Handok, Compass Advance HD-B001A Biliary Tract Cancer Drug Into U.S. Phase 2/3 Trial

Handok has completed a domestic phase 2 trial of HD-B001A (generic name: Tovecimig), a biliary tract cancer drug candidate, and a concurrent U.S.-Korea phase 2/3 trial (COMPANION-002) led by its U.S. partner Compass Therapeutics is now getting underway in earnest. In addition, the Ministry of Food and Drug Safety (MFDS) selected HD-B001A for the Global Innovative Products Fast Track (GIFT) Kiwoom Program, adding institutional support from South Korea’s regulatory authorities.

Biliary tract cancer, including cholangiocarcinoma and gallbladder cancer, is a difficult-to-treat cancer with an extremely poor prognosis because it is often detected late due to a lack of early symptoms; the 5-year survival rate for metastatic biliary tract cancer is just 2%. Approximately 210,000 people are newly diagnosed worldwide each year, including about 23,000 patients annually in the United States alone. In particular, there is effectively no approved standard second-line treatment after failure of first-line chemotherapy, leaving a substantial unmet medical need unresolved in the global market for many years.

■ Dual blockade of DLL4 and VEGF-A designed to overcome resistance

HD-B001A is a bispecific antibody drug that simultaneously blocks the DLL4 and VEGF-A signaling pathways involved in tumor angiogenesis. The underlying technology was initially developed by South Korean drug developer ABL Bio using its proprietary bispecific antibody platform (original development name: ABL001), while Handok holds the domestic rights and led a phase 2 trial at four institutions in South Korea. The candidate’s key differentiator is its design to overcome the resistance associated with existing VEGF inhibitors.

Compass Therapeutics holds global rights excluding South Korea and China, while Handok participates as a strategic investor with a significant stake in Compass Therapeutics. The two companies share a global clinical protocol and maintain a collaborative structure.

■ ORR of 17.1% vs. 5.3%, with statistical significance confirmed

According to topline phase 2/3 data announced in April 2025, the objective response rate (ORR) for the combination of tovecimig and paclitaxel in the second-line treatment group was 17.1%, demonstrating a statistically significant improvement over paclitaxel monotherapy (5.3%; p=0.031). Thomas Schutz, CEO of Compass Therapeutics, said, “Advanced biliary tract cancer is a disease with a substantial unmet need, as response rates with existing treatments are only in the single digits,” adding, “The clinical results show that it may provide a new treatment option for the majority of patients who have no alternatives after first-line treatment.”

Positive signals are also continuing on the regulatory front. HD-B001A received Fast Track designation from the U.S. FDA in April 2024, followed by orphan drug designation in April 2026. Both designations provide opportunities for close communication with the developer during the FDA review process and benefits that can shorten the review period, serving as factors that may accelerate the path to commercialization.

Industry experts are also watching the candidate closely. Juan Valle, chief medical officer of the Cholangiocarcinoma Foundation, said, “There are currently no approved alternatives in the second-line treatment setting,” adding, “We welcome continued progress and clinical achievements with new treatment options that could give patients more time.”

■ Market projected to reach $3 billion by 2034; indication expansion also in focus

The global biliary tract cancer treatment market is estimated at approximately $1.1 billion to $1.5 billion as of 2024. Driven by population aging and growing demand for targeted cancer therapies, the market is expected to grow at an average annual rate of approximately 8% or more and exceed $3 billion (approximately 4 trillion won) by around 2034.

In addition to the currently available primary endpoint results (ORR), data on secondary endpoints, including progression-free survival (PFS) and overall survival (OS), are expected to be generated after the second half of 2026. The candidate’s position as a global second-line standard treatment for biliary tract cancer is expected to be determined by the direction of these data. In addition, the DLL4-VEGF-A dual-inhibition mechanism leaves open the possibility of expanding indications into other solid tumors that show resistance to existing cancer therapies, including colorectal and gastric cancers, potentially further increasing the value of the pipeline, according to industry assessments.