Xencor reports promising kidney cancer drug results, plans late-stage trial

Xencor (XNCR) reported encouraging results from an early-stage clinical trial of its experimental kidney cancer drug XmAb819, with tumors shrinking in nearly half of patients receiving the highest dose tested. The company also outlined plans to seek a potential accelerated approval pathway from the Food and Drug Administration and begin a larger clinical trial by the end of 2027.

The phase 1 study evaluated XmAb819 in patients with advanced clear cell renal cell carcinoma, the most common form of kidney cancer. Among 11 evaluable patients receiving the selected dose of 400 micrograms per kilogram of body weight, five experienced confirmed tumor shrinkage, representing a 45.5% response rate. An additional patient had an unconfirmed response, bringing the preliminary response rate to 55%. The findings were presented at the European Society for Medical Oncology's 2026 congress in Madrid.

At six months, an estimated 82% of patients receiving the highest dose were alive without their cancer worsening, a measurement known as progression-free survival. More than 70% remained on treatment as of October 1. Patients in the study had generally received several previous cancer treatments, including immunotherapies and drugs designed to block tumor blood vessel growth.

For investors, the results suggest XmAb819 could become a new treatment option for patients whose kidney cancer has stopped responding to existing therapies. The findings also support Xencor's plans to advance the drug toward potential regulatory approval. However, the highest-dose results involve only 11 evaluable patients, and the study lacks a randomized comparison group, making it too early to determine whether XmAb819 is superior to available treatments.

Xencor (XNCR) plans to discuss accelerated approval possibilities with the FDA during the first half of 2027, particularly for patients who have exhausted standard treatments. The company also intends to launch a global randomized trial comparing XmAb819 with tivozanib, an existing kidney cancer therapy, to support a potential application for full approval. Xencor (XNCR) said its cash reserves are expected to fund operations into 2029.