896P - Long-responders to ICI in R/M-HNSCC: A retrospective multicentric French cohort

Background

Immune checkpoint inhibitors (ICI) have been approved in recurrent/metastatic head and neck squamous cell carcinoma (R/M-HNSCC), in 1^st line or in subsequence treatment after platinum failure. However overall response rate (ORR) and median progression free survival (mPFS) were low with any predictive factors described. We describe a cohort of patients with long response to ICI (single or combination) for R/M-HNSCC.

Methods

We conducted a retrospective analysis in 11 French centers from December 1^st, 2014 to March 1^st, 2020. Long-responders to ICI were defined as patients who confirmed a complete response (CR), or partial response (PR) /stable disease (SD) during at least one year. We made descriptive analysis to characterize this population and compare patients with CR vs PR/SD in terms of PFS and overall survival (OS).

Results

A total of 87 patients (pts) were included with HNSCC of oropharynx (40%), oral cavity (24%), larynx (21%) and hypopharynx (13%). 16 pts had HPV-related oropharynx cancer (46%). Median age of pts was 62 years (range 30-84), 83% were male, 37% were ECOG 0 and 54% ECOG 1. 41% had loco-regional relapse, 36% metastatic disease and 20% both. Monotherapy ICI was received in 71%. 54% pts received one prior line of chemotherapy and 8% two prior lines, chemo-radiation therapy occurred within 6 months (mos) for 6% pts. 52% pts presented a neutrophil lymphocyte ratio <5 at instauration of ICI. Estimated mPFS is 34 mos and mOS is 47 mos. CR, PR and SD represented 40.2%, 40.2% and 19.5% respectively. CR was associated with better PFS or OS (not reached vs 23 mos, p <0,0001) (NR vs 44 mos, p=0,002) respectively. Interruption of treatment (IT) occurred in 71% (n=62 pts): 40% (n=25) PD, 40% (n=25) medical/patient choice and 16% (n=10) toxicity. Two pts died with no PD (ORR at the time of death CR and PR). ORR at the time of IT was CR 63% (n=22), PR 20% (n=7) and SD 17% (n=6). After IT, PD occurred in 7 pts (20%), the rate of PFS at 12 mo was 86% for pts with CR. ICI was re-challenged in 3 pts: 2 presented PD and 1 present clinical benefice for almost 6 mos.

Conclusions

This is the first study characterizing long-responders to ICI in RM-HNSCC with similar characteristics than previous studies with no clear predictive factors expect for ratio N/L. CR population present significant better outcomes.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

A. Daste: Financial Interests, Personal, Advisory Board: Merck; Financial Interests, Personal, Advisory Board: BMS; Financial Interests, Personal, Advisory Board: MSD. All other authors have declared no conflicts of interest.