Firefly Bio

Private

#KRAS-Mutant Solid Tumors #Antibody-Drug Conjugates #Site-Specific Bioconjugation #Pancreatic Cancer #Colorectal Cancer #Non-Small Cell Lung Cancer

Firefly Bio is a clinical-stage bioconjugate and antibody-drug conjugate (ADC) company leveraging chemistry pioneered by Nobel laureate Carolyn Bertozzi to develop next-generation ADCs targeting KRAS-mutant and other solid tumors. Its lead programs combine site-specific bioconjugation with tumor-selective payload chemistries designed to widen the therapeutic index versus first-generation ADC platforms.

Company Info

Sector: Biotechnology / Antibody-Drug Conjugates (Oncology)

Headquarters: Watertown, Massachusetts, USA

Founded: 2015

Website: fireflybiologics.com/

Funding Round: Acquired by Johnson & Johnson (June 2026)

Total Funding: Acquired for up to $1B by J&J; prior private funding undisclosed

Funding & Investor Relations

IPO Outlook / Plans

Was on a path toward a potential standalone public listing prior to the J&J acquisition announcement in June 2026.

Upcoming Milestones & Key Dates

H2 2026

Corporate

Expected close of Johnson & Johnson acquisition (subject to regulatory approvals)

Late 2026 / 2027

Regulatory

FF-101 IND filing post-J&J integration

Clinical Development Pipeline

FF-101

Target: Anti-KRAS G12D antibody with site-specific topoisomerase 1 payload

KRAS G12D-mutant solid tumors (pancreatic, colorectal, NSCLC)

Preclinical

Phase 1

Phase 2

Phase 3

Approved

FF-201

Target: Anti-KRAS G12C antibody with MMAE payload (Bertozzi chemistry)

KRAS G12C-mutant NSCLC and other solid tumors

Preclinical

Phase 1

Phase 2

Phase 3

Approved

Undisclosed ADC programs

Target: Site-specific bioconjugate platform; targets undisclosed

Solid tumors (multiple undisclosed targets)

Preclinical

Phase 1

Phase 2

Phase 3

Approved

J&J Makes $1B Move for Firefly Bio, Carolyn Bertozzi's Twist on ADCs in the KRAS Field ↗

Johnson & Johnson agreed to acquire Firefly Bio for up to $1 billion, gaining an antibody-drug conjugate platform that applies chemistry pioneered by Nobel laureate Carolyn Bertozzi to the KRAS-mutant cancer field, one of the most competitive targets in oncology.

Leadership Team

Scott Hirsch

Co-Founder and Chief Executive Officer

Carolyn Bertozzi

Scientific Co-Founder (Nobel Laureate, Stanford)

To be announced

Chief Medical Officer (incoming post-J&J integration)

Careers & Job Openings

See all open roles

Multiple Departments

See careers page

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