Long-Term HERIZON-BTC-01 Data Shows Zanidatamab’s Potential in HER2+ BTC

Shubham Pant, MD, professor in the Department of Gastrointestinal Medical Oncology with a joint appointment in the Department of Investigational Cancer Therapeutics at The University of Texas MD Anderson Cancer Center, discusses background on zanidatamab (ZW25) and findings from the HERIZON-BTC-01 trial (NCT04466891) of the agent for HER2-positive biliary tract cancer (BTC) treatment.

Updated findings from the phase 2b trial were presented at the 2024 American Society of Clinical Oncology Annual Meeting.

Transcription:

0:09 | Zanidatamab is a bispecific anti-HER2-directed antibody which binds on 2 domains on HER2 called ICD2 and ICD4. So last year, we presented the phase 2B HERIZON-BTC-01 trial, which is a global trial in patients with biliary tract cancers. We presented our 80 patients who were HER2-positive, and the way we defined them was IHC3+ or IHC2+, and they were ISH-positive, in situ hybridization-positive.

0:41 | Eighty patients were on the trial, they got zanidatamab maybe once every 2 weeks [intravenously], and we followed them out. The primary end point was overall response rate. Then, we have secondary end points like progression-free survival, overall survival, toxicity, so we presented that last year. And this year, we are presenting the updated results, long-term follow-up of that trial.

1:04 | Last year, our confirmed overall response rate was 41.3% [and] we had a duration of response of about 12.9 months, that was a duration of response. We followed those patients out, and now, the median duration of follow-up is 21.9 months. And again, the confirmed overall response rate remained the same, which is good, 41.3%. For comparison, let's say FOLFOX, which is chemotherapy in the second-line setting for BTC, has a response rate of 5%. This was obviously very promising.

1:42 | What we have seen is that the confirmed overall response rate remained the same, but the duration response increased to 14.9 months, so that actually improved and we were kind of happy about that. The median overall survival that we could report the data out [for, and] that we did not have the data mature last year, is about 15.5 months, so promising for these patients.

2:03 | We also are presenting the updated safety analysis, in which there were no new safety signals. In the original trial, we saw some diarrhea, which was the main one that kind of stayed, but we did not see any updated safety parameters.