Questions remain
George W. Sledge Jr, MD, professor of medicine (oncology) at Stanford University Medical Center, Palo Alto, California, was the invited discussant after the presentation.
He said that “positive trials raise as many questions as they answer, and monarchE is no exception.”
For example, there is the conundrum posed by the negative results of the very similar PALLAS trial, which looked at the addition of palbociclib to adjuvant endocrine therapy for HR+, HER2-negative early breast cancer and was also presented at the ESMO meeting.
Returning to monarchE, Sledge asked what the ultimate increase in invasive disease- and distant relapse-free survival will be with the drug combination, noting that the trial has “very, very short follow-up.”
“Second, will the improvements seen in disease-free survival lead to what we really care about: improved overall survival? Again, time will tell, but health care systems and patients care deeply about the answer to this question.”
Sledge continued: “How about late recurrence? Do CDK4/6 inhibitors kill off dormant or slow-growing micro-mets that lead to recurrences 5 or more years out?”
He also asked what the optimum duration of therapy would be: “Is it more than we need, or not enough?”
Sledge wondered whether it is possible to determine who benefits “and why the drug fails some patients.”
Finally, Sledge said, “These drugs are expensive. ... 2 years of adjuvant therapy is simply out of reach for the majority of patients around the globe who might be candidates for adjuvant CDK4/6 inhibitor therapy.”
And he observed an important truism: “A patient cannot benefit from a drug she cannot take.”
The study was funded by Eli Lilly. Johnston, Sledge, and Curigliano have financial ties to Eli Lilly and multiple other drug companies.
This article first appeared on Medscape.com.