Adds company comment in paragraph 4, drug details throughout

By Siddhi Mahatole and Puyaan Singh

May 13 (Reuters) - BeOne Medicines 688235.SS said on Wednesday that the U.S. Food and Drug Administration had approved its drug for a type of blood cancer.

The drug, branded as Beqalzi, was greenlit to treat relapse or refractory mantle cell lymphoma, an aggressive cancer of the lymphatic system, which contains disease-fighting white blood cells that relapses after initial treatment or fails to respond to it.

The drug is expected to launch in the second half of this year, a company spokesperson told Reuters.

The regulator's accelerated approval was based on an early-to-mid-stage study in which the drug showed a complete response, or disappearance of all detectable signs of cancer, in 16% of the patients on the drug.

BeOne said Beqalzi works by blocking a key survival protein (BCL2) with stronger and more precise action with the potential to work better while being safer and easier for patients to take.

The drug is the first in its class of BCL‑2 inhibitors to be approved for mantle cell lymphoma. AbbVie ABBV.N and Roche's ROPC.S Venclexta, another drug from the class, is approved for other types of blood cancer.

In the U.S., FDA-approved options for mantle cell lymphoma include Takeda's 4502.T Velcade, Bristol Myers' BMY.N Revlimid and Breyanzi, BeOne's Brukinsa, Lilly's LLY.N Jaypirca and Gilead's GILD.O Tecartus.

In the U.S., around 3,300 new cases of mantle cell lymphoma are diagnosed each year, BeOne said.

Beqalzi is already approved in China to treat relapsed or refractory mantle cell lymphoma, and also for adults with a type of blood cancer who have had at least one prior treatment.

Data from its early-to-mid stage study in mantle cell lymphoma is being reviewed by regulators in Europe and other regions, the company said.