If You Invested in Io Biotech, Inc. (IOBT)

IO Biotech, Inc. (Nasdaq: IOBT) is a clinical-stage biopharmaceutical company focused on developing novel, immune-modulatory, off-the-shelf therapeutic cancer vaccines. The company’s programs are based on its proprietary T-win® platform, which is described as a novel approach to cancer vaccines designed to activate T cells to target both tumor cells and the immune-suppressive cells in the tumor microenvironment.

According to company disclosures, IO Biotech is advancing its lead cancer vaccine candidate Cylembio® (IO102-IO103) through multiple clinical trials. Cylembio is an investigational, immune-modulatory, off-the-shelf therapeutic cancer vaccine candidate composed of imsapepimut and etimupepimut, adjuvanted. It is designed to kill both tumor cells and immune-suppressive cells in the tumor microenvironment by stimulating activation and expansion of T cells against indoleamine 2,3-dioxygenase 1 (IDO1)-positive and/or programmed death-ligand 1 (PD-L1)-positive cells.

Core scientific and clinical focus

The T-win platform underpins IO Biotech’s approach to cancer immunotherapy. Company materials state that the platform is based on activating T cells to target both tumor cells and key immune-suppressive cells in the tumor microenvironment. This dual targeting is intended to modulate tumor-induced immunosuppression while directly addressing cancer cells. IO Biotech describes its vaccines as immune-modulatory and off-the-shelf, meaning they are developed as standardized products rather than individualized therapies.

Cylembio is being evaluated in several clinical settings. IO Biotech reports that it is conducting a pivotal Phase 3 trial (IOB-013/KN-D18; NCT05155254) of Cylembio in combination with Merck’s anti-PD-1 therapy KEYTRUDA® (pembrolizumab) versus pembrolizumab alone in patients with previously untreated, unresectable or metastatic (advanced) melanoma. The primary endpoint of this trial is progression-free survival, with secondary endpoints including overall response rate, overall survival, durable objective response rate, complete response rate, duration of response, time to complete response, disease control rate, and safety and tolerability measures. IO Biotech has stated that topline results from this trial were reported in the third quarter of 2025.

In addition to the Phase 3 melanoma program, IO Biotech is sponsoring Phase 2 basket trials of Cylembio in combination with pembrolizumab. The IOB-022/KN-D38 (NCT05077709) trial is a non-comparative, open-label study in first-line metastatic non-small cell lung cancer (NSCLC) and recurrent/metastatic squamous cell carcinoma of the head and neck (SCCHN) at sites in the United States, Spain, and the United Kingdom. The IOB-032/PN-E40 (NCT05280314) trial is a multicenter Phase 2 basket study of Cylembio plus pembrolizumab as neo-adjuvant/adjuvant treatment of patients with solid tumors, including melanoma and SCCHN, at sites in Australia, the United States, France, Germany, Spain, and Denmark. Company updates indicate that enrollment in these company-sponsored Phase 2 trials has been completed.

Pipeline beyond the lead program

Beyond Cylembio, IO Biotech reports additional pipeline candidates derived from the T-win platform that are in preclinical development. These include IO112, which targets arginase 1 (Arg1), and IO170, which targets transforming growth factor (TGF)-β. Pre-clinical data presented by the company describe IO112 as a therapeutic cancer vaccine candidate where vaccination leads to expansion of Arg1-specific T cells that target and reprogram immune-suppressive myeloid cells, including tumor-associated macrophages, with associated tumor growth inhibition in preclinical models. For IO170, pre-clinical data presented by IO Biotech describe a TGF-β-directed immune-modulatory vaccine that activates TGF-β-specific T cells to target TGF-β-expressing cells, with reported tumor growth inhibition and reduction of lung metastasis in a cancer model.

These preclinical programs are presented by the company as extensions of the same T-win platform concept, directed against additional immune-suppressive pathways in the tumor microenvironment. IO Biotech has stated that it expects IO112 to be the next candidate to enter clinical development, subject to regulatory processes such as an Investigational New Drug application.

Regulatory and development context for Cylembio

IO Biotech has reported that results from the MM1636 Phase 1/2 trial of IO102-IO103 in metastatic melanoma, in combination with PD-1 blockade, supported a Breakthrough Therapy Designation by the U.S. Food and Drug Administration (FDA) for the treatment of unresectable/metastatic melanoma in combination with pembrolizumab. The company also notes that five-year follow-up data from this trial showed durable clinical activity and identified potential vaccine-specific immune biomarkers of long-term benefit, providing rationale for integrating immune-modulatory vaccination into immunotherapy regimens for melanoma.

For the pivotal Phase 3 IOB-013/KN-D18 trial in advanced melanoma, IO Biotech has disclosed that treatment with Cylembio plus pembrolizumab improved progression-free survival compared to pembrolizumab alone, but the trial narrowly missed the prespecified threshold for statistical significance on the primary endpoint. Following a pre-BLA meeting, the company reported that the FDA recommended it not submit a Biologics License Application based on the IOB-013 data set. IO Biotech has stated that it plans to continue dialogue with the FDA on the design of a potential new registrational study for Cylembio and to discuss the IOB-013 data with European regulators to determine a path to submission in the European Union.

Operations, collaborations, and geography

Company communications state that IO Biotech is headquartered in Copenhagen, Denmark and has U.S. headquarters in New York, New York. The company’s common stock, with a par value of $0.001 per share, is registered on The Nasdaq Stock Market LLC under the symbol IOBT, as reflected in its SEC filings.

