The NATALEE trial found that combining Kisqali with standard hormone therapy improved outcomes in a common type of early-stage breast cancer. Dennis Slamon - who leads UCLA's Hematology-Oncology division and is a professor of medicine - said the regimen cut the chance of death by about 19% at six years.
He will present the data Friday at the European Society for Medical Oncology meeting in Madrid. He also noted the advantage continued to grow even though, on average, patients had stopped taking Kisqali more than three years earlier.
At six years, 91.9% of those on Kisqali were alive, compared with 89.7% on hormone therapy alone, after growing beyond the 1.2-percentage-point margin reported the year before.
The study also showed fewer invasive recurrences with Kisqali. The proportion without invasive disease favored Kisqali by 5.3 percentage points, rising from a 4.1-point advantage.
Kisqali is already cleared for use after tumor removal to help prevent the cancer from returning. Demonstrating a survival benefit matters since this breast cancer subtype may recur many years after the initial therapy. "I think it will change how physicians think about it," Slamon said. He added that the growing benefit over time for both survival and recurrence "is a manifestation of the fact that the drug's going to have a long-term effect."
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Discussing the findings at ESMO, independent expert Fumikata Hara called the survival result "clinically meaningful," while cautioning that treatments patients received after recurrence could have affected the outcomes. Hara said it is not clear why the benefit widened after stopping Kisqali, suggesting the trend might stem from an impact on lingering tumor cells, or merely from postponed recurrences.
A key question is the extent of use in patients diagnosed earlier who face a lower risk of relapse. NATALEE included some of these lower-risk groups, such as women without lymph node involvement.
The results indicate they may benefit as well, though Hara said the evidence is less certain in some of these groups owing to the smaller patient numbers and event counts. Even so, Slamon said the data support use across a wide range of eligible patients. "The inclusivity of the trial has told us the drug can benefit a large swath of that important group of patients," he said.
For Novartis watchers, the picture now includes an overall survival gain in early disease on top of fewer invasive recurrences, with results slated for a high-profile ESMO presentation. Independent commentary highlighted both the strength of the survival signal and the open questions about subsequent treatments, biology and how widely doctors will use the drug in lower-risk patients.
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