Abstract 687P
Background
Anti-PD1 agent pembrolizumab has obtained favorable results in recurrent/metastatic head and neck squamous cell carcinomas (R/M HNSCC) with a combined positive score (CPS) equal or greater than 1. The possible temporal and spatial heterogeneity of this parameter could have a relevant clinical impact by requiring the re-biopsy of the R/M lesions.
Methods
HNSCC pairs of primaries (oral cavity, oropharynx, larynx, and hypopharynx) and corresponding relapsing (local, nodal or distant metastasis) tumor samples were retrieved in 2 Italian referral centers and stained with Dako pharm-DX kit. CPS was blindly scored (<1; between 1 and 19; >20) on stained slides by an expert pathologist. The probability of CPS shift according to clinical variables of interest was estimated using a logistic regression model.
Results
Fifty-six patients were included (Table). CPS score was concordant in primary vs recurrent HNSCC in 66.1% of sample pairs. Only in 3.6% cases PD-L1 status changed from negative (CPS<1) to positive (CPS≥1); positive-to-negative change occurred in 7.2%. Shift from CPS 1-19 to CPS>20 occurred in 12.5% of the cases, while the opposite in 10.6%. Referral hospital (p=0.5), gender (p=0.12), smoking (p=0.09) or alcohol assumption (p=0.7), disease-free interval (p=0.6), tumor site (oro- and hypopharynx, p=0.4; larynx, p=0.7), previous treatments (surgery, p=0.3; radiotherapy, p=0.6; chemotherapy, p=0.2) did not influence CPS variation. Table: 687P
| Variable | N (%) | |
| Gender | Male | 43 (76.8%) |
| Female | 13 (23.2%) | |
| Smoke | Yes | 26 (46.4%) |
| No | 4 (7.1%) | |
| Unknown | 26 (46.4%) | |
| Alcohol assumption | No | 10 (17.9%) |
| Yes | 16 (28.6%) | |
| Unknown | 30 (53.6%) | |
| Tumor site | oral cavity | 11 (19.6%) |
| oropharynx | 20 (35.7%) | |
| larynx | 11 (19.6%) | |
| hypopharynx | 14 (25%) | |
| Stage | I-II | 5 (8.9%) |
| III-IV | 51 (91.1%) | |
| Treatment | Surgery | 36 (64.3%) |
| Exclusive radiotherapy | 23 (41.1%) | |
| Adjuvant radiotherapy | 19 (33.9%) | |
| Induction chemotherapy | 8 (14.3%) | |
| Concomitant chemotherapy | 23 (41.1%) | |
| Recurrence site | Local | 24 (42.9%) |
| Nodal | 15 (26.8%) | |
| Distant spread | 15 (26.8%) | |
| Multiple | 2 (3.6%) | |
| Disease free interval (months) | Median: 16.4; Mean: 22.6; Range 2.8-115.9 |
Conclusions
PD-L1 expression levels can vary between primary and relapsing HNSCC, however PD-L1 status rarely changes. No clinical variable apparently influenced CPS PD-L1 modifications in R/M disease.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
P. Bossi: Financial Interests, Personal, Advisory Board: MSD, Merck, Angelini, BMS, Sanofi, SunPharma, GSK, Molteni, Kyowa Kyrin. All other authors have declared no conflicts of interest.