EU Expands Merck’s Keytruda Use on Breast Cancer

Merck, known as MSD outside the US and Canada, announced that the European Commission has approved its flagship monoclonal antibody drug – Keytruda, as treatment after surgery for patients with locally advanced or early-stage triple-negative breast cancer at high risk of recurrence.

Triple-negative breast cancer (TNBC) does not have estrogen or progesterone receptors while also making too little or none of the HER2 protein. Because the cancer cells are not expressing these proteins, hormone therapies and drugs that target HER2 are useless, hence chemotherapy is the main systemic treatment option. Even though TNBC tends to respond well to chemotherapy initially, it also tends to recur more frequently than other breast cancers. Approximately 10-15% of patients with breast cancer are diagnosed with TNBC.

Keytruda was first cleared for breast cancer in Europe in October 2021, for use in combination with chemotherapy as first-line treatment for patients with locally recurrent unresectable or metastatic TNBC. This news is the second indication for the drug in TNBC.

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Phase 3 KEYNOTE-522 trial

The EU approval came after US FDA’s approval in July last year, both were based on the Phase 3 KEYNOTE-522 study with a size of 1174 participants. Keytruda demonstrated to be better in reducing the risk of disease progression and recurrence. The main outcome measures were pathological complete response (pCR) rate and event free survival (EFS). The pCR rate, the disappearance of all invasive cancer in the breast after completion of therapy, was 63% for patients who received Keytruda in combination with chemotherapy compared with 56% for patients who received chemotherapy alone. The number of patients who experienced an EFS event was 16% and 24%, respectively.

“Triple-negative breast cancer has a high risk of recurrence within the first five years, so it’s meaningful for patients to have access to new therapies that can reduce the risk of disease progression,” said Dr. Peter Schmid, lead of Centre for Experimental Cancer Medicine, London’s Barts Cancer Institute.

Keytruda, a cancer drug that harnesses a patient’s immune system to fight tumors, is approved in dozens of indications around the world. Sales of the drug hit $17 billion last year. Beside Keytruda, GSK’s Jemperli is also a PD-L1 immunomodulator approved for subsets of patients with advanced breast cancer that has DNA mismatch repair deficiency (dMMR).

Author

Fujie Tham