Overcoming the Adverse Effects of Everolimus to Achieve Maximum Efficacy in the Treatment of Inoperable Breast Cancer: A Review of 11 Cases at Our Hospital

Everolimus is an effective treatment for advanced and/or metastatic breast cancer, especially in hormone receptor-positive cases. However, adverse events have prevented considerable numbers of clinicians from using this drug. Herein, we reviewed our clinical experiences and endeavored to identify patients in whom the benefits of everolimus treatment would outweigh these adverse events. If measures were available to prevent or minimize adverse effects prior to treatment, everolimus would be a more widely applicable drug. This retrospective study involved 11 patients in whom nonresectable or recurrent breast cancers were treated with everolimus between April 2014 and January 2016. Two patients achieved a partial response (PR) and 4 showed stable disease (SD) (1 showed long SD, i.e., > 24 weeks). The response rate was 18%, and the clinical benefit rate (PR + long SD) was 27%. Regarding adverse events, interstitial pneumonia (grade 3) developed in 3 patients (18%), necessitating treatment discontinuation. When using everolimus, it may be important to select suitable patients for whom this treatment can be continued with sufficient control of adverse events. Herein, we provide information relevant to the clinical use of everolimus based on our daily practice experiences with this agent.