Docetaxel and herceptin: foundation for future strategies

Functional and Nonclinical Similarity of ABP 980, a Biosimilar of Trastuzumab

Purpose

The in vitro and in vivo pharmacologic assessment of ABP 980 similarity to its reference product is intended to compare the activity of ABP 980 and trastuzumab and support the overall conclusion of similarity based on a comprehensive analytical and functional evaluation.

Methods

This work complements the primary assessment of functional similarity with additional in vitro assays, binding studies, and non-clinical studies including human epidermal growth factor receptor-2 (HER2) kinetic binding, HER2 signaling, HER2 internalization, synergy with docetaxel chemotherapy, FcγR kinetic binding, primary natural killer and monocyte cell binding, antibody-dependent cellular phagocytosis activity, in vivo xenograft studies, and toxicokinetic parameters.

Results

The results contribute to the totality of evidence with respect to functional similarity and support that ABP 980 is similar to trastuzumab in all primary and secondary mechanisms of action.

Conclusions

These results also support the scientific justification of extrapolation to all approved indications of trastuzumab given the established functional similarity of the two products and the same mechanisms of action across all conditions of use.

Electronic supplementary material

The online version of this article (10.1007/s11095-019-2702-8) contains supplementary material, which is available to authorized users.

Targeting HER2 Positive Breast Cancer with Chemopreventive Agents

Human epidermal growth factor receptor 2-positive (HER2+) breast cancer is a subtype of breast cancer that is exhibited in approximately 20-30% of breast cancer cases. The overexpression of HER2 is typically associated with a more aggressive disease and poor prognosis. Currently, the therapeutic drugs trastuzumab and lapatinib are the most commonly used to combat HER2+ breast cancer. However, tumors can develop resistance to these drugs. A better understanding of the mechanism of how HER2+ breast cancer works will help aid the development for new therapeutic approaches which more closely target the source of the signaling dysfunction. This review summarizes four major points in the context of HER2 over-expressing breast cancer (i) HER2 as a molecular target in breast cancer therapy, (ii) current treatment options as well as ongoing clinical studies, (iii) animal and cellular models for the study of HER2 over-expressing breast cancer, and (iv) future therapies and chemopreventive agents used to target HER2+ breast cancer.

QLT0267, a small molecule inhibitor targeting integrin-linked kinase (ILK), and docetaxel can combine to produce synergistic interactions linked to enhanced cytotoxicity, reductions in P-AKT levels, altered F-actin architecture and improved treatment outcomes in an orthotopic breast cancer model

Introduction

Substantial preclinical evidence has indicated that inhibition of integrin linked-kinase (ILK) correlates with cytotoxic/cytostatic cellular effects, delayed tumor growth in animal models of cancer, and inhibition of angiogenesis. Widely anticipated to represent a very promising therapeutic target in several cancer indications, it is increasingly evident that optimal therapeutic benefits obtained using ILK targeting strategies will only be achieved in combination settings. The purpose of this study was to investigate the therapeutic potential of the ILK small molecule inhibitor, QLT0267 (267), alone or in combination with chemotherapies commonly used to treat breast cancer patients.

Methods

A single end-point metabolic assay was used as an initial screen for 267 interactions with selected chemotherapeutic agents. These in vitro assays were completed with seven breast cancer cell lines including several which over-expressed human epidermal growth factor receptor 2 (Her2). One agent, docetaxel (Dt), consistently produced synergistic interactions when combined with 267. Dt/267 interactions were further characterized by measuring therapeutic endpoints linked to phosphorylated protein kinase B (P-AKT) suppression, inhibition of vascular endothelial growth factor (VEGF) secretion and changes in cytoarchitecture. In vivo efficacy studies were completed in mice bearing orthotopic xenografts where tumor growth was assessed by bioluminescence and calliper methods.

Results

The combination of 267 and Dt resulted in increased cytotoxic activity, as determined using an assay of metabolic activity. Combinations of cisplatin, doxorubicin, vinorelbine, paclitaxel, and trastuzumab produced antagonistic interactions. Further endpoint analysis in cell lines with low Her2 levels revealed that the 267/Dt combinations resulted in: a three-fold decrease in concentration (dose) of 267 required to achieve 50% inhibition of P-AKT; and a dramatic disruption of normal filamentous-actin cellular architecture. In contrast to Her2-positive cell lines, three-fold higher concentrations of 267 were required to achieve 50% inhibition of P-AKT when the drug was used in combination with Dt. In vivo studies focusing on low Her2-expressing breast cancer cells (LCC6) implanted orthotopically demonstrated that treatment with 267/Dt engendered improved therapeutic effects when compared with mice treated with either agent alone.

