose of RC48.ResultsFifty-seven patients were enrolled, the MTD was unavailable due to termination of 3.0 mg/kg cohort; 2.5 mg/kg Q2W was declared the RP2D. RC48 was well tolerated, the most frequent grade 3 or worse TRAEs included neutropenia (19.3%), leukopenia (17.5%), hypoesthesia (14.0%), and increased conjugated blood bilirubin (8.8%). Four deaths occurred during the whole study, three of which were believed to be related to RC48. Overall, ORR and DCR were 21.0% (12/57) and 49.1% (28/57). Notably, patients who were HER2 IHC2+/FISH- responded similarly to those who were IHC2+/FISH+ and IHC3+, with ORRs of 35.7% (5/14), 20% (2/10), and 13.6% (3/22), respectively. In patients who were pretreated with HER2-targeted drugs, RC48 also showed promising efficacy, with ORR of 15.0% (3/20) and DCR of 45.0% (9/20).ConclusionRC48 was well tolerated and showed promising antitumor activity in HER2-positive solid tumors, including gastric cancer with HER2 IHC 2+/FISH- status.Clinical trial informationNCT02881190.

Development of a Nanostructured Platform for Identifying HER2-Heterogeneity of Breast Cancer Cells by Surface-Enhanced Raman Scattering.

Biosensor technology has great potential for the detection of cancer through tumor-associated molecular biomarkers. In this work, we describe the immobilization of the recombinant humanized anti-HER2 monoclonal antibody (trastuzumab) on a silver nanostructured plate made by pulsed laser deposition (PLD), over a thin film of Au(111). Immobilization was performed via 4-mercapto benzoic acid self-assembled monolayers (4-MBA SAMs) that were activated with coupling reagents. A combination of immunofluorescence images and z-stack analysis by confocal laser scanning microscopy (CLSM) allowed us to detect HER2 presence and distribution in the cell membranes. Four different HER2-expressing breast cancer cell lines (SKBR3 +++, MCF-7 +/−, T47D +/−, MDA-MB-231 −) were incubated during 24 h on functionalized silver nanostructured plates (FSNP) and also on Au(111) thin films. The cells were fixed by means of an ethanol dehydration train, then characterized by atomic force microscopy (AFM) and surface-enhanced Raman scattering (SERS). SERS results showed the same tendency as CLSM findings (SKBR3 > MCF-7 > T47D > MDA-MB-231), especially when the Raman peak associated with phenylalanine amino acid (1002 cm−1) was monitored. Given the high selectivity and high sensitivity of SERS with a functionalized silver nanostructured plate (FSNP), we propose this method for identifying the presence of HER2 and consequently, of breast cancer cells.

Predicting the Efficacy of HER2-Targeted Therapies: A Look at the Host

HER2 is overexpressed in 20% of invasive breast cancers (BCs) and correlates with a more aggressive disease. Until the advent of targeted agents, HER2 was associated with worse outcomes. Rationally designed HER2-targeted agents have been developed and introduced into clinical practice for women with HER2-amplified BC, improving disease-free and overall survival for primary and metastatic tumors. Trastuzumab, a recombinant humanized anti-HER2 monoclonal antibody, combined with chemotherapy, remains the standard of care for patients with HER2-positive BCs. However, many patients do not respond to this agent, whereas newer drugs have proven to be efficacious in clinical trials. The identification of biomarkers that select sensitive tumors and patients who will benefit from these new agents would help the incorporation of these therapies, limiting the risk of side effects and overtreatment and improving the outcomes of all patients with early-stage HER2-positive BC. We review the mechanisms of action of HER2-targeting agents, focusing on the involvement of the immune system and related predictive biomarkers.

Predictive biomarkers in the treatment of HER2-positive breast cancer: an ongoing challenge.

