Epidermal growth factor receptor blockers for the treatment of ovarian cancer

BACKGROUND

Ovarian cancer is the seventh most common cause of cancer death in women world-wide. Treatment consists of a combination of surgical debulking and platinum-based chemotherapy, alone or in combination with paclitaxel. Between 55% and 75% of women who respond to first-line therapy relapse within two years of completing treatment. Second-line chemotherapy is palliative and aims to reduce symptoms and prolong survival. Increased understanding about the molecular basis of ovarian cancer has led to the development of novel agents, such as epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors, and their effectiveness and toxicities in women with advanced ovarian cancer needs to be assessed.

OBJECTIVES

To compare the effectiveness and toxicities of epidermal growth factor receptor (EGFR) inhibitors alone or in combination with standard chemotherapy in the treatment of ovarian cancer.

SEARCH STRATEGY

We searched the Cochrane Gynaecological Cancer Group Trials Register, The Cochrane Central Register of Controlled Trials (CENTRAL) Issue 4, 2010, MEDLINE and EMBASE up to October 2010. We also searched registers of clinical trials, abstracts of scientific meetings, and reference lists of included studies, and contacted experts in the field.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing anti-EGFR agents with or without conventional chemotherapy versus conventional chemotherapy alone or no treatment in women with histologically proven ovarian cancer.

DATA COLLECTION AND ANALYSIS

Two review authors independently abstracted data and assessed risk of bias. We reported adjusted hazard ratios (HRs) for overall and progression-free survival and risk ratios (RRs) comparing adverse events in women who received gemcitabine plus pertuzumab and gemcitabine plus placebo.

MAIN RESULTS

We found only one completed and three ongoing RCTs that met our inclusion criteria. The completed trial randomised 131 women with relapsed ovarian cancer to receive gemcitabine and pertuzumab or placebo and gemcitabine (control). There was no statistically significant difference in overall survival (OS), progression-free survival (PFS) and response between women who received gemcitabine and pertuzumab and those who received control, although PFS approached borderline significance (adjusted HR = 0.66, 95% CI 0.43 to 1.03; P = 0.06). The trial reported a higher rate of adverse events in the gemcitabine and pertuzumab arm for most outcomes, but most were not statistically significant (although many approached borderline significance) because the trial lacked statistical power due to its relatively small size and the low number of observed events. The trial was at moderate risk of bias.

AUTHORS' CONCLUSIONS

EGFR inhibitors, including pertuzumab, may add activity to conventional chemotherapy for treatment of platinum-resistant ovarian cancer. Certain subsets of women with particularly aggressive tumours resistant to conventional chemotherapy may benefit from EGFR inhibitor treatment. Further RCTs are necessary before EGFR inhibitors are introduced as first- or second-line treatment of ovarian cancer.

Phase I trial of liposomal doxorubicin and ZD1839 in patients with refractory gynecological malignancies or metastatic breast cancer

BACKGROUND

Pegylated liposomal doxorubicin has activity in both breast and ovarian cancer. Preclinical data noted that ZD1839 acts synergistically with chemotherapy. Given the lack of cross-resistance between these two agents, a phase I trial was initiated examining the safety and efficacy of the combination of liposomal doxorubicin and ZD1839 in patients with recurrent gynecologic or metastatic breast cancer.

METHODS

Dose-limiting toxicity (DLT) was defined within the first two cycles of treatment. Escalating doses of liposomal doxorubicin were administered every 4 weeks with ZD1839. Pharmacokinetic analysis and correlative studies were performed.

RESULTS

Thirty-five patients were enrolled in this study: six in each cohort. One DLT (febrile neutropenia) was observed in cohort 2. Dose level 3 was determined to be the maximum tolerated dose (MTD), and an additional ten patients were accrued. Serious adverse events (SAEs) included one patient with mental status changes believed secondary to disease progression and two central nervous system (CNS) bleeds believed to be unrelated to the combination of study agents. Toxicities were generally mild except for skin and gastrointestinal toxicity. No cardiac toxicity was observed. The best response to therapy included four partial responses and 20 patients with stable disease.

