CHICAGO — Adding carboplatin to standard anthracycline/taxane treatment for early-stage triple-negative breast cancer (TNBC) improves event-free and overall survival in the neoadjuvant and adjuvant setting, according to a phase 3 trial presented on June 3 at the American Society of Clinical Oncology (ASCO) 2024 annual meeting.
The event-free survival benefit reached statistical significance (P = .012), while the overall survival benefit was just shy of statistical significance (P = .057).
The outcomes of the South Korean study, dubbed PEARLY, provide strong evidence for incorporating carboplatin into both the neoadjuvant and adjuvant settings in patients with early-stage TNBC, said lead investigator and presenter Joohyuk Sohn, MD, PhD, a medical oncologist at Yonsei University, Seoul, South Korea.
In early-stage TNBC, carboplatin is already being incorporated into the neoadjuvant setting on the basis of trial results from KEYNOTE-522 that demonstrated improved pathologic complete response rates and event-free survival with the platinum alongside pembrolizumab.
However, the overall survival benefit of carboplatin in this setting remains unclear, as does the benefit of platinum add-on in the adjuvant setting, Sohn explained.
Sohn and colleagues randomized 868 patients evenly to either standard treatment — doxorubicin, anthracycline, and cyclophosphamide followed by a taxane — or an experimental arm that added carboplatin to the taxane phase of treatment.
About 30% of women were treated in the adjuvant setting, the rest in the neoadjuvant setting. The two arms of the study were generally well balanced — about 80% of patients had stage II disease, half were node-negative, and 11% had deleterious germline mutations.
The primary endpoint, event-free survival, was broadly defined. Events included disease progression, local or distant recurrence, occurrence of a second primary cancer, inoperable status after neoadjuvant therapy, or death from any cause.
Adding carboplatin increased 5-year event-free survival rates from 75.1% to 82.3% (hazard ratio [HR], 0.67; P = .012) with the benefit holding across various subgroup analyses and particularly strong for adjuvant carboplatin (HR, 0.26).
Five-year overall survival was also better in the carboplatin arm — 90.7% vs 87% in the control arm (HR, 0.65; 95% CI, 0.42-1.02) — but that benefit did not reach statistical significance (P = .057)
Invasive disease-free survival (HR, 0.73) and distant recurrence-free survival (HR, 0.77) favored carboplatin, but the results also weren't statistically significant.
Overall, 46% of patients had a pathologic complete response with carboplatin vs nearly 40% in the control arm. The pathologic complete response benefit from carboplatin add-on was consistent with past reports.
As expected, adding carboplatin to treatment increased hematologic toxicity and other adverse events, with three quarters of patients experiencing grade 3 or worse adverse events vs 56.7% of control participants. There was one death in the carboplatin arm from pneumonia and two in the control arm — one from septic shock and the other from suicide.
Sohn and colleagues, however, did not observe a quality-of-life difference between the two groups.
"The PEARLY trial provides compelling evidence for including carboplatin in the treatment of early-stage TNBC," Sohn concluded, adding that the results underscore the benefit in the neoadjuvant setting and suggest "potential applicability in the adjuvant setting post-surgery."
Study discussant Javier Cortes, MD, PhD, believes that the PEARLY provides a strong signal for adding carboplatin in the adjuvant setting.
"That's something I would do in my clinical practice," said Cortes, head of the International Breast Cancer Center in Barcelona, Spain. "After ASCO this year, I would offer taxanes plus carboplatin following anthracyclines."
An audience member, William Sikov, MD, a breast cancer specialist at Brown University in Providence, Rhode Island, said he hopes "we've reached the end of a road that started many years ago in terms of incorporating carboplatin as part of neoadjuvant and adjuvant therapy for triple-negative breast cancer, where we finally [reach] consensus that this is necessary in our triple-negative patients."
The work was funded by the government of South Korea and others. Sohn reported stock in Daiichi Sankyo and research funding from Daiichi and other companies. Cortes disclosed numerous industry ties, including honoraria, research funding, and/or travel expenses from AstraZeneca, Daiichi, and others.
M . Alexander Otto is a physician assistant with a master's degree in medical science and a journalism degree from Newhouse. He is an award-winning medical journalist who worked for several major news outlets before joining Medscape Medical News. Email: aotto@mdedge.com.