What 858 Therapeutics does

858 Therapeutics is a clinical-stage biotechnology company developing first-in-class and best-in-class small molecule therapeutics that exploit tumor dependencies in DNA damage response (DDR) pathways. The company is targeting oncology indications with high unmet medical need, principally BRCA-mutated advanced solid tumors including platinum-resistant, high-grade serous ovarian cancer and HR+/HER2- breast cancer. Its portfolio is organized around three interconnected biological focus areas: DDR (anchored by lead candidate ETX-19477), RNA epigenetics (built on the 2021 Gotham Therapeutics acquisition, including a METTL3 inhibitor program), and innate immunity (extending insights from predecessor Jecure Therapeutics' NLRP3 inflammasome work).

The company's lead program, ETX-19477, is an oral, potent, and selective small-molecule inhibitor of poly(ADP-ribose) glycohydrolase (PARG), a DDR enzyme that removes PAR chains from proteins. PARG inhibition produces hyperPARylation and selective cancer cell death under replication stress in tumors with replication fork protection defects (including BRCA-mutated tumors) via a mechanism distinct from PARP inhibition, with potential to address PARP-inhibitor resistance. ETX-19477 is currently being evaluated in an open-label, multicenter Phase 1/2 study (ERADIC8; NCT06395519), with 45 patients enrolled in Phase 1a/b escalation/expansion and 53 patients in the expanded dataset for ASCO 2026; preliminary data showed a 57% objective response rate in the Phase 2-eligible subset. The internal discovery platform combines proprietary in vitro biochemical, biophysical, and cellular assays; early-stage discovery capabilities have been augmented through a 2024 collaboration with OpenBench, whose structure-based machine learning platform identifies chemical matter against 858-nominated targets.

858 Therapeutics is pre-revenue with no approved products or product sales; it funds operations through venture capital and partnership transactions. The company has raised an aggregate of approximately $110 million in disclosed venture funding across a $60 million Series A (September 2021, led by Versant Ventures) and a $50 million Series B (September 2024, led by Avidity Partners). Near-term revenue is not anticipated; any future revenue would derive from out-licensing deals, co-development partnerships (such as the OpenBench collaboration, under which OpenBench is eligible for success-based milestone payments), or eventual commercialization of approved drug candidates. The company is operationally headquartered in San Diego, CA (3115 Merryfield Row, Suite 110) with 11–50 employees and a stated plan to reach approximately 40 staff, and operates a multi-center U.S. clinical trial footprint for ETX-19477 development.

Name

858 Therapeutics

Legal name

858 Therapeutics

Website

https://8five8tx.com

Company type

Private

Founded year

2021

Operating status

Operating

Headcount range

11–50 employees

Short description

858 Therapeutics is a clinical-stage biotechnology company developing first-in-class small molecule DDR inhibitors for oncology, with lead asset ETX-19477 (an oral selective PARG inhibitor) in Phase 1/2 trials for BRCA-mutated ovarian and breast cancers.

Ownership category

akta.pro rank

Product category

Precision Oncology Pharmaceuticals

NAICS

Research and Development in Biotechnology (except Nanobiotechnology) (541714)

SIC

Pharmaceutical Preparations (2834)

akta.pro primary industry

Pharmacogenomics (PGx) Decision Support (HLAAANAB)

akta.pro secondary industry

Genome Editing Gene Therapies (CRISPR/TALEN/ZFN; in vivo/ex vivo) (HLAAACAD)

Keywords

• Precision oncology therapeutics
• Small molecule drugs
• PARG inhibitor development
• DNA damage response
• RNA modifying proteins

Headquarters

HQ city

San Diego

HQ country

United States

HQ region

North America

Offices2 records

Markets served

GTM type

B2B

Offering type

Hardware or Manufacturing

Cost components

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

Revenue model

1. None (pre-revenue): 858 Therapeutics is a clinical-stage biotechnology company with no approved products and no current product revenue. The company is funded by venture capital and uses proceeds to advance its pipeline of small molecule therapeutics through preclinical and clinical development; near-term revenue is not anticipated. Future revenue, if any, would be generated from out-licensing deals, partnerships, or commercialization of its oncology drug candidates.

