Merck’s Keytruda is the dominant cancer immunotherapy and, of the seven of its type that are approved, the only that’s cleared for use in cervical cancer, the fourth most commonly diagnosed cancer in women in the U.S.

The study the latest approval is based on, a Phase 3 clinical trial called Keynote-826, proved that adding Keytruda to chemo and, if doctor’s chose, Avastin extended survival compared to those other drugs alone.

Detailed data showed that, among patients whose tumors expressed PD-L1, treatment with Keytruda reduced the risk of death by 36% and the risk of disease progression or death by 38%. A greater proportion of patients responded to treatment when Keytruda was added as well, and those responses lasted a median of about eight months longer.

Although Keynote-826 enrolled patients regardless of PD-L1 status, nearly 90% of participants had tumors that expressed the protein, a statistic that likely factored into the FDA’s decision to focus approval only for treatment of cancers that are PD-L1 positive.

According to Merck, Keytruda is the first new drug approved for use in front-line cervical cancer since the FDA cleared Avastin in 2014.

Other immunotherapies could soon join Keytruda as cervical cancer treatments, although Keytruda’s first-line OK will likely stand alone for some time.

Regeneron and partner Sanofi are awaiting an FDA decision by next January for their immunotherapy Libtayo as a second-line treatment, while Roche is studying two of its immunotherapies together.

The biotech Agenus, meanwhile, hopes to receive an OK from the regulator by December for its experimental drug balstilimab in second-line use.