A groundbreaking new study has found that a drug known as trastuzumab provokes a strong immune system response that results in an attack on some forms of breast cancer.

Scientists at Case Western University found that just one doze of trastuzumab resulted in an immune response in one subtype of HER2-positive breast cancer tumors, which doesn’t happen in the first dose of chemotherapy, according to a UPI report. It’s a major finding that could pave the way to more effective treatments of certain types of breast cancer.

Trastuzumab, also known as Herceptin, was developed specifically to battle HER2-positive breast cancer, along with other forms of cancers. Half of women with this type of cancer responded to the drug before surgery, with 60 percent expected to have a complete response when trastuzumab is combined with other treatments, according to the report.

It’s the first time that trastuzumab has been shown to specifically promote an immune response in certain types of breast cancer. This will help with future trials to determine what immunotherapy drugs should be added to trastuzumab.

“Our study showed, for the first time, that the immune-cell-activating properties of trastuzumab are likely related to the subtypes of breast cancer,” Vinay Varadan, PhD, assistant professor at Case Western Reserve University School of Medicine and member of the Case Comprehensive Cancer Center, said in a statement. “Knowing this can inform future trials studying the usefulness of adding immunotherapy drugs to trastuzumab.”

Varadan added: “Also, the predictive ability of the Immune Index test was not observed in patient tumors before any therapy was given, suggesting that just a single dose exposure may be a beneficial way to identify which patients are most likely to benefit from trastuzumab-based chemotherapy and, thus, do not need additional anti-HER2 treatment.”