Conflicting results have been reported on the potential role of Tumor Mutational Burden (TMB) as predictive biomarker for immune checkpoint inhibitors. However, the recent approval of TMB as agnostic biomarker for pembrolizumab in previously treated patients with solid tumors is increasing the interest of laboratories to provide this test. In this scenario, the harmonization of the procedures for TMB evaluation and the availability of an external quality assurance (EQA) scheme is important to ensure that patients receive a TMB test of adequate quality and with a correct clinical interpretation. IQN Path launched a project on TMB testing with the aims to validate control material for EQA schemes for TMB testing, to organize a pilot EQA scheme for TMB testing and to compare different commercial panels for TMB testing in clinical samples.
The first phase was completed last year by means of the analysis of ten cell lines samples provided by Seracare. These samples were analysed by four different TMB panels developed by ThermoFisher (Oncomine Tumor Mutational Load); Roche (FoundationOne CDx); Qiagen (QiaSeq Tumor Mutational Burden); Illumina (TruSight Oncology 500). Afterwards, we chose 5 cell lines based on the obtained results for the EQA scheme. However, we have had a delay in our timeline because of this pandemic emergency due to COVID-19 infection. The project re-started in July, when we shipped the reference material to 29 different laboratories, selected by a survey in which it was assessed the centres expertise and the technology used for TMB testing. We are now collecting the results submitted by the participating centres and should be able to have a final report by the first quarter of 2021. Meanwhile, we went ahead with the third part of the project and we started to analyse the FFPE blocks of lung cancer patients with four different commercial TMB panels. We are finalizing the analysis and we plan to have final results at the end of November.
Riziero Esposito Abate, TMB Project Leader
October 2020