For millennia, parasites have been evolving sophisticated mechanisms to live inside us undetected. Helminths colonize the gut for years. Viruses commandeer our cellular machinery without setting off alarms. Ticks gorge themselves for days, suppressing inflammation at the bite site with molecular finesse. Each has spent millennia honing exquisite tools to evade, dampen, or redirect the human immune system—tools that, a growing number of biotech entrepreneurs believe, could treat the approximately 15.44 million Americans (4.6% of the U.S. population) struggling with autoimmune disease.
The idea borders on poetic irony: weaponizing the very organisms that have plagued humanity to calm the immune system when it turns on itself. But unlike the live-worm therapies that flamed out a decade ago, this new wave of startups is doing something different. They're mining the parasite proteome for nature's own immune modulators, then engineering them into drugs—refined molecules, not squirming infections.
It's a gambit that carries echoes of the hygiene hypothesis, which holds that our modern, sanitized lives may have left immune systems untrained and prone to misfiring. But this time, there's no talk of deliberately infecting patients with hookworm. Instead, computational biology and AI are sifting through millions of parasite proteins to find the ones that could work in a vial.
Whether this represents a genuine breakthrough or just another clever research angle destined to stumble in the clinic is the question investors, regulators, and patients are now beginning to ask.
A Market in Flux
The autoimmune therapy market is undergoing something of an identity crisis. Biosimilars have upended the economics through a complex process of regulatory approval and competitive market dynamics. By late 2024, adalimumab copycats had seized roughly a fifth of Humira's U.S. market share following major formulary shake-ups—CVS notably dropped the blockbuster from coverage in April 2024, catalyzing a biosimilar prescribing surge. Ustekinumab biosimilars followed in 2025. The days of unchallenged $20 billion franchises may be waning.
At the same time, the FDA continues greenlighting targeted biologics with narrower, more precise mechanisms. Inebilizumab (UPLIZNA) picked up approvals for IgG4-related disease and generalized myasthenia gravis in 2025. Sibeprenlimab (VOYXACT) won accelerated approval for IgA nephropathy in November that year. The regulatory mood seems receptive to innovation, provided the data holds up.
But the more profound shift, perhaps, is philosophical. An AP News feature in November 2025 quoted Johns Hopkins clinicians describing a "new era" in autoimmune treatment—one focused on reprogramming the immune system and inducing tolerance, rather than suppressing it indefinitely with blunt instruments. CAR-T therapies that wipe out autoreactive B cells (Kyverna's KYV-101 is now in Phase 2/3 across multiple indications) and nanoparticle platforms designed to teach the immune system to tolerate specific antigens (Cour Pharmaceuticals published mechanistic results in Science Advances in January 2026) are the vanguard of this thinking.
The NIH, for its part, signaled federal alignment. In July 2025, it launched an Office of Autoimmune Disease Research and released the first NIH-Wide Strategic Plan for Autoimmune Disease Research, spanning fiscal years 2026 through 2030. Translation: funding is flowing toward autoimmune science in ways it hasn't before.
The Biological Rationale
The scientific case for parasite-inspired drugs rests on well-documented immune evasion tactics. Helminths, for instance, induce regulatory T cells—the immune system's peacekeepers—and reprogram dendritic cells to adopt tolerogenic profiles that tamp down inflammation. They modulate Th1, Th17, and Type 2 immune pathways through a cocktail of secreted proteins. Recent reviews in the Annual Review of Immunology (published in early 2024) and FEMS Microbiology Reviews (September 2024) catalog these strategies in painstaking molecular detail.