Pricing tiers

Go-to-market motion2 records

Distribution channels2 records

Core offering

858 Therapeutics is a clinical-stage biotechnology company developing first-in-class and best-in-class small molecule drugs targeting oncology and immunology. Its lead program, ETX-19477, is an oral, potent, and selective PARG inhibitor that exploits DNA damage response vulnerabilities in advanced solid tumors, including BRCA-mutated ovarian and breast cancers. The company also maintains a proprietary discovery platform spanning RNA-modifying protein biology and DNA damage response (DDR) drug discovery.

Product overview

858 Therapeutics operates as a clinical-stage biotechnology company with a single integrated pipeline-and-platform model rather than a multi-product SaaS architecture. Its portfolio is organized around three interconnected focus areas in cancer biology: DNA damage repair (anchored by its lead candidate ETX-19477, an oral, potent, and selective PARG inhibitor in Phase 1/2 for advanced solid tumors), innate immunity (extending insights from predecessor company Jecure Therapeutics' NLRP3 inflammasome work), and RNA epigenetics (built on the Gotham Therapeutics acquisition and including the METTL3 inhibitor program). These pipeline programs are supported by an internal small-molecule discovery platform of proprietary in vitro biochemical, biophysical, and cellular assays, with external discovery capabilities augmented through a 2024 AI-enabled drug discovery collaboration with OpenBench. The company's product offering therefore consists of the lead clinical asset ETX-19477, the METTL3 inhibitor program, and the broader DNA Damage Response, RNA Epigenetics, and Innate Immunity pipeline programs it is advancing toward the clinic.

Differentiator

Problem solved

Functional benefit

Products and services

• ETX-19477 ETX-19477 is an oral, potent, and selective small-molecule inhibitor of poly(ADP-ribose) glycohydrolase (PARG), a key DNA damage response enzyme. It exploits cancer cell vulnerabilities related to replication stress and defects in replication fork protection pathways, with potential to address PARP-inhibitor resistance in solid tumors. ETX-19477 is being evaluated in an open-label, multicenter Phase 1/2 study (ERADIC8; NCT06395519) in patients with advanced solid tumors, including BRCA-mutated platinum-resistant ovarian cancer and HR+/HER2- breast cancer.
• METTL3 Inhibitor Program Program targeting METTL3, an RNA methyltransferase implicated in several cancers. Acquired through the September 2021 acquisition of Gotham Therapeutics and supports 858's RNA epigenetics portfolio alongside its PARG inhibitor and innate immunity programs.
• RNA Epigenetics & Innate Immunity Pipeline Portfolio of small molecule therapeutics directed against novel oncology and immunology targets beyond the lead PARG program, including proteins that regulate RNA modification (epitranscriptomics) and the innate immune response. Built on a proprietary discovery platform of in vitro biochemical, biophysical, and cellular assays to assess the impact of RNA-modifying proteins on disease biology.
• DNA Damage Response (DDR) Pipeline Pipeline of first-in-class and best-in-class small molecule therapies designed to target tumor dependencies in DNA damage response (DDR) pathways. Lead program ETX-19477 exploits replication stress and replication fork protection defects to deliver precision oncology treatments for advanced solid tumors, including BRCA-mutated platinum-resistant ovarian cancer.

Quantifiable outcome

• 57% objective response rate (n=7) in Phase 2-eligible subset of BRCA-mutated platinum-resistant ovarian cancer and HR+/HER2- breast cancer patients treated with ETX-19477
• +2 more outcomes

Named customers1 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 strategic / co-development and foundational / acquired entity.

