Editing Away Autoimmunity at the HLA Source

Episode Summary

Executive Summary: The episode explores Rumogen’s strategy to treat autoimmune disease by editing HLA genes, the immune system’s antigen-presenting molecules, rather than broadly suppressing immunity. CEO Richard Freed explains how the company’s “anchor editing” approach aims to silence disease-associated HLA alleles, starting with rheumatoid arthritis, with the goal of durable or potentially curative outcomes using ex vivo stem-cell editing and a lower-cost manufacturing model.

Main Topics: HLA biology and autoimmune disease (Priority: 5/5): Freed explains that HLA proteins present peptides to T cells and that certain alleles can misidentify self-proteins as threats, helping drive conditions like rheumatoid arthritis, MS, T1D, and celiac disease. Why HLA is a therapeutic target (Priority: 5/5): Rumogen’s premise is that autoimmune disease begins at the HLA–T cell interaction point; by changing the source signal, the company hopes to prevent downstream inflammation instead of managing it after it starts. Anchor editing platform (Priority: 5/5): The company shifted from allele-specific edits to a shared position-82 'anchor editing' strategy intended to reduce peptide presentation across multiple class II HLA alleles while preserving overall immune competence. Ex vivo stem-cell therapy workflow (Priority: 4/5): Rumogen collects hematopoietic stem cells, edits them in the lab, freezes and ships them back, and reinfuses them as a one-time outpatient treatment without myeloablation. Lead program in rheumatoid arthritis (Priority: 5/5): RG0401 targets the DRB0401 allele in RA, selected because of its strong HLA association and large unmet need among refractory patients who do not respond to current drugs. Regulatory, durability, and commercial strategy (Priority: 4/5): Freed says the FDA has been receptive, initial studies show no off-target effects, and the company is pursuing lower-cost manufacturing and payback economics that could make the therapy viable in common diseases. Financing and patient-organization support (Priority: 3/5): Rumogen has advanced on relatively modest funding, including a $15 million Series A and support from Beyond Celiac, which helps validate the platform and inform indication selection.

Key Arguments: Autoimmune diseases often originate from specific HLA alleles that present self-antigens as foreign; editing these alleles targets the root cause rather than downstream inflammation. A small amino-acid change deep in the HLA groove may be enough to reduce pathogenic antigen presentation without provoking immune rejection, contrary to prior immunology assumptions. Anchor editing creates a platform approach because the same edit can apply across multiple class II HLA-linked autoimmune diseases, not just one allele or one indication. Ex vivo edited hematopoietic stem cells may repopulate the immune system and create lasting tolerance, potentially making the effect durable or permanent. Rheumatoid arthritis is an attractive first indication because it is common, HLA-linked, and still leaves many patients uncontrolled despite existing therapies. The therapy is designed to avoid myeloablation and hospital-level procedures, which could improve safety, scalability, and access. Lower manufacturing costs are essential because autoimmune diseases are chronic and large-market; the company aims to compete with the lifetime cost of current care rather than rare-disease pricing. Patient groups can accelerate development by validating unmet need, shaping indication priorities, and helping de-risk novel approaches for investors and pharma.

Data Points: HLA alleles in each person: about a dozen - Freed says each person carries roughly 12 HLA alleles that make up their immune 'flavor profile'. Total HLA alleles: tens of thousands - He notes there are many HLA variants, though only a few dozen are strongly tied to autoimmune disease. HLA alleles linked to most autoimmune diseases: a few dozen - The company focuses on the subset most associated with disease susceptibility. Position targeted by anchor editing: amino acid position 82 - Rumogen’s platform alters a shared residue involved in peptide binding. Rheumatoid arthritis prevalence: about 1% of the global population - Used to justify RA as a large initial market. Patients not reaching remission on current RA drugs: 60% - Freed cites persistent inadequacy of existing therapies. Refractory RA patients: 20% to 30% - Patients who have failed multiple medications and remain difficult to treat. Patient dissatisfaction with current therapies: about 75% - Used to argue the market is ready for a step-change therapy. Initial safety/efficacy cohort: 9 to 12 RA patients - Planned first-in-human study in Australia for refractory RA patients. Seed round timing: November 2019 - Rumogen’s first funding round closed just before the pandemic. Series A size: $15 million - Announced at JP Morgan; intended to fund the first human trial. Current therapy annual cost: $50,000 to $60,000 per year - Freed contrasts chronic drug spending with the one-time gene-editing approach. Potential cost recovery period: 2 to 4 years - Company believes therapy could pay back versus ongoing autoimmune care costs.

Pivotal Quotes: "That was the Bet the Company experiment a few years back where we put human HLA into mice and did skin transplants between them. And lo and behold, you can get away with that." — Richard Freed: Describing the foundational experiment supporting the idea that subtle HLA edits may not trigger rejection. "We're not interested in incremental improvements." — Richard Freed: Explaining the company’s willingness to use the word 'cure' and its ambition to address disease at the source. "If we're the only ones that can impact what's going on at the source of the disease, that's why we think we can treat these untreatable patients and get them to a point where they can be cured." — Richard Freed: Justifying Rumogen’s curative framing for autoimmune disease.

Implications: If successful, Rumogen could shift autoimmune care from chronic suppression to one-time, potentially curative immune reprogramming. The model may also broaden gene editing into common diseases, forcing new conversations about safety, pricing, and access.