Abstract
IMPORTANCE: Immunotherapy is approved for first-line treatment of recurrent/metastatic head and neck cancer (HNC). The prescribing patterns are largely unreported, and assessment of immune-related adverse events (irAEs) in patients with HNC is limited. OBJECTIVE: To assess the prescribing patterns of immunotherapy and the incidence and risk factors for irAEs using a claims-based database. DESIGN, SETTING, AND PARTICIPANTS: A retrospective cohort study of MarketScan Commercial and multistate Medicaid databases of all patients with HNC from January 1, 2016, to December 31, 2022, was performed. Inclusion criteria were patients with HNC, defined by International Statistical Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) codes with 6 months or longer of insurance enrollment prior to diagnosis and 1 or more months of follow-up. The databases excluded patients 65 years or older. Statistical analysis was conducted from October 1, 2024, through December 31, 2024. EXPOSURE: Prescription of an immunotherapeutic within 12 months after HNC diagnosis. OUTCOMES: The primary outcome measure was prescribing rate of immunotherapeutics overall and per year. The relative use of each immunotherapeutic was also explored. Secondary outcome measures were incidence of irAEs, severe irAEs, and univariable/multivariate risk factors for irAEs. RESULTS: A total of 47 365 patients with HNC were included, and 2254 (4.8%) of these patients received immunotherapy. Overall, 32 195 participants were male individuals (68%) and 14 607 were female individuals (32%), with a mean (SD) age of 54 (9) years. The rate of immunotherapy prescriptions slightly increased over time from 2.3% of patients with HNC in 2017 to 2.8% in 2022 (percent change, 0.5%; 95% CI, 0.1%-0.9%). Following initial approval by the US Food and Drug Administration (FDA), prescribing patterns of pembrolizumab and nivolumab were similar, but divergence in 2019 led to 87% of the market share dominated by pembrolizumab by 2022. The 90-day overall irAE-rate was 41.2% and severe irAE rate was 2.7%. There was no association between medication use and irAEs. Comorbidity score was associated with severe irAEs at 90 days (odds ratio [OR], 1.02; 95% CI, 1.02-1.03). Baseline hypothyroidism (adjusted OR [aOR], 6.7; 95% CI, 5.0-9.0) and liver disease (aOR, 1.7; 95% CI, 1.1-2.7) were independently associated with the development of irAEs. CONCLUSIONS: This cohort study found that pembrolizumab dominated the immunotherapy prescribing market, but the relative use of immunotherapy has minimally increased in patients younger than 65 years since FDA approval. irAEs were frequent and associated with key individual comorbidities. Severe irAEs were rare and associated with overall comorbidity status.