CHICAGO -- A second-line triplet regimen involving the novel intravenous drug gedatolisib significantly reduced the risk of progression or death in PIK3CA-mutant hormone receptor (HR)-positive breast cancer, a phase III study showed.
Among patients previously treated with CDK4/6 inhibition and an aromatase inhibitor (AI), median progression-free survival (PFS) reached 11.1 months with gedatolisib plus palbociclib (Ibrance) and fulvestrant, as compared with 5.6 months in a control arm that included fulvestrant plus alpelisib (Piqray), an approved drug for PIK3CA-mutant disease (HR 0.50, 95% CI 0.37-0.68, P<0.0001).
Though not formally tested, a third study arm found that the doublet of gedatolisib plus fulvestrant resulted in a similarly high PFS of 11.3 months. Treatment discontinuation due to toxicity was low in the two investigational arms, Sara Hurvitz, MD, of the University of Washington and Fred Hutch Cancer Center in Seattle, reported at the American Society of Clinical Oncology (ASCO) annual meeting.
"Gedatolisib plus fulvestrant, with or without palbociclib, represents a potential new standard of care for patients with this disease that has progressed on or after treatment with a CDK4/6 inhibitor," she said during a late-breaking presentation.
