Place of fulvestrant in the treatment of patients with metastatic luminal Her2-negative breast cancer

Hormone therapy alone or in combination with targeted agents (CDK4/6 inhibitors, alpelisib, everolimus) is currently the standard treatment of metastatic luminal Her2-negative breast cancer. Aromatase inhibitors and fulvestrant are the main hormone therapy agents. Fulvestrant belongs to a special class of antiestrogens – selective estrogen receptor degraders (SERD) and does not have estrogen receptor agonist activity, unlike tamoxifen. In addition, the efficacy of fulvestrant does not depend on the presence of ESR1 mutations in the tumor. The combination of aromatase inhibitors with CDK4/6 inhibitors is the standard first-line treatment in patients with hormone-sensitive tumors, that is, with progression of more than 1 year after the end of adjuvant hormone therapy. Whereas fulvestrant ± CDK4/6 inhibitors are used for disease progression on adjuvant hormonal therapy in the 1st line or as 2nd line for progression on aromatase inhibitor therapy for metastatic cancer. The choice of treatment for patients with a PIK3CA mutation with progression on the 1st line of fulvestrant with a CDK4/6 inhibitor is difficult. This article presents a clinical example of the use of a combination of fulvestrant and alpelisib in a patient with secondary hormone resistance (progression on the adjuvant therapy with aromatase inhibitors) and progression on the first-line therapy with fulvestrant and palbociclib. Carrying out therapy with fulvestrant and alpelisib as the 2nd line provided a long-term (for 14 months) stabilization of the tumor process.