What Siren Biotechnology does

Siren Biotechnology is a clinical-stage biotechnology company developing a Universal AAV Immuno-Gene Therapy platform that combines adeno-associated virus (AAV) gene therapy with cytokine immunotherapy into a single therapeutic modality for solid tumor cancers. The company was founded in 2021 by Nicole K. Paulk, PhD, as a spin-out of her laboratory at the University of California, San Francisco, and is headquartered in San Francisco's Mission Bay biotech district. Its lead clinical asset, SRN-101, is a recombinant AAV vector expressing engineered immunomodulatory cytokine payloads (including interferons) that are delivered directly to tumors via convection-enhanced delivery (CED), enabling localized and sustained cytokine expression within the tumor microenvironment. SRN-101 is being evaluated in a first-in-human Phase 1 investigator-initiated trial in adult patients with recurrent high-grade glioma at UCSF, and has received FDA Orphan Drug Designation, Rare Pediatric Disease Designation, and Fast Track Designation.

The platform's core technological differentiators include a universal drug product design intended to function across multiple solid tumor indications regardless of specific tumor mutations, an immunologically optimized AAV genome that limits non-specific immune activation, and a self-limiting payload mechanism in which cytokine expression ceases as tumor cells die. Localized intratumoral delivery via CED bypasses the blood-brain barrier — a key advantage for brain cancer — and avoids the pre-existing anti-AAV immunity challenges that constrain systemically administered AAV gene therapies. Preclinical data reported across three high-grade glioma models (n=450 mice) demonstrated tumor regression, widespread apoptosis within 48 hours, and complete tumor eradication by day 7. In April 2026, the company published its foundational preclinical dataset in Molecular Therapy Oncology.

Siren is pre-revenue and funds operations entirely through equity investments, non-dilutive grants, and community investment rounds. The company has raised approximately $32-36 million to date, including a $28 million seed round led by Founders Fund and Lux Capital (May 2023), a $4 million CIRM TRAN1 translational research grant (November 2023), an SEC-registered exempt offering of approximately $32.4 million (April 2024), and a community investment round on Wefunder (June 2025). Clinical manufacturing is conducted through a strategic partnership with Catalent at its Baltimore cGMP facility. The company's go-to-market is currently investigator-initiated clinical research at a single academic medical center; future commercialization would target neuro-oncology departments at major academic medical centers following regulatory approval.

Name

Siren Biotechnology

Legal name

Siren Biotechnology, Inc.

Website

https://sirenbiotechnology.com

Company type

Private

Founded year

2020

Operating status

Operating

Headcount range

1–10 employees

Short description

Siren Biotechnology is a clinical-stage biotech developing a Universal AAV Immuno-Gene Therapy platform that delivers vectorized cytokines directly to solid tumors via convection-enhanced delivery. Its lead asset SRN-101 targets recurrent high-grade glioma and has received FDA Orphan, Rare Pediatric, and Fast Track designations.

Ownership category

akta.pro rank

Product category

Gene Therapy / Immuno-Oncology

NAICS

Biological Product (except Diagnostic) Manufacturing (325414), Research and Development in Biotechnology (except Nanobiotechnology) (541714), Scientific Research and Development Services (5417)

SIC

Biological Products, (No Disgnostic Substances) (2836), Pharmaceutical Preparations (2834)

akta.pro primary industry

Oncology Gene Therapies (incl. oncolytic vectors & gene-modified approaches) (HLAAACAF)

akta.pro secondary industry

AAV Vector Gene Therapy Developers (HLAAACAA)

Keywords

• AAV gene therapy
• Cytokine immunotherapy
• Immuno-gene therapy
• Oncology therapeutics
• Solid tumor treatment

Headquarters

HQ city

San Francisco

HQ country

United States

HQ region

North America

Offices2 records

Markets served

GTM type

B2B

Offering type

Hardware or Manufacturing

Cost components

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

Revenue model

1. Gene Therapy Development and Commercialization: As a clinical-stage biotech, Siren Biotechnology is developing AAV immuno-gene therapies for cancer. Revenue would come from commercialization of therapeutic products upon FDA approval. The company is pre-revenue with all funding from equity investments, grants, and community investment rounds.

Go-to-market motion1 record

Distribution channels1 record

Marketing channels10 records

Core offering

Siren Biotechnology develops a Universal AAV Immuno-Gene Therapy platform that combines AAV gene therapy with cytokine immunotherapy into a single therapeutic modality for solid tumor cancers. The platform delivers engineered immunomodulatory cytokine payloads (interferons) directly into tumors via convection-enhanced delivery, enabling localized, sustained immune activation. The lead clinical asset SRN-101 targets recurrent high-grade glioma and is currently in a first-in-human Phase 1 trial at UCSF.

Product overview

Siren Biotechnology offers a Universal AAV Immuno-Gene Therapy Platform that combines AAV gene therapy with cytokine immunotherapy into a single modality for treating solid tumors. The platform is designed to deliver vectorized cytokines directly to the tumor microenvironment, enabling localized and durable immune activation. The lead clinical asset is SRN-101 for recurrent high-grade glioma, which received FDA Fast Track Designation, Orphan Drug Designation, and Rare Pediatric Disease Designation. The platform's universal design allows the same therapy drug product to be used across multiple cancer indications, reducing clinical development and manufacturing timelines.

