Findings from the phase III BOLERO-2 trial showed nearly a 6-month improvement in progression-free survival when using everolimus and exemestane in comparison with exemestane alone in patients with resistant breast cancer (median PFS 10.6 vs 4.1 months; HR = 0.36). While he was disappointed BOLERO-2 did not demonstrate an overall survival benefit, Richard Finn, MD, comments that it is certainly an option before proceeding to chemotherapy.

Kim Blackwell, MD, states tends to use the BOLERO-2 regimen in individuals who have progressed on a type 2 aromatase inhibitor. Side effects, says Blackwell, include pneumonitis and anemia. The most frequently observed grade 3/4 adverse events with everolimus versus without were stomatitis (8% vs 1%), anemia (6% vs <1%), dyspnea (4% vs 1%), hyperglycemia (4% vs <1%), fatigue (4% vs 1%), and pneumonitis (3% vs 0%).

Ruth O’Regan, MD, notes that toxicities tend to be manageable using supportive care, and overall, patients are generally able to tolerate therapy once they reach the appropriate dose. Lee Schwartzberg, MD, shares that clinicians should not abandon endocrine therapy for cytotoxic chemotherapy too soon. Instead, in many situations, the addition of everolimus could counteract resistance, such as was seen in the BOLERO-2 study.