Fund of the Week: 4BIO Capital

4BIO Capital is a London venture firm that builds and backs companies in cell, gene and RNA therapies and other new modalities. It manages two venture funds with $263.6M of gross assets, and began selling interests in a fourth in May 2026. It holds no royalties or revenue interests. Its contingent claims come from exits: up to $740M of milestones on the sale of Araris to Taiho, a contingent value right on Orchard, and milestones on a gene therapy whose trial did not show efficacy.

On 10 November 2026 Oyster Therapeutics, a London company formerly called Kesmalea, closed a $60M Series A led by 4BIO Capital, to take an oral tau degrader for Alzheimer's disease into the clinic. Eli Lilly joined as a new investor, alongside Syncona and Oxford Science Enterprises from earlier rounds.

The money behind those rounds is changing. A Form D filed on 15 July 2026 records a new vehicle, 4Bio Ventures IV LP, organised in Guernsey in 2025. Its first sale was on 12 May 2026, to one investor, for $10M, the stated minimum. The firm's two previous funds are limited partnerships organised in the United Kingdom. On its Form ADV of the same day, 4BIO reported their gross assets at $109.6M for Ventures II and $154.0M for Ventures III.

The firm earns its returns as an equity holder. Its largest disclosed exit, the sale of Araris Biotech to Taiho in 2025 for $400M upfront and up to $740M in milestones, left Araris's former shareholders, Ventures II among them, with a contingent claim on the development of three preclinical antibody-drug conjugates.

At a Glance

• What it is: a venture firm that founds, incubates and finances companies in advanced therapies and other new modalities, from seed to Series B
• Manager: 4BIO Partners LLP, London, authorised by the Financial Conduct Authority (FRN 842764) and reporting to the SEC as an exempt reporting adviser
• Founded: 2014; the founders say they have invested in the sector since 2010
• Funds: 4BIO Ventures II (first close 2019, target $150M), 4BIO Ventures III (vintage 2023, target $200M to $300M), 4Bio Ventures IV (first sale May 2026)
• Gross assets: $109.6M and $154.0M in Ventures II and III, July 2026
• Named limited partners: Children's Minnesota, Kyowa Kirin, the Development Bank of Japan, UPMC and Exor
• Owners of the manager: Andrey Kozlov and Dmitry Kuzmin, 25 to 50 per cent each, and Kieran Mudryy, 10 to 25 per cent
• Royalty book: none. The Form ADV lists two private equity funds, and no royalty or revenue-interest vehicle
• Contingent claims from exits: Araris milestones of up to $740M; an Orchard contingent value right of $1.00 a share, triggered by approval in March 2024; RetroSense milestones from 2016

A Note on Scope

4BIO does not publish returns, fund sizes at final close, or a full list of its limited partners. Fund figures in this profile come from SEC filings: two Form D notices for Ventures III, one for Ventures IV, and the Form ADV of 15 July 2026. Gross asset value on Form ADV is the value of a fund's assets, which differs from the commitments it has raised. The limited partners named below are those identified by 4BIO or by the investors themselves.

The profile treats a contingent payment on a portfolio sale as a royalty-type claim, because it pays out on a product's development rather than on the buyer's general credit. Whether 4BIO held each position at the moment a payment was triggered is not public, except for Araris, which 4BIO says was held in Ventures II.

Investment Thesis and Mandate

4BIO began as a specialist in what it called advanced therapies. When Ventures II opened in 2019, the firm described it as one of the first international venture funds investing only in cell and gene therapy, RNA-based therapy, targeted therapies and the microbiome. It planned eight to 12 companies, without a geographic limit.

Endpoints reported a plan to put 60 per cent into Europe and the rest into Japan and America, and Fierce Biotech reported that a third would go to companies 4BIO created, mostly from British universities.

The language has widened since. In 2024 releases the firm invested in "advanced therapies and other emerging technologies". In 2026 it describes itself as a specialist biotech venture firm "transforming innovative technologies into breakthrough precision therapies". Its 2025 and 2026 investments include radiopharmaceuticals at Actithera, T cell engager antibodies at Cytospire and a protein degrader at Oyster, alongside RNA and gene therapy companies.