The transmembrane tyrosine kinase receptor HER2 is overexpressed in 20% of invasive breast cancers and is associated with more aggressive disease. Until the advent of targeted agents, HER2 was associated with worse outcome. Trastuzumab, a recombinant humanized anti-HER2 monoclonal antibody, combined with chemotherapy improves disease-free and overall survival in both primary and metastatic tumors and represents a foundation of care for patients with HER2-positive breast cancers. However, a sizeable number of patients do not respond to this reagent, indicating the need for a biomarker able to recognize resistant tumors. Here, we review various studies on mechanisms of action and resistance to trastuzumab that have proven relevant in understanding how tumor care can be tailored to all HER2-positive patients.

Abstract 5226: Potential of PET imaging to predict the response to anti-HER2 therapy in breast cancer

Abstract Overexpression of HER2 is associated with resistance to standard therapies and, consequently, poor prognosis. The most successful of HER2-targeted therapies, and the only one approved by the FDA, uses trastuzumab (Herceptin) - a recombinant humanized anti-HER2 monoclonal antibody. Currently, alteration of gross tumor volume is used to assess the response to trastuzumab. However, this approach provides only a late indicator of response. The ex vivo assays of tissue samples are potentially valuable, but their procurement through biopsies is invasive and might be biased by tumor heterogeneity. We studied the feasibility of PET imaging to quantify changes in HER2 expression and to predict the response to trastuzumab in breast cancer xenograft model using 18F-ZHER2-Affibody molecule as a tracer. We administered the tracer to mice bearing subcutaneous BT474 tumors, which display very high HER2 expression. The control and treatment groups consisted of 15-20 animals each. The tumor volume was in 100-250 mm3 range. The tumor size was monitored twice weekly using caliper measurements. Trastuzumab (50 mg/kg loading dose, 25 mg/kg maintenance dose) or saline (control) were given i.p. twice a week for a total of 5 doses. Animals were scanned before the treatment, 48 h and two weeks after the beginning of therapy. Immediately after the last scan, animals were euthanized and pieces of tumors were fixed and/or frozen for further analysis. The HER2 expression and activation of HER2 signaling pathways in the tumor samples were assessed by Western blot, ICH and ELISA. Quantitative analysis of PET images indicated decrease of HER2 expression, associated with significant tumor regression (>30% volume reduction), in 12 of 20 treated tumors. However, only negligible changes in HER2 expression and stable disease were found in the remaining treated mice. No changes in HER2 expression and intensive growth of the tumors (increase more than 100% of tumor volume) were observed in the control group over the 2 weeks of therapy. These results were confirmed by ex vivo analysis showing dramatic decrease of total HER2 level in responding tumors. Despite the reduction of HER2 levels, there was persistent HER2 phosphorylation in all tumors. As previously shown, it might be due to activation of alternative HER receptors as a result of ADAM17-mediated autocrine ligand release. Tissue analysis showed a trend for trastuzumab-treated xenografts to have higher levels of ADAM17 and heregulin compared to the untreated mice. Other mechanisms that might account for the observed difference between the responders and the non-responders are currently investigated. Our results suggest that monitoring of changes in HER2 expression after five doses of trastuzumab allows predicting the tumor response and identifying mice that would not fully benefit from the treatment. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5226.

Lyophilized HER2-specific PEGylated immunoliposomes for active siRNA gene silencing

The development of a tumor-specific immunoliposome delivering small interfering RNA (siRNA) represents a practical way in cancer gene therapy. In this study, we developed PEGylated 3β-[N-(N′, N′-dimethylaminoethane) carbamoyl] cholesterol (DC-Chol)/dioleoylphosphatidyl ethanolamine (DOPE) immunoliposomes conjugated with the Fab' of recombinant humanized anti-HER2 monoclonal antibody (PIL) for siRNA delivery. The results demonstrated that the lyophilized PIL (LPIL) prepared by the lyophilization/rehydration method possessed a significantly enhanced HER1 gene, a model target, silencing ability compared with PIL in HER2-overexpressing SK-BR3 cells. Among a series of LPIL with different PEGylation degree, LPIL containing 2.5%PEG (2.5%PEG LPIL) showed the best HER1 gene silencing activity. Confocal microscope studies demonstrated that 2.5%PEG LPIL could specifically bind to SK-BR3 cells and were sequentially internalized into them. Using RhoA as a cancer therapeutic target, 2.5%PEG LPIL entrapping anti-RhoA siRNA could specifically silence RhoA expression and inhibit cell invasion in SK-BR3 cells. In conclusion, these finding demonstrated the potential use of 2.5%PEG LPIL in specifically delivering siRNA to HER2-overexpressing cancers.

