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Inhibrx Biosciences
Mark Lappe's Inhibrx Biosciences spun out in 2024 to advance a clinical oncology pipeline built on a proprietary single-domain antibody platform.
Inhibrx Biosciences
Inhibrx Biosciences, Inc. is a clinical-stage biotechnology company founded by Mark Lappe and Brendan Eckelman, based in La Jolla, California. The firm develops biologic therapeutics using its proprietary single-domain antibody (sdAb) platform. The platform allows for the genetic fusion of multiple sdAbs into one molecule, combined with a human Fc domain, enabling generation of multivalent and multispecific therapeutic candidates with optimized target binding that conventional monoclonal antibodies cannot easily replicate. The firm's strategy concentrates on engineering differentiated biologics across oncology and orphan diseases. Its pipeline includes INBRX-109, a tetravalent DR5 agonist currently in registrational trials for chondrosarcoma and pancreatic adenocarcinoma. INBRX-101, an Fc-fused mutant AAT, is in development for alpha-1 antitrypsin deficiency. The platform has also generated INBRX-106, a hexavalent OX40 agonist being tested in multiple solid tumor types, and INBRX-105, a conditional bispecific targeting PDL1 and 4-1BB. In each case, the engineering goal is enhanced target clustering and conditional activation to reduce systemic toxicity. In May 2024, the firm completed a corporate restructuring, spinning its INBRX-101 program into a new entity, Inhibrx Biosciences, Inc., while the legacy parent was acquired by Sanofi. The Sanofi deal, announced in January 2024, valued the original company at approximately $2.2 billion, with the acquirer taking INBRX-101 into Phase 2 and retaining the platform for future programs. The restructured Inhibrx Biosciences retained INBRX-109, INBRX-106, and INBRX-105, and received $200 million in cash to advance its oncology pipeline. The structural differentiator for Inhibrx Biosciences lies in its post-spinout positioning as a focused oncology pure-play with a validated platform but a leaner operational profile. Unlike many biotech spinouts that license a single asset, the firm retains a multi-program pipeline targeting high-unmet-need cancers, armed with cash to reach key clinical readouts without immediate public-market financing pressure. The staggered mechanism of action across its DR5 and OX40 programs creates a portfolio effect within a single engineering platform, a governance structure unusual for a company of its post-spin scale.
General information
Firm type
Asset Manager
Year founded
—
AUM
Undisclosed
Location
Region
North America
Country
United States
City
La Jolla
Corporate office
La Jolla, CA, United States
Principals
Mark Lappe
CEO
Sector focus
Frequently asked questions
What is Inhibrx Biosciences' relationship to the original Inhibrx, Inc.?
Inhibrx Biosciences was created through a corporate spinout in May 2024 after Sanofi acquired the original parent company, Inhibrx, Inc. Sanofi retained the INBRX-101 program for alpha-1 antitrypsin deficiency and access to the sdAb platform, while Inhibrx Biosciences emerged as an independent public company with INBRX-109, INBRX-106, INBRX-105, and $200 million in operating capital.
How does the single-domain antibody platform work?
The sdAb platform engineers small antibody fragments derived from heavy-chain-only antibodies. These fragments are genetically fused to a human Fc domain in multivalent arrangements, allowing the resulting drug candidates to bind multiple targets or multiple sites on a single target. The platform can tune valency — tetravalent for DR5, hexavalent for OX40 — to achieve specific receptor-clustering pharmacology not possible with standard IgG antibodies.
What is the lead oncology program?
INBRX-109 is a tetravalent DR5 agonist in registrational trials for chondrosarcoma, a rare bone cancer, and in Phase 1/2 for pancreatic adenocarcinoma. The tetravalent design is intended to supercluster DR5 receptors to trigger tumor cell apoptosis while avoiding hepatotoxicity seen in earlier bivalent DR5-targeting antibodies from other developers.
What is the cash position and runway?
The firm received $200 million in cash at spinout in May 2024. This is intended to fund operations through key clinical readouts without requiring immediate dilutive financing.
What was the structure of the Sanofi transaction?
Announced in January 2024 and closed in May 2024, Sanofi acquired Inhibrx, Inc. for $30 per share in cash, plus a contingent value right tied to future regulatory milestones, valuing the company at approximately $2.2 billion. As part of the transaction, shareholders received stock in the newly formed Inhibrx Biosciences, which retained the non-INBRX-101 pipeline.
Which indications does the pipeline target?
The pipeline targets chondrosarcoma, pancreatic adenocarcinoma, and several solid tumor indications. INBRX-106 is being evaluated in combination with pembrolizumab across multiple tumor types. INBRX-105 targets PDL1 and 4-1BB conditionally to direct immune activation only within the tumor microenvironment.
Who runs investment decisions at Inhibrx Biosciences?
As a publicly traded biotech company, capital allocation is governed by the board and executive team led by CEO Mark Lappe. The firm is not an investment vehicle — it is an operating biotechnology company. Decisions about trial funding, partnership economics, and equity raises follow standard public-company governance.
Profile maintained by Altss using OSINT (open-source intelligence), regulatory filings, licensed data partners, and verified direct submissions. Read the methodology. Last updated: . Continuous refresh with full update cycles at least every 30 days.
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