Xencor, Inc. (NASDAQ:XNCR), a clinical-stage biopharmaceutical company developing engineered antibodies for the treatment of cancer and autoimmune diseases, will host a conference call and webcast on Friday, October 24 at 1:30 p.m. ET (10:30 a.m. PT) to discuss initial results from the ongoing Phase 1 dose-escalation study of XmAb819, an ENPP3 x CD3 T-cell engaging bispecific antibody, in development for patients with advanced clear cell renal cell carcinoma.

The live webcast of the conference call may be accessed through this link and through "Events & Presentations" in the Investors section of the Company's website, located at investors.xencor.com. A recording will be available for at least 30 days.

The results will be presented at the AACR-NCI-EORTC Conference on Molecular Targets and Cancer Therapeutics in Boston, Massachusetts, during Poster Session B on Friday, October 24 from 12:30 to 4:00 p.m. ET in a poster titled "Preliminary Phase 1 safety and antitumor activity of XmAb819, a first-in-class ENPP3 x CD3 bispecific antibody, in patients with advanced clear cell renal cell carcinoma (ccRCC)."

About XmAb819

XmAb819 is a first-in-class, tumor-targeted, T-cell engaging XmAb 2+1 bispecific antibody in development for patients with clear cell renal cell carcinoma (ccRCC). XmAb819 engages the immune system and activates T cells for highly potent and targeted lysis of tumor cells expressing ENPP3, an antigen highly expressed on kidney cancers. ENPP3 is a differentially expressed target, with high level expression in renal cell carcinoma (RCC) and low-level expression on normal tissues. With two tumor-antigen binding domains and one T-cell binding domain, Xencor's XmAb® 2+1 format enables antibodies to bind more avidly and selectively kill tumor cells with higher antigen density, potentially sparing normal cells. Xencor is conducting a Phase 1 study to evaluate XmAb819 in patients with advanced ccRCC.

About Xencor

Xencor is a clinical-stage biopharmaceutical company developing engineered antibodies for the treatment of patients with cancer and autoimmune diseases. More than 20 candidates engineered with Xencor's XmAb® technology are in clinical development, and multiple XmAb medicines are marketed by partners. Xencor's XmAb engineering technology enables small changes to a protein's structure that result in new mechanisms of therapeutic action. For more information, please visit www.xencor.com.

Forward-Looking Statements

Certain statements contained in this press release may constitute forward-looking statements within the meaning of applicable securities laws. Forward-looking statements include statements that are not purely statements of historical fact, and can generally be identified by the use of words such as "potential," "can," "will," "plan," "may," "could," "would," "expect," "anticipate," "seek," "look forward," "believe," "committed," "investigational," "indicates," "supports," and similar terms, or by express or implied discussions relating to Xencor's business, including, but not limited to, statements regarding expectations for clinical progress, planned presentations of clinical data, planned and in process clinical trials, and other statements that are not purely statements of historical fact. Such statements are made on the basis of the current beliefs, expectations, and assumptions of the management of Xencor and are subject to significant known and unknown risks, uncertainties and other factors that may cause actual results, performance or achievements and the timing of events to be materially different from those implied by such statements, and therefore these statements should not be read as guarantees of future performance or results. Such risks include, without limitation, the risks associated with the process of discovering, developing, manufacturing and commercializing drugs that are safe and effective for use as human therapeutics and other risks, including the ability of publicly disclosed preliminary clinical trial data to support continued clinical development and regulatory approval for specific treatments and the risks, uncertainties and other factors described under the heading "Risk Factors" in Xencor's annual report on Form 10-K for the year ended December 31, 2024 as well as Xencor's subsequent filings with the Securities and Exchange Commission. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. This caution is made under the safe harbor provisions of the Private Securities Litigation Reform Act of 1995, as amended to date. All forward-looking statements are qualified in their entirety by this cautionary statement and Xencor undertakes no obligation to revise or update these forward-looking statements to reflect events or circumstances after the date hereof, except as required by law.

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Charles Liles

cliles@xencor.com

(626) 737-8118

Xencor to Host Webcast and Conference Call to Discuss Initial Results from the Ongoing Phase 1 Dose-Escalation Study of XmAb819 in Advanced Clear Cell Renal Cell Carcinoma