30May

Association of tumor mutational burden (TMB) and clinical outcomes with pembrolizumab (pembro) versus chemotherapy (chemo) in patients with metastatic triple-negative breast cancer (mTNBC) from KEYNOTE-119.


Abstract No : 1013

Abstract Type : Poster Discussion Session

Indication : Triple Negative Breast Cancer

Intervention : pembrolizumab

Company : Merck

Technology : Tumor Mutational Burden


Results:

TMB data were available for 253/601 (42.1%) treated patients (pembro, n = 132; chemo, n = 121); baseline characteristics were similar to that of the overall study population. One-sided P values for the association of TMB and clinical outcomes in pembro-treated patients were 0.154 for ORR, 0.014 for PFS, and 0.018 for OS; the area under the ROC curve ([AUROC] 95% CI) for predicting ORR was 0.58 (0.43-0.73). Two-sided P values for the association of TMB and clinical outcomes in chemo-treated patients were 0.114 for ORR, 0.478 for PFS, and 0.906 for OS; AUROC (95% CI) was 0.43 (0.27-0.59). Twenty-six patients had TMB $10 mut/Mb. Thus, the prevalence of TMB $10 mut/Mb was ~10%. Outcomes based on TMB cutpoint.


Conclusion:

Data from this exploratory analysis from KEYNOTE-119 suggest a potential positive association between TMB and clinical benefit with pembro but not chemo in patients with mTNBC. Although precision is limited by sample size and the number of patients with TMB $10 mut/Mb, ORR and HRs for OS suggested a trend towards increased benefit with pembro versus chemo in patients with TMB $10 mut/Mb.


Commentary:

There is a positive association between Tumor Mutational Burden (TMB) and clinical benefit with pembrolizumab in patients with mTNBC.


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