Stemline Therapeutics Inc.'s experimental cancer drug Elzonris shrank tumors in patients with a rare type of cancer that affects the bone marrow, peripheral blood and skin.

The company is evaluating the drug in a late-stage trial in patients with blastic plasmacytoid dendritic cell neoplasm, or BPDCN. BPDCN is characterized by the malignant increase of cells known as plasmacytoid dendritic cells, which are normally produced in the bone marrow, circulate in the blood and accumulate in lymph nodes when an immune response is triggered.

Results from the trial showed that 90% of the 29 patients who received Elzonris as the initial treatment experienced reductions in their tumors. Among the 13 patients whose cancer had returned or was unresponsive to treatment, 69% showed a decrease in their tumor size with Elzonris as treatment.

The company has initiated a rolling submission to seek the U.S. Food and Drug Administration's approval for Elzonris to treat BPDCN and has been granted a breakthrough therapy designation for this usage.