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FDA Grants Fast Track Designation to Novel Bispecific Antibody Plus Paclitaxel for Advanced Biliary Tract Cancer

Image credit: Matthieu |

Compass Therapeutics, Inc’s novel bispecific antibody CTX-009 was granted Fast Track Designation (FTD) by the FDA in combination with paclitaxel to treat patients with metastatic or locally advanced biliary tract cancer following prior therapy.1 The investigational treatment was designed to simultaneously block the Delta-like ligand 4 (DLL4) and vascular endothelial growth factor A (VEGF-A) signaling pathways that are vital in the process of angiogenesis and tumor vascularization.

“We are delighted that CTX-009 has received FDA Fast Track Designation highlighting the large unmet need in patients with advanced BTC where current therapies have low, single digit response rates, and limited effect on patient survival,” Thomas Schuetz, MD, PhD, co-founder, president of R&D, and vice chairman of the Compass board, said in a press release. “Our current study is evaluating the combination of CTX-009 with paclitaxel following the observation of nine partial responses in 24 patients treated in our Phase II study, leading to an overall response rate of 37.5% (n= 9/24), a median progression-free survival (PFS) of 9.4 months and a median overall survival (OS) of 12.5 months. Compass remains on track to complete enrollment by mid-year and reporting top-line data by year end.”

In preclinical and early clinical trials, investigators have found that blocking the DLL4 and VEGF-A pathways with CTX-009 produced antitumor activity in various solid tumors, which includes cholangiocarcinoma, colorectal, gastric, and pancreatic cancers, as well as non–small cell lung cancer. Further, CTX-009 generated a partial response as a monotherapy in heavily pretreated patients with VEGF-mediated resistance.

The FTD was based on findings from the multicenter, open-label, randomized, Phase II/III COMPANION-002 trial (NCT05506943).2 In the press release, Compass Therapeutics stated that topline data from the trial should be released by the end of 2024.1

Investigators randomly assigned participants to either receive intravenous (IV) CTX-009 combined with paclitaxel or IV paclitaxel monotherapy. The novel bispecific antibody will be administered on days one and 14 of each 28-day cycle, whereas paclitaxel will be administered via IV infusion on days one, eight, and 15 of each 28-day cycle. Participants who were randomly assigned to the paclitaxel monotherapy cohort will be permitted to move over to the experimental combination cohort following documented disease progression per RECIST v1.1 criteria.

The trial’s primary endpoint is best overall response as per RECIST v1.1 criteria, with secondary endpoints that include PFS, duration of response, OS, disease control rate, safety, patient-reported quality of life, and exposure response.

Enrollment criteria includes being at least 18 years of age with a confirmed diagnosis of unresectable advanced, metastatic, or recurrent biliary tract cancers. This includes ampullary carcinoma, extrahepatic cholangiocarcinoma, intrahepatic cholangiocarcinoma, and gallbladder cancer. Further, participants are required to have documented radiological progression following first-line treatment with gemcitabine and a platinum-containing regimen for locally advanced unresectable or metastatic disease. Patients who were administered perioperative treatment or whose frontline regimen was modified due to toxicity before experiencing disease progression may also be eligible for enrollment.2


1. Compass Therapeutics receives FDA fast track designation for the investigation of CTX-009 in combination with paclitaxel for the treatment of patients with metastatic or locally advanced biliary tract tumors that have been previously treated. News release. Compass Therapeutics. April 25, 2024. Accessed April 26, 2024.

2. A study of CTX-009 in combination with paclitaxel in adult patients with unresectable advanced, metastatic or recurrent biliary tract cancers (COMPANION-002). Updated April 2, 2024. Accessed April 26, 2024.