Xencor Shares Jump 24% on Promising Kidney Cancer Drug Data

Shares of Xencor Inc. (NASDAQ:XNCR) surged 24% on Monday after the biotechnology company presented encouraging Phase 1 clinical trial data for its cancer drug candidate, XmAb819. The results, unveiled at the European Society for Medical Oncology Congress 2026, support the drug's potential as a treatment for patients with advanced clear cell renal cell carcinoma (ccRCC).

Positive Trial Data Drives Surge

Xencor announced it has selected a proposed recommended Phase 3 dose of 400 mcg/kg for XmAb819, a bispecific T-cell engager. The decision was based on strong efficacy signals from the Phase 1 dose-selection study in a heavily pre-treated patient population.

Key efficacy data for the selected dose included:

• A 45.5% confirmed objective response rate (ORR).
• An 82% estimated 6-month progression-free survival rate.
• Of the 25 patients with a confirmed response, one had a complete response and 24 had partial responses.

Next Steps and Regulatory Path

Ad

Buoyed by the results, Xencor plans to engage with the U.S. Food and Drug Administration (FDA) during the first half of 2027 to discuss a potential accelerated approval pathway for the treatment. An accelerated pathway could significantly shorten the time to market for the drug in certain patient subgroups.

The company also intends to initiate a global randomized study comparing XmAb819 as a monotherapy against tivozanib. Xencor anticipates starting a potential registration-enabling study by the end of 2027 and stated it has a sufficient cash runway into 2029 to fund its operations.

Study Details and Safety Profile

The Phase 1 study enrolled 119 patients with advanced ccRCC as of September 1, 2026. The trial participants were heavily pre-treated, with a median of three prior lines of therapy, indicating a difficult-to-treat population. The median time on treatment was reported as seven months.

According to the company, XmAb819 was generally well tolerated. The rate of treatment discontinuation due to related adverse events was 5.9%. However, Grade 3 or higher related treatment-emergent adverse events were observed in 72.1% of patients, primarily consisting of liver enzyme elevations and rash.