Arcellx Announces First Patient Treated with T Cell Therapy Utilizing the Company’s Novel Binding Domain

– Phase 1 trial is designed to validate novel binding domain; first step in evaluating Arcellx T cell therapy platform in the clinic – – Future trials will use Arcellx platform to direct T cell activity and target multiple tumor antigens – – Therapy granted Fast Track Designation for treatment of relapsed and refractory multiple myeloma –

Gaithersburg, Md. – Feb. 28, 2020 – Arcellx today announced that the first patient has been dosed with its engineered T cell therapy utilizing a novel deimmunized synthetic binding domain in the treatment of patients with relapsed and refractory multiple myeloma. This first-in-human Phase 1 trial is the first in a series of clinical trials planned for efficient, stepwise development of the Arcellx ARC-T + sparX cell therapy platform, with BCMA as an initial target.

“Validating this novel binding domain facilitates subsequent ARC-T + sparX trials in the investigation of titratable T cell activity and redirection to multiple tumor antigens,” said Angela Shen, M.D., M.B.A., Chief Medical Officer at Arcellx.

“We believe our novel binding domain serves as the foundation for a new class of therapeutics,” stated David Hilbert, Ph.D., President, Chief Executive Officer and Founder of Arcellx. “The ARC-T + sparX platform potentially offers multiple advantages over existing cell therapies that could enable much broader access for patients being treated in academic medical centers as well as community practices.”

The FDA has granted the Arcellx ddBCMA cell therapy Fast Track Designation forthe treatment of relapsed and refractory multiple myeloma. Fast Track is a process designed to facilitate the development and expedite the review of drugs intended to treat serious conditions and that demonstrate, through clinical or preclinical data, the potential to fill an unmet medical need.

About the Arcellx ddBCMA T Cell Therapy Phase 1 Trial
The open label Phase 1 trial is evaluating an engineered T cell therapy that uses the company’s novel synthetic binding domain in the treatment of patients with relapsed and refractory multiple myeloma. In the trial, a patient’s T cells are engineered to express a receptor targeting the B-cell maturation antigen (BCMA) on the tumor cell surface using the novel binding domain. The binding domain, which is a deimmunized synthetic protein, is a key component of the Arcellx ARC-T + sparX cell therapy platform. The Arcellx ddBCMA cell therapy has been granted Fast Track Designation by the U.S. Food and Drug Administration (FDA). Additional information about the trial can be found at https://www.clinicaltrials.gov/ct2/show/NCT04155749.

About ARC-T + sparX Technology
Arcellx has developed a novel proprietary platform in which ARC-T (Antigen Receptor Complex T cells) are controlled by the administration of a tumor-targeting protein called a sparX (Soluble Protein AntigenReceptor X-linker). A library of sparX proteins that recognizes different cell surface antigens are functional as monovalent, bivalent, or bispecific constructs, and could potentially be administered simultaneously or sequentially to address the inherent heterogeneity of diseases such as cancer. The ARC-T cells can be readily silenced, activated and reprogrammed by sparX, allowing dose control to minimize toxicities and multiple antigen targeting to improve efficacy and address relapse. The ARC-T + sparX therapeutic platform is designed to potentially provide enhanced efficacy, safety, patient accessibility and efficiency of manufacturing relative to existing cell therapies.

About Arcellx, Inc.
Arcellx is a clinical-stage biopharmaceutical company devoted to providing patients with superior immune cell therapies through scientific innovation and accelerated development of next-generation technology. Arcellx initially is developing the ARC-T cell therapies for cancer indications, and in the future, broader indications, including autoimmune disease. More information can be found at www.arcellx.com.

Contact:
Zara Lockshin (media), Solebury Trout
O: +1 646-378-2960
M: +1 330-417-6250
Email: zlockshin@nulltroutgroup.com

Alan Lada (investors), Solebury Trout
O: +1 646-378-2927
Email: alada@nulltroutgroup.com