Lassen Therapeutics is developing first-in-class monoclonal antibodies, including LASN01 (an IL-11R blocker) for fibro-inflammatory disorders such as thyroid eye disease (TED) and IPF, and LASN500 (an IL-18BP blocker) for cancer. LASN01 showed preclinical activity in orbital fibroblasts from TED patients, suppressing hyaluronan production, cell proliferation, and procollagen, and completed a Phase 1 study in healthy volunteers with a favorable safety profile, pharmacokinetics, and target engagement. The company has expanded the Phase 1 program into patient cohorts for TED and IPF and has dosed the first patient in the TED cohort. Lassen received US IND clearance and a UK MHRA CTA and is initiating and expanding a Phase 2 program in TED in the US and ex‑US. Proceeds from an oversubscribed $85 million Series B will support the LASN01 clinical programs and advance IND-enabling activities for LASN500. The company has also initiated process development for a subcutaneous formulation of LASN01 and added board members concurrent with the financing. Lassen Therapeutics emerged from stealth to develop antibodies as potential treatments for fibrosis, rare diseases and oncology. The company’s lead candidate, LASN01, is described as a best-in-class monoclonal antibody targeting IL-11 receptor alpha (IL-11R). Lassen acquired human anti-IL-11R antibodies from CSL Limited to accelerate development and has partnered with FUJIFILM Diosynth Biotechnologies to streamline antibody production for clinical trials. The company was founded in 2019 and was formed as part of Frazier Healthcare Partners’ company creation efforts. Leadership includes co‑founders Mark Barrett (CEO) and David King, Ph.D. (CSO), and the team reports collective experience bringing more than twenty antibody therapeutics into the clinic with several products on the market. Lassen plans to rapidly advance LASN01 and build a pipeline of novel antibodies toward clinical evaluation.

Total raised

$116M

Funding rounds

2

Latest round

Series B

Latest activity

Dec 2023