MUSTBIO
7 known investors
Korean immuno-oncology biotech developing multi-specific antibody and immune-cytokine fusion therapies for cancer.
Also known as MustBio · 머스트바이오
Investors · 7
Also in the syndicate · 5
Company profile
researched Aug 2026MUSTBIO (머스트바이오) is a Korean biotechnology company developing first-in-class and best-in-class multi-specific antibodies and immune-cytokine fusion proteins for cancer treatment. The company positions its programs as next-generation immuno-oncology therapies intended to address unmet needs in oncology by directing immune activation to tumors while limiting the toxicity associated with conventional cytokine therapy.
The company's work is built on two proprietary platforms. BICSTA is a patented multi-specific antibody engineering platform that maximizes the formation rate of Fc heterodimers, which MUSTBIO describes as supporting high productivity and target expandability in multi-specific drug production. STARKINE is a cytokine engineering platform that uses rational design and computational modeling to modulate cytokine affinity, selectivity and stability, enabling rapid screening of disease-optimized cytokine variants; the company also describes STARKINE as an immune cytokine platform aimed at the tumor microenvironment. Combining the two, its Antibody Targeting Cytokine (ATC) approach fuses antibodies with engineered cytokines.
The disclosed pipeline consists of bispecific and trispecific fusion proteins, including MB5029 (αPD-1 x IL-2v, bispecific), MB4 (αPD-1 x IL-2v x TAA, trispecific), MB7 (αPD-1 x IL-21v x TAA, trispecific) and MB6 (αCD3 x TAA x TAA, trispecific). Press coverage of the company's 2026 financing identifies MB5 (αPD-1/IL-2v) as an IL-2-based lead candidate moving toward clinical development and MB7 (αPD-1/αVEGF/IL-21v) as an IL-21-based triple-fusion program in research.
Founding story
MUSTBIO was founded by Maengsup Kim, Ph.D., who serves as Founder and CEO. He holds a Ph.D. in chemistry from KAIST and previously led R&D at Ahngook Pharm, Beijing Hanmi Pharmaceutical, Daewoong Pharmaceutical and Hanmi Pharmaceutical. He is credited as inventor of the PENTAMBODY bispecific antibody platform and the ORASCOVERY oral drug discovery platform, with prior involvement in Korea's first 505(b)(2) development and commercialization and in global oncology licensing agreements.
Business model
MUSTBIO is a research and development-stage drug developer, advancing its own preclinical and clinical-stage biologics while pursuing partnerships, co-development and licensing arrangements with pharmaceutical companies, as illustrated by its co-development and licensing agreement with Celltrion.
Stated plans center on global partnerships and licensing deals for its oncology pipeline and platform technologies; a co-development and licensing agreement with Celltrion covers an αPD-1/αVEGF/IL-2v triple-fusion candidate.
Traction
Reported traction includes cumulative funding of $42.6 million since 2021, including a $23.5 million Series C in March 2026; a Korean patent registration for an IL-2v based multi-specific fusion protein; preclinical data presentations at AACR 2023 and AACR 2024 and a preclinical publication in 2024; selection into JLABS Korea in January 2025; and an October 2025 co-development and licensing agreement with Celltrion. The lead candidate MB5 (αPD-1/IL-2v) is being advanced toward clinical development.
Latest developments
In March 2026 the company announced a $23.5 million Series C at a pre-money valuation of $39.6 million, with seven returning investors and two new backers, to fund clinical development of MB5 (αPD-1/IL-2v) and R&D on MB7 (αPD-1/αVEGF/IL-21v), alongside global partnering and licensing efforts. Preceding developments include joining JLABS Korea in January 2025 and signing a co-development and licensing agreement with Celltrion in October 2025 for an αPD-1/αVEGF/IL-2v triple-fusion candidate.
▸Full profile — market position, technology, go-to-market, geography, history
Market position
MUSTBIO operates in immuno-oncology, specifically the multi-specific antibody and engineered immune-cytokine segment, and describes its objective as developing first-in-class and best-in-class tumor-directed multi-specific antibodies. Its financing has been backed by a syndicate of Korean institutional investors and a strategic corporate investor, and it has secured a co-development and licensing partnership with a large Korean biopharmaceutical company.
