Merck KGaA, Darmstadt, Germany has announced topline data from the Phase II INTR@PID BTC 047 study evaluating bintrafusp alfa as a monotherapy in the second-line treatment of patients with locally advanced or metastatic biliary tract cancer (BTC) who have failed or are intolerant of first-line platinum-based chemotherapy.

In the study of 159 patients, bintrafusp alfa demonstrated single-agent efficacy and durability with a manageable safety profile after more than nine months of follow-up, with an Independent Review Committee (IRC)-adjudicated objective response rate (ORR) of 10.1% (95% CI: 5.9% to 15.8%) per RECIST 1.1. Though single-agent activity was observed, the study did not meet the pre-defined threshold that would have enabled regulatory filing for BTC in the second line setting. The results will be submitted for presentation at an upcoming medical meeting or publication.

"Given the high unmet treatment need in BTC, where single agent immunotherapy in PD-L1 all comers has shown an ORR of 5.8%, we are encouraged by the single agent clinical activity of bintrafusp alfa in this study as a second-line treatment," said Milind Javle, MD, professor of GI medical oncology, MD Anderson Cancer Center, and an investigator for the INTR@PID BTC 047 study. "The bintrafusp alfa 047 study is one of the most important clinical investigations conducted for chemo-refractory biliary cancers, and I would like to thank the patients, families, and study team for their valuable participation."

"This study demonstrates single-agent activity with bintrafusp alfa in locally advanced or metastatic BTC, a disease that has been historically difficult to treat," said Danny Bar-Zohar, M.D., Global Head of Development for the Healthcare business sector of Merck KGaA, Darmstadt, Germany. "The data will contribute to our understanding of addressing both TGF-β and PD-L1 inhibition in the tumor microenvironment."

A Phase II/III study of bintrafusp alfa in combination with chemotherapy as a first-line treatment for BTC (INTR@PID BTC 055), which is assessing a different hypothesis than the second-line monotherapy study, has completed enrollment in the Phase II portion and is currently ongoing.

BTCs are a group of rare, aggressive gastrointestinal cancers associated with poor outcomes and limited treatment options. There is currently no globally accepted standard of care in the second-line setting and chemotherapy as well as immunotherapies have demonstrated low response rates in BTC. Epithelial-to-mesenchymal transition (EMT), a hallmark of tumor progression and drug resistance, plays an important role in BTC, and has been shown to be triggered by TGF-β signaling.