Stemline Therapeutics to Present SL-401 Updated Data from Stage 1 and 2 of Ongoing Pivotal Phase 2 BPDCN Trial at Upcoming European Hematology Association (EHA) Meeting

NEW YORK, May 18, 2017 -- Stemline Therapeutics, Inc. (Nasdaq:STML), a clinical-stage biopharmaceutical company developing novel therapeutics for oncology indications of unmet medical need, announced today that SL-401 Stage 1 and 2 data from its ongoing pivotal Phase 2 trial in blastic plasmacytoid dendritic cell neoplasm (BPDCN) has been accepted for poster presentation at the 2017 European Hematology Association (EHA) Annual Meeting, to be held June 22-25, 2017 in Madrid, Spain.

Details on the presentation is as follows:

Stemline remains on track to provide an update on BPDCN patients enrolled in Stage 3 of the Phase 2 pivotal trial in the second half of this year.

About Stemline Therapeutics
Stemline Therapeutics, Inc. is a clinical stage biopharmaceutical company developing novel therapeutics for oncology indications of unmet medical need. A Phase 2 pivotal trial with SL-401, a targeted therapy directed to the interleukin-3 receptor (CD123), has completed enrollment of patients with blastic plasmacytoid dendritic cell neoplasm (BPDCN) in the Stage 3 cohort, and patients continue to be followed. SL-401 has been granted Breakthrough Therapy Designation (BTD) for the treatment of BPDCN. Additional Phase 1/2 trials with SL-401 are enrolling patients with other malignancies including high-risk myeloproliferative neoplasms (MPN) and acute myeloid leukemia (AML) in remission with minimal residual disease (MRD). A Phase 1/2 trial of SL-401 in combination with pomalidomide is enrolling patients with relapsed/refractory multiple myeloma. A Phase 1 dose escalation trial with SL-801, a novel oral small molecule reversible inhibitor of XPO1, is enrolling patients with advanced solid tumors. A Phase 2 trial with SL-701, an immunotherapy designed to activate the immune system to attack tumors, has completed dosing and patients with second-line glioblastoma are being followed for survival.

Forward-Looking Statements
Some of the statements included in this press release may be forward-looking statements that involve a number of risks and uncertainties. For those statements, we claim the protection of the safe harbor for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995. The factors that could cause our actual results to differ materially include: the success and timing of our clinical trials and preclinical studies for our product candidates, including site initiation, institutional review board approval, scientific review committee approval, patient accrual, safety, tolerability and efficacy data observed, and input from regulatory authorities including the risk that the FDA or other ex-U.S. national drug authority ultimately does not approve any of our product candidates; our plans to develop and commercialize our product candidates; market acceptance of our products; reimbursement available for our products; our available cash and investments; our ability to obtain and maintain intellectual property protection for our product candidates; our ability to manufacture; the performance of third-party manufacturers, clinical research organizations, clinical trial sponsors and clinical trial investigators; and other risk factors identified from time to time in our reports filed with the Securities and Exchange Commission. Any forward-looking statements set forth in this press release speak only as of the date of this press release. We do not intend to update any of these forward-looking statements to reflect events or circumstances that occur after the date hereof.

Contact
Investor Relations
Stemline Therapeutics, Inc.
750 Lexington Avenue
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New York, NY 10022
Tel: 646-502-2307
Email: [email protected]