A new triple therapy for advanced breast cancer can slow disease progression, delay the need for further chemotherapy, and help patients live longer, research shows. The combination includes two targeted drugs, inavolisib and palbociclib, along with the hormone therapy fulvestrant. Patients on this regimen saw an average survival gain of seven months compared to those on palbociclib and fulvestrant alone.
Delayed Progression and Chemotherapy
The study reported that the triple therapy group experienced 17.2 months of disease control, while the control group averaged 7.3 months. Patients receiving inavolisib were able to postpone additional chemotherapy by nearly two years, significantly longer than the control group.
International Trial and Funding
Funded by Roche, the trial’s findings were presented at the American Society of Clinical Oncology (ASCO) annual meeting in Chicago and published in the New England Journal of Medicine. The international trial enrolled 325 patients from 28 countries, including the United States, United Kingdom, Australia, Singapore, Brazil, France, and Germany.
Targeting HR+, HER2-, PIK3CA-Mutated Breast Cancer
Experts note that triple therapy could be a breakthrough for hormone receptor–positive (HR+), HER2-negative breast cancer with PIK3CA mutations. About 70% of breast cancer patients have HR+, HER2- disease, and 35–40% of those harbor PIK3CA mutations, which fuel tumor growth, drive progression, and lead to treatment resistance.
Dr. Jane Lowe Meisel, co-director of breast medical oncology at Emory University’s Winship Cancer Institute and an ASCO breast cancer specialist, said:
“The INAVO120 trial identified a targeted option that can significantly improve survival in untreated patients with PIK3CA-mutated metastatic breast cancer. This is a major step forward for these patients.”
Higher Response Rates and Expert Praise
Results showed that 62.7% of patients on triple therapy had significant reductions in cancer cell growth, compared with 28% in the control group. Dr. Simon Vincent, director of research at Breast Cancer Now, called the findings a “major breakthrough.”
Dr. Nisharnthi Duggan of Cancer Research UK added:
“These results are excellent news for people with hard-to-treat breast cancer. Adding inavolisib to targeted therapy improved survival, slowed progression, and reduced the need for chemotherapy. This can greatly improve quality of life.”
Trial Details and Patient Selection
Over half of the trial participants had cancer that had already spread to three or more organs. Researchers used a ctDNA liquid biopsy to check for PIK3CA mutations. Eligible patients were then randomized to receive either inavolisib plus palbociclib and fulvestrant or palbociclib, fulvestrant, and a placebo.
Inavolisib works by blocking the PIK3CA protein’s activity. The combination therapy was generally well tolerated, with only a few patients stopping treatment due to side effects.
UK Leadership and Future Implications
The UK arm of the trial was led by Prof. Nick Turner, of the Institute of Cancer Research, London, and consultant medical oncologist at The Royal Marsden NHS Foundation Trust. He emphasized:
“This therapy not only extended life but also more than doubled the time before cancer worsened. It gave patients extra time to avoid follow-up chemotherapy, something they deeply value.”
He added:
“These results give us confidence that triple therapy could become a new option for patients with HR+, HER2-, PIK3CA-mutated breast cancer. It shows clear improvements in survival and quality of life.”
