Accutar Biotechnology Presents Phase 1 Data of AC699 Monotherapy in Patients with ER+ / HER2- Breast Cancer at ASCO 2024

• Differentiated Mechanism of Action of a Chimeric Degrader as Compared to Fulvestrant and Novel SERDs
• Treatment with AC699 Monotherapy Resulted in 21% ORR for All Evaluable Patients, and 50% for Those Who Had an ESR1 Mutation
• Favorable Safety and Tolerability Profile at All Doses with No DLTs or ≥ Grade 3 Adverse Events Related to AC699

CRANBURY, N.J.--(BUSINESS WIRE)-- Accutar Biotechnology, Inc., a biotechnology company focusing on artificial intelligence (AI)-enabled drug discovery, announced data from an ongoing Phase 1 study of AC699 monotherapy in patients with ER-positive / HER2-negative locally advanced or metastatic breast cancer. The data will be presented in a poster discussion session at the American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, IL on June 1, 2024.

AC699 is a potent and selective orally bioavailable, chimeric degrader of estrogen receptor (ER) α, and offers a potential new breast cancer treatment option based on a differentiated mechanism of action as compared to fulvestrant and novel SERDs with deeper ERα degradation as demonstrated in preclinical studies. AC699 is currently being evaluated in an ongoing Phase 1 clinical study as a single agent for the treatment of ER-positive / HER2-negative locally advanced or metastatic breast cancer (NCT05654532). The primary objectives are to evaluate the safety and tolerability of AC699. Secondary and exploratory objectives include pharmacokinetics, preliminary efficacy and pharmacodynamic evaluation. The study uses a 3+3 dose-escalation design, with once-daily oral dosing of AC699 at 100, 200, 300, 400, and 600 mg.

Phase 1 Study Results:

• As of April 8, 2024, 29 participants were enrolled and treated with AC699 at doses ranging from 100-400 mg. The participants had a median of 5 (range 2-10) prior lines of therapy, including 3 (range 1-8) prior lines in the metastatic setting
• The objective response rate was 21% (4/19) and increased to 50% (4/8) for those who had an ESR1 mutation
• There were no > Grade 3 drug-related adverse events (AEs), no dose limiting toxicities, no discontinuations and no dose reductions due to AEs
• AEs related to AC699 occurred in 38% of participants and included nausea (14%), hot flush (14%), and fatigue (10%)
• The maximum tolerated dose had not been reached yet

Details of the poster presentation at ASCO 2024 are as follows:

• Date/Time: June 1, 2024, 9:00 AM – 12:00 PM CDT
• Abstract Number: 3074
• Title: Preliminary results from a phase 1 study of AC699, an orally bioavailable chimeric estrogen receptor degrader, in patients with advanced or metastatic breast cancer.
• Session: Developmental Therapeutics—Molecularly Targeted Agents and Tumor Biology
• Abstracts and full session details can be accessed through the ASCO meeting planner: Link

“We are extremely pleased with the groundbreaking safety and efficacy that AC699 has demonstrated thus far in Phase 1, with early evidence of its best-in-class potential, especially for patients with ESR1 mutations,” said Jie Fan, Ph.D., Chief Executive Officer of Accutar Biotechnology, Inc. “We look forward to completing the dose escalation portion of the study and starting the Phase 2 study soon. We believe that the oral dosing of AC699 and its differentiated mechanism of action, as compared to fulvestrant and novel SERDs, can potentially provide a new safe and effective treatment option for this patient population.”

About AC699 and the Phase 1 Study (AC699-001)

AC699 is an investigational orally bioavailable, chimeric degrader of estrogen receptor (ER) α. In preclinical studies, AC699 has demonstrated potent and selective protein degradation of ERα wildtype and mutants with favorable pharmacological properties, as well as promising anti-tumor activities in ER-positive animal tumor models.

The purpose of the Phase 1 multi-center, open-label study is to assess the safety, tolerability, pharmacokinetics, and preliminary anti-tumor activity of AC699 treatment in patients with ER-positive / HER2-negative locally advanced or metastatic breast cancer (NCT05654532). Additional information on this clinical trial can be found on www.clinicaltrials.gov.

About Accutar Biotechnology, Inc.

Accutar is a clinical stage biotech company focused on AI-enabled drug discovery, and its application to the discovery and development of clinically differentiated medicines.

Be transformative. For patients.

To learn more about Accutar, please visit us at www.accutarbio.com.

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