Tumor-targeted PE38KDEL delivery via PEGylated anti-HER2 immunoliposomes

We previously reported the development of PE38KDEL-loaded anti-HER2 poly(lactic-co-glycolic acid) (PLGA) nanoparticles that bind and internalize in HER2-overexpressing breast cancer cells, enabling potent anti-tumor activity. To overcome the problems associated with the short half-lives of this drug delivery system, we have constructed PE38KDEL-loaded anti-HER2 PEGylated liposomes (PE-HER-liposomes). PE-HER-liposomes were constructed with Fab′ of recombinant humanized anti-HER2 monoclonal antibody (anti-HER2 Fab′) covalently linked to PEGylated liposomes containing PE38KDEL (PE-liposomes). We attached anti-HER2 Fab′ to the terminus of PEG (polyethylene glycol) on PEGylated liposomes. Incorporation of pyridylthiopropionoylamino-PEG-distearoylphosphatidylethanolamine (PDP-PEG-DSPE) into PEGylated liposomes followed by mild thiolysis of the PDP groups resulted in the formation of reactive thiol groups at the periphery of the liposomes. Efficient attachment of maleimide-derivatized anti-HER2 Fab′ took place under mild conditions. The characterization of PE-HER-liposomes, such as particle size, was evaluated by dynamic light-scattering detector. The Micro BCA method was used to determine the encapsulation efficiency of PE38KDEL and the quantity of conjugated Fab′. Flow cytometry and confocal microscopy showed that PE-HER-liposomes possessed receptor-specific binding and internalization for HER2-overexpressing SK-BR3 cells. Remarkably, PE-HER-liposomes were more cytotoxic than non-targeted PE-liposomes in HER2-overexpressing breast cancer cells. In conclusion, PE-HER-liposomes could serve as a promising therapeutic candidate for the treatment of HER2-overexpressing breast cancers.

Lovastatin enhances the antiproliferative effect of trastuzumab in HER2 over expressing breast cancer cells

2546 Background: Trastuzumab, a recombinant humanized anti-HER2 monoclonal antibody, has been found to have potent antiproliferative effects in HER2 overexpressing human breast tumors. Lovastatin, an HMG-CoA reductase inhibitor suppresses growth, and induces apoptosis in breast cancer cells. Both agents induce a G0/G1 arrest of cell cycle progression. The purpose of this study was to evaluate the antiproliferative effect of the novel combination of lovastatin and trastuzumab in human breast cancer cell lines. Methods: Increasing doses of lovastatin (0.16-40 μM) and trastuzumab (0.039-1 μg/ml) were tested alone and in combination. Three breast carcinoma cell lines were studied: two HER2 overexpressing lines (BT474 and SKBR3) and one cell line that expresses low levels of the receptor (MCF7). Inhibition of growth was assessed after 7 days of treatment by the MTT colorimetric assay, while apoptosis was detected using an in situ DNA Fragmentation Detection kit. Results: A dose-dependent growth inhibition was demonstrated in all three cell lines tested with lovastatin, while trastuzumab was only effective in the HER2 overexpressing cells. Trastuzumab (0.06 μg/ml) inhibited cell growth by 29.3% and 40.1%, while lovastatin (2.5 μM) caused an inhibition of 19.1% and 43% in the BT474 and SKBR3 cell lines, respectively. The combination of trastuzumab and lovastatin, at these doses, significantly inhibited growth in BT474 and SKBR3 cells by 45.4% and 68.9% (P < 0.001, oneway ANOVA) compared to either agent alone. Conclusions: Lovastatin plus trastuzumab treatment led to increased growth inhibition in HER2 positive breast cancer cell lines. Further studies in an animal model are warranted. This combination may also have important clinical therapeutic implications. No significant financial relationships to disclose.

