Long-term outcomes of a phase II trial of neoadjuvant immunotherapy for advanced, resectable cutaneous squamous cell carcinoma of the head and neck (CSCC-HN).

Abstract

9519 Background: In a pilot phase II trial, we investigated the use of neoadjuvant immunotherapy to induce a pathologic response in patients with stage III/IV (M0) cutaneous squamous cell carcinoma of the head and neck (CSCC-HN). Here, we report the long-term outcomes according to pathologic response. Methods: Patients with newly diagnosed or recurrent stage III/IV (M0) (AJCC 8th Ed) CSCC-HN were treated with 2 doses of cemiplimab 350 mg intravenously every 3 weeks prior to surgery. The primary endpoint was overall response rate (ORR) per RECIST v1.1. Secondary endpoints included safety, pathologic response, disease-free and overall survival. Results: Of 20 patients enrolled, 7 (35%) had recurrent disease and 12 (60%) were stage IV on presentation. Neoadjuvant immunotherapy was generally well-tolerated and there were no surgical delays. Adverse events (AEs) were observed in 7 (35%) patients; 1 (5%) grade 3 diarrhea, 6 (30%) ≤ grade 2 AEs. ORR by RECIST was 30%. However, 85% (17/20) achieved a pathologic response (≤50% viable tumor), with pathologic complete response (pCR) in 11 (55%), major pathologic response (MPR, ≤10% viable tumor) in 4 (20%) and pathologic partial response (pPR, >10% and ≤50% viable tumor) in 2 (10%). Patients with a pCR did not receive planned radiotherapy after surgery. Patients who did not have a pathologic response (> 50% viable tumor) either progressed and died (1, 5%) or developed recurrence (2, 10%) despite surgery and adjuvant radiation or chemoradiation. At a median follow up of 34.5 months (range: 7.7-42.7), none of the patients who achieved a pathologic response have recurred. Conclusions: Consistent with other cancer types, pathologic response to neoadjuvant immunotherapy is durable in patients with advanced, resectable CSCC-HN. Adjuvant radiation therapy may be spared in patients who achieve a pCR and warrants further investigation. Clinical trial information: NCT03565783.