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Interleukins — a group of signaling proteins that help immune cells communicate — have long been recognized as powerful tools in modulating immune responses. Over the years, companies have explored interleukin as treatments for cancer, autoimmune conditions, and inflammatory diseases. But while some interleukin-based drugs have reached the market, many early attempts were held back by toxicity and a lack of precision.
Today, that’s starting to change. Advances in protein engineering, mRNA technology, and cell-targeted delivery have opened up new ways to harness interleukins more safely and effectively. Big pharma is already active in this space, but a growing number of smaller biotech companies are helping to push the field forward.
In this list, we take a look at some of the most interesting biotech companies and emerging players developing interleukin therapeutics.
Table of contents
Ankyra Therapeutics
- Headquarters: Cambridge, Massachusetts
- Founded: 2019
- Recent News: Presented preliminary phase 1 clinical data for ANK-101 at the AACR Annual Meeting
Ankyra Therapeutics is a biotech developing anchored immunotherapies aimed at enhancing the therapeutic window of cytokine-based treatments. The company’s lead candidate, ANK-101 (tolododekin alfa), is an interleukin-12 (IL-12) cytokine anchored to aluminum hydroxide, designed for localized delivery to tumors.
ANK-101 employs Ankyra’s proprietary Anchored Immunotherapy Platform, which involves fusing IL-12 with an alum-binding peptide, allowing the complex to bind to aluminum hydroxide (Alhydrogel). This formulation is administered intratumorally, creating a depot that retains IL-12 within the tumor microenvironment for several weeks to enhance local immune activation while minimizing systemic exposure and associated toxicities.
The ongoing phase 1 ANCHOR trial comprises two parts: Part 1 focuses on patients with superficially accessible tumors, while part 2 includes patients with visceral tumors accessible via interventional procedures.
Preliminary data from part 1, presented at the 2025 AACR annual meeting, indicated that ANK-101 was well-tolerated and increased CD8+ T cell infiltration and PD-L1 expression within the tumor microenvironment, resulting in a robust local immune activation.
Asher Bio
- Headquarters: South San Francisco, California
- Founded: 2019
- Recent news: Announced a clinical trial collaboration to test its IL-2 candidate AB248 alongside a bispecific T-cell engager for small cell lung cancer
Asher Bio is developing a new generation of cytokine therapies designed to eliminate the broad and often toxic effects that have limited their success so far. The company’s approach, which it calls “cis-targeting,” is all about control: by engineering cytokines to only act when bound to a specific immune cell type, Asher hopes to deliver the full immune-stimulating potential of interleukins without setting off unintended damage elsewhere in the body.
IL-2 has long been seen as a powerful immune activator, but its clinical use has come with a cost. Traditional IL-2 therapies can amplify not just cancer-fighting CD8+ T cells but also regulatory T cells and NK cells, leading to dangerous side effects and counterproductive immune responses. Asher’s lead candidate, AB248, is a version of IL-2 designed to avoid that problem. The molecule is fused to a targeting antibody fragment that locks it onto CD8+ T cells and leaves other populations largely untouched.
AB248 is currently in a phase 1a/1b clinical trial in patients with advanced solid tumors, including melanoma, non-small cell lung cancer, renal cell carcinoma, and head and neck cancers. The trial is testing the drug both alone and in combination with pembrolizumab. Early results showed immune activation in tumors and tolerability that compares favorably to older IL-2 therapies.
That same year, Asher published preclinical data in Cancer Discovery, showing that AB248 helped restore activity in exhausted T cells — a common roadblock in cancer immunotherapy. This helped build the case for using the drug as part of combination regimens, particularly in tumors that have failed to respond to checkpoint inhibitors alone.
In January 2025, Asher took this one step further by launching a collaboration to test AB248 alongside a bispecific T-cell engager in small cell lung cancer.
Coya Therapeutics
- Headquarters: Houston, Texas
- Founded: 2018
- Recent news: Shared interim results about its lead candidate in frontotemporal dementia.
Coya Therapeutics is taking a different path into cytokine therapy, using low-dose IL-2, not to attack cancer, but to calm the immune system in neurodegenerative diseases. The company’s work focuses on frontotemporal dementia (FTD), a condition with few treatment options and growing recognition of the role inflammation may play in its progression.
Coya’s lead program, COYA 302, combines two immunomodulators: low-dose IL-2, which is known to boost regulatory T cells (Tregs), and CTLA4-Ig, a fusion protein that tones down overactive immune responses. The idea is to restore balance in the immune system, not by suppressing it broadly, but by nudging it toward a more regulated, anti-inflammatory state. In FTD and other neurodegenerative diseases, this could help slow or prevent damage driven by chronic inflammation in the brain.
