The economics of counterfeit Avastin: a geospatial and statistical analysis of demographic correlates to FDA warning letters

PURPOSE

In 2012, the Food and Drug Administration (FDA) sent warning notices to clinics and medical practitioners that may have purchased or administered counterfeited versions of the angiogenesis cancer drug Avastin Genentech, South San Francisco, California, USA. The purpose of this study was to explore potential differences in demographic, economic, and healthcare coverage characteristics between areas that received these counterfeit warning notices and those that did not receive notices. The aims of this study are to improve future counterfeit drug surveillance and better assess potential risk factors associated with counterfeit cancer drugs.

METHODS

Addresses for warning notices sent to healthcare practitioners were obtained from the FDA and then geocoded using arcgis. Variables chosen for statistical and geospatial analyses were then identified and assessed based on their potential association with Avastin access and affordability. These variables included demographic and economic factors (percent below the poverty line, percent uninsured, and median household income) and healthcare coverage data (percent Medicare enrollees) available from the US Center for Medicare and Medicaid Services. All variables were analyzed at the US county level.

RESULTS

Our analysis uncovered 401 distinct US counties where the FDA sent at least one counterfeit Avastin warning notice. A hot spot analysis of notices and variables was carried out using arcgis software to identify and visualize risk features with high and low values of clustering. In a multiple logistic regression model reassessing visually observed geospatial associations, the receipt of a notice was not significantly associated with percent uninsured (p = 0.3121), but was significantly associated with percent Medicare enrollees (OR = 0.874 per 10% increase; p = 0.0121), individuals below federal poverty line (OR = 2.990 per 10% increase; p < 0.0001), and median household income (OR = 2.698 per $10 000 increase; p < 0.0001).

CONCLUSIONS

Our study found that county-level economic and demographic factors are potentially associated with counterfeit Avastin warning receipt after controlling for the total number of people residing in each county. These geographic associations indicate that individuals in counties where patients have greater ability to afford more expensive treatment, and consequently where providers can seek higher reimbursement, may have been at higher risk to counterfeit Avastin exposure. These findings can help inform future efforts to improve drug safety surveillance and more proactively identify patients at the highest risk for counterfeit cancer drugs.

Antiangiogenic therapy for breast cancer

Angiogenesis is an important component of cancer growth, invasion and metastasis. Therefore, inhibition of angiogenesis is an attractive strategy for treatment of cancer. We describe existing clinical trials of antiangiogenic agents and the challenges facing the clinical development and optimal use of these agents for the treatment of breast cancer. Currently, the most promising approach has been the use of bevacizumab, a humanized monoclonal antibody directed against the most potent pro-angiogenic factor, vascular endothelial growth factor (VEGF). Small molecular inhibitors of VEGF tyrosine kinase activity, such as sorafenib, appear promising. While, the role of sunitinib and inhibitors of mammalian target of rapamycin (mTOR) in breast cancer has to be defined. Several unanswered questions remain, such as choice of drug(s), optimal duration of therapy and patient selection criteria.

Antiangiogenic strategies in breast cancer management

Angiogenesis is considered one of the key mechanisms of tumour growth and survival. Therefore it represents an ideal pharmaceutical target. Many antiangiogenic agents have been developed so far in several solid tumours and also in breast cancer. Vascular endothelial growth factor (VEFG) is the main target and both monoclonal antibodies and small molecules belonging to the tyrosine kinase inhibitors directed against VEGF(R) have been developed. Some other therapeutic approaches have shown to exert some antiangiogenic activity, such as hormonal agents, metronomic chemotherapy, bisphosphonates and others. In this paper we provide an introduction of the current data supporting the angiogenesis in breast cancer and a review of the most relevant antiagiogenic therapies which have been investigated so far.

Letrozole

IMPORTANCE OF THE FIELD

Aromatase is an enzyme which converts adrenal androgens to estrogens in postmenopausal women. Given the importance of estrogens in breast cancer growth, aromatase inhibitors are used to treat breast cancer in different settings. This review focuses on letrozole, a third generation aromatase inhibitor, encompassing pharmacodynamic and pharmacokinetic aspects as well as its clinical efficacy and safety.

AREAS COVERED IN THIS REVIEW

A literature search and review of the studies published on letrozole were carried out using the MEDLINE database up to November 2009.

WHAT THE READER WILL GAIN

The paper provides the reader with information about pharmacodynamic and pharmacokinetic aspects of letrozole, its preclinical and clinical efficacy and its safety.

TAKE HOME MESSAGE

Letrozole is a well-tolerated and effective drug in metastatic breast cancer in postmenopausal women. Two clinical trials conducted in early breast cancer have confirmed its role in the adjuvant setting in postmenopausal women. More recently, data have confirmed its efficacy as neoadjuvant treatment in breast cancer. Future developments include the combination of letrozole with new biologic agents and tailoring of treatment with gene expression profiling studies.

Biologic therapy of breast cancer: focus on co-inhibition of endocrine and angiogenesis pathways

There remains a high unmet need for effective treatments for metastatic breast cancer. In recent years there have been many advances in the understanding of biological basis of cancer. Several cellular pathways have been identified that play crucial roles in causing or maintaining the cancer phenotype. Many new agents that target these pathways have entered the clinic or are being investigated. In order to improve the therapeutic efficacy seen with single-agent regimens, rational combinations of targeted agents are being evaluated in ongoing trials. The optimal sequencing and combination of agents has yet to be established. Endocrine and vascular endothelial growth factor pathways are the two most prominent pathways active in breast cancer cells and inhibition of either of these is associated with clinical benefit. Here we discuss the rationale for simultaneously targeting these pathways and highlight ongoing clinical trials.

Hormono-biological therapy in metastatic breast cancer: preclinical evidence, clinical studies and future directions

Breast cancer growth is regulated by coordinated actions of the estrogen receptor (ER) and various growth factor receptor signalling pathways. This complex interactive signalling potentially explains some of the reasons behind endocrine therapy action and resistance. Recent research into the molecular biology of ER signalling has revealed new molecular targets which, if present in cancer cells, might be additionally targeted using various signal transduction inhibitors to overcome or prevent resistance to endocrine therapy. The dynamic inverse relationship between the expression of ER and growth factor receptors brings more excitement to the potential of restoring ER expression in apparently ER-negative cells by inhibition of growth factor signalling. The multiple pathways involved in activating ERs also provide a rationale for combining endocrine and non-endocrine therapies that block different signalling pathways. Ongoing clinical trials promise to further improve the present care for breast cancer patients.

Overcoming endocrine resistance in breast cancer: are signal transduction inhibitors the answer?

Endocrine therapy is probably the most important systemic therapy for hormone receptor positive breast cancer. Hormonal manipulation was the first targeted treatment employed in breast cancer therapy even before the role of the estrogen (ER) and progesterone receptors (PR) had been elucidated. Unfortunately, a substantial proportion of patients, despite being ER and/or PR positive, are either primarily resistant to hormone therapies or will develop hormone resistance during the course of their disease. Signaling through complex growth factor receptor pathways, which activate the ER are emerging as important causes of endocrine resistance. Targeted therapies, such as signal transduction inhibitors (STIs), are being explored as agents to be able to potentially overcome this crosstalk and thus, resistance to hormone treatment. This article reviews the biology of the ER, the proposed mechanisms of endocrine resistance, and ongoing clinical trials with STIs in combination with hormonal manipulation as a means to overcome endocrine resistance.