A FINAL analysis from the Phase III INAVO120 trial demonstrates that adding inavolisib to palbociclib and fulvestrant significantly improves overall survival (OS) in patients with PIK3CA-mutated, hormone receptor-positive (HR+), HER2-negative, endocrine-resistant advanced breast cancer (aBC). These findings reinforce the long-term benefit and manageable safety profile of the inavolisib combination, offering new hope for delaying chemotherapy in this high-need population.
With a median follow-up of 34.2 months, median OS reached 34.0 months for patients receiving inavolisib compared with 27.0 months in the placebo arm (hazard ratio 0.67; 95% CI: 0.48–0.94; p = 0.0190). This survival advantage was consistently observed across key patient subgroups. Survival rates at 24 months were 65.8% for the inavolisib group versus 56.3% with placebo.
Objective response rates (ORR) also favored the inavolisib group, with 62.7% of patients achieving a response, compared to 28.0% in the control arm (p < 0.0001). Updated investigator-assessed progression-free survival (INV-PFS) remained durable, with median INV-PFS extending to 17.2 months versus 7.3 months, respectively (hazard ratio 0.42; 95% CI: 0.32–0.55). Time to chemotherapy (TTC) was notably prolonged, 35.6 months in the inavolisib arm compared with 12.6 months in the placebo group, highlighting the potential of this triple regimen to delay cytotoxic treatment by nearly 2 years. While adverse events (AEs) were more common in the inavolisib arm (90.7% vs. 84.7% grade 3/4 AEs), the treatment was generally well tolerated. Hyperglycemia occurred in 63.4% of patients on inavolisib versus 13.5% on placebo, yet discontinuation due to AEs remained low (6.8%). These results confirm the survival advantage and sustained disease control offered by inavolisib when combined with standard endocrine therapy, positioning it as a meaningful advancement in the management of endocrine-resistant HR+ aBC. Turner N et al. ASCO 2025. INAVO120: Phase III trial final overall survival (OS) analysis of first-line inavolisib (INAVO)/placebo (PBO) + palbociclib (PALBO) + fulvestrant (FULV) in patients (pts) with PIK3CA-mutated, hormone receptor-positive (HR+), HER2-negative (HER2–), endocrine-resistant advanced breast cancer (aBC). May 23, 2025. Available at: https://www.asco.org/abstracts-presentations/ABSTRACT505814. Last accessed: May 31, 2025. [Press release].
