Centrally determined PD-L1 among non-eligible for cisplatin-based chemotherapy recurrent/metastatic head and neck patients (R/M HNSCC pts): Pathology outcomes from the NIVOTAX trial.

Abstract

e18015 Background: PD-L1 is a biomarker of response to anti-PD1 in HNSCC. CA209-7HE trial (NCT04282109) is a randomized, open-label, multicenter, phase II trial including first line R/M HNSCC pts non-eligible for cisplatin-based chemotherapy. Pts were stratified according to Karnofsky performance status, HPV and tissue PD-L1 by Combined Positive Score (CPS). Subjects were randomized to either paclitaxel + nivolumab or paclitaxel + cetuximab. Primary objective was 2-year overall survival. We present the data on centrally determined PD-L1 patterns and its correlation with pt clinical characteristics. Methods: From 176 preliminary samples, only 141 were analyzed. 10 were excluded for not fulfilling quality requirements and 25 belonged to non-eligible pts. 74% (104) were paraffin blocks and 26% (37) tissue slides. 72.3% (102) were primary tumor biopsies, 12.7% (18) local soft tissue relapses, 9.2% (13) lymph node metastases and 5.6% (8) distant metastases. 46.6% (66) were collected from irradiated areas. Hematoxylin-eosin stain confirmed sample representativeness. At least 100 tumor cells/sample was required. Immunohistochemistry for PD-L1 was performed using DAKO PD-L1 IHC 22C3. Means and proportions were dropped for descriptive analyses. Multivariate logistic regresion was used to identify variables associated with higher CPS. Results: Clinical characteristics included 73% (103) males; 77% (108) were either former [56% (78)] or current smokers [21.2% (30)] and clinical stage was recurrent in 48.9% (69), metastatic alone in 29.8% (42) and both recurrent and metastatic in 21.3% (30). Diagnoses included 35.4% (51) oral cavity, 32.3% (45) oropharynx (only 2 pts HPV positive), 16.3% (23) larynx and 15.6% (22) hypopharynx. Mean time to CPS assessment was 5.25 days (CI 95% 4.95 – 5.55). CPS distribution was as follows: 21.7% (31) were CPS < 1, 42.8% (60) were CPS 1-20 and 35.4% (50) were CPS > 20. Multivariate model revealed that oral cavity tumors showed an increased likelihood of CPS > 20 (OR 2.35, 95%CI 1.46 - 3.78; p < 0.001) which was also seen among non-smokers (OR 3.37, 95% CI 1.16 - 9.73; p = 0.02) and pts with recurrent and metastatic disease (OR 2.75, 95% CI 1.03- 7.32; p = 0.04). Oropharyngeal tumors showed lower probability for CPS > 20 (OR 0.35, 95% CI 0.14 - 0.89; p = 0.03). Neither prior irradiation nor origin of the biopsy were associated with any significant variation in CPS. Conclusions: Central assessment of CPS is feasible with no significant treatment delay. HPV negative oropharyngeal tumors were not associated with higher CPS. We also found that oral cavity tumors, non-smokers and pts with recurrent and metastatic disease were independently associated with an increased probability of higher CPS. Future results will elucidate the promising role of combinatorial regimens with immunotherapy in these subpopulations. Clinical trial information: NCT04282109.