• OpenBenchstrategic / co-developmentStrategic or Co-development Partner · 4 November 2024Collaboration to discover small molecule inhibitors using OpenBench's structure-based machine learning platform, initially focused on an undisclosed target nominated by 858 Therapeutics. OpenBench identifies novel chemical series; 858 performs biochemical, biophysical, and cellular validation. OpenBench is eligible for success-based milestone payments for chemotypes meeting defined molecular properties; 858 retains full and exclusive rights to purchased chemotypes and is solely responsible for further R&D.
• Gotham Therapeuticsfoundational / acquired entityStrategic or Co-development Partner · 20 September 2021Acquired by 858 Therapeutics (terms undisclosed) at launch to support development of drugs targeting RNA-modifying proteins and METTL3 in cancer. Gotham is a New York City-based pioneer in epitranscriptomics and RNA modification enzymes, translating discoveries from the lab of Samie Jaffrey, M.D., Ph.D.

Scale indicators10 records

Recent moves6 records

Expansion highlights5 records

Direct peers

• Tango Therapeutics: Clinical-stage oncology biotech leveraging synthetic lethality and DNA damage response biology to develop precision small molecule therapeutics. Direct peer in mechanism-of-action and target patient population (BRCA/DDR-altered solid tumors).
• Artios Pharma: Clinical-stage oncology company developing small molecule inhibitors of DNA damage response (DDR) targets, including Polθ inhibitors and other DDR mechanisms. Closely comparable mechanism, stage, and indication overlap to 858's PARG program.
• Black Diamond Therapeutics: Clinical-stage precision oncology company developing small molecule therapies against novel targets in cancer, including DDR and kinase targets. Comparable as a clinical-stage, small-molecule, biomarker-defined oncology biotech.
• Prelude Therapeutics: Clinical-stage precision oncology company developing selective small molecule inhibitors including next-generation selective PARP inhibitors. Highly comparable in therapeutic area (PARP/DDR biology) and clinical-stage profile; 858's CMO Joseph Leveque previously served at Prelude-affiliated roles per management history.
• Repare Therapeutics: Clinical-stage precision oncology company developing synthetic-lethal small molecules targeting DNA damage response vulnerabilities, with a similar biomarker-driven patient selection strategy in BRCA-mutated and DDR-deficient tumors. Direct competitor in the DDR precision oncology niche.

Emerging players

• Constellation Pharmaceuticals: Clinical-stage epigenetics oncology company acquired by MorphoSys; developed small molecules targeting chromatin/DNA-damage-related biology. Comparable in pipeline focus and stage (now part of a larger company).
• Sierra Oncology: Clinical-stage oncology biotech focused on DDR/small molecule therapeutics that was acquired by GSK. Comparable in mechanism focus (DDR-targeted small molecules) and outcome (acquired by large pharma at clinical stage).

Others

• Jecure Therapeutics: Predecessor biotech acquired by Genentech in 2018, founded by the same team (Stafford, Veal, Bain) that founded 858 Therapeutics. Highly relevant as a founding-team comparable and as a model for 858's likely exit trajectory.

Broad incumbents

• Clovis Oncology: Developer of Rubraca (rucaparib), a PARP inhibitor approved for BRCA-mutated ovarian and prostate cancers. Direct same-mechanism comparator highlighting both the commercial benchmark for PARP/DDR drugs and the competitive threat to 858's PARG franchise.
• Mirati Therapeutics: Clinical-stage precision oncology company (acquired by BMS) whose KRAS inhibitor development was led by 858's current CMO Joseph Leveque. Comparable as a precision-oncology small molecule company at similar clinical stage that achieved a large-pharma exit.

Market position

Strengths4 records

Weaknesses4 records

Competitive moat3 records

Key risks7 records

Key highlights7 records

Customer concentration

• LinkedInlinkedin.com/company/858-therapeutics

Compliance1 record

Revenue estimate

Valuation estimate

Number of profiles

Profiles9 records

Subsidiaries1 record

Funding overview

Funding rounds3 records

Investors8 records

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M&A1 record

Investments

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

Frequently asked questions about 858 Therapeutics