Stemline Therapeutics

What Stemline Therapeutics does

Stemline Therapeutics is a commercial-stage biopharmaceutical company focused on oncology therapeutics, operating as a wholly-owned subsidiary of Menarini Group. The company markets three approved products: ORSERDU (elacestrant), an oral selective estrogen receptor degrader (SERD) approved by FDA in January 2023 as the first and only treatment specifically indicated for ESR1-mutated ER+/HER2- advanced or metastatic breast cancer; ELZONRIS (tagraxofusp-erzs), a CD123-directed diphtheria toxin fusion protein approved in 2018 (FDA) and 2021 (EMA) as the only approved treatment for blastic plasmacytoid dendritic cell neoplasm (BPDCN) in the US and EU; and NEXPOVIO (selinexor), a first-in-class oral XPO1 inhibitor for multiple myeloma, commercialized in Europe under a licensing arrangement with Karyopharm Therapeutics. Beyond approved products, the pipeline includes SL-801 (reversible XPO1 inhibitor in Phase 1 for solid tumors), SL-701 (immunotherapy in glioblastoma), and AI-discovered candidates MEN2312 (KAT6 inhibitor) and MEN2501 (KIF18A inhibitor) sourced through a multi-asset exclusive license partnership with Insilico Medicine, plus a third preclinical AI-designed oncology candidate.

The business model centers on pharmaceutical product sales through wholesale and specialty pharmacy distribution to hospitals and cancer treatment centers, supported by field sales teams and medical science liaisons targeting oncologists and hematologists. Revenue streams include direct product sales (ORSERDU, ELZONRIS in US and EU), licensing royalties (NEXPOVIO from Karyopharm's ex-US selinexor arrangement), and milestone payments from the Insilico partnership, with MEN2501 first-in-patient dosing triggering a $5 million payment in February 2026 and combined Insilico deal value exceeding $550 million. Pricing follows standard monthly specialty pharmaceutical reimbursement, with the company leveraging parent Menarini Group's global distribution infrastructure spanning 18 production sites, 9 R&D centers, and operations in 140 countries.

Stemline pursues combination therapy expansion across its portfolio, including elacestrant plus abemaciclib (mPFS 14.3 months), elacestrant plus capivasertib (88.9% disease control rate), selinexor plus ruxolitinib (SENTRY Phase 3 hit first co-primary endpoint with 49.8% SVR35 versus 28% for ruxolitinib alone), and elacestrant plus everolimus (ADELA Phase 3 with MEDSIR). The company uses AI-driven diagnostic and trial infrastructure partnerships (Tempus Next, Medidata, VisualDx) to support patient identification and clinical execution. The product franchise is concentrated in rare and biomarker-defined oncology indications where the company holds first-in-class or only-approved positions.

Name

Stemline Therapeutics

Legal name

Stemline Therapeutics, Inc.

Website

https://stemline.com

Company type

Private

Founded year

2003

Operating status

Operating

Headcount range

501–1,000 employees

Short description

Stemline Therapeutics is a commercial-stage biopharmaceutical subsidiary of Menarini Group developing and marketing oncology therapeutics. It commercializes three approved products—ORSERDU, ELZONRIS, and NEXPOVIO—and advances an AI-discovered oncology pipeline through partnerships with Insilico Medicine and others.

Ownership category

akta.pro rank

Product category

Oncology Pharmaceuticals

NAICS

Biological Product (except Diagnostic) Manufacturing (325414), Pharmaceutical and Medicine Manufacturing (3254)

SIC

Pharmaceutical Preparations (2834)

akta.pro primary industry

Oncology Specialty Pharmaceuticals (HLAIACAA)

Keywords

• Oncology therapeutics
• Targeted cancer therapy
• Breast cancer treatment
• Hematologic malignancy drugs
• Biopharmaceutical products

Headquarters

HQ city

New York

HQ country

United States

HQ region

North America

Offices3 records

Markets served

GTM type

B2B

Offering type

Hardware or Manufacturing

Cost components

Technology or R&D, Marketing or Sales, Personnel, Operations, Supply Chain

Revenue model

1. Product Sales - ORSERDU: Revenue from sales of ORSERDU (elacestrant) in the US and Europe for treatment of ER+/HER2-/ESR1-mutated advanced or metastatic breast cancer.
2. Product Sales - ELZONRIS: Revenue from sales of ELZONRIS (tagraxofusp-erzs) in the US and Europe for treatment of BPDCN, the only approved treatment for this indication.
3. Product Sales - NEXPOVIO: Revenue from sales of NEXPOVIO (selinexor) in Europe for multiple myeloma, marketed under licensing agreement with Karyopharm Therapeutics.
4. Milestone Payments from AI Partnership: Revenue received from Insilico Medicine upon achievement of development milestones for AI-discovered compounds, including $5 million for MEN2501 first-in-human dosing. Combined agreement value exceeds $550 million.

