Latest analysis from IMpassion trial confirms need for testing
One of the repeated themes of the American Society of Clinical Oncology meeting here was the need for baseline testing of any target that can inform truly precision use of targeted therapies, and that message came through loud and clear during an oral abstract session devoted to treatment of metastatic breast cancer.
For example, an updated analysis from the IMpassion130 trial provided interesting findings, but the top clinical implication of the study, singled out by the study discussant, was a confirmation of the value of the assay used in IMpassion to identify PD-L1 IC.
“Ventana SP142 is the preferred assay,” said Cesar A. Santa-Maria, MD, of Johns Hopkins Sidney Kimmel Comprehensive Cancer Center. And just to be clear, PD-L1 IC testing is a must when treating “all new metastatic triple-negative breast cancer.”
The trial recruited patients with inoperable, locally-advanced triple-negative breast cancer who had not previously received advanced therapy, said Peter Schmid, MD, PhD, of Barts Cancer Institute in London, who was one of the study authors. Patients were randomized to atezolizumab plus nab-paclitaxel (n=255) or placebo plus nab-paclitaxel (n=279).
An interim analysis at 18 months found no statistically significant overall survival benefit, but analysis of patients who tested positive for PDL1 expression found a clinically meaningful OS improvement of 7 months versus placebo and nab-paclitaxel — a median of 25 months versus 18 months. Schmid noted that more than half of the patients in the experimental arm who were PD-L1 positive were alive at 2 year versus 37% of controls.
He added that atezolizumab plus nab-paclitaxel “is approved by the FDA and is recommended for treatment of patients with PD-L1 IC+ metastatic triple negative breast cancer in the NCCN guidelines.”
Schmid disclosed grants supporting the parent study, and editorial support from F. Hoffmann-LaRoche during the conduct of the study. He also reported grants to his institution from AstraZeneca, Roche/Genentech, Oncogenex, Novartis, and Astellas outside the conduct of the study. Honoraria from Pfizer, AstraZeneca, Novartis, Roche, Merck, Boehringer Ingelheim, Bayer, Eisai, Celgene, and Puma outside the study.
Schmid P “IMpassion 130: Updated overall survival (OS) from a global, randomized, double-blind, placebo-controlled, phase III study of atezolizumab (atezo) + nab-paclitaxel(nP) in previously untreated locally advanced or metastatic triple-negative breast cancer (mTNBC)” ASCO 2019; Oral Abstract Session, Breast Cancer-Metastatic, June 4: Abstract 1003.
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