In a small preliminary trial, US researchers reported Sunday that nearly a third of advanced liver cancer patients who received a special vaccine developed by Genos Therapeutics saw their tumors shrink when combined with immunotherapy drugs.
According to the researchers, the result was twice what would be observed with immunotherapy alone.
Vaccines based on mutations found only in patients’ tumors can improve the immune system’s ability to detect and fight hard-to-treat cancers, according to preliminary research published in Nature Medicine and presented at the American Cancer Society in San Diego.
After several previous failures, the industry is one step closer to developing a successful cancer vaccine, with results being tested in larger trials. In addition, the types of cancer that can be treated with this drug can be extended.
Moderna’s partners with Merck & Co., among others, have shown promising results in combining immunotherapy and personalized vaccines to prevent skin cancer from coming back in patients after surgery.
To create a vaccine based on neoantigens—new mutations specific to each patient’s tumor—researchers collect samples from the patient’s tumor. The goal is to train the immune system to specifically target and destroy these specific proteins, sparing healthy tissue.
Liver cancer is considered a cold cancer because it has fewer mutations than skin cancer, so immunotherapy is more effective. Skin cancer is caused by many mutations in the body.
“These vaccines teach the immune system to recognize antigens that it ignores,” said Dr. Mark Charchoan, a researcher at the Johns Hopkins Kimmel Cancer Center.
A total of 36 people with hepatocellular carcinoma, the most common type of liver cancer, were enrolled in the study.
Patients received individual injections in addition to Merck’s popular immunotherapy drug Keytruda, which was the standard of care at the time.
After a median follow-up of 21.5 months, about a third of patients treated with combination therapy (30.1%) showed tumor reduction, and three had a complete response, meaning there was no visible evidence of residual tumor.
When liver cancer patients receive immunotherapy alone, the typical response rate is 12 to 18 percent.
“This shows that the vaccine is showing clinical efficacy,” he said.
The most common adverse reaction is a moderate reaction at the injection site. There were no significant adverse effects.
Unlike many vaccine offerings that rely on messenger RNA (mRNA) technology, gene therapy is a DNA vaccine that involves injecting the genetic code of a modified protein into cells using tiny electrical pulses. Up to 40 mutant genes can be targeted with a single injection.