Pricing tiers

Go-to-market motion1 record

Distribution channels2 records

Marketing channels4 records

Core offering

Stemline Therapeutics commercializes novel oncology therapeutics, including ORSERDU (elacestrant) for ER+/HER2-/ESR1-mutated advanced or metastatic breast cancer, ELZONRIS (tagraxofusp-erzs) for blastic plasmacytoid dendritic cell neoplasm (BPDCN), and NEXPOVIO (selinexor) for multiple myeloma in Europe. The company also develops a clinical pipeline of small molecule and biologic candidates, including AI-discovered assets in partnership with Insilico Medicine targeting oncology indications with high unmet medical need.

Product overview

Stemline Therapeutics is a commercial-stage biopharmaceutical company developing and commercializing novel oncology therapeutics. The company markets three approved products: ORSERDU (elacestrant), an oral SERD for ER+/HER2- ESR1-mutated metastatic breast cancer; ELZONRIS (tagraxofusp-erzs), a CD123-directed therapy for BPDCN; and NEXPOVIO (selinexor), an XPO1 inhibitor for multiple myeloma in Europe. The pipeline includes clinical-stage candidates SL-801 (XPO1 inhibitor for solid tumors), SL-701 (immunotherapy for glioblastoma), and MEN2501 (KIF18A inhibitor), plus AI-discovered assets from Insilico Medicine including MEN2312 (KAT6 inhibitor) and a second preclinical oncology asset. Multiple combination studies are ongoing for elacestrant across metastatic and early breast cancer settings.

Differentiator

Problem solved

Functional benefit

Brands

• ORSERDU: ORSERDU (elacestrant) - oral endocrine therapy for ER+, HER2- advanced or metastatic breast cancer with ESR1 mutations
• ELZONRIS
• NEXPOVIO

Products and services

• ORSERDU (elacestrant) Oral selective estrogen receptor degrader (SERD) approved for treatment of postmenopausal women or adult men with estrogen receptor-positive, HER2-negative, ESR1-mutated advanced or metastatic breast cancer following disease progression on endocrine therapy. First and only oral SERD specifically indicated for ESR1-mutated tumors.
• ELZONRIS (tagraxofusp-erzs) Novel targeted therapy directed to CD123 (IL-3R) comprising human IL-3 recombinantly fused to a truncated diphtheria toxin payload. Indicated for treatment of blastic plasmacytoid dendritic cell neoplasm (BPDCN) in adults and pediatric patients 2 years and older. The only approved treatment for BPDCN in the US and EU.
• NEXPOVIO (selinexor) First-in-class oral exportin 1 (XPO1) inhibitor approved in Europe for multiple myeloma: (i) in combination with dexamethasone for adult patients who have received at least four prior therapies, and (ii) in combination with bortezomib and dexamethasone for adults who have received at least one prior therapy. Commercialized in Europe under licensing agreement with Karyopharm Therapeutics.

Quantifiable outcome

• SVR35 (spleen volume reduction ≥35%) achieved in 49.8% of myelofibrosis patients at week 24 with selinexor + ruxolitinib vs 28% with ruxolitinib alone
• +4 more outcomes

Named customers5 records

Segments4 records

Ideal customer profiles2 records

Technology focussed No

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Integration2 records

Feature6 records

Partnerships

Nine partnerships are on record, tiered supporting, major and core.

