Key findings and next steps
The primary endpoint was progression-free survival (PFS) at 6 months, with secondary endpoints of the best overall response rate, PFS at 1 year, overall survival, and safety.
While details of the latter three endpoints are yet to be reported, Ms. Voorwerk noted that there was a median duration of response of 12 weeks and the median PFS was 15 weeks. The primary endpoint of PFS was met as four patients were free of progression at 6 months and the statistical method used called for patients to be progression free at this time point.
“We observed that stromal TILs and CD8+ cells were not associated with clinical benefits,” said Ms. Voorwerk. There was, however, “a slight trend” toward higher PD-L1 expression in responding patients.
“Further translational research is needed to provide the rationale for new strategies to improve checkpoint blockade in patients with lobular breast cancer,” she concluded.
Dr. Adams concurred, adding that a future research question was whether either atezolizumab or carboplatin was contributing to the response. This is “difficult to tell as the study was a single arm trial.”
Another question, said Dr. Adams, is are “anti-CDK 4/6 inhibitors helpful in improving response rates and durability?” In the trial, 70% of patients had prior exposure to CDK 4/6 inhibitors.
The GELATO trial was sponsored by the Netherlands Cancer Institute with funding from Roche Pharma AG. Ms. Voorwerk had nothing to disclose. Dr. Adams disclosed uncompensated consulting or advisory roles with Bristol-Myers Squibb, Genentech, and Merck from whom she has received research funding. Dr. Adams also disclosed research funding from Amgen, Celgene, and Novartis.