A multicenter, retrospective study analysis: Evaluating the efficacy and safety of pembrolizumab in the first-line treatment of recurrent or metastatic head and neck squamous cell carcinoma.

e18013 Background: PD-1-based therapy has become the first-line standard treatment for R/M HNSCC, but KN-048 lacked data on the mainland Chinese population. This study aims to conduct a pooled analysis of the efficacy and safety of first-line pembrolizumab-based therapy in patients (pts) with R/M HNSCC from different regions in China. Methods: Data comes from 17 hospitals. R/M HNSCC pts who received pembrolizumab alone or in combination with chemotherapy/targeted therapy from July 2020 to Jan 2023 were reviewed by searching the hospital HIS/medical record system. The primary endpoint of was OS, and secondary endpoints include time of pembrolizumab treatment (TOPT), safety, etc. Investigators also explored the impact of different biomarkers on survival. This study used SPSS 29 to analyze the data. Results: Total 160 pts were included. Median age was 60 yrs. 81.2% of pts was male, 95% of pts had an ECOG 0-1 . Main primary tumor site showed: oral cavity (60.6%), larynx (12.5%), oropharynx (10.6%). 88.8% of pts had undergone surgery in the past, and 65% received RT. The proportion of pts with only recurrence reached 75.6%. 79 (90.8%) had CPS of 1 or more and 44 (50.6%) had CPS of 20 or more. Other baseline information could be seen in the table. The median follow-up time was 18.5 mos. 70.6% of pts received pembrolizumab combined with chemotherapy, 17.5% received pembrolizumab alone. 48 pts subsequently received second-line treatment, more than half of which were target-based treatments. The median OS of all pts was not reach, among which the mono group vs. combination chemotherapy group (p=0.254). 18mo-OS of monotherapy was 69%, while 61% in combination. No statistical difference was seen in mTOPT (6.0 vs 4.7 mos, p=0.644). The results of the Cox Proportional Hazards Model suggest that ECOG score, smoking history, previous RT and distant metastatic of tumors were related to OS. Primary tumor location, T stage, EGFR mutation related to TOPT. Studies have not found a significant correlation between CPS and survival prognosis. 28.1% of pts experienced TRAEs, the most common of which was G1-4 myelosuppression (33.3%). The main TRAEs of G3-4 were pneumonia (11.1%), bone marrow suppression (8.9%) and abnormal liver function (4.4%). No patient died due to TRAEs. Conclusions: The data reflects that the real-world mOS with local recurrence as the main population was significantly higher than KN-048, and some clinical indicators related to prognosis were also found. In the future, the data of pembrolizumab in R/M HNSCC will be further explored to find more valuable biomarkers. Table: see text