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OA20 - Immunotherapy and Markers (ID 401)
- Event: WCLC 2016
- Type: Oral Session
- Track: Biology/Pathology
- Presentations: 1
OA20.01 - Tumor Mutation Burden (TMB) is Associated with Improved Efficacy of Atezolizumab in 1L and 2L+ NSCLC Patients (ID 6149)
11:00 - 12:30 | Author(s): M. Kowanetz
In NSCLC, atezolizumab (anti-PDL1) efficacy correlates with PD-L1 expression on tumor cells (TC) and tumor-infiltrating immune cells (IC). Here we examined the association between atezolizumab efficacy and TMB assessed by FoundationOne (F1) sequencing panel.
Pretreatment tumor specimens from 102 1L and 465 2L+ NSCLC patients enrolled on three Ph 2 atezolizumab monotherapy trials (POPLAR: randomized 2/3L trial comparing atezolizumab vs docetaxel; BIRCH/FIR: single-arm, 1L/2L+ PD-L1‒selected trials) were available for targeted genetic sequencing using the F1 panel of 315 cancer-related genes. TMB was quantified using an updated TMB algorithm and efficacy was assessed in groups defined by the 75th (high) and 50th (median) percentile of each study-specific TMB. Atezolizumab efficacy was examined at Dec 1, 2015 (POPLAR and BIRCH); and Jan 7, 2015 (FIR) data cutoffs.
Across samples, median TMB was similar in 1L and 2L+ patients (9/MB and 9.9/MB, respectively). In 1L and 2L+ PD-L1–selected patients, atezolizumab benefit was increased in those with ≥ TMB cut-offs (Table). In unselected 2L+ patients from POPLAR, the OS, PFS, and ORR benefits of atezolizumab vs docetaxel were also enhanced in patients with increased TMB. TMB and PD-L1 expression were independently associated with improved atezolizumab efficacy. TMB associations with PD-L1 expression, tumor-infiltrating lymphocyte infiltration and T-effector cell gene expression will be presented.
For the first time, we demonstrate that TMB assessed with F1 targeted sequencing is associated with improved atezolizumab outcomes in 1L and 2L+ NSCLC. Moreover, this is the first study demonstrating the association of TMB with improved anti-PD-L1/PD-1 efficacy in a randomized trial. Importantly, the association between TMB and atezolizumab efficacy occurred in both unselected and PD-L1-selected patients. Therefore, in addition to PD-L1, TMB may be an independent predictor of improved responsiveness to atezolizumab in advanced NSCLC.
Atezolizumab efficacy by TMB subgroups PD-L1‒selected BIRCH+FIR 1L n=102 2L+n=371 Median (≥9/MB) High (≥13.5/MB) Median (≥9.9/MB) High (≥17.1/MB) OS,HR[a] (95% CI) 0.79 (0.39-1.58) 0.45 (0.17-1.16) 0.87 (0.65-1.16) 0.7 (0.49-1.00) PFS,HR[a] (95% CI) 0.58 (0.36-0.94) 0.54 (0.3-0.97) 0.64 (0.5-0.8) 0.5 (0.38-0.67) ORR,above/below cutoff 28%/13% 25%/20% 25%/14% 29%/16% POPLAR 2L+ unselected n=92 Biomarker- evaluable population Median (≥9.9/MB) High (≥15.8/MB) OS,HR[b ] (95% CI) 0.65 (0.38-1.12) 0.48 (0.23-1.04) 0.5 (0.15-1.67) PFS,HR[b] (95% CI) 0.98 (0.63-1.53) 0.49 (0.25-0.93) 0.49 (0.19-1.3) ORR,atezolizumab/docetaxel 13%/15% 20%/4% 20%/8% [a]HR:efficacy-evaluable patients, atezolizumab at/above cutoff vs below.[b]HR:efficacy-evaluable patients, atezolizumab vs docetaxel at/above cutoff.
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