• Source: www.reuters.com

Merck & Co. and Japan’s Eisai Co. announced on Wednesday that they have discontinued a late-stage clinical study evaluating their experimental combination therapy for liver cancer after interim results indicated the treatment was unlikely to improve overall survival.

The phase 3 study tested Merck’s immunotherapy drug Keytruda and Eisai’s targeted therapy Lenvima in combination with transarterial chemoembolization (TACE) — a procedure used to block the blood supply to liver tumors — for patients with unresectable, non-metastatic hepatocellular carcinoma (HCC), the most common type of liver cancer.

According to both companies, the independent monitoring committee recommended halting the study after an interim analysis showed the therapy did not meet its primary endpoint of overall survival. While the treatment combination showed an improvement in progression-free survival, meaning patients lived longer without their cancer worsening, the data suggested it was unlikely to extend overall lifespan compared with TACE alone.

Liver Cancer : Study context and results

Hepatocellular carcinoma is often diagnosed at an intermediate stage when curative options such as surgery, ablation, or transplant are not possible. For these patients, TACE remains a common treatment that targets cancer cells directly in the liver.

The study aimed to evaluate whether combining Keytruda and Lenvima with TACE could improve survival outcomes. The combination had earlier shown some benefit in delaying disease progression, but failed to demonstrate the expected survival advantage during interim evaluation.

“The decision to stop the trial was based on data showing the combination is unlikely to achieve the overall survival target,” the companies said in a joint statement.

Broader implications

The early termination marks another setback for the Keytruda-Lenvima combination, which has struggled to deliver positive results in late-stage studies for other cancers, including lung, esophageal, and skin cancers. Despite those challenges, both drugs remain key components in various cancer treatment portfolios.

The companies confirmed that ongoing clinical trials investigating the Keytruda-Lenvima combination in other cancers will continue as planned. They also noted that the latest results will not affect currently approved indications.

Approved uses remain unchanged

The combination therapy is currently approved in the United States, European Union, Japan, and several other countries for treating advanced renal cell carcinoma (a type of kidney cancer) and endometrial carcinoma (a type of uterine cancer). These approvals are based on earlier trials that demonstrated significant clinical benefit in those conditions.

Merck’s Keytruda, an immune checkpoint inhibitor, works by helping the body’s immune system detect and attack cancer cells. Eisai’s Lenvima, a kinase inhibitor, blocks proteins that promote tumor growth and spread. The collaboration between the two pharmaceutical companies began in 2018 to jointly develop and commercialize Lenvima in combination with Keytruda across multiple cancer indications.

Industry outlook

Despite the latest setback, both firms continue to invest heavily in cancer research. Merck remains one of the leading developers of immunotherapies, while Eisai continues to expand its oncology portfolio. Analysts note that combination strategies remain a major area of focus in cancer treatment research, aiming to improve outcomes for patients with limited options.

The companies stated that they will share detailed data from the discontinued trial with the broader medical community at an upcoming scientific conference.

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