Novocure and Zai Lab announced that the EF-31 phase 2 pilot study, testing the safety and efficacy of Tumor Treating Fields (TTFields) together with standard-of-care (chemotherapy alone or in combination with trastuzumab for HER2-positive patients) as a first-line treatment in patients with gastric adenocarcinoma, met its primary endpoint of objective response rate with supportive signals across secondary endpoints. TTFields therapy was well tolerated, with no increase in the systemic toxicity of the XELOX chemotherapy regimen or the combination regimen, and no high-grade skin toxicities were reported. Initial analysis was conducted with a median follow-up period of 8.6 months.

The primary endpoint, confirmed objective response rate, was 50%. Median progression-free survival was 7.8 months. Duration of response was 10.3 months.

Median overall survival has not yet been reached with a one-year survival rate of 72%. The EF-31 clinical study, which is a prospective, single arm, phase 2 pilot study conducted in China, included 26 patients with unresectable, locally advanced or metastatic gastroesophageal junction or gastric adenocarcinoma who were previously untreated with systemic therapy. Patients received continuous treatment with TTFields together with the XELOX chemotherapy regimen (combination of oxaliplatin and capecitabine).

Trastuzumab was allowed for HER2-positive patients. Gastric cancer is the third leading cause of cancer deaths worldwide and the third leading cause of cancer deaths in China. The incidence of gastric cancer is approximately 478,500 new cases annually in China, and approximately 26,000 new cases annually in the U.S. Current therapies include surgery, chemotherapy, radiotherapy, targeted therapy and recently, immunotherapy.

One of the most commonly used chemotherapy regimens for treating gastric cancer is XELOX, a combination of oxaliplatin and capecitabine. In the recent phase 3 trial (CheckMate 649, NCT-02872116, Lancet 2021) studying gastric cancer, the standard-of-care chemotherapy regimens showed an objective response rate range of 41% - 45%, median progression-free survival of 6.9 months, duration of response of 6.9 months, and overall survival of 11.6 months. One-year survival was 48%.

Gastric cancer is the third most-frequent cancer in China. Currently, the five-year survival rate of locally advanced or metastatic gastric cancer ranges from 5% to 20%, and the median overall survival is approximately one year. Tumor Treating Fields NovoTTF-100L(P) is an investigational device for the treatment of gastric cancer.

Safety and efficacy have not been established. Tumor Treating Fields, or TTFields, are electric fields that disrupt cancer cell division. Fundamental scientific research extends across more than two decades and, in all preclinical research to date, TTFields have demonstrated a consistent anti-mitotic effect.

TTFields therapy is intended principally for use together with other standard-of-care cancer treatments. There is a growing body of evidence that supports TTFields' broad applicability with certain other cancer therapies, including radiation therapy, certain chemotherapies and certain immunotherapies. In clinical research and commercial experience to date, TTFields therapy has exhibited no systemic toxicity, with mild to moderate skin irritation being the most common side effect.

The TTFields global development program includes a network of preclinical collaborators and a broad range of clinical trials across all phases, including four phase 3 pivotal trials in a variety of tumor types. To date, more than 24,000 patients have been treated with TTFields therapy.