A prospective, single-arm, phase II exploratory clinical study on the efficacy and safety of neoadjuvant adebrelimab combined with cisplatin and docetaxel in patients with clinical stage IVB oral squamous cell carcinoma.

6048 Background: Oral squamous cell carcinoma (OSCC) is one of the most common malignant tumors of the head and neck. Stage IVB OSCC had long been considered unresectable with extremely poor prognosis, and mainstream guidelines encourage exploring new therapies via clinical trials. This study aimed to evaluate the efficacy and safety of adebrelimab plus cisplatin/docetaxel as neoadjuvant therapy for stage IVB OSCC (NCT06277791). Methods: IVB OSCC patients aged 18–75 years were enrolled and received 2 cycles of neoadjuvant immunochemotherapy (adebrelimab 1200 mg + cisplatin 75 mg/m²/docetaxel 75 mg/m², q3w). Three weeks after neoadjuvant treatment, patients underwent extended primary tumor resection and radical neck dissection, followed by adjuvant radiotherapy/chemoradiotherapy. The primary endpoint was pathological response rate (pCR+MPR); secondary endpoints included radiographic response, R0 resection rate, and safety. Results: 28 patients were enrolled between June 2023 and January 2026. The mean age was 47.8 years, with a male predominance (25, 89.3%). Primary tumors were mainly located in the buccal mucosa (14, 50.0%) and tongue (10, 35.7%). Smoking, alcohol consumption, and betel nut chewing histories were noted in 75.0%, 42.9%, and 64.3% of patients, respectively. Most had an ECOG performance status of 1 (75.0%). 8 cases (28.6%) were classified as cT4b and 20 cases (71.4%) as cN3b at baseline. Three patients (10.7%) were excluded from efficacy analysis due to insufficient data. In the evaluable population (n=25), no complete response (CR) was observed; 8 (28.6%) achieved partial response (PR), 14 (50.0%) stable disease (SD), and 3 (10.7%) progressive disease (PD), with an overall objective response rate (ORR) of 32.0% (8/25). Subgroup ORRs were 33.3% (2/6) for cT4b and 31.6% (6/19) for cN3b. Pathological assessment was available for 25 patients: based on the combined pathological assessment of the primary tumor and lymph nodes, 15 (60.0%) achieved MPR, 1 (4.0%) pCR, resulting in a 64.0% pathological response rate. For subgroups, the pathological response rate was 50.0% in 6 evaluable cT4b (2 MPR, 1 pCR) and 68.4% in 19 evaluable cN3b (13 MPR, no pCR). The R0 resection rate was 100% among 25 surgical patients. Treatment-related adverse events (TRAEs) were mostly grade 1–2. Grade 3 TRAEs occurred in 2 cases (7.2%), with no grade 4/5 events. At data cutoff (median follow-up: 12.0 months), 3 deaths occurred. The estimated 1-year OS rate was 87.9%, with subgroup rates of 89.1% for cN3b (median follow-up: 12.0 months) and 87.5% for cT4b (median follow-up: 19.4 months). Conclusions: Neoadjuvant adebrelimab combined with chemotherapy achieves a high pathological response rate in stage IVB OSCC, with manageable adverse events and favorable safety. Clinical trial information: NCT06277791 .