Neoadjuvant Immune Checkpoint Inhibitor Therapy in Temporal Bone Squamous Cell Carcinoma

OBJECTIVE: To present immune checkpoint inhibitor immunotherapy (IO) outcomes for temporal bone-involving squamous cell carcinoma and guide neurotologic decision-making. STUDY DESIGN: Multi-institutional retrospective cohort. SETTING: Two tertiary-care referral centers. PATIENTS: Twenty-three patients (42 to 86 years old) with biopsy-proven temporal bone-involving squamous cell carcinoma (SCC). INTERVENTIONS: Neoadjuvant IO, imaging to assess response, and surgical interventions. MAIN OUTCOME MEASURES: Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 outcomes, pathologic response, surgery de-escalation, and overall survival. RESULTS: For final RECIST 1.1 response, 6 (26.1%, 95% CI: 10%-48%) patients completely responded (CR), 4 (17.4%, 95% CI: 5%-39%) patients partially responded (PR), 3 (13.0%, 95% CI: 3%-34%) patients had stable disease (SD), and disease progressed (PD) in 10 (43.5%, 95% CI 23%-66%) patients. For primary temporal bone tumors, 36.4% (95% CI: 11%-69%) achieved pathologic CR, radiologic CR, or radiologic PR; cutaneous SCC tumors had a 66.7% (95% CI: 35%-90%) response rate. Two (8.7%) patients with resectable disease were de-escalated to nonsurgical management, and 2 (8.7%) patients were de-escalated from lateral temporal bone resection (LTBR) to mastoidectomy. Overall 3-year survival for patients with CR, PR, or SD was 100% versus 78% for PD patients (P=0.029, HR 13.2, 95% CI: 1.3-134). CONCLUSIONS: Neoadjuvant IO is an option for early-stage and advanced temporal bone SCC, with roughly 50% of patients exhibiting response and avoidance of radical surgery and/or adjuvant radiation in selected cases; ongoing phase 3 trials of neoadjuvant IO will add prospective evidence.