Xencor Shares Jump 20% to 52-Week High as Kidney Cancer Drug XmAb819 Shows 45.5% Response Rate in Early Trial

Shares of Xencor Inc. jumped nearly 20% on Monday to their highest level in a year. The biotechnology company presented early clinical data showing its experimental kidney cancer drug shrank tumors in nearly half of the patients treated at the dose it plans to take into late-stage trials.

Xencor shares rose $4.94, or 19.62%, to $30.12 in morning trading on the Nasdaq, after touching a 52-week high of $32.29. More than 4.1 million shares had changed hands, about three times the stock's three-month daily average. The company's market value rose to about $2.25 billion.

The stock is up about 76% over the past 52 weeks.

Early results

The data cover XmAb819, a bispecific antibody that targets the protein ENPP3 on tumor cells and CD3 on immune T cells. The drug is designed to steer the body's immune cells to attack cancer.

Xencor first presented updated Phase 1 results on Sunday at the European Society for Medical Oncology Congress in Madrid. It discussed them further on an investor webcast before the market opened Monday. The study is testing XmAb819 in patients with advanced clear cell renal cell carcinoma, the most common form of kidney cancer.

At the 400 microgram-per-kilogram intravenous dose:

The confirmed objective response rate was 45.5% among 11 patients who could be evaluated. Objective response means measurable tumor shrinkage. An estimated 82% of patients were alive without their disease getting worse at six months.

The company said the results support designating that dose as the proposed recommended dose for Phase 3 trials.

The data are early and based on a small number of patients. Phase 1 trials are designed mainly to assess safety and find the right dose, and their results don't always hold up in larger studies.

Path to approval

Xencor plans to talk with the U.S. Food and Drug Administration in the first half of 2027 about a possible accelerated approval pathway in selected patient groups. It also plans a global randomized Phase 3 trial of XmAb819 as a single drug.

In its second-quarter results in August, the company said a registration-enabling study of XmAb819 in advanced kidney cancer was on track to begin in 2027. Xencor is also testing an injectable version given under the skin. It is planning studies combining XmAb819 with PD-1 immunotherapy, as well as studies in other ENPP3-positive tumors, including colorectal cancer, lung cancer and papillary kidney cancer.

"We are excited to present XmAb819 results at ESMO this fall," Chief Executive Bassil Dahiyat said in August, when the company announced its presentation had been accepted for an oral session at the conference.

Xencor has said its cash should fund operations into 2029, according to market reports.

Analysts' targets

Monday's surge pushed the stock above several analysts' price targets. Wedbush reiterated an outperform rating and a $30 price target days before the webcast. Truist Securities raised its target to $29 from $27 in late September and kept a buy rating.

A crowded field

Kidney cancer is a major market. Current standard treatments include immune checkpoint inhibitors and targeted drugs, often given in combination. Many patients eventually stop responding to them, which creates demand for new options in later lines of treatment.

Bispecific T-cell engagers have become an area of intense interest across the industry. Several drugs of this kind have won approval for blood cancers, but developing them for solid tumors has been harder.

Xencor, based in Monrovia, California, is best known for its antibody engineering technology, which is used in approved drugs from other companies. In recent years it has focused on building its own pipeline of cancer and autoimmune treatments.

Biotech sentiment

Xencor was one of several biotech stocks moving sharply on Monday as companies presented data at the ESMO Congress, which runs through Oct. 27.

Broader markets were mixed as investors awaited the Fed's interest rate decision on Wednesday and earnings from big technology companies later in the week.