Differentiator

Problem solved

Functional benefit

Products and services

• SRN-101 A recombinant AAV vector expressing an engineered immunomodulatory cytokine payload, delivered via convection-enhanced delivery directly into tumors for the treatment of recurrent high-grade glioma. Targets patients with limited therapeutic options and addresses failures of systemic chemotherapy due to the blood-brain barrier.
• Universal AAV Immuno-Gene Therapy Platform A therapeutic platform combining AAV gene therapy and cytokine immunotherapy into a single modality for treating solid tumors. The universal design enables the same AAV immuno-gene therapy drug product to be deployed across multiple cancer indications regardless of tumor mutations, reducing clinical development timelines and manufacturing needs.

Quantifiable outcome

• Tumor regression and prolonged survival across three preclinical HGG models (GBM6 xenografts: P<0.2-0.001, 31-60% complete responses; GL261 allografts: P<0.0009; patient-derived xenografts: P<0.04, 30% complete responses; n=450 mice)
• +2 more outcomes

Named customers1 record

Segments2 records

Ideal customer profiles1 record

Technology focussed Yes

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

AI capability2 records

Feature6 records

Partnerships

Three partnerships are on record, tiered core and strategic.

• University of California, San Francisco (UCSF)coreStrategic or Co-development Partner · 23 March 2026Investigator-initiated Phase 1 clinical trial for SRN-101 in recurrent high-grade glioma led by Dr. Nicholas Butowski, Professor of Neurological Surgery and Neuro-Oncology. Siren provides study drug and collaborates in support of the trial. This represents the first-in-human clinical evaluation of the company's AAV-based immuno-gene therapy.
• CatalentcoreImplementation/ SI/ Consulting Partner · 8 May 2024Strategic partnership for process development and cGMP manufacturing of AAV vector-based therapeutic candidates for clinical trials. Catalent provides process optimization at its process and clinical development center in Baltimore, MD. Catalent is the only CDMO in the U.S. that has received FDA approval for AAV-based gene therapies to date, making this a significant partnership for future commercialization.
• WhiteLab GenomicsstrategicTechnology or Integration · 16 January 2024Strategic partnership to develop an AI-powered indication discovery platform for AAV immuno-gene therapies for cancer. WhiteLab Genomics performs AI-driven disease profiling and computational analyses to identify high-priority indications for Siren's Universal AAV Immuno-Gene Therapy platform, accelerating identification of new target indication candidates.

Scale indicators4 records

Recent moves7 records

Expansion highlights6 records

Direct peers

• Genenta Science: Clinical-stage gene therapy company developing a lentiviral-based platform that delivers immunomodulatory payloads (IFN-α) to tumor microenvironment via hematopoietic progenitor cell transduction — the closest direct competitor combining gene therapy delivery with cytokine immunotherapy for solid tumors.
• Candel Therapeutics: Clinical-stage developer of oncolytic viral immunotherapies for solid tumors including high-grade glioma. Comparable as a viral-vector-based immune gene therapy platform with multiple oncology indications in development.
• Turnstone Biologics: Clinical-stage biotech engineering oncolytic viruses and tumor-infiltrating lymphocyte (TIL) therapies to deliver immunomodulatory payloads for solid tumors. Overlaps with Siren's viral-delivery + immune-activation approach across multiple solid tumor indications.
• Replimune: Develops oncolytic immunotherapy platforms (RP1, RP2, RP3) that combine virus-mediated tumor killing with immune stimulation. Comparable viral-vector + cytokine-style immune activation mechanism targeting solid tumors.
• Vyriad: Developer of oncolytic virus immunotherapies engineered to express immunomodulatory transgenes (e.g., IFN-β) for solid tumor treatment — directly comparable AAV/viral platform delivering cytokine payloads into tumors.
• Precigen: Clinical-stage gene and cell therapy company with programs in oncology using novel vectors to deliver therapeutic payloads. Comparable as a regulated gene therapy developer for cancer indications.

Broad incumbents

• REGENXBIO: Established AAV gene therapy platform company with proprietary NAV vectors and a broad pipeline across ophthalmology, CNS, and rare diseases. Highly relevant AAV technology incumbent, though primarily focused on non-oncology indications.
• Novocure: Commercial-stage company treating high-grade glioma (and other solid tumors) with Tumor Treating Fields (TTFields). Directly comparable as a dedicated high-grade glioma therapy provider with FDA-approved and investigational assets in recurrent GBM.

Emerging players

• 4D Molecular Therapeutics: Clinical-stage AAV gene therapy company developing targeted vectors for ophthalmology, cardiology, and pulmonary diseases using evolved AAV capsids. Comparable as a next-generation AAV platform innovator.
• Werewolf Therapeutics: Developer of conditionally activated cytokine immunotherapies (PREDATOR platform) designed to deliver cytokine payloads selectively to the tumor microenvironment. Overlaps with Siren's cytokine-based immune-gene therapy approach for solid tumors.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat4 records

Key risks6 records

Key highlights7 records

Customer concentration

• Xx.com/sirenbio
• YouTubeyoutube.com/@SirenBiotechnology
• Facebookfacebook.com/SirenBiotechnology
• LinkedInlinkedin.com/company/siren-biotechnology-inc
• Instagraminstagram.com/sirenbio

Revenue estimate

Valuation estimate

Number of profiles

Profiles10 records

Funding overview

Funding rounds5 records

Investors10 records

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 Siren Biotechnology