Company creation remains central. 4BIO co-founded Trogenix with the University of Edinburgh and incubated Entact Bio before its $81M Series A. Japan is a second focus. In November 2024 4BIO became the first British venture fund certified by the Japan Agency for Medical Research and Development, whose grants let a company backed by a certified fund receive up to twice that fund's investment without dilution.

How Capital Enters and Returns

The funds are closed-ended partnerships. Ventures II and III are organised in the United Kingdom, with general partners such as 4BIO Ventures III GP LLP; Ventures IV is a Guernsey limited partnership. Interests are sold to accredited investors under Rule 506(b) of Regulation D. The minimum commitment was $500,000 in the Ventures III Form D, $5M on the Form ADV for Ventures II and III, and $10M for Ventures IV.

Capital leaves through company sales and listings. 4BIO's 2019 announcement cited the listings of Orchard Therapeutics and Seres Therapeutics and the 2016 sale of RetroSense to Allergan as exits of its earlier investments. The largest exit since is Araris. None of 4BIO's disclosed instruments is a loan, a royalty or a revenue interest.

Some exits pay in stages. Araris's sellers received $400M at closing and may receive up to $740M more. Orchard's shareholders received $16.00 a share in cash and a contingent value right of $1.00, paid on American approval of its lead gene therapy. RetroSense's sellers received $60M and rights to regulatory and commercial milestones. A fund holding such rights after an exit holds a claim on a product's progress, and the claim can outlast the fund's own investment period.

Financial Profile and Assets

Portfolio Book

The list below covers companies 4BIO has named as portfolio companies, with fund attribution where 4BIO or a database gives it.

Exited before Ventures II: Orchard Therapeutics (listed 2018; bought by Kyowa Kirin in January 2024); Seres Therapeutics (listed); RetroSense Therapeutics (assets sold to Allergan in 2016). European Biotechnology reported 15 companies in the first fund

Exited from Ventures II: Araris Biotech (seed 2020, Series A lead 2022; sale to Taiho agreed March 2025)

Ventures II and earlier, active: Ray Therapeutics (seed 2021, Series A 2023, Series B 2026); Code Biotherapeutics; SparingVision; LUCA Science; Entact Bio. Carisma Therapeutics, a named portfolio company in 2022, stopped research in 2025

Ventures III: March Biosciences (Series A lead, $28.4M, 2024); Actithera (Series A co-lead, $75.5M, 2025); NV Therapeutics (seed 2025); Trogenix (co-founded 2023)

Led or co-led in 2026, fund not stated: Cytospire Therapeutics (£61M ($83M) Series A, May); Cloverleaf Bio ($33M seed, September); Aptadir Therapeutics (€40M ($45M) seed, September); Undecimal Bio (€16M seed, October); Estuary Biotherapeutics (October); Oyster Therapeutics ($60M Series A, November)

Investors

4BIO names five limited partners. Children's Minnesota, a paediatric health system, cornerstoned Ventures II in 2019 as part of what its chief investment officer called a paediatric impact strategy. Kyowa Kirin committed up to $10M to Ventures II in June 2020, its first commitment to any venture fund, and the first by a drug company to that fund. Its integrated report notes that Orchard, which it bought for up to $477.6M, had been a 4BIO portfolio company.

For Ventures III, the Development Bank of Japan signed in January 2024, its first commitment to a British life sciences fund. 4BIO's releases since November 2024 list Children's Minnesota, UPMC, the Development Bank of Japan, Kyowa Kirin and Exor among Fund III's investors, with "many other endowments and foundations".

UPMC Enterprises, the health system's investment arm, has also co-invested in several 4BIO companies.

The Form ADV figures show a mostly non-American base: 84 per cent of Ventures II and 71 per cent of Ventures III is beneficially owned by non-American persons, and the manager and its related persons own about 2 per cent of each. Neither fund reports investment by funds of funds.

The firm also ran public equity strategies. From December 2021 it was one of the managers of the Harbor Disruptive Innovation ETF, recommending advanced therapy stocks to Harbor. Harbor removed 4BIO as subadviser on 11 July 2024 and liquidated the fund in December.