Some of these molecules have what drug developers call "drug-like properties." Hp-TGM, a protein from the nematode Heligmosomoides polygyrus, mimics TGF-β—a master immune regulator—and binds mammalian TGF-β receptors, potently inducing regulatory T cells. The twist? It's structurally nothing like native TGF-β. HpARI and HpBARI, from the same organism, suppress IL-33 signaling, a key alarm pathway implicated in allergy and autoimmune flares. Viral TNF inhibitors from the poxvirus family bind their targets with picomolar affinity—orders of magnitude tighter than clinical antibodies like etanercept, a blockbuster rheumatoid arthritis drug they happen to share a mechanism with. Tick-derived evasins neutralize chemokines, blunting the recruitment of inflammatory cells to injury sites.
The failures of live-helminth therapy illustrate precisely why extracting defined molecules matters. Around 2013, clinical trials of Trichuris suis ova—pig whipworm eggs—in inflammatory bowel disease largely flopped in Phase 2, and programs were shelved. A 2014 Cochrane review concluded the evidence for live-worm efficacy was weak. The biological concept wasn't necessarily wrong; the execution was impossible. Dosing variability, infection risks, and the inability to control pharmacokinetics doomed the approach.
Now, computational biology is changing the calculus. Structural proteomics tools like Foldseek, published in 2023, enable proteome-wide similarity searches at scale. Generative protein design models are producing novel binders with purported low immunogenicity—multiple preprints from 2025 on Latent-X and related architectures make such claims. These technologies theoretically make it feasible to screen millions of parasite proteins, identify those targeting human immune pathways, and engineer out undesirable properties like T-cell epitopes that trigger anti-drug antibodies.
Theoretically.
The Startups
Ditto Biosciences, a three-person team that emerged from Y Combinator's Winter 2026 batch, embodies this computational bet. The founders—Dennis Sun (CEO, with a Harvard undergrad degree and UC Berkeley PhD in computational/evolutionary biology, previously chief of staff at an undisclosed biotech reportedly valued around $500 million), Adair Borges (CSO, UCSF PhD, former UC Berkeley Miller Fellow with an extensive publication record and co-inventor of anti-CRISPR systems), and Emily Weiss (CTO, UCSD PhD with stints at DuPont and Illumina)—bring credentials in structural biology and AI-driven protein discovery.
On their Y Combinator launch page earlier this year, Ditto claimed to have analyzed over a million parasite proteins and generated early binders with affinities in the single-digit nanomolar range. In a March 2, 2026 blog post, the founders described "MoleculeMapper," a platform they say mapped roughly 10,000 viral proteins to human targets. One validation case: the system allegedly rediscovered viral TNF inhibitors that share etanercept's mechanism, citing a 2006 paper on picomolar viral binders. A LinkedIn post from a collaborator around a month before mentioned a parasite molecule binding "a key autoimmune target with single-digit nanomolar affinity" and exhibiting multispecificity—targeting more than one immune pathway simultaneously.
Ditto is also assembling a tissue biobank to map real-world immune memory to parasite proteins, a move aimed at designing around immunogenicity from the start. It's a critical concern for biological mimics, which can provoke immune responses even if evolution has "road-tested" the original parasite protein in human hosts.
The company says it's targeting rheumatoid arthritis, inflammatory bowel disease, multiple sclerosis, systemic lupus erythematosus, and Type 1 diabetes—an ambitious spread for a team that, as of late March 2026, had disclosed no funding beyond Y Combinator's standard check and no preclinical IND timelines. Enthusiastic, maybe. Proven? Not yet.
Holoclara, based in Pasadena, has moved further along. The company raised a $16 million Series A in June 2024 to advance worm-derived therapies. Their lead candidate, HC002, is an oral small molecule inspired by helminth immunomodulators. Holoclara dosed its first patient in a Phase 1 trial for eosinophilic esophagitis in late 2024. The pitch: synthesize worm-inspired molecules to preserve immunomodulatory effects while avoiding the infection risks that torpedoed live-worm programs.
