Adjuvant nivolumab following salvage resection in head and neck squamous cell carcinoma patients previously treated with definitive therapy: A single-arm phase II multi-institutional study.

Abstract

6031 Background: Salvage surgery for locally recurrent head and neck squamous cell carcinoma (rHNSCC) results in local control rates of 33-50% but only 20-40% of patients achieve long-term survival necessitating additional therapy (Haque et al., Oral Oncol. 2019). Many patients are ineligible for re-irradiation and chemotherapy alone after salvage surgeryhas shown no survival benefit. The clinical activity and tolerability of immune checkpoint inhibitors has been demonstrated in metastatic HNSCC, but the benefit after salvage surgery (SS) has not been studied. Here we report the results of a multi-center phase II investigation of nivolumab, a PD-1 inhibitor, after SS in recurrent HNSCC (NCT03355560). Methods: HNSCC patients undergoing curative-intent SS were enrolled to receive 6 months of nivolumab beginning 4-11 weeks after surgery. All received radiation with or without chemotherapy as prior definitive therapy and had no other curative treatment options at the time of surgery. Key exclusion criteria included: distant metastatic disease, gross residual disease, or a history of immunodeficiency, autoimmunity, or pneumonitis. The primary endpoint was 2-year disease-free survival (DFS) measured by Kaplan Meier curves. Safety was evaluated by CTCAE v5.0. Results: 39 patients were enrolled. Median age was 68 years (range, 49-85). 12/39 (31%) were female. 34/39 (87%) were white. Disease sites included oropharynx 9/39 (23%), oral cavity 14/39 (36%), and larynx 16/39 (41%). P16 status was 26% (+), 48% (-), and 26% (unknown). 17/39 (44%) had high risk pathologic features (positive margins or extranodal spread) at time of SS. 28/39 (72%) patients experienced treatment-related adverse events (TRAE), the most common of which were fatigue (26%), hypothyroidism (10%) and acneiform rash (13%). Grade 3-4 TRAEs were rare, occurring in 3/39 (8%) patients and included diarrhea, oral pain, neck pain, productive cough, stridor, and COPD exacerbation. 3/39 (8%) required treatment discontinuation and there were no grade 5 events. The 2-year DFS was 60% (95%CI 0.39-0.91). 2-year overall survival was 74% (95% CI 0.54-1). In single-cell multiplex cytokine analysis, patients who relapsed following adjuvant nivolumab had a significantly higher proportion of peripheral blood CD8 T cells which displayed a polyfunctional cytokine profile. IFN-γ and Granzyme were the dominant CD8 cytokines in both responders and non-responders, however CD8 expression of MIP1a and TNF-α were significantly higher in patients who ultimately relapsed. Conclusions: Nivolumab after salvage surgery in rHNSCC is well tolerated and shows promising antitumor activity in this high-risk patient population with unmet need. Immunotherapy after salvage surgery should be studied in randomized clinical trials. Clinical trial information: NCT03355560.