Two listed-equity vehicles, the 4BIO Advanced Therapies Long Equity Fund and an Irish ICAV, appear in earlier adviser filings with gross assets of about $0.44M each.

Governance and Team

Dmitry (Dima) Kuzmin and Andrey (Andrew) Kozlov co-founded the firm and are its managing partners. Kuzmin, a neurochemistry PhD, chairs Trogenix and sits on Ray's board, and chaired Araris when it was sold. Kieran Mudryy is partner, general counsel and chief compliance officer.

All three are named as promoters on each Form D. Owen Smith and Therese Liechtenstein are partners; Liechtenstein was promoted in March 2026 after two years as investment director, when Tetsu Maruyama, former head of drug discovery at Takeda, joined as venture partner.

The other venture partners are Philippe Fauchet in Japan, Brian McVeigh in America and Tay Salimullah. The advisory board includes Adrian Thrasher of University College London, and Abbas Hussain, a former chief executive of Vifor Pharma.

Regulatory note: 4BIO Partners LLP is registered at Companies House as OC424585, incorporated in October 2018, and its Form ADV ownership entries date from April 2021.

IP, Royalties and Return Economics

No Royalty Book

4BIO takes equity. Its adviser filing lists Ventures II and III, both classed as private equity funds, and no vehicle that buys royalties, revenue interests or credit. Its portfolio companies license and are licensed, and some have collected milestone and royalty rights from partners, but those rights sit with the companies. The fund's claim is on the shares.

The royalty-type exposure arises at exit, when a buyer pays part of the price in instalments tied to a product. Four cases show how such claims have played out for companies in the portfolio.

Araris and Taiho

Taiho, part of Otsuka, had worked with Araris since November 2023 on antibody-drug conjugates built with Araris's linker technology. In March 2025 it agreed to buy the company for $400M at closing and up to $740M in milestones, described in 4BIO's release as near-term and long-term.

Araris had raised about $44M to $45M before the sale, from investors including 4BIO, b2venture, Pureos Bioventures, Redalpine, Schroders Capital, VI Partners and Samsung Ventures. 4BIO invested at seed in 2020, led the Series A in 2022, and held the position in Ventures II.

The milestone schedule is unpublished. At signing Araris had three preclinical candidates, against CD79b, Nectin-4 and NaPi2b, expected to enter trials in 2025 and 2026. The milestones add up to 1.85 times the upfront. Their value to Ventures II depends on its share of Araris, which 4BIO has not disclosed, and on a development programme that Taiho now controls.

Orchard's Contingent Value Right

Kyowa Kirin agreed in October 2023 to pay $16.00 per American depositary share in cash plus a contingent value right of $1.00, payable on American approval of OTL-200 for metachromatic leukodystrophy in 2024.

The FDA approved it as Lenmeldy on 18 March 2024, which set the total price at about $477.6M. Whether 4BIO still held Orchard shares when the deal closed is not public. The case shows a one-step contingent claim, tied to a single approval within a year, beside Araris's multi-step schedule.

RetroSense

Allergan bought substantially all of RetroSense's assets in September 2016 for $60M upfront and regulatory and commercial milestones on RST-001, an optogenetic gene therapy for retinitis pigmentosa. The Phase 1/2a trial, renamed AGN-151597 and later run by AbbVie, is recorded as completed, with efficacy not demonstrated in the dose-escalation phase.

Ray Therapeutics, which 4BIO seeded in 2021, now develops a different optogenetic approach for the same disease.

A Royalty Sold Back: Carisma and Moderna

Carisma's 2022 collaboration with Moderna paid $45M upfront and a $35M convertible note, with milestones and royalties on any products. Moderna had nominated all 12 oncology targets by February 2025. After Carisma stopped research, the parties amended the agreement in September 2025. In return for a one-time payment of $4.0M,

Moderna has no further obligation to make payments, subject to specified exceptions. A company in wind-down exchanged its milestones and royalties on 12 programmes for a fixed sum.