Targeting c-erbB2 and Other Receptors of the C-ErbB Family: Rationale and Clinical Applications

The c-erbB family of receptors includes four distinct receptors, namely c-erb B1, 2, 3 and 4 (HER1, 2, 3 and 4, respectively). Trastuzumab (T) is a recombinant humanized anti-HER2 monoclonal antibody that binds the extracellular domain of the receptor and blocks intracellular signalling. In clinical studies of T, either alone or in combination with chemotherapy, in HER2 overexpressing metastatic breast cancer patients, a significant benefit was obtained—improved response rates and survival, when T was combined with chemotherapy. Several trials of adjuvant T, either singly or in combination with chemotherapy, are in progress in early breast cancer patients. Pertuzumab defines a new class of HER2 inhibitors, “dimerization inhibitors” that block both homo- and hetero-dimerization of HER2. In preclinical studies pertuzumab is inhibitory to breast, prostate and non small cell lung cancer cell lines, both over and non overexpressing HER2. In phase I clinical trials pertuzumab has shown activity in a number of human cancers. A phase II program is in progress.

Efficacy and safety of trastuzumab as a single agent in heavily pretreated patients with HER-2/neu-overexpressing metastatic breast cancer.

The human epidermal growth factor receptor 2 (HER2) protein is a unique and useful target for antibody therapy against breast cancers that overexpress the HER-2/neu gene. The recombinant humanized anti-HER2 monoclonal antibody, trastuzumab, was approved for clinical use in the United States in 1998. It became available in Japan in June 2001. This study focuses on the efficacy and safety of trastuzumab as a single agent in second-third line treatment of HER2/neu-overexpressing metastatic breast cancer. Between June 2001 and May 2002, we treated 62 patients with trastuzumab, as a single agent or in combination chemotherapy, for second-third line treatment of HER2-overexpressing metastatic breast cancer. Twenty-seven of 62 patients were treated with trastuzumab as a single agent. We reviewed retrospectively the efficacy and safety of the drug given as a single agent. The expression of HER2 was determined by immunohistochemical staining. All patients received a standard loading dose of 4 mg/kg followed by 2 mg/kg weekly. Patients received a median of 16.7 weekly infusions (range, 1-66 infusions). Trastuzumab therapy was generally well tolerated. Clinically severe adverse events (grade 3 or 4) included hypotension (7.4%), and hypoxia (3.7%). Grade 1 to 2 toxicity included fever (11.1%) and diarrhea (3.7%). Infusion-related reactions were infrequent, as were serious hematologic complications. Cardiotoxicity did not occur in the study. Three patients had a complete and 3 a partial response, 3 had no change, 17 had progressive disease, and one was not evaluated. The overall response rate in the 26 patients with available data was 23.1% (95% confidence interval, 5.7-40.4). The median duration of response was 6.4 months (range, 2.5-14.0). The median time to progression was 3.1 months (range, 0.2-16.7). Response rates differed by metastatic site as follows: lung 0% (0/12), bone 10.0% (1/10), liver 0% (0/8), skin 50.0% (4/8), lymph nodes 42.9% (3/7), brain 0% (0/2). Molecular target therapy with trastuzumab appears safe and is generally well tolerated. For treatment of metastatic breast cancer, single agent therapy produces a durable response in some patients but lacks sufficient efficacy. Single agent use of trastuzumab is a viable option for treatment in cases with non-life-threatening disease without visceral metastasis.

