The U.S. Food and Drug Administration approved Tesaro Inc’s oral drug rolapitant (Varubi) for treatment for chemotherapy-induced nausea and vomiting in adults, the company said on Wednesday.

Chemotherapy-induced nausea and vomiting, considered one of the most acute side effects of cancer therapy, occurs in up to 80% of patients, according to the National Institutes of Health.

Rolapitant was approved for use in combination with other antiemetic agents in adults for the prevention of delayed nausea and vomiting associated with initial and repeat courses of emetogenic cancer chemotherapy, including, but not limited to, highly emetogenic chemotherapy, the company said.

Rolapitant works by blocking the activation of neurokinin (NK)-1 receptors in the nervous system, which play a role in nausea and vomiting.

The approval was based on four trials of patients receiving emetogenic chemotherapy, including cisplatin, carboplatin, and anthracycline/cyclophosphamide-based regimens, the company said.

Rolapitant is Tesaro’s first product to win FDA approval. It is expected to go on sale in the fourth quarter and will address a $1 billion market in the United States, the company said.

Tesaro is also testing an intravenous (IV) formulation of rolapitant.