• MedidatasupportingTechnology or Integration · 9 March 2026Expansion of 14-year partnership deploying Medidata's AI Study Build technology to power Stemline's oncology portfolio. Technology leverages data from more than 38,000 clinical trials to automate study configurations, reducing trial startup time from months to weeks.
• VisualDxsupportingStrategic or Co-development Partner · 20 March 2025Collaboration to aid in identifying people who may have Blastic Plasmacytoid Dendritic Cell Neoplasm (BPDCN), supporting diagnosis of this rare aggressive hematologic malignancy.
• Tempus AImajorTechnology or Integration · 20 February 2025Collaboration to implement Tempus Next, AI-enabled care pathway intelligence platform for metastatic breast cancer patients. Platform analyzes clinical data and notifies clinicians when ESR1 testing is missing at disease progression, supporting appropriate testing integration into treatment journey.
• Insilico Medicine (Second Agreement)coreStrategic or Co-development Partner · 10 January 2025Second exclusive global license agreement for AI-discovered preclinical asset targeting high unmet needs in oncology. $20 million upfront payment. Combined value of all agreements exceeds $550 million. MEN2501 (KIF18A inhibitor) achieved first-in-patient dosing milestone in 2026, triggering $5 million payment to Insilico.
• MEDSIRmajorStrategic or Co-development Partner · 12 December 2024Clinical trial collaboration for ADELA Phase 3 study evaluating elacestrant + everolimus vs elacestrant alone in ER+/HER2- advanced breast cancer with ESR1 mutations. International study across Spain, Italy, France, Austria, Czech Republic, Greece, Germany, and UK. MEDSIR provides end-to-end clinical trial management.
• Insilico MedicinecoreStrategic or Co-development Partner · 4 January 2024Global exclusive license agreement for novel KAT6 inhibitor (MEN2312) for breast cancer and other oncology indications. Asset designed using Insilico's generative AI engine. Combined deal value exceeds $550 million including $20 million upfront payment, development milestones, and tiered royalties. MEN2312 advanced rapidly into clinical phase.
• Carrick TherapeuticssupportingStrategic or Co-development Partner · 19 December 2023Clinical trial collaboration to evaluate samuraciclib and elacestrant combination in breast cancer, exploring novel therapeutic combination to overcome resistance mechanisms.
• EORTC (European Organisation for Research and Treatment of Cancer)majorStrategic or Co-development Partner · 19 October 2023Collaboration to launch new clinical trial in early-stage breast cancer, expanding elacestrant development into earlier disease stages and adjuvant treatment settings.
• Karyopharm TherapeuticscoreStrategic or Co-development Partner · 1 January 2023Collaboration on selinexor development. Karyopharm commercializes selinexor as XPOVIO in the US; Menarini Group holds global licensing rights for selinexor as NEXPOVIO outside US. Conducted pivotal Phase 3 SENTRY trial of selinexor + ruxolitinib in myelofibrosis presented at EHA 2026. SENTRY achieved first co-primary endpoint with 49.8% SVR35 vs 28% for ruxolitinib alone.

Scale indicators8 records

Recent moves6 records

Expansion highlights6 records

Direct peers

• Karyopharm Therapeutics: Direct partner and co-developer of selinexor (NEXPOVIO/XPOVIO). Both companies commercialize the same molecule in different geographies for multiple myeloma and other oncology indications, making them directly comparable oncology specialty pharma companies of similar size and stage.
• Olema Oncology: Direct competitor in the oral SERD space with OP-1250 in development for ER+/HER2- breast cancer. Both companies target the same patient population with similar mechanisms of action and are at similar clinical/commercial stages.
• Arvinas: Oncology specialty biotech developing targeted therapies including ER-targeted PROTAC degraders for breast cancer. Both companies operate in similar patient populations with novel targeted mechanisms and similar size/scale.
• Radius Health: Specialty pharma company that was acquired by Menarini Group for ~$890M in 2022, focused on osteoporosis and oncology. Now operates as part of Menarini alongside Stemline, representing the most directly comparable subsidiary within the same parent company.
• MacroGenics: Clinical-stage oncology specialty biopharmaceutical company developing antibody-based therapeutics for cancer including margetuximab. Similar size, oncology focus, and pipeline stage profile to Stemline.

Broad incumbents

• ImmunoGen: Oncology biotech now part of AbbVie focused on antibody-drug conjugates for cancer including ELAHERE for ovarian cancer. Similar oncology specialty focus with comparable commercial-stage profile before acquisition.
• Seagen: Large oncology specialty company (acquired by Pfizer for $43B) developing targeted cancer therapies including ADCs. Comparable in oncology focus but at much larger scale with broader pipeline.
• Exelixis: Commercial-stage oncology company focused on genitourinary cancers with cabozantinib. Comparable specialty oncology profile with multiple approved drugs and ongoing pipeline development, though focused on different therapeutic areas.
• AstraZeneca (Oncology Division): Large pharmaceutical company with significant oncology portfolio including competing oral SERD (camizestrant) and breast cancer therapies. Operates as broader incumbent in the same oncology space with far greater resources for label expansion studies.

Emerging players

• Mersana Therapeutics: Clinical-stage oncology company developing antibody-drug conjugates including XMT-1660. Comparable size and clinical-stage oncology focus with novel platform technology targeting similar patient populations.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat5 records

Key risks6 records

Key highlights7 records

Customer concentration

• LinkedInlinkedin.com/company/stemline-therapeutics-inc-

Revenue estimate

Valuation estimate

Number of profiles

Profiles3 records

Funding overview

Funding rounds6 records

Investors1 record

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Stemline Therapeutics