# Lassen Therapeutics: Research, San Diego, United States

> Lassen Therapeutics: Lassen Therapeutics is a clinical-stage biopharmaceutical company based in San Diego, California. Based in San Diego, United States.

Source: https://millionrounds.com/startup/lassen-therapeutics (Millionrounds; every figure on the page links to its filing or article)

United States · [Research startup](https://millionrounds.com/companies)

# Lassen Therapeutics

Lassen Therapeutics is a clinical-stage biopharmaceutical company based in San Diego, California.

Email

Funding reported Last round: Series B

Research San Diego, United States

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Company summary

- **Founded:** 2019 7 years old
- **Team:** 10 1 to 10 people
- **Funding reported:** $116M in dollars
- **Last round:** Series B Dec 2023

How sure we are

- ✓ **Listed** We know it exists and what it does
- 2 **Funding reported** A company dataset reports a raise
- 3 **Observed** A filing or a dated announcement confirms a round

No round for Lassen Therapeutics has been confirmed by a filing or an announcement yet, so nothing here counts toward an investor's record. [How we decide](https://millionrounds.com/methodology)

## About Lassen Therapeutics

Lassen Therapeutics is a clinical-stage biopharmaceutical company based in San Diego, California.

Founded in 2019, the company focuses on developing novel antibody biotherapeutics for serious diseases, particularly fibrotic, inflammatory, rare, and oncology-related conditions. Lassen is led by CEO Mark Barrett and Chief Scientific Officer David King, Ph.D., both experienced in antibody drug discovery. The company has raised $117 million in funding, including an oversubscribed $85 million Series B round completed in December 2023. Lassen Therapeutics is advancing its product pipeline with lead candidates such as LASN-01, a fully human monoclonal antibody targeting the IL-11 receptor, currently in a Phase 1 trial for Thyroid Eye Disease. Another candidate, LASN-500, is in early development for oncology applications. The company aims to address unmet medical needs in fibrotic diseases and cancer, leveraging advanced antibody technologies to improve patient outcomes.

## What company datasets say Lassen Therapeutics raised

Funding, as reported

Reported in all **$116M** in dollars

Rounds **2**

Last round **Series B**

Last round size **$85M**

Last round date **Dec 2023**

Investors listed **8**

## On 3 portfolio pages

Investors who name them

- [Alta Partners](https://millionrounds.com/fund/alta-partners)
- [Longitude Capital](https://millionrounds.com/fund/longitude-capital)
- [DC Investment Partners](https://millionrounds.com/fund/dc-investment-partners)

Each firm lists Lassen Therapeutics on its own website. That is the firm's claim, a weaker thing than a round we watched, but a named source.

## The company, in detail

What they build

Known for

health care immune signaling biotechnology research il-11 patient-focused fibrotic disease models antibody technologies innovative biology industry-leading platforms monoclonal antibody il-11r blockade targeted cytokine therapy hospital & health care medical il-11 pathway inhibitor biotherapeutics

Built with from their website

WP Engine Microsoft Exchange MySQL Microsoft 365 Apps & Services GoDaddy Domains Wordpress Microsoft Exchange Online Microsoft 365 Outlook PHP

+2 more

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- **Sector:** Research
- **Industry code:** NAICS 541714, 325414, SIC 2834, 8731, 2836
- **Region:** California
- **Revenue:** $3.3M a year, as listed
- **Full record:** [Every detail in the company directory](https://millionrounds.com/directory/lassen-therapeutics)

## Research in United States

Startups like it

- [**OpenAI** San Francisco · founded 2011 *Raised*](https://millionrounds.com/company/openai)
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- [**Pathos** New York · founded 2022 *Raised*](https://millionrounds.com/company/pathos)
- [**Colossal Biosciences** Dallas · founded 2021 *Raised*](https://millionrounds.com/company/colossal-biosciences)
- [**Beeline Medicines** Stamford · founded 2025 *Raised*](https://millionrounds.com/company/beeline-medicines)
- [**Oratomic** South Pasadena *Raised*](https://millionrounds.com/company/oratomic)
- [**Element Biosciences** San Diego · founded 2017 *Raised*](https://millionrounds.com/company/element-biosciences)

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