Progress against solid tumors in danger: the metastatic breast cancer example

Bevacizumab as first-line treatment in HER2-negative advanced breast cancer: pros and cons

PURPOSE

Bevacizumab, a humanized, anti-vascular endothelial growth factor-A monoclonal antibody, has shown efficacy in a number of cancers. However, its use in metastatic breast cancer (MBC) remains controversial.

METHODS

A literature review using the PubMed database was performed to update the currently available clinical trials evidence on bevacizumab in the first-line treatment of breast cancer. In addition, the proceedings of selected oncology annual meetings were searched for relevant presentations.

RESULTS

This article reviews the available evidence for bevacizumab as first-line therapy for MBC and discusses its current and future applicability in the management of MBC. Three phase III trials (ECOG-2100, AVADO, RIBBON-1) demonstrated that the addition of bevacizumab to chemotherapy is well-tolerated and improves progression-free survival and objective response rates in the first-line setting. These findings were supported by a large clinical practice-based study (ATHENA) and a recent clinical trial in which bevacizumab added to paclitaxel showed notable activity in triple-negative MBC. However, bevacizumab has thus far not demonstrated a significant benefit in overall survival.

CONCLUSIONS

The addition of bevacizumab to chemotherapy is well-tolerated and produces substantial improvements in overall response rate and progression-free survival, compared with chemotherapy alone, in advanced HER2-negative breast cancer. Nevertheless, it has thus far not demonstrated a significant benefit in overall survival. Whether prolongation of progression-free survival is enough to consider bevacizumab efficacious is unclear. Based on the available clinical trials results, bevacizumab is a part of the complex therapeutic strategy of advanced HER2-negative breast cancer.

A Delphi consensus and open debate on the role of first-line bevacizumab for HER2-negative metastatic breast cancer

To gain consensus on the role of bevacizumab plus paclitaxel as first-line treatment for HER2-negative metastatic breast cancer, a panel of expert oncologists experienced in treating patients with metastatic breast cancer in Italy participated in a Delphi consensus study. The panel reached a full consensus on the efficacy of bevacizumab plus paclitaxel and the clinical meaningfulness of the progression-free survival benefit compared with paclitaxel alone, despite the lack of an overall survival effect in clinical trials. The participants agreed that real-world data support the effectiveness and well-defined safety profile of the regimen. Views on the use of bevacizumab plus paclitaxel in specific patient populations were not unanimous and clinical judgment remains important. Nevertheless, a high level of agreement was reached.

Use of bevacizumab as a first-line treatment for metastatic breast cancer

OBJECTIVE

During clinical practice, it can be challenging, given the lack of response biomarkers, to identify the patients with metastatic breast cancer (mbca) who would benefit most from the addition of bevacizumab to first-line standard chemotherapy. The aim of the present review was to summarize the relevant scientific evidence and to discuss the experience of a group of experts in using bevacizumab to treat mbca.

METHODS

A panel of 17 Spanish oncology experts met to discuss the literature and their experience in the use of bevacizumab as first-line treatment for mbca. During the meeting, discussions focused on three main issues: the profile of the patients who could benefit most from bevacizumab, the optimal bevacizumab treatment duration, and the safety profile of bevacizumab.

RESULTS

The subset of mbca patients who would benefit the most from the addition of bevacizumab to first-line standard chemotherapy are those with clinically defined aggressive disease. Treatment with bevacizumab should be maintained until disease progression or the appearance of unacceptable toxicity. In the mbca setting, the toxicity profile of bevacizumab is well known and can be managed in clinical practice after adequate training.

CONCLUSIONS

This expert group recommends administering bevacizumab as first-line treatment in patients with clinically aggressive disease.

