PASADENA, Calif., July 17, 2026
Xencor, Inc. announced that Phase 1 clinical results for XmAb819, its investigational ENPP3 × CD3 T-cell engaging bispecific antibody, have been selected for a proffered paper oral presentation at the European Society for Medical Oncology (ESMO) Congress 2026, scheduled for October 23–27, 2026, in Madrid, Spain. The presentation will showcase expansion cohort data from patients with advanced clear cell renal cell carcinoma (ccRCC) receiving intravenous XmAb819 at doses being evaluated for selection of the recommended Phase 3 regimen. The abstract will be presented by Sumanta Pal, M.D., FASCO, Professor and Vice Chair of Academic Affairs at City of Hope Comprehensive Cancer Center. Xencor also confirmed plans to initiate a pivotal Phase 3 clinical trial evaluating XmAb819 monotherapy in patients with advanced ccRCC during 2027, marking an important milestone in the development of its first-in-class bispecific antibody platform for kidney cancer.
XmAb819 Targets ENPP3 to Enhance Precision Immunotherapy
XmAb819 is a first-in-class tumor-targeted bispecific antibody engineered using Xencor’s proprietary XmAb® 2+1 antibody technology, designed to simultaneously bind ENPP3 on tumor cells and CD3 on T cells. This dual-targeting mechanism activates the immune system by directing T cells to selectively destroy ENPP3-expressing cancer cells, while potentially minimizing damage to normal tissues with lower antigen expression. ENPP3 is highly expressed in clear cell renal cell carcinoma, making it an attractive therapeutic target for patients with advanced kidney cancer. The XmAb® 2+1 design incorporates two tumor-antigen binding domains and one T-cell binding domain, increasing binding strength to tumor cells with high antigen density while improving selectivity. This innovative approach is intended to enhance anti-tumor activity and expand the therapeutic potential of bispecific antibody immunotherapy for patients with difficult-to-treat solid tumors.
Clinical Development Expands Beyond Kidney Cancer
Xencor continues to broaden the clinical evaluation of XmAb819 across multiple ENPP3-positive cancers through its ongoing Phase 1 clinical trial (NCT05433142). In addition to expansion cohorts evaluating intravenous administration for advanced ccRCC, the study includes dose escalation of a subcutaneous formulation, which may provide greater treatment flexibility in future clinical practice. The company has also initiated enrollment for a dedicated substudy involving patients with advanced colorectal cancer, non-small cell lung cancer, and papillary renal cell carcinoma, all of which demonstrate ENPP3 expression. Furthermore, Xencor plans to open another substudy during the third quarter of 2026 for patients with intermediate- or poor-risk advanced ccRCC whose disease has progressed following first-line treatment with the nivolumab plus ipilimumab immunotherapy combination. These expansion efforts reflect the company’s strategy of evaluating XmAb819 across a broad range of ENPP3-positive malignancies with significant unmet medical needs.
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ESMO Presentation Supports Transition Toward Pivotal Phase 3 Development
The acceptance of XmAb819 for a proffered paper oral presentation at ESMO Congress 2026 highlights the growing clinical interest in Xencor’s bispecific antibody platform and its potential to improve outcomes for patients with advanced kidney cancer. The upcoming presentation will provide important clinical evidence supporting dose selection for the planned Phase 3 pivotal trial, while demonstrating continued progress in the development of next-generation T-cell engaging immunotherapies. With more than 20 XmAb-engineered candidates currently in clinical development and multiple partnered medicines already commercialized, Xencor continues to strengthen its position in precision immuno-oncology through innovative antibody engineering technologies. The advancement of XmAb819 represents another important step toward expanding treatment options for patients with clear cell renal cell carcinoma and other ENPP3-positive solid tumors.
Source: Xencor, press release
