Zanidatamab Shows Breakthrough Survival Gains in Metastatic Gastroesophageal Cancer: Elena Elimova, MD

The landmark phase 3 HERIZON-GEA-01 (NCT05152147) trial has set new benchmarks in treating patients with metastatic gastroesophageal adenocarcinoma, with patients receiving zanidatamab-containing regimens experiencing significantly prolonged progression-free survival and overall survival, explains Elena Elimova, MD, associate professor in the Department of Medicine at the University of Toronto and staff medical oncologist at Princess Margaret Hospital.

The findings were presented at the American Society of Clinical Oncology (ASCO) Gastrointestinal (GI) Cancers Symposium.

This transcript was lightly edited; captions were auto-generated.

Transcript

Can you share the key findings of the study?

What the main findings of the study were was that number 1, when you look at the progression-free survival of patients on either one of the zanidatamab-containing regimens, the progression-free survival was significantly prolonged and surpassed 1 year, which for patients with metastatic gastroesophageal adenocarcinoma really is a new benchmark. This has never been reached in a previous study. The other thing to know is that there was a more than 4-month prolongation of median progression-free survival in this study. And again, this is very unusual, because usually we would see 2 months, but this was a more significant change. The hazard ratios we saw, which speak to the overall benefit of the treatments, were 0.63 and 0.65; both were statistically significant. I think that's a really important finding. That's in terms of the progression-free survival.

Even though this study wasn't stratified by PDL-1 TAP [Tumor Area Positivity] scores, what was interesting is that 30% of our patient population had PDL-1 TAP less than 1, and patients seem to benefit regardless of their PDL-1 TAP status. Even though this is hypothesis generating, I think it's very interesting because it's the first study to show this; some other studies have shown discordant results.

In terms of the overall survival, the overall survival with zanidatamab plus tislelizumab plus chemotherapy was extremely clinically meaningful. We achieved a median overall survival that was longer than 2 years. In particular, if you look at the actual number, it was 26.4 months vs 19.2 months, and a hazard ratio of 0.72, and again, I'll be honest with you, this is a new benchmark for us. Because when I started treating patients, and when trastuzumab was the standard of care, we were seeing sort of improvements of 2 to 3 months in most of our studies. To see a median overall survival improvement of 7 months, to date, I have never seen this in a gastroesophageal cancer study.