Abstract 4936: Activity of carfilzomib in head and neck cancer cell lines in vitro

Abstract

Abstract Background: Carfilzomib (CF) is a 2nd generation proteasome inhibitor with activity in hematologic cancer, but its study in solid tumors like squamous cell carcinoma of the head and neck (SCCHN) is limited. We investigated its antitumor activity in three SCCHN cell lines. Methods: Cells: We studied two human tongue cell lines (CAL27; SCC-25) and one pharynx line (FaDu); all HPV-negative and p53-mutant. MTT assays: We utilized MTT assays to evaluate cytotoxicity of CF, cisplatin, and their combination. The IC50 of CF and Combination Index (CI) of varying concentrations of combined CF and cisplatin were calculated. Clonogenic assays: Cells were seeded at low density and after 24 hours, cells were treated with varying concentrations of CF. Plates were incubated for 10 days. The cells were fixed and stained with crystal violet dye and colonies counted. Wound Healing assays: After cells reached 100% confluence, a scratch was created using a 200 µL micropipette. Cells were treated with CF and images were acquired at 0, 24, 48, and 72 hours post-scratch. Results: MTT assays: IC50 values as a function of exposure lengths are shown in Table 1. CAL27 was the most sensitive while SCC-25 was the most resistant. In all cell lines, the results of combined CF and cisplatin were complex: at lower doses there was evidence of antagonism, while at higher doses there was synergy. Clonogenic assays: CF significantly inhibited clonogenicity compared to DMSO control (P≤ 0.05). The surviving fraction for CF 2.5, 5, and 10 nM were 0.411. 0.151, 0.051, and 0.5, 0.339, 0.102 in CAL27 and SCC-25 cell lines, respectively. Wound Healing assays: Wound closure % after treatment with CF5 was significantly different from DMSO control (P≤0.05). Wound closure % for CF5 were 30.97, 56.75, and 28.03% compared to 94.65, 75.88, and 42.05% for control in CAL27, FaDu, and SCC-25 cell lines, respectively. Conclusion: CF exhibits antitumor effects in SCCHN in vitro. Our findings support further investigation of CF in combination with conventional agents in vitro and in vivo. IC50 values for carfilzomib in head and neck cancer cell lines Cell line 24 hours 48 hours 72 hours CAL27 18.02 (11.76- 28.22) 9.364 (7.189- 12.45) 6.401 (5.579- 7.373) FaDu 57.34 (41.98-84.90) 16.22 (13.438- 19.446) 8.237 (7.260- 9.365) SCC25 77.78 (67.18- 91.30) 12.87 (11.36- 14.64) 11.49 (10.51- 12.58) Citation Format: Abdullah S. Eldaly, Douglas B. Stairs, Mitchell Machtay. Activity of carfilzomib in head and neck cancer cell lines in vitro. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4936.