Johnson & Johnson (JNJ.N) said on Thursday the U.S. Food and Drug Administration had approved its antibody-based therapy for patients with a difficult-to-treat type of blood cancer.

The therapy, Talvey, belongs to a class of treatments called bispecific antibodies designed to bring a cancer cell and an immune cell together so the body's immune system can kill the cancer.

Talvey will be sold at a list price of $45,000 per month, the company told Reuters, adding the price could vary based on a patient's weight, prescribed dosing and treatment duration.

J&J estimates a pricing range of $270,000 to $360,000 for an average treatment duration of six to eight months.

The company expects to make the therapy available to patients within three weeks.

Talvey was approved as a weekly or biweekly injection given under-the-skin to treat patients with relapsed multiple myeloma who have received at least four prior lines of treatment.

While the FDA approved J&J's Tecvayli, another bispecific antibody, last year, Talvey is the first of its kind to target a protein known as GPRC5D, which is mainly present in cancerous plasma cells.

Around 35,730 people in the U.S. are expected to be diagnosed with multiple myeloma this year. The cancer starts in the bone marrow and disrupts production of normal blood cells.

"Although options for the treatment ... have expanded significantly in recent years, the disease remains incurable, and therefore, patients are in need of new treatment options," said Michael Andreini, CEO of the non-profit Multiple Myeloma Research Foundation.

The therapy's approval comes with FDA's "boxed" safety warning, flagging the risk of a type of aggressive immune response and neurologic toxicity.

The accelerated approval is based on mid-stage trial data, which showed 73.6% patients achieved either partial or complete disappearance of cancer from their body.