RESUMO
BACKGROUND: We evaluated whether tissue tumor mutational burden (tTMB) and STK11, KEAP1, and KRAS mutations have clinical utility as biomarkers for pembrolizumab monotherapy versus platinum-based chemotherapy in patients with programmed death ligand 1 (PD-L1)-positive (tumor proportion score ≥1%) advanced/metastatic non-small-cell lung cancer (NSCLC) without EGFR/ALK alterations in the phase III KEYNOTE-042 trial. PATIENTS AND METHODS: This retrospective exploratory analysis assessed prevalence of tTMB and STK11, KEAP1, and KRAS mutations determined by whole-exome sequencing of tumor tissue and matched normal DNA and their associations with outcomes in KEYNOTE-042. Clinical utility of tTMB was assessed using a prespecified cut point of 175 mutations/exome. RESULTS: Of 793 patients, 345 (43.5%) had tTMB ≥175 mutations/exome and 448 (56.5%) had tTMB <175 mutations/exome. No association was observed between PD-L1 expression and tTMB. Continuous tTMB score was associated with improved overall survival (OS) and progression-free survival among patients receiving pembrolizumab (Wald test, one-sided P < 0.001) but not those receiving chemotherapy (Wald test, two-sided P > 0.05). tTMB ≥175 mutations/exome was associated with improved outcomes for pembrolizumab versus chemotherapy, whereas tTMB <175 mutations/exome was not {OS: hazard ratio, 0.62 [95% confidence interval (CI) 0.48-0.80] and 1.09 (95% CI 0.88-1.36); progression-free survival: 0.75 (0.59-0.95) and 1.27 (1.04-1.55), respectively}. Improved OS [hazard ratio (95% CI)] for pembrolizumab versus chemotherapy was observed regardless of STK11 [STK11 mutant (n = 33): 0.37 (0.16-0.86), STK11 wild-type (n = 396): 0.83 (0.65-1.05)]; KEAP1 [KEAP1 mutant (n = 64): 0.75 (0.42-1.35), KEAP1 wild-type (n = 365): 0.78 (0.61-0.99)], or KRAS [KRAS mutant (n = 69): 0.42 (0.22-0.81); KRAS wild-type (n = 232): 0.86 (0.63-1.18)] mutation status. CONCLUSION: tTMB with a cut point of ≥175 mutations/exome is a potential predictive biomarker for pembrolizumab monotherapy for advanced/metastatic PD-L1 tumor proportion score ≥1% NSCLC. Pembrolizumab is a standard first-line treatment in this setting regardless of STK11, KEAP1, or KRAS mutation status.
Assuntos
Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Humanos , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Pulmonar de Células não Pequenas/patologia , Antígeno B7-H1/metabolismo , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patologia , Proteína 1 Associada a ECH Semelhante a Kelch/genética , Estudos Retrospectivos , Proteínas Proto-Oncogênicas p21(ras)/genética , Fator 2 Relacionado a NF-E2/genética , Fator 2 Relacionado a NF-E2/metabolismo , Fator 2 Relacionado a NF-E2/uso terapêutico , Mutação , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêuticoRESUMO
BACKGROUND: In the phase III KEYNOTE-061 trial (NCT02370498), pembrolizumab did not significantly improve overall survival versus paclitaxel as second-line therapy for gastric/gastroesophageal junction (GEJ) adenocarcinoma with programmed death-ligand 1 (PD-L1) combined positive score (CPS) ≥1 tumors. The association of tissue tumor mutational burden (tTMB) status and clinical outcomes was determined, including the relationship with CPS and microsatellite instability-high (MSI-H) status. PATIENTS AND METHODS: In patients with whole exome sequencing (WES) data [420/592 (71%); pembrolizumab, 218; paclitaxel, 202], the association of tTMB with objective response rate (ORR; logistic regression), progression-free survival (PFS; Cox proportional hazards regression), and overall survival (OS; Cox proportional hazards regression) were measured using one-sided (pembrolizumab) and two-sided [paclitaxel] P values. tTMB was also evaluated using FoundationOne®CDx [205/592 (35%)]. Prespecified equivalent cut-offs of 175 mut/exome for WES and 10 mut/Mb for FoundationOne®CDx were used. RESULTS: WES-tTMB was significantly associated with ORR, PFS, and OS in pembrolizumab-treated (all P < 0.001) but not paclitaxel-treated patients (all P > 0.6) in univariate analysis. The area under the receiver operating characteristics curve for WES-tTMB and response was 0.68 [95% confidence interval (CI) 0.56-0.81] for pembrolizumab and 0.51 (95% CI 0.39-0.63) for paclitaxel in univariate analysis. There was low correlation between WES-tTMB and CPS in both treatment groups (r ≤ 0.16). WES-tTMB remained significantly associated with all clinical endpoints with pembrolizumab after adjusting for CPS and with PFS and OS after excluding known MSI-H tumors (n = 26). FoundationOne®CDx-tTMB demonstrated a positive association with ORR, PFS, and OS in pembrolizumab-treated patients (all P ≤ 0.003) but not PFS or OS in paclitaxel-treated patients (P > 0.1). CONCLUSION: This exploratory analysis from KEYNOTE-061 is the first to demonstrate a strong association between tTMB and efficacy with pembrolizumab but not paclitaxel in patients with gastric/GEJ adenocarcinoma in a randomized setting. Data further suggest tTMB is a significant and independent predictor beyond PD-L1 status.