The company’s open-label trial enrolled patients with mild to moderate FTD. According to interim data, the treatment was well tolerated and appeared to increase the number and function of Tregs in the blood. More importantly, patients showed little or no cognitive decline during the study, a notable outcome in a disease that typically progresses steadily.
Cytokine therapies haven’t historically played a big role in neurodegeneration, but Coya is making a case that low-dose IL-2, paired with a targeted immune blocker, could offer a new way to slow these complex diseases. It’s an unconventional approach that shifts cytokine therapy from attack to repair, and could open the door to a new class of immune-modulating treatments for the brain.
Granite Bio
- Headquarters: San Francisco, California and Basel, Switzerland
- Founded: 2025
- Recent news: In April 2025, Granite Bio launched with $100 million in financing
Granite Bio emerged from stealth just a month ago with $100 million in funding and a focus on antibody-based therapies for immune-mediated diseases. Its pipeline includes two programs that aim to address chronic inflammation and autoimmunity through novel biological targets.
Granite’s lead asset, GRT-001, is designed to selectively deplete pro-inflammatory monocytes, a subset of immune cells implicated in the pathogenesis of autoimmune disorders. Unlike broader immunosuppressive approaches, this therapy targets disease-driving cells while sparing tissue-resident macrophages that play a role in normal immune function. GRT-001 is currently in a phase 1a trial in healthy volunteers, with an expansion to patients with inflammatory bowel disease planned later this year.
The company’s second program, GRT-002, targets interleukin-3 (IL-3), a cytokine associated with type 2 inflammation and immune dysregulation. IL-3 has historically received limited attention as a therapeutic target, so it’s definitely worth keeping an eye on GRT-002. The candidate is currently in preclinical development, with first-in-human studies expected in 2026.
Simcha Therapeutics
- Headquarters: New Haven, Connecticut
- Founded: 2019
- Recent news: Initiated two additional clinical trials for ST-067
Simcha Therapeutics’ lead program centers on a modified form of IL-18, designed to overcome the limitations that have historically hindered IL-18’s therapeutic efficacy in oncology.
IL-18 is a pro-inflammatory cytokine that activates both innate and adaptive immune cells, including natural killer (NK) cells and T lymphocytes. However, its clinical application has been limited due to the presence of IL-18 binding protein (IL-18BP), a naturally-occurring inhibitor that prevents IL-18 from engaging its receptor and eliciting an immune response.
To address this challenge, Simcha is developing ST-067, a “decoy-resistant” variant of IL-18 that is impervious to IL-18BP. By evading this inhibitory mechanism, ST-067 is designed to maintain its immunostimulatory activity within the tumor microenvironment.
ST-067 is currently in a phase 1/2 clinical trial for patients with advanced solid tumors. In preclinical studies, ST-067 demonstrated robust anti-tumor activity, both alone and in combination with immune checkpoint inhibitors. These findings could mean ST-067 will be an option for patients with tumors that are refractory to existing immunotherapies.
The company has initiated two additional clinical studies to explore the use of its interleukin therapy ST-067 in hematological malignancies, including acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), and multiple myeloma.
Strand Therapeutics
- Headquarters: Boston, Massachusetts
- Founded: 2017
- Recent news: First patient dosed in a phase 1 trial for STX-001
Strand Therapeutics is developing programmable mRNA therapies aimed at treating cancer. The company leverages synthetic biology to engineer mRNA molecules that can be programmed to activate only within specific cellular environments, such as tumor microenvironments, thereby aiming to enhance therapeutic precision and minimize systemic side effects.
The core of Strand’s technology lies in the design of genetic circuits within mRNA constructs. These circuits are engineered to sense specific molecular signatures characteristic of tumor cells, such as unique microRNA profiles. Upon detecting these signatures, the company’s mRNA is programmed to express therapeutic proteins, like IL-12, directly within the tumor cells. If the mRNA enters non-target cells lacking these signatures, it is designed to self-destruct, thereby preventing unintended protein expression in healthy tissues.
Strand’s lead investigational therapy, STX-001, is a self-replicating mRNA construct encoding IL-12. Historically, systemic administration of IL-12 has been associated with significant toxicity. STX-001 aims to mitigate this issue by ensuring localized expression of IL-12 within tumors, enhancing anti-tumor immune responses while reducing systemic exposure.
In May 2024, Strand announced the dosing of the first patient in a phase 1 clinical trial evaluating STX-001, both as a monotherapy and in combination with pembrolizumab, in patients with treatment-refractory advanced solid tumors.
Tourmaline Bio
- Headquarters: New York, State of New York
- Founded: 2021
- Recent news: Launched two phase 2 trials in 2024 for its lead IL-6 candidate, TOUR006, targeting thyroid eye disease and cardiovascular inflammation
Tourmaline Bio is building its pipeline around IL-6, one of the most clinically validated but commercially crowded cytokine targets. What makes its approach stand out is TOUR006, a long-acting monoclonal antibody designed to block IL-6 with infrequent, low-volume subcutaneous dosing. The company believes this could set a new bar for convenience and long-term disease control.
