Nivolumab and ipilimumab in combination with radiotherapy in patients with high-risk locally advanced squamous cell carcinoma of the head and neck.

BACKGROUND

The combination of nivolumab and ipilimumab has been approved for the treatment of multiple solid tumors. This was a phase I study investigating definitive radioimmunotherapy (RIT) with nivolumab and ipilimumab for the treatment of locally advanced (LA) squamous cell carcinoma of the head and neck (SCCHN).

METHODS

Patients with newly diagnosed, stage IVA-IVB SCCHN eligible for cisplatin-based chemotherapy received nivolumab (3 mg/kg every 2 weeks for a total of 17 doses) and ipilimumab (1 mg/kg every 6 weeks for a total of 6 doses) starting 2 weeks prior to radiotherapy. The primary endpoint was safety of definitive RIT. Secondary endpoints included progression-free survival (PFS) and overall survival (OS). Exploratory endpoints included the association of baseline programmed death-ligand 1 (PD-L1) expression as well as on-treatment changes in immune bias with treatment outcomes.

RESULTS

Twenty-four patients were enrolled. With a median follow-up of 36.1 months, grade 3 or higher treatment-related adverse events were reported in 21 individuals (88%); 5 individuals developed in-field soft tissue ulceration during consolidation immunotherapy, resulting in one fatality. The 3-year PFS and OS rates were 74% (95% CI 58% to 94%) and 96% (95% CI 88% to 100%), respectively. PD-L1 combined positive score (CPS) did not correlate with death or disease progression. Decreases in extracellular vesicle PD-L1 within the concurrent RIT phase were associated with prolonged PFS (p=0.006). Also, interval decreases in circulating interleukin (IL)4, IL9, IL12, and IL17a during concurrent RIT were associated with subsequent ulceration.

CONCLUSIONS

Definitive RIT with nivolumab and ipilimumab has sufficient clinical activity to support further development. Early changes in circulating biomarkers appear able to predict treatment outcomes as well as ensuing in-field soft tissue ulceration.

TRIAL REGISTRATION NUMBER

NCT03162731.