Stemline Therapeutics Announces Clinical Presentations of SL-801 and SL-701 at the Upcoming ASCO Annual Meeting

NEW YORK, April 26, 2018 -- Stemline Therapeutics, Inc. (Nasdaq:STML), a clinical-stage biopharmaceutical company developing novel oncology therapeutics, announced today that clinical data from SL-801 and SL-701 trials have been selected for poster presentations at the upcoming 54^th Annual Meeting of the American Society of Clinical Oncology (ASCO), to be held from June 1-5, 2018, at McCormick Place in Chicago, Illinois. Details of the data presentations are outlined below.

Title: Phase 2 trial of SL-701 in relapsed/refractory glioblastoma (GBM): Correlation of immune response with longer-term survival

• Abstract number: 2058
• Session: Central Nervous System Tumors
• Presenter: David Peereboom, MD; Cleveland Clinic
• Date: Saturday, June 2, 2018
• Time: 1:15 – 4:45 PM CT

Title: Interim results from a Phase 1 trial of SL-801, a novel XPO-1 inhibitor, in patients with advanced solid tumors.

• Abstract number: 2560
• Session: Developmental Therapeutics—Clinical Pharmacology and Experimental Therapeutics
• Presenter: Judy Wang, MD; Florida Cancer Specialists and Research Institute
• Date: Monday, June 4, 2018
• Time: 8:00 – 11:30 AM CT

Abstracts are scheduled to be released publicly on May 16, 2018 at 5 PM ET through the ASCO meeting website (www.asco.org). Following each presentation at the conference, the data presented will be available on Stemline’s website (www.stemline.com) under the Scientific Presentations tab.

About BPDCN
Please visit the BPDCN disease awareness booth (#4125) at ASCO 2018 and www.bpdcninfo.com.

About Stemline Therapeutics
Stemline Therapeutics, Inc. is a clinical-stage biopharmaceutical company developing novel oncology therapeutics. Stemline is developing three clinical stage product candidates, SL-401, SL-801, and SL-701. SL-401 is a targeted therapy directed to the interleukin-3 receptor (CD123) present on a range of malignancies. SL-401 has completed a pivotal trial in blastic plasmacytoid dendritic cell neoplasm (BPDCN), for which it was granted breakthrough therapy designation (BTD). The pivotal trial met its primary endpoint, and a rolling BLA submission has been initiated. SL-401 is also being evaluated in clinical trials in additional indications including chronic myelomonocytic leukemia (CMML), myelofibrosis (MF), acute myeloid leukemia (AML), and myeloma. SL-801 is a novel oral small molecule reversible inhibitor of XPO1 that is currently in a Phase 1 trial of patients with advanced solid tumors; dose escalation is ongoing. SL-701, an immunotherapeutic, has completed a Phase 2 trial in patients with second-line glioblastoma; data and next steps for the program are being evaluated.

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 BLA submission to the FDA; 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 agree with our data, find our data supportive of approval, or 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 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 SEC. 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]