IO Biotech sponsors its clinical trials and conducts them in collaboration with Merck, which is supplying pembrolizumab (KEYTRUDA) for the combination regimens. IO Biotech also states that it maintains global commercial rights to Cylembio. Clinical trial sites for the company’s programs are described across multiple regions, including the United States, Europe, Australia, Turkey, Israel, South Africa, and other countries specified in trial descriptions, reflecting a multi-national clinical development footprint.

Corporate and financial disclosures

As a publicly traded company, IO Biotech files periodic and current reports with the U.S. Securities and Exchange Commission (SEC). Recent Form 8-K filings include disclosures on financial results for quarterly periods, updates on clinical and regulatory milestones, unregistered sales of equity securities related to a term loan facility with the European Investment Bank, and corporate matters such as restructuring plans and changes in executive roles. For example, the company has reported a restructuring and workforce reduction plan intended to conserve capital while focusing on advancing development of Cylembio, and it has disclosed term loan tranches and associated warrant issuances.

These filings also confirm that IO Biotech’s common stock continues to trade on Nasdaq under the ticker IOBT, and they provide details on the company’s cash position, operating expenses, and other financial metrics as of the reported periods. Investors and analysts often review these documents to understand the company’s capital resources, operating runway, and commitments related to clinical and regulatory activities.

Sector and industry classification

Based on the provided classification, IO Biotech operates within the Pharmaceutical Preparation Manufacturing industry in the broader Manufacturing sector. Within this context, the company positions itself as a clinical-stage biopharmaceutical developer of immune-modulatory therapeutic cancer vaccines rather than a manufacturer of approved commercial pharmaceutical products. Its activities, as described in company and regulatory documents, are centered on research, development, and clinical testing of investigational therapies derived from its T-win platform.

FAQs about IO Biotech (IOBT)

• What does IO Biotech do?
  IO Biotech is a clinical-stage biopharmaceutical company developing novel, immune-modulatory, off-the-shelf therapeutic cancer vaccines. Its programs are based on the T-win® platform, which is designed to activate T cells to target both tumor cells and immune-suppressive cells in the tumor microenvironment.
• What is Cylembio® (IO102-IO103)?
  Cylembio is IO Biotech’s lead investigational cancer vaccine candidate, composed of imsapepimut and etimupepimut, adjuvanted. It is designed to stimulate T cells against IDO1-positive and/or PD-L1-positive cells to kill both tumor cells and immune-suppressive cells in the tumor microenvironment. Cylembio is being evaluated in a pivotal Phase 3 trial in advanced melanoma and in multiple Phase 2 basket trials in solid tumors, all in combination with pembrolizumab.
• What is the T-win® platform?
  The T-win platform is described by IO Biotech as a novel approach to cancer vaccines that activates T cells to target both tumor cells and immune-suppressive cells in the tumor microenvironment. Several of the company’s therapeutic vaccine candidates, including Cylembio, IO112, and IO170, are derived from this platform.
• Which cancers is IO Biotech targeting in its clinical trials?
  According to company announcements, IO Biotech is studying Cylembio in advanced melanoma in a Phase 3 trial and in Phase 2 basket trials that include metastatic non-small cell lung cancer (NSCLC) and squamous cell carcinoma of the head and neck (SCCHN). Additional trials evaluate Cylembio as neo-adjuvant/adjuvant treatment of patients with solid tumors, including melanoma and SCCHN.
• What is known about the Phase 3 trial of Cylembio in melanoma?
  The IOB-013/KN-D18 Phase 3 trial evaluates Cylembio plus pembrolizumab versus pembrolizumab alone in previously untreated, unresectable or metastatic melanoma. IO Biotech has reported that the combination improved progression-free survival compared to pembrolizumab alone, but the primary endpoint narrowly missed the prespecified threshold for statistical significance. The company has also reported detailed progression-free survival data and subgroup analyses in public communications and presentations.
• Has Cylembio received any regulatory designations?
  IO Biotech has stated that results from the MM1636 Phase 1/2 trial of IO102-IO103 in metastatic melanoma, in combination with PD-1 blockade, supported a Breakthrough Therapy Designation by the U.S. FDA for the treatment of unresectable/metastatic melanoma in combination with pembrolizumab.
• What is the status of IO Biotech’s regulatory interactions for Cylembio?
  Following the Phase 3 IOB-013 trial, IO Biotech reported that the FDA recommended the company not submit a Biologics License Application based on the current data. The company has indicated that it plans to continue discussions with the FDA regarding a potential new registrational study and to engage with European regulators about a possible path to approval in the EU.
• What other vaccine candidates is IO Biotech developing?
  In addition to Cylembio, IO Biotech has reported preclinical programs IO112, targeting arginase 1, and IO170, targeting transforming growth factor (TGF)-β. Pre-clinical data presented by the company describe anti-tumor activity and modulation of the tumor microenvironment for these candidates in cancer models.
• Where is IO Biotech headquartered?
  Company descriptions state that IO Biotech is headquartered in Copenhagen, Denmark and has U.S. headquarters in New York, New York.
• On which exchange does IO Biotech trade and what is its ticker?
  According to recent SEC filings, IO Biotech’s common stock is listed on The Nasdaq Stock Market LLC under the trading symbol IOBT.