The company differentiates on its two in-house platforms: BICSTA, which it says maximizes Fc heterodimer formation for high-productivity, expandable multi-specific antibody production, and STARKINE, which enables rapid generation of engineered cytokine variants tuned for specific diseases and tumor microenvironment targeting. Combining them, its ATC immuno-cytokine candidates are intended to reduce the side effects associated with conventional cytokine therapies while increasing efficacy.
Technology
The company's core technologies are BICSTA, a patented antibody engineering platform that maximizes Fc heterodimer formation to enable high-productivity, target-expandable multi-specific drugs, and STARKINE, a cytokine engineering platform that uses rational design and computational modeling to tune cytokine affinity, selectivity and stability and to screen disease-specific cytokine variants. The Antibody Targeting Cytokine (ATC) approach applies BICSTA to combine antibodies with engineered cytokines, with the stated aim of reducing cytokine-related side effects while improving efficacy. Candidates are constructed as bispecific and trispecific fusion proteins engaging PD-1, PD-L1, CD3, IL-2v, IL-21v, VEGF and tumor-associated antigens.
Go-to-market
The company advances proprietary programs through preclinical and clinical development while presenting data at scientific conferences such as the AACR Annual Meeting, and pursues global partnerships, licensing deals and open innovation programs, including participation in Johnson & Johnson's JLABS Korea.
Cancer patients are the intended beneficiaries of its therapies; its direct commercial counterparties are pharmaceutical and biotechnology partners for co-development and licensing of its pipeline and platform technologies.
Geography
MUSTBIO is headquartered in Suwon-si, Gyeonggi-do, Republic of Korea (B-701, 102 Edutown-ro, Yeongtong-gu), with a laboratory at the same address (B-3F). It states an intent to collaborate with global partners and participates in JLABS Korea for international R&D collaboration.
History
According to press coverage, the company was founded in 2021 and has since raised a Series A, a Series B and, in March 2026, a Series C. Company notices record new stock issuances in February and March 2023 and a shareholders' meeting convocation in March 2024. Research milestones include AACR Annual Meeting presentations in 2023 (αPD-L1 x CD3) and 2024 (αPD-1 x IL-2v), a Korean patent registration for an IL-2v based multi-specific fusion protein in April 2024, and publication of preclinical results for an anti-PD-L1 x IL-2v bispecific fusion protein in June 2024. The company joined JLABS Korea in January 2025 and signed a co-development and licensing agreement with Celltrion in October 2025.
Compiled by commissioned research from 5 cited public sources — announcements, filings, and press listed under research sources below.
Key figures
latest reportedCompany-reported or press-reported figures, each dated to when it was claimed — not independently audited.
Timeline · 7
launches, deals, and filingsClosed a $23.5M (₩35 billion) Series C at a pre-money valuation of $39.6M (₩59 billion), bringing total funding to $42.6M. Seven existing investors (Korea Investment Partners, Premier Partners, Partners Investment, Korea Development Bank, Ahngook Pharm, Wonik Investment Partners, Shinhan Capital) participated alongside new investors Atinum Investment and BNH Investment. Proceeds are earmarked for clinical development of MB5 (αPD-1/IL-2v) and R&D on MB7 (αPD-1/αVEGF/IL-21v).
$23.5M source ↗
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.
Admitted to JLABS Korea, Johnson & Johnson's open innovation program, for access to international R&D collaborations, industry networks and funding opportunities.
Company announced publication of pre-clinical study results of a novel anti-PD-L1 x IL-2v bispecific fusion protein.
MustBio introduced a novel αPD-1 x IL-2v candidate at the American Association for Cancer Research Annual Meeting 2024 (reported by Biospectator).
Patent registered at the Korea Intellectual Property Office covering an IL-2v based multi-specific fusion protein.
MustBio introduced a novel αPD-L1 x CD3 candidate at the American Association for Cancer Research Annual Meeting 2023 (reported by Biospectator).
Dated company events from announcements, filings, and press; legal rows summarize public dockets and regulator releases.
▸Research sources · 5
primary sources listed
- 머스트바이오 MUSTBIOmustbio.com · web
5 public sources were cited for this profile; the first-party ones are listed here.
Frequently asked questions
- What does MUSTBIO do?
- Korean immuno-oncology biotech developing multi-specific antibody and immune-cytokine fusion therapies for cancer.
- Who are MUSTBIO's investors?
- MUSTBIO's investors include Atinum Investment Co. Ltd., Premier Partners.