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§ Private Profile · 124 Washington Street, Ste. 101, Foxboro, MA 02035
Biotech company developing small-molecule cancer therapies for solid tumor patients, focused on translation regulation pathways.
Based in Solana Beach, California, Effector Therapeutics was a clinical-stage biopharmaceutical company that developed small-molecule cancer therapies targeting translation regulation pathways to enhance checkpoint inhibitor efficacy in solid tumors. The enterprise advanced clinical candidates like tomivosertib and zotatifin, supported by substantial private financing that included a $45 million Series A round and a $56 million Series C round. In 2021, the firm transitioned to public markets through a SPAC merger on the NASDAQ exchange, generating approximately $61.5 million in gross proceeds to fund ongoing oncology research. Prior to ceasing operations in February 2025, the business established strategic development partnerships with major pharmaceutical entities, notably securing a collaboration agreement with Pfizer before co-founder Siegfried Reich departed for Turning Point Therapeutics. Effector Therapeutics was founded in 2012 by Stephen Worland, Kevan Shokat, Davide Ruggero, Gary Ruvkun, and Siegfried Reich.
Effector Therapeutics has raised $140.0M across 4 funding rounds.
Effector Therapeutics has raised $140.0M in total across 4 funding rounds.
Effector Therapeutics has raised $140.0M across 4 funding rounds. Most recently, it raised $39.0M Series C in July 2017.
| Date | Round | Lead Investors | Other Investors | Status |
|---|---|---|---|---|
| Jul 1, 2017 | $39M Series C | — | Sofinnova Investments, AbbVie Ventures, Abingworth, Alexandria Venture Investments, Astellas Venture Management, Biomed Ventures, Novartis, Sectoral Asset Management, SR ONE, The Column Group, U.S. Venture Partners | Announced |
| Feb 1, 2016 | $16M Series B | Maha Katabi, Phd, CFA | Sofinnova Investments | Announced |
| Dec 1, 2015 | $40M Series B | — | ED Mathers, Omega Funds, Osage University Partners | Announced |
| May 1, 2013 | $45M Series A | — | ED Mathers, Omega Funds, Osage University Partners, KEN Haas, Astellas Venture Management, Markus Goebel, Mission BAY Capital, Simeon George, Larry Lasky | Announced |
Effector Therapeutics has raised $140.0M in total across 4 funding rounds.
Effector Therapeutics's investors include Sofinnova Investments, AbbVie Ventures, Abingworth, Alexandria Venture Investments, Astellas Venture Management, BioMed Ventures, Novartis, Sectoral Asset Management, SR One, The Column Group, U.S. Venture Partners, Maha Katabi, PhD, CFA.
eFFECTOR Therapeutics, Inc. (EFTR) was a clinical-stage biopharmaceutical company headquartered in Solana Beach, California, focused on developing a novel class of oncology drugs called Selective Translation Regulator Inhibitors (STRIs) to target cancer signaling pathways.[1][2][3] The company aimed to address unmet needs in cancer treatment through innovative therapies like tomivosertib (MNK1/2 inhibitor for non-small cell lung cancer, Phase 2), zotatifin (eIF4A inhibitor for solid tumors, Phase 1/2), and others targeting CDK4, eIF4E, and related mechanisms.[3] It served oncology patients and researchers by advancing precision medicine, but ceased operations, with its website now stating it is no longer active.[4]
Growth momentum stalled amid challenges, reflected in stock performance showing a 52-week high of $0.16, recent close at $0.00, and zero market capitalization as of mid-2025 data.[2] No recent SEC filings are available, signaling wind-down.[1]
eFFECTOR Therapeutics emerged as a biotech firm pioneering STRIs for oncology, formerly operating under the name Locust Walk Acquisition Corp. before rebranding.[2] Key details on specific founders are not detailed in available sources, but the company built traction through clinical trials starting around 2021, including tomivosertib (initiated June 2021), zotatifin studies (March 2023), and collaborations like with Stanford University.[3] Pivotal moments included advancing multiple small-molecule drugs into Phase 2 for cancers like non-small cell lung cancer and ER-positive endometrial carcinoma, alongside earlier approvals like one in 2017 for an eIF4A inhibitor.[3]
Based initially in Solana Beach, CA, it shifted focus to rigorous clinical development in tumor growth pathways, but ultimately discontinued operations, redirecting inquiries to EFFECTOR@vlpc.com.[4]
eFFECTOR rode the wave of precision oncology, targeting translation regulation in cancer—a trend amplified by advances in molecular targeting post-2020, amid rising demand for pathway-specific therapies in immuno-oncology and solid tumors.[1][3] Timing aligned with booming biotech investment in STRIs during early 2020s, fueled by successes in CDK4/6 and eIF4A inhibitors, but market forces like clinical setbacks, funding droughts, and high failure rates in Phase 2 oncology trials likely contributed to its closure.[2][4]
It influenced the ecosystem by validating STRIs through trials and collaborations, contributing data to broader research on tumor signaling, even if short-lived—exemplifying risks in clinical-stage biopharma where 90%+ attrition is common.[3]
With operations ceased, eFFECTOR's legacy lies in its STRI pipeline advancements, potentially licensing assets like tomivosertib or zotatifin to acquirers amid ongoing oncology M&A trends.[3][4] Rising AI-driven drug discovery and combination therapies could revive its molecules, but as a defunct entity, influence is archival. Trends like bispecifics and ADCs may overshadow STRIs unless repurposed, tying back to its origins as a bold precision medicine bet that highlighted biotech volatility.[1][2]