Efficacy and safety of SCT200 in patients with recurrent or metastatic head and neck squamous cell carcinoma after platinum failure: A phase 2 study.

BACKGROUND: There are limited treatment options for patients with recurrent or metastatic head and neck squamous cell carcinoma (R/M HNSCC) progressing after platinum-based therapy. Epidermal growth factor receptor (EGFR)-targeting monoclonal antibodies (mAbs) have demonstrated efficacy in R/M HNSCC. This phase 2 study evaluated the efficacy and safety of SCT200, a novel fully humanized EGFR mAb, in Chinese patients with R/M HNSCC progressing after platinum-based therapy. METHODS: This was a single-arm, multi-center phase 2 study, which enrolled patients with R/M HNSCC who had progressed after ≥2 cycles of platinum-based therapy. All patients received SCT200 at 6.0 mg/kg weekly for the first 6 weeks, followed by 8.0 mg/kg every 2 weeks until disease progression or unacceptable toxicity. The primary endpoint was the objective response rate (ORR). RESULTS: Between November 14, 2018, and April 2, 2020, 36 patients were enrolled. The ORR was 13.9% (5/36, 95% confidence interval [CI]: 4.7-29.5), the complete response rate was 2.8% (1/36), while the partial response rate was 11.1% (4/36). The disease control rate was 69.4% (25/36, 95% CI: 51.9-83.7). The median time to response was 1.38 months (95% CI: 0.99-2.60). The median duration of response was 5.95 months (95% CI: 2.60-not reached [NR]). The median progression-free survival and overall survival were 3.98 months (95% CI: 2.76-5.32) and 8.77 months (95% CI: 6.64-NR), respectively. Grade ≥3 treatment-related adverse events occurred in 44.4% (16/36) of patients, with the most common being hypomagnesemia (7/36, 19.4%, 95% CI: 8.2-36.0), hypokalemia (3/36, 8.3%, 95% CI: 1.8-22.5), rash (2/36, 5.6%, 95% CI: 0.7-18.7), and anemia (2/36, 5.6%, 95% CI: 0.7-18.7). CONCLUSIONS: This study demonstrated promising efficacy and a manageable safety profile of SCT200 in patients with R/M HNSCC progressing after platinum-based chemotherapy. TRIAL REGISTRATION: Clinical Trials.gov, NCT03713372; https://www.clinicaltrials.gov.