150P - Interim results of the multicenter phase II study on induction pembrolizumab plus chemotherapy followed by radiotherapy in locally advanced head and neck cancer

Background

The induction chemotherapy with docetaxel + cisplatin + 5-FU has a high risk of unacceptable adverse effects (AE) in locally advanced head and neck cancer (LAHNSCC) patients (pts). The toxicity could also compromise the delivery of further chemoradiation (CRT), increasing the risk of progression and death. We aimed to evaluate the efficacy of immunochemotherapy followed by CRT as an induction regimen for these patients.

Methods

We conducted a prospective multicenter non-randomized phase II study (NCT05551767) with the following inclusion criteria: pts with unresectable, stage III-IV, PD-L1 positive (CPS ≥1), squamous cell cancer of larynx, oropharynx, or hypopharynx, ECOG performance status 0-2. Eligible pts received induction therapy with pembrolizumab, cisplatin and docetaxel followed by CRT. We report interim results of study, including objective response rate (ORR) by RECIST 1.1, safety, CRT omission and noncompletion rate.

Results

Since January 2022, a total of 120 pts have been included. The median age was 60 (from 35 to75), the majority of whom were male (n=105; 87.5%). ORR was assessed in 116 of 120 pts. ORR in the induction phase was 62,9% (n=73), including 16,4% of complete responses. The median change of target lesions was -55% (from -100% to 65%). Only 7 pts did not start CRT in time due to disease progression (4 pts) or consent withdrawal. Among 95 pts who completed radiation therapy, 94,7% received radiation dose ≥66Gy. The incidence of grade 3-4 AE was 30,8% and required hospital readmission in 6 (5%) cases. No grade 5 AE were observed. The most common AE was hematological with neutropenia grade 3-4 in 28 (23.3%) pts. Febrile neutropenia occurred in 2 (1.7%) pts. The use of cisplatin in dose 100 mg/m2 q3w resulted in a trend of decline in the glomerular filtration rate (median decrease was 10.5% from baseline), although none of pts required hemodialysis.

Conclusions

Induction therapy with pembrolizumab, cisplatin and 5-FU provides substantial ORR and an acceptable safety profile in LAHNSCC. Hematological toxicity has emerged as a predominant AE, while it does not significantly affect further CRT. Additional follow-up is needed to assess long-term efficacy and safety.

Clinical trial identification

NCT05551767.

Legal entity responsible for the study

Oncological Center No.1 of Moscow City Hospital named after S.S. Yudin.

Funding

Moscow Center For Healthcare Innovations.

Disclosure

All authors have declared no conflicts of interest.