Ambrx Biopharma Inc. Announces Acceptance of Two Poster Presentations at the 2021 San Antonio Breast Cancer Symposium

– Ambrx’s abstract of the ongoing ACE-Breast-01 clinical trial for ARX788 was selected for a Spotlight Poster Discussion –

SAN DIEGO–(BUSINESS WIRE)–​Ambrx Biopharma Inc., or Ambrx (NYSE: AMAM), a clinical stage biopharmaceutical company using an expanded genetic code technology platform to discover and develop Engineered Precision Biologics (EPBs), today announced the publication of two abstract poster presentations to be conducted at the 2021 San Antonio Breast Cancer Symposium (SABCS), which is being held from December 7-10, 2021. The abstract poster presentations will highlight clinical data from Ambrx’s ongoing ACE-Breast-03 and ACE-Breast-01 clinical trials of ARX788. The company’s ACE-Breast-01 abstract was selected as a Spotlight Poster Discussion.

All posters will be available virtually on the SABCS website at www.SABCS.org as well as in the symposium poster hall beginning Wednesday, December 8, 2021 at 9:00 AM ET. Details on the abstracts and corresponding poster presentations are shown below.

Poster Number: OT1-02-02

Title: “A global, phase 2 study of ARX788 in patients with HER2-positive metastatic breast cancer whose disease is resistant or refractory to T-DM1, and/or T-DXd, and/or tucatinib-containing regimens”

Presentation Time: December 8, 2021 at 5:00 PM CST

Session Name: Ongoing Trials Poster Session 1

Presenters: Sara Hurvitz, MD; Janice Lu, MD; Joy Yan, MD, PhD

Spotlight Poster Discussion Number: PD8-04

Poster Title: “Safety and anti-tumor activity of ARX788 in HER2-positive metastatic breast cancer patients whose disease is resistant/refractory to HER2 targeted agents (trastuzumab, ADCs, TKIs, and bispecific antibodies): ACE-Breast-01 trial results”

Presentation Time: December 9, 2021 at 7:00 AM CST

Session Name: Spotlight Poster Discussion 8

Presenters: Xichun Hu, MD; Jiang Zhang, MD

About Ambrx Biopharma Inc. (Ambrx)

Ambrx is a clinical stage biopharmaceutical company using an expanded genetic code technology platform to discover and develop Engineered Precision Biologics. These include next generation antibody drug conjugates (ADCs), bispecifics, targeted immuno-oncology therapies, novel cytokines to modulate the immune system, and long-acting therapeutic peptides for metabolic and cardiovascular disease. Ambrx is advancing a robust portfolio of clinical and preclinical programs designed to optimize efficacy, safety and ease of use, in multiple therapeutic areas, including its lead product candidate ARX788. In addition, Ambrx has clinical collaborations with multiple partners, for drug candidates generated using Ambrx technology. For more information, please visit www.ambrx.com.

Contacts

INVESTORS

Laurence Watts

Managing Director

Gilmartin Group, LLC.

619-916-7620

[email protected]

MEDIA

Ian Stone

Managing Director

Canale Communications

(619) 849-5388

[email protected]