FILE PHOTO: The Eli Lilly logo is shown on one of the company's offices in San Diego, California, U.S., September 17, 2020. REUTERS/Mike Blake//File Photo

By Siddhi Mahatole and Padmanabhan Ananthan

(Reuters) -Eli Lilly said on Thursday the U.S. Food and Drug Administration has approved its treatment for a form of advanced breast cancer in adult patients who have received prior therapy.

The therapy, Inluriyo, was approved based on data from a late-stage trial in which patients had a 38% lower chance of their cancer progressing or death compared to those on standard treatments, the drugmaker said.

Metastatic breast cancer, also called Stage IV breast cancer, occurs when the disease has spread beyond the breast and nearby lymph nodes to other parts of the body, most commonly the bones, lungs, liver or brain.

Some breast cancers develop ESR1 mutations, which make estrogen receptors overly active. These receptors normally help regulate cell growth, but when mutated, they can drive cancer progression.

Inluriyo is designed to target these overactive receptors by binding to the estrogen receptor, blocking its activity and breaking it down to help slow the spread of the disease.

The therapy is expected to be available in the United States in the next few weeks, with a list price of $22,500 per 28 days for the 400 mg dose, the company told Reuters in an email.

Its label includes a warning for embryo-fetal toxicity, which refers to potential harm to developing embryos and fetuses caused by exposure during pregnancy.

In the late-stage trial, patients on Inluriyo went 5.5 months, on average, without their cancer worsening, compared to 3.8 months with other treatments, the company said.

The once-daily oral therapy is recommended at a dose of 400 mg, administered as two 200 mg tablets taken on an empty stomach — either two hours before or one hour after a meal.

The drug is also being tested in a late-stage trial in combination with Eli Lilly's abemaciclib for advanced breast cancer and as an adjuvant therapy in early-stage disease.

(Reporting by Siddhi Mahatole in Bengaluru; Editing by Alan Barona and Krishna Chandra Eluri)