ProBioGen and VarmX have entered a collaboration to develop a cell line for VarmX’s second therapeutic Factor X candidate.

The partnership will use ProBioGen’s HEK293 host cell line platform to support development of the candidate, expanding a relationship between the German biotechnology company and the Dutch developer of Factor X therapies.

The collaboration will focus on cell line development for VarmX’s Factor X programme, with ProBioGen contributing its expertise in recombinant protein production and coagulation factor development.

ProBioGen said its experience includes development programmes involving Factor VII and Factor VIII therapeutics, while the company will use its HEK293 platform and DirectedLuck transposase technology in the new collaboration.

ProBioGen expands coagulation factor development work

The companies said the collaboration will address the development requirements associated with producing coagulation factors, including protein maturation and proteolytic processing.

Volker Sandig, chief scientific officer at ProBioGen, said: “We are excited to partner with VarmX on this compelling and demanding molecule.”

He added that ProBioGen’s HEK293 platform and experience in coagulation factor development could support the development of VarmX’s second Factor X candidate.

VarmX founder Pieter Reitsma said the company selected ProBioGen based on its experience with coagulation factors and cell line technology.

“Partnering with ProBioGen for our Factor X program was a strategic decision based on their proven track record in coagulation factor development,” Reitsma said.

The collaboration will build on VarmX’s wider development programme targeting Factor X, a protein involved in the blood coagulation cascade.

VarmX’s lead compound, VMX-C001, is a modified recombinant blood Factor X being developed for the treatment of severe spontaneous bleeding and to prevent bleeding during urgent surgery in people taking Factor Xa inhibitors.

The company entered into a strategic collaboration and option agreement with CSL in September 2025 to fund the Phase 3 trial of VMX-C001 and support its late-stage development and potential commercialisation.

The new collaboration with ProBioGen relates to a second therapeutic Factor X candidate in VarmX’s pipeline. The companies have not disclosed further details about the candidate or provided a timeline for its development.

Highlighting the role of specialist cell line development tech

The partnership highlights the role of specialist cell line development technologies in advancing recombinant protein therapeutics, particularly for complex biological products that require specific protein maturation and processing.

VarmX was founded in 2016 as a spin-off from Leiden University Medical Center and is focused on developing treatments for bleeding disorders and other conditions involving haemostasis and thrombosis.

The company’s lead programme, VMX-C001, is being developed as a potential treatment for bleeding associated with Factor Xa inhibitor use, while the new collaboration expands its development activities around Factor X therapeutics.

The financial terms of the ProBioGen and VarmX collaboration were not disclosed.