What Sairopa does

Sairopa B.V. is a clinical-stage biotechnology company headquartered in Rotterdam, Netherlands, founded in 2021 to develop immunotherapeutic monoclonal antibodies for cancer. The company targets the unmet need that only approximately 30% of cancer patients respond to existing immune checkpoint inhibitors, with programs designed to modulate multiple points of the cancer-immunity cycle — tumor antigen release, antigen presentation, T-cell activation, and local immunosuppression in the tumor microenvironment.

The company's pipeline is built on the proprietary B-Select antibody platform, originally developed by BioNovion/Aduro Biotech Europe — the same platform used to discover pembrolizumab (Keytruda). Lead clinical programs include ADU-1604, an anti-CTLA4 antibody in Phase 1 for advanced melanoma patients who have failed PD-1 checkpoint therapy, where it has shown efficacy in 4/27 patients with a milder safety profile than existing CTLA-4 inhibitors; and ADU-1805, an anti-SIRPalpha antibody in Phase 1 for solid tumors as monotherapy and in combination with PD-1 inhibitors. A preclinical SIRPalpha-PD-L1 bispecific antibody is also advancing, with IND filing planned for 2026. Sairopa's scientific leadership traces to CSO Hans van Eenennaam, co-inventor of pembrolizumab and the company's lead antibodies, and CMO Prof. Alexander Eggermont, former General Director of Gustave Roussy Cancer Campus.

Sairopa operates a partnership-driven business model. The company was formed and funded by Van Herk Investments through the 2021 acquisition of a therapeutic antibody portfolio from Chinook Therapeutics (which retained approximately 40% equity and one board seat). In parallel, Sairopa entered an exclusive clinical development and option agreement with Exelixis covering ADU-1805 and other anti-SIRPalpha antibodies, with total potential value of up to $110 million in upfront and milestone payments plus future licensing royalties. Exelixis retains an option — not an obligation — to license worldwide development and commercialization rights following Phase 1 data review. Sairopa has 1-10 employees, operates from CIC Stationsplein in Rotterdam, and runs clinical trials across US and European sites.

Name

Sairopa

Legal name

Sairopa B.V.

Website

https://sairopa.com

Company type

Private

Founded year

2021

Operating status

Operating

Headcount range

1–10 employees

Short description

Sairopa is a clinical-stage biotech developing immunotherapeutic antibodies for cancer, built on the B-Select platform that produced pembrolizumab. Lead programs ADU-1604 (anti-CTLA4) and ADU-1805 (anti-SIRPalpha) target patients failing PD-1 checkpoint therapy.

Ownership category

akta.pro rank

Product category

Immuno-oncology therapeutics

NAICS

Biological Product (except Diagnostic) Manufacturing (325414)

SIC

Biological Products, (No Disgnostic Substances) (2836)

akta.pro primary industry

Monoclonal Antibody Therapeutics (mAbs) (HLAAAAAA)

akta.pro secondary industries

Antibody Discovery & Engineering Platforms (display tech, bispecifics, Fc engineering) (HLAAAIAB), Bispecific & Multispecific Antibodies (HLAAAAAF)

Keywords

• Cancer immunotherapy
• Monoclonal antibodies
• Immune checkpoint inhibitors
• Clinical stage biotechnology
• Therapeutic antibody development

Headquarters

HQ city

Rotterdam

HQ country

Netherlands

HQ region

Europe

Offices1 record

Markets served

GTM type

B2B

Offering type

Services

Cost components

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

Revenue model

1. Partnership/Licensing revenues: Strategic partnership with Exelixis provides upfront payment ($40M), milestone payments tied to clinical development achievements ($35M IND clearance, $35M clinical milestones), and potential future licensing/royalty revenues if Exelixis exercises option to license worldwide development and commercialization rights.
2. Clinical development and potential commercialization: Revenue derived from advancing proprietary pipeline programs through clinical development with intent to commercialize or partner resulting products.

Go-to-market motion1 record

Distribution channels1 record

Marketing channels3 records

Core offering

Sairopa is a clinical-stage biotechnology company that develops proprietary monoclonal antibody therapeutics modulating the cancer-immunity cycle. Its lead clinical candidates are ADU-1604 (anti-CTLA4 antibody) and ADU-1805 (anti-SIRPalpha antibody), both discovered via the proprietary B-Select antibody platform and currently in Phase 1 clinical trials for advanced melanoma and solid tumors. The company partners late-stage development and commercialization to larger pharmaceutical companies such as Exelixis under licensing and milestone-based agreements.

Product overview

Sairopa is a clinical-stage biotechnology company developing a pipeline of therapeutic monoclonal antibodies targeting the cancer-immunity cycle. The company's core products include ADU-1604 (anti-CTLA4 antibody in Phase 1 for melanoma) and ADU-1805 (anti-SIRPalpha antibody in Phase 1 for solid tumors), both developed from the B-Select antibody platform. Preclinically, Sairopa is advancing a SIRPalpha-PD-L1 bispecific antibody targeting tumor immunosuppression, with IND filing planned for 2026. The company leverages partnerships with Exelixis for ADU-1805 development and is backed by Van Herk Investments.