Other players remain in earlier or less visible stages. Paragen Bio, an Australian spinout focused on hookworm proteins, and Macrobiome Therapeutics, positioning itself around hookworm-derived biologics for chronic wounds and IBD, have surfaced in company databases but offer scant recent public updates. ES-62, a molecule derived from the parasitic nematode Acanthocheilonema viteae, has generated a body of evidence in arthritis models since 2013, with small-molecule analogs showing anti-inflammatory activity and epigenetic effects on synovial fibroblasts (Journal of Medicinal Chemistry, 2013; mechanistic updates through 2024). Yet none has reached the clinic with headline-grabbing data.
The Translational Gauntlet
The hurdles are considerable, and immunogenicity tops the list. Even if a parasite protein has been "validated" by millions of years of evolution in human hosts, therapeutic dosing, routes of administration, and chronic exposure differ vastly from natural infection. FDA guidance on immunogenicity assessment for therapeutic proteins—issued in 2014 and still active—requires robust, risk-based strategies, including evaluation of neutralizing antibodies and T-cell epitopes. For biological mimics, integrated summaries of immunogenicity data will face intense scrutiny.
Ditto's tissue biobank approach—mapping pre-existing immune memory to guide protein engineering—represents one attempt to navigate this minefield. Computational de-immunization, informed by structural epitope prediction and donor panel screening (demonstrated in recent preprints on antibody design), offers another. But clinical proof remains elusive.
Market dynamics add another layer of complexity. The autoimmune landscape is crowded with potent, established drug classes: IL-17 and IL-23 inhibitors in dermatology and gastroenterology, JAK inhibitors across multiple indications, and a rising wave of cell therapies. Payer pressure from biosimilars—intensified by formulary shifts like CVS's Humira exclusion—demands clear differentiation in efficacy, safety, durability, or convenience. A parasite-derived biologic will need to outperform not just legacy antibodies but also lower-cost biosimilars and emerging cellular approaches.
The strategic opportunity, proponents argue, lies in mechanistic novelty. Parasite proteins access immune pathways—TGF-β receptor agonism without TGF-β's structure, IL-33 pathway suppression, multispecific targeting—that may offer durability or tissue-selectivity advantages conventional antibodies can't match. If Ditto or its peers can demonstrate a molecule that resets immune tolerance rather than chronically suppressing inflammation, the clinical and commercial differentiation could be meaningful.
Perhaps.
Investor appetite appears present, at least for now. DealForma's H1 2025 review highlighted autoimmune disease as a strength area in biopharma partnerships, with deals emphasizing AI-driven discovery and targeted biologics. IQVIA's January 2026 outlook cited immunology as a priority alongside oncology and cardiovascular/metabolic diseases. BioPharma Dive's February 2026 trends piece noted that after a challenging 2023–2024 financing period, momentum improved in 2025, with immunology singled out for continued strategic interest.
Proof in the Clinic
What remains to be seen is execution. Ditto's platform claims—10,000 viral proteins mapped, nanomolar binders, immune memory biobanking—are intriguing, but the company is pre-seed, pre-IND, and operating in a field where preclinical enthusiasm has often met clinical disappointment. Holoclara's Phase 1 data, expected sometime around now or in the coming months, will offer the first human signals for this modality class. Regulatory receptivity to novel immune targets (UPLIZNA's 2025 expansions, VOYXACT's accelerated approval) suggests pathways exist for well-validated approaches with strong biomarkers.
The next 18 to 24 months will clarify whether mining parasites for cures is a sustainable investment thesis or an elegant research concept that stumbles in the messy realities of human biology. For now, the convergence of evolutionary genomics, structural AI, and a federal strategic plan elevating autoimmune research has created a window. Whether Ditto and its peers can translate millions of years of parasite evolution into safe, effective, and commercially viable drugs is the essential question.
Evolution gave parasites extraordinary tools to manipulate the human immune system. Whether biotech can borrow those tools without inheriting the parasites' other baggage—immunogenicity, variability, unpredictability—will determine if this is the beginning of a new therapeutic class or just another detour on the long road to treating autoimmune disease.
