Third Patient Death Reported in SL-401 Drug Trial for Patients With BPDCN and AML

The manufacturers of SL-401, a targeted therapy directed at the interleukin-3 receptor CD123, reported a third patient death in the ongoing phase II trial of patients with blastic plasmacytoid dendritic cell neoplasm (BPDCN) and acute myeloid leukemia (AML).

The previous two deaths (one patient with AML and another with BPDCN) were related to capillary leak syndrome (CLS) – a sometimes fatal and documented adverse event of SL-401. Though the third patient developed CLS, it has not yet been determined whether CLS was the direct cause of death.

The study is ongoing, but the CLS events have been noted in filings with the Securities and Exchange Commission and the FDA, as well as in the study’s informed consent forms and other information provided to investigators. The manufacturers will continue to report data to the FDA.

Preliminary results of the multicenter trial were presented at the 2016 ASH Annual Meeting. Researchers reported that among the 15 evaluable patients with BPDCN, 87 percent (n=13) responded to treatment with SL-401. The overall response rate was 100 percent when SL-401 was used as frontline treatment (n=10/10) and 60 percent when it was used in the relapsed/refractory setting (n=3/5).

Source: Stemline Therapeutics, Inc., news release, February 4, 2017.