Differentiator

Problem solved

Functional benefit

Products and services

• ADU-1604 Proprietary anti-CTLA4 monoclonal antibody in Phase 1 clinical development that enhances T cell priming and activation to induce tumor cytotoxic immune responses. Being evaluated in advanced melanoma patients who have failed PD-1 checkpoint inhibitor therapy.
• ADU-1805 Proprietary anti-SIRPalpha monoclonal antibody in Phase 1 clinical development that enhances tumor cell uptake and presentation to T cells to induce priming and activation. Evaluated both as monotherapy and in combination with PD-1 checkpoint therapies in patients with advanced solid tumors; partnered with Exelixis under an exclusive worldwide license option.
• SIRPalpha-PD-L1 Bispecific Antibody Proprietary preclinical-stage bispecific antibody that simultaneously targets SIRPalpha and PD-L1 checkpoints to inhibit local immunosuppression in tumors; IND filing is planned for 2026.

Quantifiable outcome

• Clinical efficacy observed in 4/27 melanoma patients who failed PD-1 therapy with ADU-1604 treatment
• +3 more outcomes

Named customers2 records

Segments1 record

Ideal customer profiles2 records

Technology focussed Yes

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Feature4 records

Partnerships

Two partnerships are on record, tiered core and minor.

• Exelixis, Inc.coreStrategic or Co-development Partner · 17 December 2024Exclusive clinical development and option agreement where Exelixis has exclusive option to license worldwide development and commercialization rights for ADU-1805 and other anti-SIRPalpha antibodies following review of Phase 1 clinical study data. Exelixis provides milestone payments totaling up to $110M ($40M upfront, $35M IND, $35M clinical milestones). Collaboration combines Exelixis' oncology development and commercialization expertise with Sairopa's antibody discovery capabilities.
• Chinook TherapeuticsminorOthers · 5 April 2021Through the Aduro Biotech merger, Chinook held non-renal antibody programs including those now licensed to Sairopa. Chinook owns approximately 40% of Sairopa after first tranche of financing and has one seat on Sairopa's Board of Directors.

Scale indicators3 records

Recent moves7 records

Expansion highlights5 records

Broad incumbents

• Genmab: Established antibody therapeutics company with DuoBody bispecific platform and broad clinical pipeline including oncology checkpoint assets. Comparable in antibody modality and bispecific focus to Sairopa's SIRPalpha-PD-L1 bispecific program, but at a much larger commercial scale.
• AstraZeneca: Large pharma with tremelimumab (anti-CTLA-4, Imjudo) approved in combination with durvalumab for HCC, and extensive IO pipeline. The named incumbent in the CTLA-4 space that Sairopa's ADU-1604 seeks to differentiate against via improved safety.

Emerging players

• Compugen: Clinical-stage immuno-oncology company developing antibody therapeutics targeting novel immune checkpoints (e.g., PVRIG, TIGIT). Comparable in early clinical stage, oncology focus, and differentiation through novel checkpoint targeting — adjacent to Sairopa's anti-CTLA4/SIRPalpha pipeline.
• Surface Oncology: Clinical-stage IO company developing antibodies targeting immunosuppressive cells in the tumor microenvironment (e.g., anti-IL-27, anti-CD39). Comparable clinical stage and IO focus, though targeting different mechanisms than Sairopa's CTLA-4/SIRPalpha assets.
• CytomX Therapeutics: Clinical-stage oncology company developing Probody therapeutics — masked monoclonal antibodies conditionally activated in the tumor microenvironment. Comparable in platform-based antibody approach to Sairopa's B-Select platform, with overlapping Phase 1 oncology assets.

Others

• Exelixis: Sairopa's strategic partner for ADU-1805 (anti-SIRPalpha) with exclusive option to license worldwide development and commercialization rights. Also a relevant oncology comparator as a commercial-stage biotech with Cabometyx/Cometriq franchise and IO pipeline.

Direct peers

• ALX Oncology: Clinical-stage oncology company developing anti-CD47/SIRPalpha antibodies (e.g., evorpacept). Direct competitor to Sairopa's ADU-1805 in the SIRPalpha/CD47 myeloid checkpoint space, with similar Phase 1 development stage and combination strategy with PD-1 inhibitors.
• MacroGenics: Clinical-stage biotech developing therapeutic monoclonal antibodies and bispecifics in oncology, including checkpoint inhibitors (e.g., enoblituzumab, MGC018). Comparable modality (mAbs/bispecifics), clinical stage, and IO focus to Sairopa's pipeline.
• Trillium Therapeutics: Developed anti-SIRPalpha antibodies (TTI-621, TTI-622) for hematologic and solid tumors. Acquired by Pfizer in 2021 for $2.3B. Direct competitor to ADU-1805 in the SIRPalpha mechanism, validating both the target class and the strategic value of differentiated SIRPalpha assets.
• Aduro Biotech: Originator of the B-Select antibody platform (via BioNovion/Aduro Biotech Europe) that produced pembrolizumab and Sairopa's pipeline assets. Sairopa's assets were carved out of Aduro Biotech Europe via the Chinook Therapeutics merger, making Aduro the direct historical and technical predecessor.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat5 records

Key risks6 records

Key highlights6 records

Customer concentration

• LinkedInlinkedin.com/company/sairopa-b-v

Revenue estimate

Valuation estimate

Number of profiles

Profiles17 records

Funding overview

Funding rounds

Investors

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M&A

Investments

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Frequently asked questions about Sairopa