Xencor Announces Proffered Paper Oral Presentation at ESMO 2026 for Phase 1 Clinical Study of XmAb819 in Advanced Clear Cell Renal Cell Carcinoma

-- ESMO presentation to highlight expansion-cohort results for IV doses evaluated for recommended Phase 3 dose --

-- Pivotal study of XmAb819 monotherapy in advanced ccRCC, planned to begin in 2027 --

PASADENA, Calif.--(BUSINESS WIRE)--Xencor, Inc. (NASDAQ:XNCR), a clinical-stage biopharmaceutical company developing engineered antibodies for the treatment of cancer and autoimmune diseases, today announced that results from a Phase 1 study of XmAb819, an ENPP3 x CD3 T-cell engaging bispecific antibody, in advanced clear cell renal cell carcinoma (ccRCC) were accepted for a proffered paper oral presentation at the European Society of Medical Oncology (ESMO) Congress 2026, to be held October 23-27 in Madrid, Spain.

Details of the Proffered Paper Oral Presentation

• Title: Phase 1 results of XmAb819, a novel ENPP3 x CD3 bispecific, in advanced clear cell renal cell carcinoma (ccRCC)
• Presenter: Sumanta Pal, M.D., FASCO, Professor and Vice Chair of Academic Affairs, City of Hope Comprehensive Cancer Center

ESMO has indicated that the abstract will be available on its website at 3:05 p.m. PDT on Sunday, October 18.

XmAb819 Evaluation Across ENPP3+ Tumors

XmAb819 is being evaluated for the treatment of patients with ENPP3+ tumors in a Phase 1 clinical study (Clinicaltrials.gov Identifier: NCT05433142). Initial results from dose-escalation in advanced ccRCC were presented during the AACR-NCI-EORTC Conference in October 2025. Currently:

• Expansion cohorts are evaluating intravenous doses to support selection of a dose for the planned Phase 3 pivotal study for patients with advanced ccRCC,
• Dose escalation of subcutaneous administration in advanced ccRCC is ongoing,
• A sub-study for patients with ENPP3+ advanced colorectal cancer, non-small cell lung cancer and papillary renal cell carcinoma opened to enrollment in the second quarter of 2026, and
• A sub-study for patients with intermediate- or poor-risk advanced ccRCC who have progressed after nivolumab in combination with ipilimumab as a first-line treatment (IO doublet therapy) is planned to open to enrollment in the third quarter of 2026.

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) and other tumors with high ENPP3 expression, including colorectal cancer, non-small cell lung cancer and papillary renal cell carcinoma. XmAb819 engages the immune system and activates T cells for highly potent and targeted lysis of tumor cells expressing ENPP3. 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.

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 the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995. 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 the timing and content of a presentation on the results from a Phase 1 study of XmAb819 in advanced clear cell renal cell carcinoma, projected clinical study timelines, 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, the ability of publicly disclosed preliminary clinical trial data to support continued clinical development and regulatory approval for specific treatments, the risk of loss of key members of management, the risk that the fair value of our marketable equity securities will decline 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, 2025 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. 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.