USA – US Food and Drug Administration (USFDA) has approved Merck & Co.’s immunotherapy Keytruda for use in early kidney cancer, making it the first treatment of its kind available to patients whose renal cell carcinoma tumors haven’t spread widely.

The approval for Keytruda includes adjuvant use — after surgery to remove a kidney or metastatic lesions — for patients who are at intermediate or high risk of their cancer recurring.

The approval of Keytruda in this setting comes about six months after Merck revealed preliminary findings from a study called Keynote-564, which showed that the immunotherapy could help keep kidney cancers in remission for longer periods of time.

In the primary study that supported its approval, Keytruda reduced the risk of cancer recurrence, spread, or death by 32% when compared to a placebo.

The benefit was calculated using a metric known as disease-free survival, which is the time it takes for a patient to die or for their cancer to recur or metastasize.

Patients who are treated early, when their tumors are still small or local enough to be removed surgically, typically live much longer than those who are treated later, when their tumors are already advanced or metastatic.

This means that studies must be conducted for a longer period of time to demonstrate that the drugs being tested actually extend patients’ lives rather than simply lengthening the amount of time in remission.

Measuring disease-free survival allows drugmakers to demonstrate that their drugs have an effect sooner, though some criticize the endpoint for exaggerating a treatment’s benefit.

When Keynote-564 was reviewed to assess Keytruda’s benefit on disease-free survival, only 5% of the nearly 1,000 participants had died, leaving too few to determine whether the drug also extended overall survival.

Merck said in a statement following the FDA’s approval that the trial will continue to assess overall survival.

Prior to the arrival of Keytruda, Pfizer’s kinase inhibitor Sutent had been approved as an adjuvant therapy to prevent the recurrence of kidney cancer in high-risk patients since 2017.

However, due to its limited efficacy and a high rate of side effects, the treatment has not become standard of care.

Merck is not the only company developing cancer immunotherapies. Other pharmaceutical companies such as Bristol-Myers Squibb and Roche are also researching immunotherapies as adjuvant treatments for other cancer types such as skin, lung, and breast tumors.

Roche’s Tecentriq became the first in the PD-1/L1 class to enter post-surgery non-small cell lung cancer with an FDA approval in stage II to IIIA.

The drugs, which are already best-sellers, could become even more profitable for their manufacturers if they are widely used in conjunction with surgery.

While Keytruda is the first to be studied in kidney cancer, results from studies of Roche’s Tecentriq, Bristol Myers’ Opdivo, and AstraZeneca’s Imfinzi are also expected.

The FDA granted Keytruda approval for this indication under priority review, which expedites the regulator’s review.

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