The experimental cholangiocarcinoma treatment CTX-009 advanced to the second part of a phase 2a clinical trial, Compass Therapeutics, Inc., the developer of the treatment, announced in a press release. 

Thomas Schuetz, MD, PhD, the chief executive officer and scientific founder of Compass, stated, “We are looking forward to filing our [Investigational New Drug Application] in the United States this quarter and pursuing the global development of CTX-009.”

Cholangiocarcinoma is a type of liver malignancy that originates in the cells of the biliary tree. Patients with cholangiocarcinoma have limited therapeutic options after front-line combination chemotherapy.

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CTX-009 is a bispecific antibody that can block the Delta-like ligand 4/Notch (DLL4) and vascular endothelial growth factor A (VEGF-A) signaling pathways at the same time. Both of these pathways are critical for angiogenesis and tumor vascularization. 

The phase 2 study was initiated by Handok Pharmaceuticals in the first quarter of 2021. 

Investigators had already observed 5 partial responses in 17 patients treated with CTX-009 in combination with paclitaxel; this corresponds to a preliminary overall response rate of 29%. They also found that all 17 patients had stable disease and 16 of them had a decline in tumor burden, corresponding to a clinical benefit rate of 100%.

The preliminary adverse event profile of CTX-009 was consistent with those of previous studies. Hypertension and neutropenia were the most common adverse events related to treatment with CTX-009 and paclitaxel, respectively.

Forty-five more patients will now be enrolled for the second part of the study. 

Subject to the application going into effect with the US Food and Drug Administration (FDA), Compass is planning to initiate another phase 2 study of the treatment in the United States in the second quarter of 2022.

Compass holds the global rights to CTX-009, but Handok holds the South Korean rights.


Compass reports the advancement of CTX-009, a bispecific antibody, to phase 2a development in patients with biliary tract cancers (BTC), and the clearance of a key clinical hurdle. News release. Compass Therapeutics, Inc.; November 1, 2021.