Alpelisib hydrochloride (BYL-719 hydrochloride) is a potent PI3Kα inhibitor (IC₅₀ = 5 nM) with selectivity and oral bioavailability, exhibiting activity against PI3Kβ/γ/δ that is dozens of times weaker than against PI3Kα (IC₅₀ = 250/290/1200 nM). Alpelisib exhibits targeting activity against PIK3CA-mutated tumors and may be utilized in cancer research.

Alpelisib hydrochloride (BYL-719) potently inhibits the two most common PIK3CA somatic mutations (H1047R, E545K), with an IC₅₀ of approximately 4 nM. Alpelisib hydrochloride can robustly suppress the phosphorylation level of protein kinase B (Akt) in PI3Kα-transfected cells, with an IC₅₀ of 74±15 nM; in contrast, its inhibitory activity is significantly reduced in cells transfected with the PI3Kβ or PI3Kδ isoform, showing a ≥15-fold decrease compared with that in PI3Kα-transfected cells [2].
Alpelisib hydrochloride (0–50 μM, 72 h) exerts a dose-dependent inhibitory effect on the proliferation of human osteosarcoma cell lines MG63, HOS, POS-1, and MOS-J [3].
Alpelisib hydrochloride (25 μM, 18 h) induces G₀/G₁ phase cell cycle arrest in both human and murine osteosarcoma cell lines [3].

Alpelisib hydrochloride (BYL-719) was administered orally at varying doses daily, with 12.5 mg/kg and 50 mg/kg doses for C57Bl/6J mice and 50 mg/kg for female Rj:NMRI nude mice, significantly reducing tumour volume and decreasing the deposition of bone matrix at the parazacco spilurus subsp. spilurus site [3].
Following intravenous injection of 1 mg/kg Alpelisib hydrochloride in rats, the terminal elimination half-life of the drug was moderate, at 2.9 ± 0.2 hours [1].