Conclusions

The findings indicate that the 267/Dt drug combination confers increased (synergistic) therapeutic efficacy towards human breast cancer cells that express low levels of Her2.

Safety and efficacy of the combination of trastuzumab with docetaxel for HER2-positive women with advanced breast cancer. A review of the existing clinical trials and results of the expanded access programme in the UK

Trastuzumab is a humanised monoclonal antibody against the extracellular domain of HER2 (human epidermal growth factor receptor-2) that is overexpressed in about 25% of human breast cancers. It has shown clinical benefit in HER2-positive breast cancer cases when used alone or in combination with chemotherapy. Trastuzumab increases the response rate to chemotherapy and prolongs survival when used in combination with taxanes. In this article, we review the clinical trials where trastuzumab has been administered together with docetaxel, and we present the results of the trastuzumab expanded access programme (EAP) in the UK. Combination of trastuzumab with docetaxel results in similar response rates and time-to-progression with the trastuzumab/paclitaxel combinations. The toxicity of the combination and the risk of heart failure are low. The clinical data for the docetaxel/trastuzumab combination indicate a favourable profile from both the efficacy and the safety point of view and confirm the feasibility and safety of trastuzumab administration both as monotherapy and in combination with docetaxel.

Current status of antibody therapy for breast cancer

Antibody therapy with trastuzumab has greatly impacted breast cancer treatment. Combination treatment with trastuzumab is regarded currently as a first-line therapy for metastatic breast cancers that overexpress Her-2. It has become routine practice to examine the status of Her-2 expression in primary tumors. The impact of this therapy might be as great as that of endocrine therapy from a historical point of view. A number of new approaches using trastuzumab for seeking individualized treatment are being tested in current clinical trials. We reviewed recent advances in trastuzumab treatment and discuss the future of antibody therapy for breast cancer.

Mode of action of docetaxel - a basis for combination with novel anticancer agents

Different tumors have different aberrations in signaling and growth stimulation pathways that drive cancer growth. An understanding of these processes is key to the development of new anticancer agents and to identifying optimal treatment strategies and patient populations suitable for specific therapies. It is becoming clear that certain chemotherapeutic drugs such as docetaxel are not simply inhibitors of mitosis and may interact with these tumorigenic mechanisms at a number of levels. This review describes docetaxel's mechanism of action, and provides a basis for understanding how its antitumor activity can integrate with that of different novel agents. Against this background, key docetaxel-novel agent combinations that are currently under clinical investigation are reviewed. How these strategies can be targeted towards specific patient populations (e.g., HER-2 overexpressing metastatic breast cancer patients) to provide optimal therapy is highlighted.

Safety and activity of docetaxel and trastuzumab in HER2 overexpressing metastatic breast cancer: a pilot phase II study

We conducted a pilot phase II trial of trastuzumab administered concurrently with docetaxel in women with HER2-overexpressing advanced breast cancer. Twenty-five women with HER2-positive (3+ by immunohistochemistry = 16, 2+ = 9) metastatic breast cancer received docetaxel (75 mg/m every 3 weeks for 6 cycles) and trastuzumab (4 mg/kg loading dose, 2 mg/kg weekly thereafter). Twenty-three patients (92%) had visceral metastatic involvement. Twenty-three patients had received prior chemotherapy as part of adjuvant (18), metastatic (2), and both (3) treatment. The number of cycles administered was 121 (median 6, range 1-6). Symptomatic cardiotoxicity (GIII) occurred in one patient. The most common grade GIII/IV toxicity was neutropenia (80% of the cycles), although febrile neutropenia did not occur. No other GIII/IV toxicities were observed. Response rate was 70% (1 complete response and 15 partial responses) in 23 evaluable patients. The combination of docetaxel and trastuzumab is well tolerated and has clinically meaningful antitumor activity.

Docetaxel: overview of an active drug for breast cancer

Docetaxel and paclitaxel differ in their precise molecular targets and pharmacokinetics. Docetaxel is more avidly taken up by tumor cell lines than paclitaxel, and its efflux is slower. Comparative cytotoxicity data suggest greater potency. These factors may help explain the clinical differences that have been observed between the taxanes in patients with breast cancer.