Cardiac effects of adjuvant therapy for early breastcancer

Adjuvant chemotherapy is an established standard of care for most patients diagnosed with early breast cancer, and its popularity is gaining worldwide. The systemic armamentarium presently includes anthracyclines and taxanes, alkylating agents, fluoropyrimidines, and antimetabolites; in the future, it may include platinum compounds and the recombinant humanized anti-HER2 monoclonal antibody, trastuzumab, as well. Anti-estrogens continue to play an important role in the adjuvant setting for hormone-sensitive primary breast cancer. Adjuvant radiotherapy is common in the setting of early-stage disease as breast conservation gains popularity, and radiation is often employed in the postmastectomy setting as well. As treatment guidelines continue to evolve with newer data, the relative benefits of treatment in many situations continues to grow. Refinement of the optimal identification of patients at risk for local and distant relapse is a continued challenge facing the treating clinician. Parallel to this effort, and of equal importance, is the ability to shield patients that will gain little, if any, benefit from treatment and to identify those who may be at greater risk to suffer from potential toxicities. Until these factors are better defined, the recognition by clinicians of long-term side effects associated with adjuvant therapy is obligatory. Acute toxicities from treatment are often reversible, but late onset adverse effects of therapy can increase morbidity and mortality in long-term survivors, and continue to be of concern. One of the most serious side effects of adjuvant therapy of early breast cancer is cardiac toxicity. This article will provide an overview of the cardiac effects of adjuvant therapy in the treatment of early breast cancer.

Antibodies as molecular target-based therapy: trastuzumab.

The HER2 gene is overexpressed or amplified in approximately 30% of breast cancers. Breast cancer patients with HER2 overexpression or amplification have shortened disease-free and overall survivals. The HER2 protein is thought to be a unique and useful target for antibody therapy of cancers overexpressing the HER2 gene. The recombinant humanized anti-HER2 monoclonal antibody, trastuzumab (Herceptin) is now available for clinical use. In a large phase II trial, trastuzumab produced a favorable response rate as a single agent in patients with metastatic breast cancer who had received one or two prior chemotherapies. Furthermore, a large phase III trial showed that trastuzumab plus chemotherapy as a first-line treatment for metastatic breast cancer significantly improved response rate, time to disease progression, and overall survival compared with chemotherapy alone. As a single agent and in combination with chemotherapy, trastuzumab was generally well tolerated. Thus, trastuzumab plays an important role in the treatment strategy of metastatic breast cancer overexpressing HER2 protein. In this article, details of this novel biologic agent are reviewed, in conjunction with an overview of clinical studies performed in Japan.

Expression of HER2/erbB-2 Correlates With Survival in Osteosarcoma

In osteosarcoma, prognostic factors at diagnosis other than clinical stage have not been clearly identified. The aim of this study was to determine whether human epidermal growth factor receptor 2 (HER2)/erbB-2, p-glycoprotein, or p53 expression correlated with histologic response to preoperative chemotherapy or event-free survival. We performed a retrospective immunohistochemical study on material obtained from patients treated on the Memorial Sloan-Kettering Cancer Center T12 protocol between 1986 and 1993. Paraffin-embedded tissue was identified from 53 patients (73% of patients enrolled onto protocol) and stained for HER2/erbB-2, p53, and p-glycoprotein expression using standard monoclonal antibodies and methods. At the time of initial biopsy, 20 (42.6%) of 47 samples demonstrated high levels of HER2/erbB-2 expression. Higher frequencies of expression were observed in samples from patients with metastatic disease at presentation and at the time of relapse. Expression of HER2/erbB-2 correlated with a significantly worse histologic response (P =.03). In patients presenting with nonmetastatic disease, expression of HER2/erbB-2 at the time of initial biopsy was associated with a significantly decreased event-free survival (47% v 79% at 5 years, P =.05). p53 and p-glycoprotein expression did not correlate with histologic response or patient event-free survival. The correlation of HER2/erbB-2 expression with histologic response to preoperative chemotherapy and event-free survival in this study suggests that HER2/erbB-2 should be evaluated prospectively as a prognostic indicator. The correlation also suggests that clinical trials of antibodies that target this receptor, such as recombinant humanized anti-HER2 monoclonal antibody (Herceptin; Genentech, San Francisco, CA), should be considered for the treatment of osteosarcoma.