MUSTBIO, a Korean biotech building multi-specific antibody-based cancer immunotherapies, has closed a $23.5M (₩35 billion) Series C round at a pre-money valuation of $39.6M (₩59 billion). The raise puts the company’s total funding at $42.6M (₩63.5 billion) since it was founded in 2021 — stacking on top of a $6.0M (₩9 billion) Series A and a $13.1M (₩19.5 billion) Series B.

Seven existing investors returned for the round: Korea Investment Partners, Premier Partners, Partners Investment, Korea Development Bank, Ahngook Pharm, Wonik Investment Partners, and Shinhan Capital. Atinum Investment and BNH Investment came in as new backers. Worth noting: Korea Investment Partners, Premier Partners, and Partners Investment have written checks in every single round since Series A — a sign of sustained confidence in the company’s direction.

The fresh capital will go toward two pipeline priorities: pushing MB5 (αPD-1/IL-2v), an IL-2-based immuno-oncology candidate, through clinical development, and advancing R&D on MB7 (αPD-1/αVEGF/IL-21v), a novel IL-21-based triple-fusion therapy.

MUSTBIO’s platform rests on two in-house technologies. BICSTA is a multi-specific antibody engineering platform built for high productivity, while STARKINE is an immune cytokine platform that targets the tumor microenvironment (TME) — activating the immune response precisely where it’s needed. Together, they form the backbone of the company’s triple-fusion immunotherapy pipeline.

The company has also been building out its global footprint. In January of last year, MUSTBIO landed a spot in JLABS Korea, Johnson & Johnson’s open innovation program, opening doors to international R&D collaborations, industry networks, and funding opportunities. That October, it signed a co-development and licensing deal with Celltrion to jointly develop αPD-1/αVEGF/IL-2v, a triple-fusion candidate designed for tumor-selective immune cell activation and proliferation.

“MUSTBIO has developed world-class technology in immune cytokines that can selectively target specific cancer cells,” said Maengsub Kim, CEO. “We’ll use this funding to accelerate clinical trials for our lead programs, advance new triple-antibody research, and pursue global partnerships and licensing deals.”