Following the news that  single agent Keytruda has failed to meet its primary endpoint for a benefit in overall survival (OS) for the treatment of triple-negative breast cancer (TNBC),

Adam Pearson, PhD, Healthcare Analyst at GlobalData, a leading data and analytics company, offers his view on the future for Keytruda in the treatment of TNBC:

“Merck & Co’s attempt to outmanoeuvre its rival Roche has failed after Keytruda, its blockbuster checkpoint inhibitor, did not meet its primary endpoint for a benefit in OS. Critically, this Phase III failure follows Roche’s FDA approval of Tecentriq, which is now the standard of care in first-line treatment of metastatic TNBC patients.

“Experts interviewed by GlobalData believe that the use of checkpoint inhibitors is most efficacious in the first-line setting and in combination with chemotherapy, this failure consolidates that opinion. Crucially, Roche identified the greatest OS benefit in patients who exhibit PD-L1 positive tumor infiltrating lymphocytes (TILs) rather than Merck who determined PD-L1 positivity by tumour status, where no OS benefit was observed. This discrepancy may indicate PD-L1 status on TILs to be more predictive in potentiating responses to checkpoint inhibition.

“Merck will now pursue opportunities combining Keytruda with chemotherapy and in earlier disease settings. However, the future commercial success of Roche and Merck in this market may be determined by establishing the relative importance of; 1. Line of therapy 2. Correct combinatorial regimen 3. Correct stratification of PD-L1 status.”