TQ-B3525 + fulvestrant

TQ-B3525 + fulvestrant is a combination therapy consisting of TQ-B3525, a novel and selective oral small molecule inhibitor of phosphoinositide 3-kinase alpha and delta (PI3Kα/δ), and fulvestrant, a selective estrogen receptor degrader (SERD). - **TQ-B3525** inhibits both PI3Kα and PI3Kδ isoforms, disrupting PI3K-Akt signaling pathways critical for tumor cell proliferation and survival, especially in B-cell malignancies and solid tumors[1][2][3][5][6]. - **Fulvestrant** is an approved SERD that binds to estrogen receptor (ER), leading to its degradation and thereby inhibiting ER-mediated signaling, primarily used in hormone receptor-positive breast cancer. - The combination leverages the anti-tumor effects of both PI3K pathway inhibition (by TQ-B3525) and estrogen receptor blockade (by fulvestrant), which is a rational strategy for ER-positive cancers due to frequent PI3K pathway alterations. - While TQ-B3525 monotherapy is under active clinical trial development for lymphoma and solid tumors, the combination with fulvestrant has been explored preclinically and may be in early-stage clinical investigation, especially for ER-positive solid tumors such as breast or gynecologic cancers.