Use of xeno-free serum substitutes in ex vivo HNSCC tissue cultures to predict the therapy response

Introduction Checkpoint inhibitors are increasingly used in the treatment of head and neck squamous cell carcinoma (HNSCC). However, the response rate is only <20%. Therefore, we treated ex vivo models from vital HNSCC tissue cultures with cisplatin and pembrolizumab and correlated the response of the model tumors with the clinical course. Considering the 3R principles  (refine, reduce, replace), xeno-free serum substitutes were used as an alternative to fetal bovine serum (FBS).

Methods ex vivo preparations were treated with pembrolizumab and cisplatin in the nutrient media FBS, hPl (human plasma serum), and StemMACS MSC Expansion Media from human bone marrow cells for up to ten days. The PD-L1 and Ki-67 status were determined immunohistochemically using the TPS (Tumor Proportion Score) and Ki-67 index and compared them with negative controls.

Results The cultures with serum substitutes did not show any increased contamination rate in the sense of fungal or bacterial growth compared with samples in FCS. TPS and Ki-67 index could be determined validly and consistently regardless of the nutrient medium. The IHC results are continuously correlated with the follow-up of the donor patients.

Discussion The aim of implementing the 3R principle in experimental oncological research is to question the use of animal products critically. Therefore, the ex vivo tissue culture model established in our working group could be kept vital in culture in hPl and MCS without time or quality restrictions. Furthermore, as expected, the cohort showed a heterogeneous response to the experimental treatment. We consider the ex vivo model to be a helpful tool to establish a predictive platform for selecting optimal treatment strategies.

Projektförderung durch das Land Baden-Württemberg (Förder-Nr.: 33-7533-6-1522/10/4)

Publication History

Article published online:
24 May 2022