A combo of two blockbuster breast cancer drugs was so successful in keeping an aggressive type of the disease from worsening, it is likely to change how young patients are treated, experts said after results of a large clinical trial were made public Saturday.

Gilead’s Trodelvy — an antibody-drug conjugate, the new line of more targeted chemotherapy — was combined with Merck’s immunotherapy Keytruda as an initial treatment for triple-negative breast cancer, which is unresponsive to standard hormone therapies and represents 10-20% of breast cancer diagnoses.

The combination decreased the risk of the disease progressing by 35%, researchers said.

The findings suggest the combination “will likely become a new front-line standard of care in this setting,” Dr. Jane Lowe Meisel, co-director of breast oncology at Emory University School of Medicine said.

Patients getting the combo went 11.2 months without their cancer progressing, compared to nearly 8 months for those treated with regular chemo and Keytruda.

They also responded to the treatment for a median of 16.5 months, compared with 9.2 who were not given the same drugs, according to full results of the study presented at the American Society of Clinical Oncology scientific meeting in Chicago.

In another trial presented at the meeting, a combination triple therapy for a different type of common aggressive breast cancer was found to delay cancer progression by 10 months and chemotherapy by two years longer than the standard treatment.

Patients who got Roche’s inavolisib, in addition to Pfizer’s palbociclib and the hormone therapy fulvestrant, lived seven months longer than those getting only the latter two.

The study, funded by Roche, looked at PIK3CA-mutated HR+ HER2- breast cancer, which represents 30-40% of cases, and is linked to tumor growth, disease progression and treatment resistance.

Meisel called it a big step forward for these patients.