Abstract 1784P
Background
Genomic alterations in the FGF/FGFR pathway are emerging as promising therapeutic targets. However, not all patients respond to therapy and resistance occurs. We investigated the molecular characteristics of patients (pts) treated with FGFR inhibitor-based therapies, including combination approaches.
Methods
We reviewed pts presented at the Molecular Tumor Board who received FGFR inhibitor to target FGFR pathway alterations. Pt demographics, molecular characteristics, therapy, response, progression-free survival (PFS), and overall survival (OS) were evaluated.
Results
Seventeen pts (pan-cancer diagnosis) with FGFR pathway alterations received FGFR inhibitors (median age: 61, male N=7 [41.2%]). The most common diagnosis was gastroesophageal cancer (29.4%), followed by biliary cancer (17.6%). FGF/FGFR amplification (amp) occurred in 13 pts, single nucleotide variant (SNV) in 3 pts, and fusions in 2 pts (N=1 patient had both amp and SNV). The most frequently co-altered pathways/genes were: TP53 pathway (70.6% of pts); cell cycle (52.9%); PI3K pathway (41.2%) and MEK/RAS (35.3%). The median number of co-alterations, excluding FGF/FGFR alterations, was 5 (range, 0-10). The median number of prior therapies was 2 (range 1-12). Six pts (35%) received FGFR inhibitors as monotherapy; 11 pts (65%) with customized combination. Durable partial response (PR) was seen in 3 pts (9, 12 and 22 months) and additional 3 pts achieved stable disease (SD) ≥6 months (13, 15 and 31 months) (6/17 [35%] had clinical benefit (SD≥6 months/PR)). The median PFS and OS were 4.4 months and 10.2 months. Clinical benefit was seen among biliary cancer (N=2) (FGFR2 fusion/FRS2 amp), osteosarcoma with FGF6/23 and FRS2 amp, glioneuronal tumor with FGFR1 SNV, ovarian cancer with FGFR4 amp, gastrointestinal stromal tumor with FGFR1 amp (N=1 each). The patient with the longest duration of benefit (PFS: 31months, OS: 52 months) had osteosarcoma including CDK4 amp treated with palbociclib (targeting cell cycle pathway) and lenvatinib (targeting FGFR pathway).
Conclusions
Most tumors with FGFR pathway abnormalities had co-genomic alterations. Targeting FGFR signaling achieved a clinical benefit rate of 35% (median duration= 14 months) in the pan-cancer setting.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
University of California San Diego.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.