ETX-19477 / 858 Therap - LARVOL DELTA

858 Therapeutics Announces FDA Fast Track Designation for PARG Inhibitor ETX-19477 for the Treatment of Patients with BRCA-Mutated, HR+/HER2- Unresectable or Metastatic Breast Cancer (Businesswire) - "ETX-19477 is being evaluated in an ongoing Phase 1/2, open-label, multicenter study in patients with advanced solid tumors, designed to assess safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary anti-tumor activity. The trial is currently enrolling patients in Phase 2 monotherapy cohorts in BRCA-mutated ovarian cancer and BRCA-mutated HR+/HER2- breast cancer."

Fast track • Trial status • HER2 Negative Breast Cancer • Hormone Receptor Positive Breast Cancer

First-in-human phase 1/2 study of ETX-19477, an oral, potent, and selective PARG inhibitor, in patients with advanced solid tumors (ERADIC8). (ASCO 2026) - P1/2 | "ETX-19477 was well tolerated and showed anti-tumor activity in heavily pretreated pts with BRCAm, platinum-resistant HGSOC during dose escalation. These findings provide the first clinical proof-of-concept of PARG inhibition in HGSOC. ETX-19477 is being further evaluated in the dose expansion phase of the study."

Clinical • First-in-human • Metastases • P1/2 data • Breast Cancer • Gastric Cancer • Neutropenia • Oncology • Solid Tumor

858 Therapeutics Announces Initial Data from First-in-Human Phase 1/2 Trial of PARG Inhibitor ETX-19477 to be Presented at 2026 ASCO Annual Meeting (Businesswire) - "The ASCO abstract released today includes clinical data from 45 patients enrolled in the Phase 1a/b dose escalation and expansion portions of the study....ETX-19477 demonstrated robust efficacy, with a 57% objective response rate in BRCA-mutated platinum-resistant ovarian cancer and earlier-line HR+/HER2- breast cancer (n=7). Favorable safety profile, including low rates of hematologic toxicity, supports further monotherapy development and future combination strategies."

First-in-human • P1 data • Platinum resistant • HER2 Negative Breast Cancer • Hormone Receptor Positive Breast Cancer • Ovarian Cancer

Discovery of ETX-19477, a novel and selective PARG inhibitor with high potency against tumors with underlying replication stress (AACR 2024) - "Preclinical data show ETX-19477 demonstrates potent and specific anti-proliferative effects by exposing underlying existing replication stress vulnerabilities in cancer cells across multiple tumor types. ETX-19477 will be advanced into clinical trials in 2024."

Gastric Cancer • Gastrointestinal Cancer • HER2 Negative Breast Cancer • Oncology • Solid Tumor • BRCA • ER • HER-2

858 Therapeutics…announced that the U.S. Food and Drug Administration (FDA) has granted Fast Track designation to ETX-19477, the company’s internally discovered PARG inhibitor (Businesswire) - "The designation has been granted for the treatment of adult patients with BRCA-mutated, platinum-resistant, high-grade serous ovarian cancer (HGSOC)....This designation was based on preclinical data and emerging clinical data from our ongoing Phase 1/2 trial of ETX-19477, including anti-tumor activity at tolerable doses....The trial is currently enrolling patients in Phase 1 backfill cohorts at multiple dose levels and enriching for select solid tumors harboring BRCA mutations, including HGSOC."

Fast track • Platinum resistant • Trial status • High Grade Serous Ovarian Cancer • Ovarian Cancer

ERADIC8: A Study of PARG Inhibitor ETX-19477 in Patients With Advanced Solid Malignancies (clinicaltrials.gov) - P1/2 | N=120 | Recruiting | Sponsor: 858 Therapeutics, Inc. | Phase classification: P1 ➔ P1/2 | N=48 ➔ 120 | Trial primary completion date: Dec 2025 ➔ Dec 2026

Enrollment change • Phase classification • Trial primary completion date • Breast Cancer • Castration-Resistant Prostate Cancer • Colorectal Cancer • Endometrial Cancer • Epithelial Ovarian Cancer • Gastric Cancer • Genito-urinary Cancer • Hormone Receptor Breast Cancer • Oncology • Ovarian Cancer • Prostate Cancer • Solid Tumor • BRCA

858 Therapeutics Announces $50 Million Series B Financing (Businesswire) - "Investment will support ongoing clinical development of PARG inhibitor ETX-19477 and further advancement of pipeline...858 Therapeutics today announced it raised $50 million in a Series B financing led by Avidity Partners with participation from Insight Partners, Mirae Asset Capital, and Alexandria Venture Investments, as well as existing investors Versant Ventures, NEA, and Logos Capital. As part of the financing, Monal Mehta, Ph.D., Managing Director at Avidity Partners, will join the company’s Board of Directors...858 Therapeutics plans to use the proceeds to advance its pipeline of small molecule therapeutics."

Financing • Oncology • Solid Tumor

ERADIC8: A Study of PARG Inhibitor ETX-19477 in Patients With Advanced Solid Malignancies (clinicaltrials.gov) - P1 | N=48 | Recruiting | Sponsor: 858 Therapeutics, Inc.

Metastases • New P1 trial • Breast Cancer • Castration-Resistant Prostate Cancer • Colorectal Cancer • Endometrial Cancer • Gastric Cancer • Gastrointestinal Cancer • Genito-urinary Cancer • Hormone Receptor Breast Cancer • Oncology • Ovarian Cancer • Prostate Cancer • Solid Tumor • BRCA

858 Therapeutics to Present Preclinical Data on ETX-19477 at the AACR 2024 Annual Meeting (Businesswire) - "858 Therapeutics today announced an upcoming poster presentation at the American Association for Cancer Research (AACR) Annual Meeting 2024, taking place April 5-10 in San Diego, California. The presentation will describe the preclinical characterization of ETX-19477, including potent antitumor activity in multiple animal models."

Preclinical • Oncology • Solid Tumor