hC Bioscience

hC Bioscience, Inc. is a Cambridge, Massachusetts biotechnology company founded in 2021 to develop tRNA-based therapeutics aimed at protein dysfunction in genetically defined diseases. Its lead platform used engineered transfer RNAs to address diseases caused by nonsense mutations, also described as premature termination codons (PTCs), where a premature stop signal prevents production of a full-length, functional protein. The company described the approach as "precision protein editing" and stated that a single tRNA therapy could potentially treat many diseases regardless of the affected gene or the location of the mutation, and that genetically defined conditions account for 10-15% of all human disease.

Reported program focus varies across sources. Company materials from 2022 cited lead drug candidates in cancer and genetic disease, with delivery of tRNA both locally and systemically. Secondary profiles list programs or areas of interest including severe hemophilia A (restoration of full-length Factor VIII), Duchenne muscular dystrophy, Dravet syndrome, cystic fibrosis, and oncology indications involving loss of tumor suppressor function. Leadership named in sources includes Leslie Williams as co-founder, president, CEO and director, Steven Gillis as chairman of the board, and, per one aggregator profile, Michael Koeris as co-founder and chairman and John Ripple as co-founder and CSO.

A Fierce Biotech feature published October 31, 2025 reported that the company, referred to there as HC Bioscience, had shut down after early preclinical data on its transfer RNA treatment for hemophilia A, concluding that the challenges of pioneering a new class of medicines were too great.

Founding story

Sources give differing accounts of founding. One aggregator states Leslie Williams founded the company in 2021 based on the idea that tRNA-based protein editing could functionally reverse disease-causing nonsense mutations; the same source describes the company as arising from academic research on tRNAs and engineered anticodons that alter how ribosomes translate specific codons. A company press release refers to Leslie Williams as co-founder, director and CEO, and another profile names Michael Koeris and John Ripple as co-founders.

Business model

Venture-funded therapeutics developer. The company pursued preclinical drug discovery and development on its own engineered-tRNA platform, financed by equity rounds from biotech venture investors and corporate venture arms, with value expected to come from advancing proprietary drug candidates toward clinical trials rather than from near-term product revenue.

No revenue is reported in any source; a financial data profile shows no disclosed revenue, gross profit, or net income figures for 2020-2024.

Traction

Traction reported in sources is preclinical: in vitro and in vivo proof-of-concept for restoring Factor VIII in hemophilia A models, public disclosure of lead programs, preclinical data presented at ASGCT, and preparation for IND-enabling studies. No clinical trials, revenue, or partnerships with disclosed economics are reported. Total disclosed funding was $40 million across two rounds.

Latest developments

The most recent source, a Fierce Biotech special report dated October 31, 2025, lists the company among biotechs that shut down in the preceding twelve months, attributing the decision to disappointing early preclinical data for its transfer RNA treatment for hemophilia A and the difficulty of pioneering a new class of medicines. Prior to that, secondary profiles report in vivo delivery data for Factor VIII restoration in the liver, a 2024 rebrand, and preparation for IND-enabling work.