Measures of outcome in metastatic breast cancer: insights from a real-world scenario

No gold standard treatment exists for metastatic breast cancer (MBC). Clinical decision making is based on knowledge of prognostic and predictive factors that are extrapolated from clinical trials and, sometimes, are not reliably transferable to a real-world scenario. Moreover, misalignment between endpoints used in drug development and measures of outcome in clinical practice has been noted. The roles of overall survival (OS) and progression-free survival (PFS) as primary endpoints in the context of clinical trials are the subjects of lively debate. Information about these parameters in routine clinical practice is potentially useful to design new studies and/or to interpret the results of clinical research. This study analyzed the impact of patient and tumor characteristics on the major measures of outcome across different lines of treatment in a cohort of 472 patients treated for MBC. OS, PFS, and postprogression survival (PPS) were analyzed. The study showed how biological and clinical characteristics may have different prognostic value across different lines of therapy for MBC. After first-line treatment, the median PPS of luminal A, luminal B, and human epidermal growth factor receptor 2 (HER2)-positive groups was longer than 12 months. The choice of OS as a primary endpoint for clinical trials could not be appropriate with these subtypes. In contrast, OS could be an appropriate endpoint when PPS is expected to be low (e.g., triple-negative subtype after the first line; other subtypes after the third line). The potential implications of these findings are clinical and methodological.

A systematic review of bevacizumab efficacy in breast cancer

Angiogenesis is a key component of cancer growth, invasion and metastasis. Therefore, inhibition of angiogenesis is an attractive strategy for the treatment of cancer. We systematically describe phase II and III clinical trials of bevacizumab for the treatment of breast cancer.

METHODS

A computer-based literature search was carried out using PUBMED and conference databases. Original phase II and III studies reporting ≥15 patients who received bevacizumab were included.

RESULTS

41 phase II trials were identified in the metastatic setting. Most trials found bevacizumab treatment feasible. Response rates (RR) varied from 0% to 76.5%, time to progression (TTP)/progression free survival (PFS) from 2.4 to 25.3 months and overall survival from 11.5 to more than 38 months. 14 phase III trials including more than 4400 patients with MBC unanimously showed increased RR and PFS, however, no trials demonstrated an OS benefit. In the neoadjuvant setting 23 phase II and III trials were identified. All studies found increased pCR/tpCR but no benefit in terms of OS could be demonstrated. The only study conducted in the adjuvant setting failed to show any survival benefit of bevacizumab.

CONCLUSION

Despite increased response rates in both the metastatic and neoadjuvant setting, bevacizumab has failed to show any OS benefit. Future trials should include identification of robust predictive biomarkers in order to improve our understanding of molecular biomarkers and mechanisms.

Should we move beyond VEGF inhibition in metastatic colorectal cancer? Lessons from early phase clinical trials

Data from recent clinical trials utilizing bevacizumab or other anti-VEGF agents in patients with metastatic colorectal cancer (mCRC) show improvements in progression-free survival (PFS) but modest, if any, improvements in overall survival (OS). Despite modest improvements, use of bevacizumab beyond first and second progression is routinely done in clinical practice. Recently, the CORRECT trial using regorafenib, a multi-kinase inhibitor with VEGF inhibitory properties, reported modest improvements in PFS and OS when compared to placebo, leading to FDA approval in the third-line setting. Prior to regorafenib, heavily pre-treated patients were often enrolled onto early phase clinical trials with many of these studies reporting efficacy amongst patients with mCRC; however, a collective efficacy analysis of mCRC patients enrolled into early phase clinical trials stratified by class of agents and their mechanism of action has not been done. To assess this, we performed an analysis of efficacy and stratified these findings based on VEGF inhibition versus non-VEGF inhibition in mCRC patients enrolled onto phase I trials at our institution from 3/2004-9/2012. Similar to many reported clinical studies, our data showed that VEGF inhibitors have a statistically significant improvement in PFS when compared to non-VEGF targeting agents; however, no differences in OS were observed between these two different classes of agents. We were not able to identify predictive biomarkers that correlate with efficacy of VEGF inhibitors. This should be further explored in prospective studies in order to identify active agents in this heavily pre-treated population that improve efficacy while minimizing cost and toxicity.

