Rational Use of Cytotoxic Chemotherapy for Recurrent Ovarian Cancer

Mining the Human Proteome: Biomarker Discovery for Human Cancer and Metastases

As our knowledge of the mechanisms underlying cancer development and progression has increased, so too have more effective, less toxic, and targeted therapies begun to reach the clinic. However, the full impact of these clinical advances and the practical success of the emerging field of precision medicine are dependent on the discovery and validation of sensitive and accurate biomarkers that can enable appropriate and rigorous sample type and patient selection, reliable longitudinal monitoring of therapeutic efficacy, and even risk assessment and early detection. Within the context of this review, we examine state-of-the-art approaches to the discovery and validation of noninvasive cancer biomarkers, with a specific emphasis on those that are protein or protein-associated ones. We also review sample selection strategies, currently utilized proteomic approaches for both discovery and validation requirements, and data analysis standards. Finally, we provide examples of these elements of biomarker discovery and validation from our own biomarker research.

A distinct pre-existing inflammatory tumour microenvironment is associated with chemotherapy resistance in high-grade serous epithelial ovarian cancer

Background:

Chemotherapy resistance is a major determinant of poor overall survival rates in high-grade serous ovarian cancer (HGSC). We have previously shown that gene expression alterations affecting the NF-κB pathway characterise chemotherapy resistance in HGSC, suggesting that the regulation of an immune response may be associated with this phenotype.

Methods:

Given that intrinsic drug resistance pre-exists and is governed by both tumour and host factors, the current study was performed to examine the cross-talk between tumour inflammatory microenvironment and cancer cells, and their roles in mediating differential chemotherapy response in HGSC patients. Expression profiling of a panel of 184 inflammation-related genes was performed in 15 chemoresistant and 19 chemosensitive HGSC tumours using the NanoString nCounter platform.

Results:

A total of 11 significantly differentially expressed genes were found to distinguish the two groups. As STAT1 was the most significantly differentially expressed gene (P=0.003), we validated the expression of STAT1 protein by immunohistochemistry using an independent cohort of 183 (52 resistant and 131 sensitive) HGSC cases on a primary tumour tissue microarray. Relative expression levels were subjected to Kaplan–Meier survival analysis and Cox proportional hazard regression models.

Conclusions:

This study confirms that higher STAT1 expression is significantly associated with increased progression-free survival and that this protein together with other mediators of tumour–host microenvironment can be applied as a novel response predictive biomarker in HGSC. Furthermore, an overall underactive immune microenvironment suggests that the pre-existing state of the tumour immune microenvironment could determine response to chemotherapy in HGSC.

Profiles of genomic instability in high-grade serous ovarian cancer predict treatment outcome

PURPOSE

High-grade serous cancer (HGSC) is the most common cancer of the ovary and is characterized by chromosomal instability. Defects in homologous recombination repair (HRR) are associated with genomic instability in HGSC, and are exploited by therapy targeting DNA repair. Defective HRR causes uniparental deletions and loss of heterozygosity (LOH). Our purpose is to profile LOH in HGSC and correlate our findings to clinical outcome, and compare HGSC and high-grade breast cancers.

EXPERIMENTAL DESIGN

We examined LOH and copy number changes using single nucleotide polymorphism array data from three HGSC cohorts and compared results to a cohort of high-grade breast cancers. The LOH profiles in HGSC were matched to chemotherapy resistance and progression-free survival (PFS).

RESULTS

LOH-based clustering divided HGSC into two clusters. The major group displayed extensive LOH and was further divided into two subgroups. The second group contained remarkably less LOH. BRCA1 promoter methylation was associated with the major group. LOH clusters were reproducible when validated in two independent HGSC datasets. LOH burden in the major cluster of HGSC was similar to triple-negative, and distinct from other high-grade breast cancers. Our analysis revealed an LOH cluster with lower treatment resistance and a significant correlation between LOH burden and PFS.

CONCLUSIONS

Separating HGSC by LOH-based clustering produces remarkably stable subgroups in three different cohorts. Patients in the various LOH clusters differed with respect to chemotherapy resistance, and the extent of LOH correlated with PFS. LOH burden may indicate vulnerability to treatment targeting DNA repair, such as PARP1 inhibitors.

Bevacizumab and its use in epithelial ovarian cancer

Bevacizumab is a monoclonal antibody that binds to VEGF, a circulating protein involved in the promotion of angiogenesis and probably tumor growth and progression. Bevacizumab has demonstrated anticancer activity in several cancers, either combined with chemotherapy or when used as a single agent, and has been approved by the US FDA as a treatment for several cancers. As VEGF has been implicated in ovarian cancer progression and ascites formation, and high levels of VEGF have been found in plasma and ascites in women with ovarian cancer, bevacizumab has been tested as an anticancer therapy in ovarian cancer. Documented single-agent activity of bevacizumab in recurrent ovarian cancer has led to combination studies with both biologic agents as well as other chemotherapy agents in both recurrent and newly diagnosed cancer. One trial in patients with recurrent, heavily pretreated ovarian cancer demonstrated a higher than predicted risk of gastrointestinal perforation, and although a lower incidence of gastrointestinal perforation has been reported in less heavily pretreated patients, patients and their physicians must be aware of this risk. Upfront studies testing the impact of adding bevacizumab to carboplatin and paclitaxel chemotherapy for the treatment of newly diagnosed cancer are currently underway, and one Phase III randomized study (Gynecologic Oncology Group study 218) was recently presented and will be discussed in this article.

A phase II study of weekly topotecan and docetaxel in heavily treated patients with recurrent uterine and ovarian cancers

OBJECTIVES

A phase II trial designed to evaluate the safety and efficacy of weekly topotecan and docetaxel in heavily treated patients with recurrent uterine or epithelial ovarian cancers.

METHODS

Eligible patients with recurrent epithelial ovarian or uterine cancers were treated with weekly topotecan 3.5 mg/m(2) and docetaxel 30 mg/m(2) for 3 consecutive weeks. Cycles were repeated every 4 weeks for 6 cycles or until evidence of disease progression, unacceptable toxicity, or death. Response was assessed as per RECIST or Rustin's criteria. Time to best response and overall survival were calculated using Kaplan-Meier statistical methods.

RESULTS

Twenty-seven patients registered, of which 24 were evaluable for response. The majority of patients had received 2 prior chemotherapy regimens. Of the total 86 cycles of chemotherapy that were administered, there were three grade 4 (all neutropenia) and ten grade 3 toxicities. Six of the grade 3 non-hematologic toxicities were unrelated to treatment. There were 8 dose delays and 4 dose reductions. The overall response rate was 25% (95% CI: 7.7%-42.3%, 8% CR, 17% PR), and 38% of the patients had clinical benefit (95% CI: 18.1%-56.9%; CR+PR+13% SD). The median duration of response was 8.5 months (range 3-19 months). The median overall survival was 18.5 months (range 1.8-50.7 months).

CONCLUSION

The combination of weekly topotecan and docetaxel has clinical benefit and is well tolerated in this heavily treated patient population. Patients with platinum-resistant tumors had clinical benefit and should be considered for further study with this regimen.