The FDA’s approval of inavolisib breast cancer treatment in combination with palbociclib and fulvestrant is significant. It provides a new treatment option for a challenging patient population. This treatment is specifically for adults with endocrine-resistant, PIK3CA-mutated, hormone receptor (HR)-positive, human epidermal growth-factor receptor 2 (HER2)-negative, locally advanced or metastatic breast cancer. Patients eligible for this approval have experienced recurrence after completing adjuvant endocrine therapy.

The FoundationOne Liquid CDx assay was approved as a companion diagnostic device. This device helps identify which breast cancer patients are eligible for the inavolisib treatment regimen.

Efficacy Outcomes

– The primary efficacy outcome was assessed for progression-free survival (PFS) by investigators per RECIST version 1.1.
– The median PFS was 15.0 months (95% CI: 11.3, 20.5) for the inavolisib + palbociclib + fulvestrant arm, compared to 7.3 months (95% CI: 5.6, 9.3) for the placebo + palbociclib + fulvestrant arm (Hazard ratio 0.43 [95% CI: 0.32, 0.59], p-value < 0.0001).

Overall Survival

Although the interim analysis of overall survival did not achieve statistical significance, it suggested a trend in favor of the inavolisib regimen.

Regulatory Collaboration

This approval took place under Project Orbis, which is part of the FDA Oncology Center of Excellence. It involves collaboration with various international regulatory agencies, including the Australian Therapeutic Goods Administration (TGA), Health Canada, and Switzerland’s Swissmedic.