New challenges for comparative effectiveness in oncology: choice of primary end points for randomized clinical trials

Recent advances have led to a steady improvement in cancer treatments. The increasing number of therapeutic options and the corresponding improvement in outcomes pose a number of challenges for comparative effectiveness research in oncology. This review is focused on the choice of primary end points and their interpretation in randomized clinical trials that are designed to inform patients and clinicians on the relative benefits of cancer therapies. We discuss end points that directly measure clinical benefit as well as end points that are thought to be surrogates for clinical benefit. Particular attention is given to the issues associated with the use of overall survival as the primary end point in randomized clinical trials.

SEOM clinical guidelines for the management of metastatic breast cancer 2013

Patients with metastatic breast cancer should be offered comprehensive and personalized medical attention including, but not limited to, psychosocial, supportive and symptom-related interventions. A large number of treatment options are available and several prognostic and predictive factors are useful to identify the best therapeutic options individually.

First-line bevacizumab in combination with chemotherapy for HER2-negative metastatic breast cancer: pooled and subgroup analyses of data from 2447 patients

BACKGROUND

Bevacizumab has consistently demonstrated improved progression-free survival (PFS) and response rate when combined with first-line chemotherapy for HER2-negative metastatic breast cancer (mBC). However, the lack of a significant overall survival (OS) difference continues to attract debate, and identification of patients deriving greatest benefit from bevacizumab remains elusive.

PATIENTS AND METHODS

Individual patient data from three randomised phase III trials in the first-line HER2-negative mBC setting were analysed, focusing specifically on efficacy in poor-prognosis patients.

RESULTS

The meta-analysis (n = 2447) demonstrated a PFS hazard ratio (HR) of 0.64 (95% confidence interval [CI] 0.57-0.71; median 9.2 months with bevacizumab versus 6.7 months with non-bevacizumab therapy) and response rate of 49% versus 32%, respectively. The OS HR was 0.97 (95% CI 0.86-1.08); median 26.7 versus 26.4 months, respectively. In patients with triple-negative mBC, the HRs for PFS and OS were 0.63 (95% CI 0.52-0.76) and 0.96 (95% CI 0.79-1.16), respectively. Median PFS was 8.1 months with bevacizumab versus 5.4 months with chemotherapy alone, median OS was 18.9 versus 17.5 months, respectively, and 1-year OS rates were 71% versus 65%.

CONCLUSIONS

Bevacizumab improves efficacy, including 1-year OS rates, both overall and in subgroups of poor-prognosis patients with limited treatment options.

Adjuvant therapy reduces the benefit of palliative treatment in disseminated breast cancer - own findings and review of the literature

BACKGROUND

Adjuvant treatment concepts have improved the 10-year cure rate of breast and colon cancer, but new treatments for metastatic disease have yielded only incremental benefit. If treatments for disseminated cancer were actually prolonging life rather than only increasing remission rates, this effect should have been documented over the last 30+ years. However, published data concerning advances in treatment for disseminated cancer have been contradictory.

PATIENTS AND METHODS

To add data-based information, we analyzed 2 sources: a regional population-based cancer registry (Hamburgisches Krebsregister, HKR), and a research cancer registry (Projektgruppe Internistische Onkologie, PIO). We compared the survival of several thousand patients with metastatic disease who received treatment only after dissemination with that of patients who received initial adjuvant therapy.

RESULTS

After adjuvant treatment, survival in patients with disseminated breast cancer is up to a third shorter than that of patients without adjuvant therapy.

CONCLUSIONS

In accordance with published evidence, we conclude that ineffective adjuvant treatment shortens survival after documentation of metastatic disease. This is probably due to the elimination of chemo-sensitive tumor cells or to the induction of resistance in remaining micrometatases. This negative effect on survival after dissemination has been shown clearly for breast cancer and is also probable for cancer of the colon and other sites.