WCLC 2019: Tumor Mutational Burden and Treatment Efficacy With Pembrolizumab
Posted: Thursday, September 26, 2019
According to data from the KEYNOTE-189 trial, presented at the International Association for the Study of Lung Cancer (IASLC) 2019 World Congress on Lung Cancer (WCLC) in Barcelona (Abstract OA04.06), tumor mutational burden, a predictive biomarker for many types of cancer, was not found to be related to survival outcomes in patients receiving pembrolizumab plus chemotherapy or placebo plus chemotherapy in the first-line treatment of metastatic nonsquamous non–small cell lung cancer.
“Pembrolizumab plus chemotherapy had a similar overall survival benefit in tumor mutational burden–high and tumor mutational burden–low subgroups,” noted Marina Chiara Garassino, MD, of the Istituto Nazionale dei Tumori in Milan, Italy, in an IASLC press release.
The study included 616 patients who were randomly assigned 2:1 to receive either pembrolizumab plus chemotherapy or placebo plus chemotherapy. Of the entire study group, 293 participants (207 treated with pembrolizumab, 86 treated with placebo) had evaluable tumor mutational burden data, gathered via whole-exome sequencing of DNA from tumor and normal cells.
Although pembrolizumab plus chemotherapy was found to improve overall survival, progression-free survival, and objective response rate, it did so for patients with a low tumor mutational burden (< 175 Mut/exome) as well as a high tumor mutational burden (≥ 175 Mut/exome). For patients with a mid-range tumor mutational burden (≥ 150 and < 150 Mut/exome), survival outcomes were similar.
Between the total study population and the evaluable subgroup, survival outcomes and characteristics were similar. Despite improved survival benefits in the pembrolizumab group, no meaningful association was noted between tumor mutational burden and overall survival, progression-free survival, or objective response rate with either pembrolizumab plus chemotherapy (one-sided P = .174, .075, and .072, respectively) or placebo plus chemotherapy (two-sided P = .856, .055, and .434, respectively).
Disclosure: The study authors’ disclosure information may be found at wclc2019.iaslc.org.