Prognostic Significance of Plasma Osteopontin in Patients with Locoregionally Advanced Head and Neck Squamous Cell Carcinoma Treated on TROG 02.02 Phase III Trial

Abstract

High plasma osteopontin (OPN) levels have been reported to be an adverse prognostic factor in head and neck squamous cell carcinomas (HNSCC), correlate with tumor hypoxia, and be predictive of benefit from hypoxia-targeted therapy. We sought to confirm the prognostic and predictive significance of OPN in patients treated on a large international trial. Patients with stage III/IV HNSCC were randomized to receive definitive radiotherapy concurrently with cisplatin or cisplatin plus the hypoxic cell cytotoxin, tirapazamine (TPZ). Eligibility criteria for this prospective substudy included plasma sample availability for OPN assay by ELISA and absence of major radiation therapy deviations (N = 578). OPN concentrations were analyzed for overall survival (OS) and time to locoregional failure (TTLRF), adjusting for known prognostic factors. Additional analysis was carried out in patients with available tumor p16(INK4A) staining status. The median OPN level was 544 ng/mL (range: 7-2,640). High OPN levels were not associated with worse OS (relative HR, 1.03 for highest tertile) or TTLRF (relative HR 0.91 for highest tertile). There was no interaction between OPN and treatment arm for OS or TTLRF (P = 0.93 for OS; P = 0.87 for TTLRF). For the highest tertile the 2-year OS was 66% on control arm and 67% on TPZ arm (HR = 1.11, P = 0.67). Similarly for p16(INK4A) negative patients in the highest tertile, the 2-year OS was 61% on control arm and 63% on TPZ arm (HR = 1.05, P = 0.86). We found no evidence that high plasma OPN levels were associated with an adverse prognosis in HNSCC, or were predictive of benefit with hypoxia targeting therapy.