A phase II umbrella clinical trial of advanced salivary gland cancer based on molecular typing.

e18062 Background: Salivary gland cancers (SGCs) exhibit high heterogeneity in molecular and genomic characteristics, which provides a basis for targeted therapies of SGCs. Until recently, the gene targets of precision therapy drugs mainly included HER2, NTRK, TROP2, androgen-receptor (AR), etc. Herein, we report the preliminary result of a single-center, open-label, phase II umbrella clinical trial evaluating the efficacy and safety of molecular subtype-guided precision therapy for advanced salivary gland cancer (NCT05924256). Methods: Patients (pts) diagnosed as advanced SGC were recruited into 3 arms according to genetic subtypes. Pts with HER2 mutation/amplification or HER2 overexpression (IHC 3+ or IHC 2+/ISH+) will be assigned to arm 1 and receive SHR-A1811(anti-HER2) 4.8 mg/kg i.v. on day 1 of each 21-day cycle. IHC AR+ pts will be assigned to arm 2 and will receive rezvilutamide 240mg p.o. qd plus leuprolide 3.75mg s.c. on day 1 of each 28-day cycle. Pts with HER2 negative and AR negative will be assigned to arm 3 to receive SHR-A1921(anti-TROP2) 3.0 mg/kg or 4.0 mg/kg i.v. on day 1 of each 21-day cycle. A Simon’s two-stage optimal design was applied to each arm. The primary endpoint was the objective response rate (ORR) per RECIST1.1. Secondary endpoints included adverse events (AEs), disease control rate (DCR), progression-free survival (PFS), and overall survival (OS), etc. Results: Between Aug 2, 2023, and Jan 21, 2024, 21 pts were enrolled (arm 1/2/3: 9/5/7 pts, respectively). All pts were included in the safety set. In arm 1, of 6 evaluable pts, the unconfirmed ORR and DCR accounted for 100.0% and 100.0%, respectively. The most common treatment-related adverse events (TRAEs) in arm 1 were decreased lymphocyte count, neutrophil count, and decreased appetite (44.4% each). In arm 2, of 5 evaluable pts, the unconfirmed ORR and DCR were 20.0% and 100.0%, respectively. Rash, alanine aminotransferase increased, aspartate aminotransferase increased, and gamma-glutamyltransferase increased (20% each) were the most common TRAEs. In arm 3, of 6 evaluable pts, the unconfirmed ORR and DCR were 33.3% and 66.7%, respectively. In this arm, the most common TRAEs were stomatitis and vomiting (42.9% each). Conclusions: This molecular subtype-guided precision therapy for advanced salivary gland cancer showed promising results with acceptable toxicity. Clinical trial information: NCT05924256 .