Blue Team

• Gross assets of $263.6M across Ventures II and III, with audited accounts
• An exit at $400M upfront from Araris, which had raised about $45M, with up to $740M more in milestones
• Limited partners that include a pharmaceutical company, a state-owned Japanese bank and two health systems
• Four rounds led in 2026, at Cytospire, Cloverleaf, Aptadir and Oyster, with Lilly, AbbVie Ventures, Boehringer Ingelheim and Servier among co-investors
• A founding position in Ray Therapeutics through three rounds to a $125M Series B
• Certification by Japan's medical research agency, which lets portfolio companies apply for grants of up to twice 4BIO's investment
• A new fund, Ventures IV, with a first sale in May 2026

Red Team

• No published fund returns or final fund sizes; Ventures III had sold $86.6M of a $200M offering by September 2024, against a $200M to $300M target and a final close planned for 2024
• Araris milestones depend on three preclinical candidates under Taiho's control, on an unpublished schedule
• RetroSense milestones attach to a programme whose trial did not show efficacy
• Carisma, a named portfolio company, stopped research in 2025 and settled its Moderna royalties for $4.0M
• Harbor removed 4BIO as an ETF subadviser in 2024, months before liquidating the fund
• Ventures IV had one investor and $10M at its first sale
• A mandate that has moved from advanced therapies to a wider range of modalities

Implications for the Pharmaceutical Royalty and Biotech Capital Markets

For a venture fund, the contingent part of an exit price behaves like a royalty without a sales base. Araris's milestones are a capped claim on the progress of three preclinical programmes, owned by a buyer with its own priorities, and payable to a fund that may want to return capital before they fall due.

A buyer of such a claim would price it on the schedule, the acquirer's diligence obligations and any transfer restrictions, and none of these is public for Araris.

The Carisma amendment shows a royalty valued at the end of a company's life. Moderna paid $4.0M to end milestones and royalties on 12 nominated programmes. Carisma had $2.8M of cash at 30 September 2025, and Moderna had stopped funding research under the collaboration in March.

For the limited partners, Kyowa Kirin's position runs both ways. It is an investor in 4BIO's second fund and, through Orchard, a buyer of one of the firm's earlier companies.

The Development Bank of Japan's commitment and the medical research agency's certification tie 4BIO's Japanese work to state funding, a link between public grants and private returns that the CIRM profile in this series described from the grant side.

Recent Developments

• 4BIO leads Oyster Therapeutics' $60M Series A, with Lilly as a new investor, on 10 November 2026
• Undecimal Bio and Estuary Biotherapeutics raise seed rounds with 4BIO in October 2026
• 4BIO leads Aptadir's €40M ($45M) seed on 29 September 2026 and Cloverleaf Bio's $33M seed on 8 September
• 4BIO files its annual Form ADV and a Form D for Ventures IV on 15 July 2026
• Ventures IV makes its first sale, $10M to one investor, on 12 May 2026
• 4BIO leads Cytospire's £61M ($83M) Series A on 5 May 2026
• Ray Therapeutics closes a $125M Series B on 21 April 2026
• Therese Liechtenstein becomes a partner and Tetsu Maruyama joins as venture partner on 30 March 2026

Financial History and Recent Developments

Conclusion

4BIO has spent a decade building and backing companies in new therapeutic modalities, with limited partners that include a Japanese drug company, a Japanese state bank and two American health systems.

Its two funds reported $263.6M of gross assets in July 2026, and a third, domiciled in Guernsey, took its first $10M in May. It holds no royalties.

The firm's exposure to product-linked payments comes after exits. Araris's former shareholders, Ventures II among them, may receive up to $740M as three antibody-drug conjugates move through Taiho's development. In the week that 4BIO led Oyster's $60M round, no Araris milestone payment had been announced, 20 months after the sale was agreed.

All information in this report was accurate as of the research date and is derived from publicly available sources including court opinions, regulatory guidance, academic literature, SEC filings, and financial news reporting. Information may have changed since publication. This content is for informational purposes only and does not constitute investment, legal, or financial advice. The author is not a lawyer or financial adviser.