The clinical case presented in the article demonstrates the effectiveness of orange in combination with fulvestrant in metastatic estrogen receptor-positive HER2/neu-negative breast cancer with a mutation in the PIK3CA gene. The resistance of hormone therapy requires the search for new therapeutic options. The results of the SOLAR-1 and BYLieve studies have shown not only the effectiveness of alpelisib, but also new types of toxicity characteristic of this therapy. At the moment, recommendations have been developed for the prevention and treatment of the most frequent adverse events, allowing the drug to be used as safely as possible. With the introduction of alpelisib, the possibilities of non-chemotherapeutic treatment options for prognostically unfavorable patients have not only expanded, but there has also been a trend towards the use of personalized medicine and targeted therapy.

The article presents a clinical case illustrating the effectiveness of abemaciclib in combination with anastrozole in metastatic estrogen receptor-positive HER2/neu-negative breast cancer (BC). CDK4/6 inhibitors have changed the paradigm of treatment of patients with hormone-positive HER2 metastatic BC. Thanks to the ability of palbociclib, ribociclib and abemaciclib to delay and overcome resistance to endocrine therapy, the effectiveness of treatment of patients not only with newly diagnosed disease, but also with endocrine – resistant, and taking into account the independent effectiveness of abemaciclib and chemorefractor BC has increased. The combination of aromatase inhibitors and abemaciclib is associated with an increase in the effectiveness of treatment in the most prognostically unfavorable contingent of patients.