Two months earlier than expected, the US Food and Drug Administration (FDA)  has greenlighted the use of Merck & Co’s multi-indication cancer treatment Keytruda in combination with Pfizer’s Inlyta as a treatment for previously untreated advanced renal cell carcinoma.

Early approval for Keytruda in the new application should give the combination a head start on competitive products, analysts said.

The Keytruda/Inlyta combination is expected to provide serious competition for Bristol-Myers Squibb’s immunotherapy combination of Opdivo and Yervoy, which is currently regarded as the “gold standard” for previously untreated advanced kidney cancer patients.

According to IBES data from Refinitiv, a financial risk strategic partnership between Thomson Reuters and private equity funds managed by Blackstone, Keytruda’s sales have surged past Opdivo’s, and the drug is expected to pad US Merck’s sales total by more than $10 billion in 2019.

Keytruda, which works by increasing the ability of the patient’s immune system to help detect and fight tumor cells, has recently been Merck’s most important revenue growth driver especially in the lung cancer field.

A study published earlier this year claims to have shown that some 90% patients who received the Keytruda/Inlyta combination were alive after 12 months, compared with about 78% of patients treated with an older Pfizer standalone therapy Sutent.