Single-institute outcomes of palliative chemotherapy in metastatic head and neck squamous cell carcinoma (HNSCC)

e18513 Background: Distantly metastatic HNSCC carries a poor prognosis with limited palliative systemic treatment options and a paucity of literature examining factors impacting outcomes of such therapy. We sought to evaluate characteristics conferring more favorable responses to frontline palliative systemic therapy after distant failure (DF). Methods: From an IRB-approved database, we identified 332 pts with metastatic HNSCC treated from 1999 to 2019. Pts with locoregional HNSCC who developed DF and subsequently were treated with palliative systemic therapy were included. Pts were categorized by disease factors, and outcomes were analyzed for progression-free survival (PFS) and overall survival (OS) with Kaplan-Meier curves and log-rank p-values. Results: A total of 85 pts were identified with median age 59.5 years (37-89); 82.4% male, 90.6% Caucasian, 52.9% with > 10 pack-years tobacco use history. Oropharynx primary was the most common site (36.5%) followed by oral cavity (23.5%). All 31 oropharynx cancer pts were HPV-related. Sixty-six pts initially received definitive chemoradiotherapy, with 43 receiving concurrent radiosensitizing cisplatin. Median time to DF was 15 months (m). Thirty pts (35.3%) had concurrent locoregional failure with DF. 62.4% had only one metastatic organ site, with lung-only metastasis in 43.5%. Carboplatin/paclitaxel was the most commonly used frontline palliative chemotherapy (50.6%); 22.4% received frontline nivolumab or pembrolizumab, and 9.4% were treated with frontline platinum/5-FU/cetuximab (9.4%). 63.5% of pts achieved a best response of stable disease or better with frontline therapy. At two years after initial DF, 6 pts (7%) were disease-free. Sixteen pts were alive at last follow-up. After DF, median PFS was 6.5 m and median OS was 10.6 m. On univariate analysis, HPV-related disease was associated with increased PFS (9.5 vs 5.1 m, p < 0.0001) and increased OS (21.1 vs 7.7 m, p < 0.0001). Pts with one metastatic organ site had better OS (11.0 vs 6.2 m, p = 0.047). There was a trend of increased OS with lung-only metastasis (14.4 vs 7.7 m, p = 0.0776), and absence of concurrent locoregional failure (10.8 vs 8.3 m, p = 0.1153). Conclusions: Our results demonstrate that HPV-related metastatic HNSCC is associated with a statistically significant increased PFS and OS. Additionally, there was a trend of increased OS with lower locoregional and distant metastatic burden at DF though statistical significance was not achieved.