Ganymed Pharmaceuticals’ experimental therapy IMAB362 significantly boosted advanced gastric cancer patients’ overall survival, according to company data presented on Sunday at the American Society of Clinical Oncology (ASCO) meeting in Chicago. That’s significant because, on average, just 30% of those afflicted with stomach cancer are still alive five years or more after being diagnosed, according to the National Cancer Institute.

IMAB362 is a targeted treatment that harnesses the body’s immune system to battle tumors. It goes after a specific biological signal in cancerous gastrointestinal cells called Claudin18.2.

Click here to subscribe to our new Brainstorm Health Daily Newsletter.

“We are very excited to see that patients in our study benefited very significantly from being treated with IMAB362 with more than twice the number of patients still living at the end of the study after receiving IMAB362 plus chemotherapy compared to chemotherapy alone,” said Ganymed CEO Özlem Türeci in a statement.

The medication’s effectiveness swells along with how much Claudin18.2 is present in patients’ cancer cells. In those with the highest levels of the protein, a regimen of IMAB362 combined with standard chemotherapy extended overall survival rates to 16.7 months. That’s nearly double the rate versus treatment with chemotherapy alone. The therapy also significantly boosted survival rates in patients with lower levels of the protein without producing unacceptable spikes in side effects.

What’s most promising about Ganymed’s therapy is that the unique protein it targets is also present in a large number of bile duct, ovarian, and lung cancers, meaning the drug could eventually pick up a large number of potential applications if its results hold in larger trials.

Ganymed’s majority shareholder is ATS Beteiligungsverwaltung GmbH, and the company was spun off from the Universities of Mainz and Zurich.

Fortune has been reporting on the biggest developments out of ASCO. You can read all of our coverage here.