A Roundtable Discussion of the Breast Cancer Therapy Expert Group (BCTEG): Clinical Developments and Practice Guidance on Human Epidermal Growth Factor Receptor 2 (HER2)-positive Breast Cancer

Expression of human epidermal growth factor receptor 2 (HER2) in breast cancer defines a subset of patients (∼15%-20%) who are candidates for anti-HER2 therapies, most notably, trastuzumab, pertuzumab, antibody drug conjugates (eg, T-DM1), and tyrosine kinase inhibitor (TKI) drugs (eg, lapatinib and neratinib), all of which have dramatically changed the prognosis for this aggressive subtype of breast cancer. A roundtable meeting of the Breast Cancer Therapy Expert Group (BCTEG) was convened in March 2018 in an effort to discuss and clarify, from the perspective of the practicing community oncologist, recent developments in the diagnosis and treatment of HER2-positive (HER2⁺) breast cancer. Members of the group selected 4 key topics for discussion prior to the meeting, including diagnosis of HER2⁺ disease, and its treatment in the neoadjuvant, adjuvant, and metastatic settings. Approved testing methods, such as immunohistochemistry and fluorescence in situ hybridization, are used to demonstrate overexpression and/or amplification of HER2 in breast tumors, and established clinical guidelines are used to appropriately define treatment plans for patients with HER2⁺ disease. The panel acknowledges a range of treatment options now available for treatment of HER2⁺ breast cancer in the neoadjuvant, adjuvant, and advanced/metastatic settings, although it is noted that many controversies remain, including the optimal sequence of therapies, the most appropriate treatment(s) for subsets of patients with HER2⁺ disease (eg, hormone receptor-negative or -positive/HER2⁺), and uncertainties surrounding the diagnosis and definition of HER2⁺ disease. The current report summarizes the discussion of the BCTEG panel on this topic.

Automated density-based counting of FISH amplification signals for HER2 status assessment

BACKGROUND

Automated image analysis can make quantification of FISH signals in histological sections more efficient and reproducible. Current detection-based methods, however, often fail to accurately quantify densely clustered FISH signals.

METHODS

We propose a novel density-based approach to quantifying FISH signals. Instead of detecting individual signals, this approach quantifies FISH signals in terms of the integral over a density map predicted by Deep Learning. We apply the density-based approach to the task of counting and determining ratios of ERBB2 and CEN17 signals and compare it to common detection-based and area-based approaches.

RESULTS

The ratios determined by our approach were strongly correlated with results obtained by manual annotation of individual FISH signals (Pearson's r = 0.907). In addition, they were highly consistent with cutoff-scores determined by a pathologist (balanced concordance = 0.971). The density-based approach generally outperformed the other approaches. Its superiority was particularly evident in the presence of dense signal clusters.

CONCLUSIONS

The presented approach enables accurate and efficient automated quantification of FISH signals. Since signals in clusters can hardly be detected individually even by human observers, the density-based quantification performs better than detection-based approaches.

Reliability of Human Epidermal Growth Factor Receptor 2 Immunohistochemistry in Breast Core Needle Biopsies

Purpose

Core needle biopsies (CNBs) are widely used to determine human epidermal growth factor receptor 2 (HER2) status in breast cancer. Recent publications reported up to 20% false-positive results on CNBs if immunohistochemistry (IHC) is compared with fluorescent in situ hybridization (FISH). To clarify, if confirmation of IHC positivity by FISH is generally required, we analyzed the reliability of IHC positivity on CNBs versus surgical specimens in a multi-institutional study.

Patients and Methods

Five pathologic laboratories contributed to this study by performing IHC on 500 CNBs and the corresponding surgical specimens overall. If IHC revealed score 2+ or 3+, HER2 status was confirmed by FISH in a central laboratory. We compared evaluation according to US Food and Drug Administration–approved scoring criteria and recently published American Society of Clinical Oncology (ASCO)–College of American Pathologists (CAP) guidelines.

Results

CNBs scored 3+ revealed five false-positive results if scoring followed the US Food and Drug Administration criteria (five of 40; 12.5%) and two false-positives in terms of the ASCO-CAP criteria (two of 33; 6.1%). IHC was false negative in one CNB only. By contrast, IHC on surgical specimens revealed five false-negative results, but only one false-positive result (one of 35; 2.9%) if scored following US Food and Drug Administration–approved criteria. With the aid of the ASCO-CAP criteria, false-positive IHC results were obtained in only one of the five participating institutions.

Conclusion

IHC 3+ scores on CNBs proved to be reliable in four of the five participating institutions if scoring followed the ASCO-CAP criteria. Therefore, accurate determination of HER2 status in breast cancer is possible on CNB using the common strategy to screen all cases by IHC and retest only 2+ scores by FISH. Prerequisites are quality assurance and the application of the new ASCO-CAP criteria.

Role of capecitabine and irinotecan combination therapy in advanced or metastatic gastric cancer

Gastric cancer is one of the most common cancers and the second leading cause of cancer-related death. So far, the only curative treatment for gastric cancer is surgery. However, approximately half of all patients present with nonoperable tumors. Therefore, combination chemotherapy regimens are being accepted nowadays as first-line treatment for this disease. Despite the numerous efforts of randomized trials on advanced gastric cancer, no globally accepted regimen has yet been established. Historically, the most widely adopted protocols use 5-fluorouracil or platinum-based therapy with a response rate not exceeding 50% in combination therapy with a high rate of toxicity. Recently, many new drugs have emerged on the market and have been used in treating advanced or metastatic gastric cancer allowing the creation of new combination regimens with better clinical benefit. The combination of irinotecan plus capecitabine is one of these new combinations that seem to provide an acceptable response rate and good toxicity profile. In this article, we review the efficacy, tolerability, and feasibility of this combination for the treatment of advanced or metastatic gastric cancer and we summarize the clinical trials using this regimen.