Tissue tumor mutation burden (tTMB) has been under study for some time as a biomarker that could predict which patients are most likely to respond to immunotherapy.
In June, it was approved by the US Food and Drug Administration as a biomarker for pembrolizumab (Keytruda) use in patients with advanced cancers who have progressed on prior therapy.
Now the data supporting that approval have been published in Lancet Oncology.
They come from analysis of outcomes from 790 patients who participated in the phase 2 KEYNOTE-158 study of treatment with pembrolizumab in 10 tumor-type-specific groups.
The results show better responses in patients who had a high tissue TMB (≥10 mutations per megabase), which was found in 102 (13%) of the 790 participants.
The majority of these patients (87%) did not have high tTBM.
Of the 102 patients with high tTMB, 29% achieved an objective response to pembrolizumab compared with 6% in