Blood-based tumor mutational burden (bTMB) helped to predict which patients with non-small cell lung cancer (NSCLC) would numerically benefit from atezolizumab monotherapy, according to results of the B-F1RST trial presented at the European Society for Medical Oncology (ESMO) Congress 2019.
A primary analysis of the study done with 6 months or more of follow-up showed that patients with bTMB high (score of ≥16) had a higher overall response rate compared with bTMB low (28.6% vs 4.4%, respectively).
The study was conducted in 152 patients with untreated stage IIIB to stage IVB NSCLC. Patients received atezolizumab monotherapy until disease progression, intolerance, or loss of benefit.
This final analysis of the data was done with 18 months or more of follow-up. The overall response rate was 17%, with a median progression-free survival of 4.1 months and a median overall survival of 14.8 months.
Median progression-free survival was numerically higher among patients with bTMB-high compared with mTMB-low (5.0 months vs 3.5 months, respectively), as was the median overall survival (23.9 vs 13.4 months, respectively).
The researchers also evaluated serum C-reactive protein (CRP) as a surrogate biomarker. Patients with a CRP at C3D1 to CRP at screening ratio of less than 0.5 had a median progression-free survival of 14.1 months compared with 4.6 months with a ratio of 0.5 or higher (hazard ratio [HR], 0.43; 90% CI, 0.24-0.77).
Approximately 1 in 5 patients (18%) had adverse events that led to treatment discontinuation. Grade 3/4 adverse events occurred in 20% of patients.
According to the researchers, “this final analysis confirmed that patients with bTMB ≥16 had numerical benefit for progression-free and overall survival.”
Disclosure: The study was funded by F. Hoffman-La Roche, Ltd. For a full list of author disclosures, please refer to the original abstract.
Socinski M, Velcheti V, Mekhail T, et al. Final efficacy results from B-F1RST, a prospective phase II trial evaluating blood-based tumour mutation burden (bTMB) as a predictive biomarker for atezolizumab (atezo) in 1L non-small cell lung cancer (NSCLC). Presented at: LBA83. Presented at: European Society for Medical Oncology (ESMO) Congress 2019; September 27-October 1, 2019: Barcelona, Spain.