Imlonstrant is a substance under investigation that acts as a selective estrogen receptor modulator (SERM) and is specifically designed to treat advanced breast cancer, particularly hormone receptor-positive (HR+) and human epidermal growth factor 2 (HER2-)-negative breast cancer.However, a significant proportion of patients develop resistance to these drugs over time, often due to mutations in the estrogen receptor 1 (ESR1) gene or through adaptive cellular mechanisms that keep ER receptor signaling active.To overcome the obstacle of resistance to hormone therapy, new therapeutic approaches such as selective estrogen receptor lysates (SERLs) have been developed.