Tourmaline is testing TOUR006 in two indications that reflect the molecule’s broad potential. The first, thyroid eye disease (TED), is an autoimmune condition where IL-6 is known to play a central role in inflammation and tissue remodeling. Results are expected in the second half of 2025.
The second trial, TRANQUILITY, is targeting cardiovascular risk, an area where IL-6 inhibition is gaining traction. Patients with elevated C-reactive protein, which is a biomarker for inflammation, and chronic kidney disease are being treated with TOUR006 to assess its ability to reduce systemic inflammation. Interim data from this study are expected in early 2025.
By focusing on precision dosing and underexplored indications, Tourmaline is positioning itself not just as another IL-6 player, but as one of the few pushing this class of drugs into new territory. It’s still early, but TOUR006’s potential to move beyond autoimmunity into cardiometabolic disease makes this company one to watch.
Werewolf Therapeutics
- Headquarters: Watertown, Massachusetts
- Founded: 2017
- Recent news: Initiated a phase 1b/2 trial for its IL-12 candidate WTX-330 and presented new data on IL-18 and IL-21 programs at AACR 2024.
Werewolf Therapeutics is a biotech company developing a new generation of interleukin therapies designed to act inside the tumor. Through its INDUKINE platform, the company engineers cytokine prodrugs that remain inactive in circulation and are activated specifically in the tumor microenvironment. This selective approach is intended to limit systemic toxicity while preserving the potent immune-stimulating effects of cytokines.
Its lead IL-12 candidate, WTX-330, entered a phase 1b/2 trial recently following preclinical studies that showed strong local immune activation and anti-tumor activity. Werewolf’s IL-2 candidate, WTX-124, is already in clinical testing and being evaluated both alone and in combination with pembrolizumab.
The company is also advancing IL-18 and IL-21 candidates in preclinical development. WTX-518, a modified IL-18 molecule designed to resist inhibition by IL-18 binding protein, has shown durable tumor regressions in animal models. WTX-712 delivers IL-21 selectively in tumors and aims to enhance CD8+ T cell function, particularly in cancers unresponsive to checkpoint inhibitors.
Xilio Therapeutics
- Headquarters: Waltham, Massachusetts
- Founded: 2016
- Recent news: In March 2024, Gilead Sciences signed an exclusive license agreement with Xilio for its tumor-targeted IL-12 program.
Xilio Therapeutics is one of several companies trying to give cytokine therapies a second life, but with a more sophisticated delivery system. The company is developing tumor-activated versions of powerful immune-stimulating agents like IL-12. Xilio’s pitch is simple: unlock IL-12’s power, but only inside the tumor.
Its lead candidate, XTX301, is built to do just that. IL-12 is fused to a masking domain that keeps it inactive as it travels through the bloodstream. Only when it reaches the tumor, where certain enzymes are present in higher concentrations, is the mask removed and the molecule switched on. The idea is to concentrate the immune-stimulating effects of IL-12 where they’re needed most, sparing healthy tissues from the inflammatory blowback that plagued earlier IL-12 therapies.
This tumor-activated logic is a hallmark of Xilio’s broader platform, which the company is applying to other cytokines and checkpoint inhibitors as well.
XTX301 is currently in phase 1 for patients with advanced solid tumors. The company reported initial results in late 2024: no dose-limiting toxicities, signs of immune activation in the tumor, and a pharmacokinetic profile that suggests the drug stays put where it’s injected. Earlier in 2024, Gilead jumped in, licensing the program with an eye toward future combinations with checkpoint inhibitors or other immunotherapies.
Making interleukin therapies safer and more precise
Interleukin-based therapies have long been recognized for their ability to modulate the immune system, but early attempts were often hampered by toxicity and a lack of precision. These challenges limited their clinical impact and slowed progress across multiple indications. Today, a new generation of biotech companies is addressing the shortcomings of interleukins.
This renewed momentum is mirrored in the market outlook. The global interleukin inhibitors market was valued at around $32.5 billion in 2024 and is projected to grow at a compound annual growth rate (CAGR) of 17.3% from 2025 to 2030. Interleukin-6 inhibitors alone account for a significant share of that growth, but that segment remains largely dominated by big pharma companies like Roche, J&J, and Novo Nordisk.
In contrast, the interleukin-focused companies featured in this list are pushing the boundaries of what’s next. Whether by localizing IL-12 expression to tumors, engineering IL-2 to avoid off-target toxicity, or developing entirely new uses for IL-18 and IL-3, they’re shaping a more precise, tolerable, and versatile generation of cytokine therapies.
Oncology R&D trends and breakthrough innovations
