Incyte Corp said on Wednesday its monoclonal antibody, Zynyz, has won accelerated approval from the U.S. health regulator for treating a rare and aggressive type of skin cancer in adults.

The U.S. Food and Drug Administration approved the therapy in Merkel cell carcinoma (MCC) patients for whom the cancer has come back or spread to other parts of the body.

The company said it expects Zynyz will be available to eligible patients by early April.

MCC impacts less than 1 per 100,000 people in the U.S. but incidence rates are rising, the company said.

Zynyz belongs to a class of drugs known as PD-1 inhibitors that help the immune system to attack cancer by blocking a mechanism tumors use to evade detection.

Incyte said the monthly price of treatment with Zynyz will be comparable with other drugs in the same class that are currently available.

Drugs such as Merck & Co Inc's blockbuster Keytruda and Merck KGaA and Pfizer Inc's Bavencio are approved to treat MCC.

The list price for each dose of Keytruda when it is given every three weeks is $10,683.52, according to its website.

Keytruda is "heavily entrenched" in the indication, brokerage William Blair said, adding that it sees limited commercial opportunity for Zynyz.

The therapy was developed by MacroGenics Inc and licensed to Incyte in 2017.

MacroGenics shares were down nearly 5%, while Incyte was down about 1%.

The approval for Zynyz was based on a mid-stage study, which showed the therapy helped decrease the size of tumors or remove all signs of the cancer in patients.

An accelerated approval means companies will still be required to conduct studies to confirm the anticipated clinical benefit.