A new drug combination has demonstrated a significant breakthrough in treating HR+/HER2- breast cancer driven by mutations in the PIK3CA gene. The trial, involving 325 patients across 28 countries, revealed that the combination of inavolisib, palbociclib, and fulvestrant nearly doubled the time before disease progression compared to a placebo-controlled group. This advancement offers new hope for patients with this challenging form of cancer.
Trial Details and Findings
The study included patients with advanced breast cancer, many of whom had already undergone chemotherapy. Participants were divided into two groups: one receiving inavolisib, palbociclib, and fulvestrant, and the other receiving a placebo with palbociclib and fulvestrant. The results indicated a striking difference in progression-free survival.
Patients on the three-drug therapy experienced a median of 15 months before their disease progressed, compared to just 7.3 months in the placebo group. Furthermore, at 18 months, 46.2% of patients receiving the new combination showed no signs of disease progression, while only 21.1% in the placebo group remained progression-free.
Expert Commentary
Lead researcher Nick Turner, professor of molecular oncology at the Institute of Cancer Research, London, emphasized the significance of the findings: "The results show the combination significantly improves progression-free survival when given as a first treatment. It is a huge breakthrough. It could represent a transformative advance for people with this type of breast cancer."
Impact and Context
Breast cancer remains a significant health challenge, with over 56,000 new cases diagnosed annually in the UK and nearly 11,500 deaths. Approximately 70% of patients are diagnosed with HR+/HER2- breast cancer, the subtype targeted by this novel drug combination. Palbociclib combined with fulvestrant has been available on the NHS since 2022 for certain breast cancer cases. The addition of inavolisib to this regimen has been approved in the United States but is not yet available in the UK.
Mechanism of Action and Resistance
The three drugs target critical pathways in PIK3CA-mutated breast cancer. By blocking cancer growth and preventing resistance to therapy, this combination offers a more effective treatment strategy. According to Prof. Turner, "This new combination helps prevent the cancer becoming resistant to therapy."
Patient Experience
Anne Lury, a participant in the Royal Marsden’s trial, shared her positive experience: “Aside from fatigue, I had minimal side effects. Although I’m now on other treatment, I wouldn’t be here if I hadn’t had the opportunity to join the trial.”