CONCLUSIONS

Liposomal doxorubicin with ZD1839 is an active regimen but is associated with increased skin toxicity in patients with advanced breast and gynecologic cancer.

Novel anticancer targets: revisiting ERBB2 and discovering ERBB3

Aberrant receptor expression or functioning of the epidermal growth factor receptor (Erbb) family plays a crucial part in the development and evolution of cancer. Inhibiting the signalling activity of individual receptors in this family has advanced the treatment of a range of human cancers. In this Review we re-evaluate the role of two important family members, ERBB2 (also known as HER2) and ERBB3 (also known as HER3), and explore the mechanisms of action and preclinical and clinical data for new therapies that target signalling through these pivotal receptors. These new therapies include tyrosine kinase inhibitors, antibody-chemotherapy conjugates, heat-shock protein inhibitors and antibodies that interfere with the formation of ERBB2-ERBB3 dimers.

The promise and perils of 'targeted therapy' of advanced ovarian cancer

For several reasons, ovarian cancer is an excellent malignancy to consider the use of 'targeted' therapeutic strategies. However, to date, despite considerable effort, there remains limited evidence that such approaches are clinically relevant in the malignancy. The one important exception is the delivery of anti-angiogenic anti-neoplastic agents, which actually appear to be more biologically active as single drugs in ovarian cancer than in other solid tumors where they have been examined. It is anticipated that future trials of 'targeted' therapy in ovarian cancer will focus on molecular targets of documented relevance in the malignancy.

Development of antiangiogenic agents for ovarian cancer

Epithelial ovarian cancer (EOC) remains a major source of cancer morbidity and mortality, despite advances in surgical and chemotherapeutic management. The molecular pathways that control angiogenesis have been demonstrated to be key to the pathogenesis of EOC, and have been shown to have prognostic significance. Increased understanding of the pathways and molecules involved in angiogenesis has allowed the identification of a number of targets for antiangiogenic therapies and the development of a variety of antiangiogenic drugs. There is now significant preclinical evidence, and a growing body of clinical data, demonstrating promising results with antiangiogenic drugs in the treatment of EOC. Single-agent VEGF inhibitor response rates in pretreated patients of between 15 and 20% have been reported, with much higher response rates when used in combination with chemotherapeutic agents. These benefits, however, must be balanced with the toxicities associated with these drugs, particularly the more serious ones, such as gastrointestinal perforation. The results of ongoing and future randomized clinical trials will confirm if, and how, antiangiogenic therapies should be integrated into the routine management of EOC. However, critical issues, such as the relative importance of combination remission induction regimens and maintenance therapy, remain poorly defined.

Herceptin

The biology of the human epidermal growth factor (EGF) receptor-2 (HER2) has been reviewed numerous times and provides an excellent example for developing a targeted cancer therapeutic. Herceptin, the FDA-approved therapeutic monoclonal antibody against HER2, has been used to treat over 150,000 women with breast cancer. However, the developmental history of Herceptin, the key events within the program that created pivotal decision points, and the reasons why decisions were made to pursue the monoclonal antibody approach have never been adequately described. The history of Herceptin is reviewed in a way which allows the experience to be shared for the purposes of understanding the drug discovery and development process. It is the objective of this review to describe the pivotal events and explain why critical decisions were made that resulted in the first therapeutic to successfully target tyrosine kinases in cancer. New approaches and future prospects for therapeutics targeting the HER family are also discussed.

HER2 targeted therapy in breast cancer...beyond Herceptin

HER2, is a member of the ErbB family of receptor tyrosine kinases, that plays a key role in the pathogenesis of breast cancer, and when overexpressed, can correlate with a particularly aggressive clinical phenotype. It is estimated in roughly 18 to 20% of breast cancer patients, there is amplification of the HER2 gene resulting in aberrant overexpression of p185HER2 protein. As such, HER2 represents an attractive therapeutic target. In this review, we explore the clinical evolution of trastuzumab, a humanized monoclonal antibody with high specificity and affinity for the HER2 extracellular domain, and additionally examine more recent efforts targeting the intracellular tyrosine kinase domain of HER2 using small molecule tyrosine kinase inhibitors.